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  21 <title>Chapter 6. BIND 9 Configuration Reference</title>
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  31 <tr><th colspan="3" align="center">Chapter 6. <acronym class="acronym">BIND</acronym> 9 Configuration Reference</th></tr>
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  42 <div class="chapter" lang="en">
  43 <div class="titlepage"><div><div><h2 class="title">
  44 <a name="Bv9ARM.ch06"></a>Chapter 6. <acronym class="acronym">BIND</acronym> 9 Configuration Reference</h2></div></div></div>
  45 <div class="toc">
  46 <p><b>Table of Contents</b></p>
  47 <dl>
  48 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#configuration_file_elements">Configuration File Elements</a></span></dt>
  49 <dd><dl>
  50 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#address_match_lists">Address Match Lists</a></span></dt>
  51 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2573342">Comment Syntax</a></span></dt>
  52 </dl></dd>
  53 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#Configuration_File_Grammar">Configuration File Grammar</a></span></dt>
  54 <dd><dl>
  55 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2573996"><span><strong class="command">acl</strong></span> Statement Grammar</a></span></dt>
  56 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#acl"><span><strong class="command">acl</strong></span> Statement Definition and
  57           Usage</a></span></dt>
  58 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574186"><span><strong class="command">controls</strong></span> Statement Grammar</a></span></dt>
  59 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage"><span><strong class="command">controls</strong></span> Statement Definition and
  60           Usage</a></span></dt>
  61 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574614"><span><strong class="command">include</strong></span> Statement Grammar</a></span></dt>
  62 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574631"><span><strong class="command">include</strong></span> Statement Definition and
  63           Usage</a></span></dt>
  64 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574654"><span><strong class="command">key</strong></span> Statement Grammar</a></span></dt>
  65 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574678"><span><strong class="command">key</strong></span> Statement Definition and Usage</a></span></dt>
  66 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574769"><span><strong class="command">logging</strong></span> Statement Grammar</a></span></dt>
  67 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574963"><span><strong class="command">logging</strong></span> Statement Definition and
  68           Usage</a></span></dt>
  69 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577060"><span><strong class="command">lwres</strong></span> Statement Grammar</a></span></dt>
  70 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577133"><span><strong class="command">lwres</strong></span> Statement Definition and Usage</a></span></dt>
  71 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577197"><span><strong class="command">masters</strong></span> Statement Grammar</a></span></dt>
  72 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577241"><span><strong class="command">masters</strong></span> Statement Definition and
  73           Usage</a></span></dt>
  74 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577256"><span><strong class="command">options</strong></span> Statement Grammar</a></span></dt>
  75 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#options"><span><strong class="command">options</strong></span> Statement Definition and
  76           Usage</a></span></dt>
  77 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#server_statement_grammar"><span><strong class="command">server</strong></span> Statement Grammar</a></span></dt>
  78 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#server_statement_definition_and_usage"><span><strong class="command">server</strong></span> Statement Definition and
  79             Usage</a></span></dt>
  80 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#statschannels"><span><strong class="command">statistics-channels</strong></span> Statement Grammar</a></span></dt>
  81 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2589011"><span><strong class="command">statistics-channels</strong></span> Statement Definition and
  82             Usage</a></span></dt>
  83 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#trusted-keys"><span><strong class="command">trusted-keys</strong></span> Statement Grammar</a></span></dt>
  84 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2589219"><span><strong class="command">trusted-keys</strong></span> Statement Definition
  85             and Usage</a></span></dt>
  86 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2589266"><span><strong class="command">managed-keys</strong></span> Statement Grammar</a></span></dt>
  87 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#managed-keys"><span><strong class="command">managed-keys</strong></span> Statement Definition
  88             and Usage</a></span></dt>
  89 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#view_statement_grammar"><span><strong class="command">view</strong></span> Statement Grammar</a></span></dt>
  90 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2589844"><span><strong class="command">view</strong></span> Statement Definition and Usage</a></span></dt>
  91 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#zone_statement_grammar"><span><strong class="command">zone</strong></span>
  92             Statement Grammar</a></span></dt>
  93 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2591339"><span><strong class="command">zone</strong></span> Statement Definition and Usage</a></span></dt>
  94 </dl></dd>
  95 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#id2594764">Zone File</a></span></dt>
  96 <dd><dl>
  97 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#types_of_resource_records_and_when_to_use_them">Types of Resource Records and When to Use Them</a></span></dt>
  98 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2596926">Discussion of MX Records</a></span></dt>
  99 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#Setting_TTLs">Setting TTLs</a></span></dt>
 100 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2597542">Inverse Mapping in IPv4</a></span></dt>
 101 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2597669">Other Zone File Directives</a></span></dt>
 102 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2597942"><acronym class="acronym">BIND</acronym> Master File Extension: the  <span><strong class="command">$GENERATE</strong></span> Directive</a></span></dt>
 103 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#zonefile_format">Additional File Formats</a></span></dt>
 104 </dl></dd>
 105 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#statistics">BIND9 Statistics</a></span></dt>
 106 <dd><dl><dt><span class="sect2"><a href="Bv9ARM.ch06.html#statistics_counters">Statistics Counters</a></span></dt></dl></dd>
 107 </dl>
 108 </div>
 109 <p>
 110       <acronym class="acronym">BIND</acronym> 9 configuration is broadly similar
 111       to <acronym class="acronym">BIND</acronym> 8; however, there are a few new
 112       areas
 113       of configuration, such as views. <acronym class="acronym">BIND</acronym>
 114       8 configuration files should work with few alterations in <acronym class="acronym">BIND</acronym>
 115       9, although more complex configurations should be reviewed to check
 116       if they can be more efficiently implemented using the new features
 117       found in <acronym class="acronym">BIND</acronym> 9.
 118     </p>
 119 <p>
 120       <acronym class="acronym">BIND</acronym> 4 configuration files can be
 121       converted to the new format
 122       using the shell script
 123       <code class="filename">contrib/named-bootconf/named-bootconf.sh</code>.
 124     </p>
 125 <div class="sect1" lang="en">
 126 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
 127 <a name="configuration_file_elements"></a>Configuration File Elements</h2></div></div></div>
 128 <p>
 129         Following is a list of elements used throughout the <acronym class="acronym">BIND</acronym> configuration
 130         file documentation:
 131       </p>
 132 <div class="informaltable"><table border="1">
 133 <colgroup>
 134 <col>
 135 <col>
 136 </colgroup>
 137 <tbody>
 138 <tr>
 139 <td>
 140                 <p>
 141                   <code class="varname">acl_name</code>
 142                 </p>
 143               </td>
 144 <td>
 145                 <p>
 146                   The name of an <code class="varname">address_match_list</code> as
 147                   defined by the <span><strong class="command">acl</strong></span> statement.
 148                 </p>
 149               </td>
 150 </tr>
 151 <tr>
 152 <td>
 153                 <p>
 154                   <code class="varname">address_match_list</code>
 155                 </p>
 156               </td>
 157 <td>
 158                 <p>
 159                   A list of one or more
 160                   <code class="varname">ip_addr</code>,
 161                   <code class="varname">ip_prefix</code>, <code class="varname">key_id</code>,
 162                   or <code class="varname">acl_name</code> elements, see
 163                   <a href="Bv9ARM.ch06.html#address_match_lists" title="Address Match Lists">the section called &#8220;Address Match Lists&#8221;</a>.
 164                 </p>
 165               </td>
 166 </tr>
 167 <tr>
 168 <td>
 169                 <p>
 170                   <code class="varname">masters_list</code>
 171                 </p>
 172               </td>
 173 <td>
 174                 <p>
 175                   A named list of one or more <code class="varname">ip_addr</code>
 176                   with optional <code class="varname">key_id</code> and/or
 177                   <code class="varname">ip_port</code>.
 178                   A <code class="varname">masters_list</code> may include other
 179                   <code class="varname">masters_lists</code>.
 180                 </p>
 181               </td>
 182 </tr>
 183 <tr>
 184 <td>
 185                 <p>
 186                   <code class="varname">domain_name</code>
 187                 </p>
 188               </td>
 189 <td>
 190                 <p>
 191                   A quoted string which will be used as
 192                   a DNS name, for example "<code class="literal">my.test.domain</code>".
 193                 </p>
 194               </td>
 195 </tr>
 196 <tr>
 197 <td>
 198                 <p>
 199                   <code class="varname">namelist</code>
 200                 </p>
 201               </td>
 202 <td>
 203                 <p>
 204                   A list of one or more <code class="varname">domain_name</code>
 205                   elements.
 206                 </p>
 207               </td>
 208 </tr>
 209 <tr>
 210 <td>
 211                 <p>
 212                   <code class="varname">dotted_decimal</code>
 213                 </p>
 214               </td>
 215 <td>
 216                 <p>
 217                   One to four integers valued 0 through
 218                   255 separated by dots (`.'), such as <span><strong class="command">123</strong></span>,
 219                   <span><strong class="command">45.67</strong></span> or <span><strong class="command">89.123.45.67</strong></span>.
 220                 </p>
 221               </td>
 222 </tr>
 223 <tr>
 224 <td>
 225                 <p>
 226                   <code class="varname">ip4_addr</code>
 227                 </p>
 228               </td>
 229 <td>
 230                 <p>
 231                   An IPv4 address with exactly four elements
 232                   in <code class="varname">dotted_decimal</code> notation.
 233                 </p>
 234               </td>
 235 </tr>
 236 <tr>
 237 <td>
 238                 <p>
 239                   <code class="varname">ip6_addr</code>
 240                 </p>
 241               </td>
 242 <td>
 243                 <p>
 244                   An IPv6 address, such as <span><strong class="command">2001:db8::1234</strong></span>.
 245                   IPv6 scoped addresses that have ambiguity on their
 246                   scope zones must be disambiguated by an appropriate
 247                   zone ID with the percent character (`%') as
 248                   delimiter.  It is strongly recommended to use
 249                   string zone names rather than numeric identifiers,
 250                   in order to be robust against system configuration
 251                   changes.  However, since there is no standard
 252                   mapping for such names and identifier values,
 253                   currently only interface names as link identifiers
 254                   are supported, assuming one-to-one mapping between
 255                   interfaces and links.  For example, a link-local
 256                   address <span><strong class="command">fe80::1</strong></span> on the link
 257                   attached to the interface <span><strong class="command">ne0</strong></span>
 258                   can be specified as <span><strong class="command">fe80::1%ne0</strong></span>.
 259                   Note that on most systems link-local addresses
 260                   always have the ambiguity, and need to be
 261                   disambiguated.
 262                 </p>
 263               </td>
 264 </tr>
 265 <tr>
 266 <td>
 267                 <p>
 268                   <code class="varname">ip_addr</code>
 269                 </p>
 270               </td>
 271 <td>
 272                 <p>
 273                   An <code class="varname">ip4_addr</code> or <code class="varname">ip6_addr</code>.
 274                 </p>
 275               </td>
 276 </tr>
 277 <tr>
 278 <td>
 279                 <p>
 280                   <code class="varname">ip_port</code>
 281                 </p>
 282               </td>
 283 <td>
 284                 <p>
 285                   An IP port <code class="varname">number</code>.
 286                   The <code class="varname">number</code> is limited to 0
 287                   through 65535, with values
 288                   below 1024 typically restricted to use by processes running
 289                   as root.
 290                   In some cases, an asterisk (`*') character can be used as a
 291                   placeholder to
 292                   select a random high-numbered port.
 293                 </p>
 294               </td>
 295 </tr>
 296 <tr>
 297 <td>
 298                 <p>
 299                   <code class="varname">ip_prefix</code>
 300                 </p>
 301               </td>
 302 <td>
 303                 <p>
 304                   An IP network specified as an <code class="varname">ip_addr</code>,
 305                   followed by a slash (`/') and then the number of bits in the
 306                   netmask.
 307                   Trailing zeros in a <code class="varname">ip_addr</code>
 308                   may omitted.
 309                   For example, <span><strong class="command">127/8</strong></span> is the
 310                   network <span><strong class="command">127.0.0.0</strong></span> with
 311                   netmask <span><strong class="command">255.0.0.0</strong></span> and <span><strong class="command">1.2.3.0/28</strong></span> is
 312                   network <span><strong class="command">1.2.3.0</strong></span> with netmask <span><strong class="command">255.255.255.240</strong></span>.
 313                 </p>
 314                 <p>
 315                   When specifying a prefix involving a IPv6 scoped address
 316                   the scope may be omitted.  In that case the prefix will
 317                   match packets from any scope.
 318                 </p>
 319               </td>
 320 </tr>
 321 <tr>
 322 <td>
 323                 <p>
 324                   <code class="varname">key_id</code>
 325                 </p>
 326               </td>
 327 <td>
 328                 <p>
 329                   A <code class="varname">domain_name</code> representing
 330                   the name of a shared key, to be used for transaction
 331                   security.
 332                 </p>
 333               </td>
 334 </tr>
 335 <tr>
 336 <td>
 337                 <p>
 338                   <code class="varname">key_list</code>
 339                 </p>
 340               </td>
 341 <td>
 342                 <p>
 343                   A list of one or more
 344                   <code class="varname">key_id</code>s,
 345                   separated by semicolons and ending with a semicolon.
 346                 </p>
 347               </td>
 348 </tr>
 349 <tr>
 350 <td>
 351                 <p>
 352                   <code class="varname">number</code>
 353                 </p>
 354               </td>
 355 <td>
 356                 <p>
 357                   A non-negative 32-bit integer
 358                   (i.e., a number between 0 and 4294967295, inclusive).
 359                   Its acceptable value might further
 360                   be limited by the context in which it is used.
 361                 </p>
 362               </td>
 363 </tr>
 364 <tr>
 365 <td>
 366                 <p>
 367                   <code class="varname">path_name</code>
 368                 </p>
 369               </td>
 370 <td>
 371                 <p>
 372                   A quoted string which will be used as
 373                   a pathname, such as <code class="filename">zones/master/my.test.domain</code>.
 374                 </p>
 375               </td>
 376 </tr>
 377 <tr>
 378 <td>
 379                 <p>
 380                   <code class="varname">port_list</code>
 381                 </p>
 382               </td>
 383 <td>
 384                 <p>
 385                   A list of an <code class="varname">ip_port</code> or a port
 386                   range.
 387                   A port range is specified in the form of
 388                   <strong class="userinput"><code>range</code></strong> followed by
 389                   two <code class="varname">ip_port</code>s,
 390                   <code class="varname">port_low</code> and
 391                   <code class="varname">port_high</code>, which represents
 392                   port numbers from <code class="varname">port_low</code> through
 393                   <code class="varname">port_high</code>, inclusive.
 394                   <code class="varname">port_low</code> must not be larger than
 395                   <code class="varname">port_high</code>.
 396                   For example,
 397                   <strong class="userinput"><code>range 1024 65535</code></strong> represents
 398                   ports from 1024 through 65535.
 399                   In either case an asterisk (`*') character is not
 400                   allowed as a valid <code class="varname">ip_port</code>.
 401                 </p>
 402               </td>
 403 </tr>
 404 <tr>
 405 <td>
 406                 <p>
 407                   <code class="varname">size_spec</code>
 408                 </p>
 409               </td>
 410 <td>
 411                 <p>
 412                   A 64-bit unsigned integer, or the keywords
 413                   <strong class="userinput"><code>unlimited</code></strong> or
 414                   <strong class="userinput"><code>default</code></strong>.
 415                 </p>
 416                 <p>
 417                   Integers may take values
 418                   0 &lt;= value &lt;= 18446744073709551615, though
 419                   certain parameters may use a more limited range
 420                   within these extremes.  In most cases, setting a
 421                   value to 0 does not literally mean zero; it means
 422                   "undefined" or "as big as psosible", depending on
 423                   the context. See the expalantions of particular
 424                   parameters that use <code class="varname">size_spec</code>
 425                   for details on how they interpret its use.
 426                 </p>
 427                 <p>
 428                   Numeric values can optionally be followed by a
 429                   scaling factor:
 430                   <strong class="userinput"><code>K</code></strong> or <strong class="userinput"><code>k</code></strong>
 431                   for kilobytes,
 432                   <strong class="userinput"><code>M</code></strong> or <strong class="userinput"><code>m</code></strong>
 433                   for megabytes, and
 434                   <strong class="userinput"><code>G</code></strong> or <strong class="userinput"><code>g</code></strong>
 435                   for gigabytes, which scale by 1024, 1024*1024, and
 436                   1024*1024*1024 respectively.
 437                 </p>
 438                 <p>
 439                   <code class="varname">unlimited</code> generally means
 440                   "as big as possible", though in certain contexts,
 441                   (including <code class="option">max-cache-size</code>), it may
 442                   mean the largest possible 32-bit unsigned integer
 443                   (0xffffffff); this distinction can be important when
 444                   dealing with larger quantities.
 445                   <code class="varname">unlimited</code> is usually the best way
 446                   to safely set a very large number.
 447                 </p>
 448                 <p>
 449                   <code class="varname">default</code>
 450                   uses the limit that was in force when the server was started.
 451                 </p>
 452               </td>
 453 </tr>
 454 <tr>
 455 <td>
 456                 <p>
 457                   <code class="varname">yes_or_no</code>
 458                 </p>
 459               </td>
 460 <td>
 461                 <p>
 462                   Either <strong class="userinput"><code>yes</code></strong> or <strong class="userinput"><code>no</code></strong>.
 463                   The words <strong class="userinput"><code>true</code></strong> and <strong class="userinput"><code>false</code></strong> are
 464                   also accepted, as are the numbers <strong class="userinput"><code>1</code></strong>
 465                   and <strong class="userinput"><code>0</code></strong>.
 466                 </p>
 467               </td>
 468 </tr>
 469 <tr>
 470 <td>
 471                 <p>
 472                   <code class="varname">dialup_option</code>
 473                 </p>
 474               </td>
 475 <td>
 476                 <p>
 477                   One of <strong class="userinput"><code>yes</code></strong>,
 478                   <strong class="userinput"><code>no</code></strong>, <strong class="userinput"><code>notify</code></strong>,
 479                   <strong class="userinput"><code>notify-passive</code></strong>, <strong class="userinput"><code>refresh</code></strong> or
 480                   <strong class="userinput"><code>passive</code></strong>.
 481                   When used in a zone, <strong class="userinput"><code>notify-passive</code></strong>,
 482                   <strong class="userinput"><code>refresh</code></strong>, and <strong class="userinput"><code>passive</code></strong>
 483                   are restricted to slave and stub zones.
 484                 </p>
 485               </td>
 486 </tr>
 487 </tbody>
 488 </table></div>
 489 <div class="sect2" lang="en">
 490 <div class="titlepage"><div><div><h3 class="title">
 491 <a name="address_match_lists"></a>Address Match Lists</h3></div></div></div>
 492 <div class="sect3" lang="en">
 493 <div class="titlepage"><div><div><h4 class="title">
 494 <a name="id2573109"></a>Syntax</h4></div></div></div>
 495 <pre class="programlisting"><code class="varname">address_match_list</code> = address_match_list_element ;
 496   [<span class="optional"> address_match_list_element; ... </span>]
 497 <code class="varname">address_match_list_element</code> = [<span class="optional"> ! </span>] (ip_address [<span class="optional">/length</span>] |
 498    key key_id | acl_name | { address_match_list } )
 499 </pre>
 500 </div>
 501 <div class="sect3" lang="en">
 502 <div class="titlepage"><div><div><h4 class="title">
 503 <a name="id2573137"></a>Definition and Usage</h4></div></div></div>
 504 <p>
 505             Address match lists are primarily used to determine access
 506             control for various server operations. They are also used in
 507             the <span><strong class="command">listen-on</strong></span> and <span><strong class="command">sortlist</strong></span>
 508             statements. The elements which constitute an address match
 509             list can be any of the following:
 510           </p>
 511 <div class="itemizedlist"><ul type="disc">
 512 <li>an IP address (IPv4 or IPv6)</li>
 513 <li>an IP prefix (in `/' notation)</li>
 514 <li>
 515                 a key ID, as defined by the <span><strong class="command">key</strong></span>
 516                 statement
 517               </li>
 518 <li>the name of an address match list defined with
 519                 the <span><strong class="command">acl</strong></span> statement
 520               </li>
 521 <li>a nested address match list enclosed in braces</li>
 522 </ul></div>
 523 <p>
 524             Elements can be negated with a leading exclamation mark (`!'),
 525             and the match list names "any", "none", "localhost", and
 526             "localnets" are predefined. More information on those names
 527             can be found in the description of the acl statement.
 528           </p>
 529 <p>
 530             The addition of the key clause made the name of this syntactic
 531             element something of a misnomer, since security keys can be used
 532             to validate access without regard to a host or network address.
 533             Nonetheless, the term "address match list" is still used
 534             throughout the documentation.
 535           </p>
 536 <p>
 537             When a given IP address or prefix is compared to an address
 538             match list, the comparison takes place in approximately O(1)
 539             time.  However, key comparisons require that the list of keys
 540             be traversed until a matching key is found, and therefore may
 541             be somewhat slower.
 542           </p>
 543 <p>
 544             The interpretation of a match depends on whether the list is being
 545             used for access control, defining <span><strong class="command">listen-on</strong></span> ports, or in a
 546             <span><strong class="command">sortlist</strong></span>, and whether the element was negated.
 547           </p>
 548 <p>
 549             When used as an access control list, a non-negated match
 550             allows access and a negated match denies access. If
 551             there is no match, access is denied. The clauses
 552             <span><strong class="command">allow-notify</strong></span>,
 553             <span><strong class="command">allow-recursion</strong></span>,
 554             <span><strong class="command">allow-recursion-on</strong></span>,
 555             <span><strong class="command">allow-query</strong></span>,
 556             <span><strong class="command">allow-query-on</strong></span>,
 557             <span><strong class="command">allow-query-cache</strong></span>,
 558             <span><strong class="command">allow-query-cache-on</strong></span>,
 559             <span><strong class="command">allow-transfer</strong></span>,
 560             <span><strong class="command">allow-update</strong></span>,
 561             <span><strong class="command">allow-update-forwarding</strong></span>, and
 562             <span><strong class="command">blackhole</strong></span> all use address match
 563             lists.  Similarly, the <span><strong class="command">listen-on</strong></span> option will cause the
 564             server to refuse queries on any of the machine's
 565             addresses which do not match the list.
 566           </p>
 567 <p>
 568             Order of insertion is significant.  If more than one element
 569             in an ACL is found to match a given IP address or prefix,
 570             preference will be given to the one that came
 571             <span class="emphasis"><em>first</em></span> in the ACL definition.
 572             Because of this first-match behavior, an element that
 573             defines a subset of another element in the list should
 574             come before the broader element, regardless of whether
 575             either is negated. For example, in
 576             <span><strong class="command">1.2.3/24; ! 1.2.3.13;</strong></span>
 577             the 1.2.3.13 element is completely useless because the
 578             algorithm will match any lookup for 1.2.3.13 to the 1.2.3/24
 579             element.  Using <span><strong class="command">! 1.2.3.13; 1.2.3/24</strong></span> fixes
 580             that problem by having 1.2.3.13 blocked by the negation, but
 581             all other 1.2.3.* hosts fall through.
 582           </p>
 583 </div>
 584 </div>
 585 <div class="sect2" lang="en">
 586 <div class="titlepage"><div><div><h3 class="title">
 587 <a name="id2573342"></a>Comment Syntax</h3></div></div></div>
 588 <p>
 589           The <acronym class="acronym">BIND</acronym> 9 comment syntax allows for
 590           comments to appear
 591           anywhere that whitespace may appear in a <acronym class="acronym">BIND</acronym> configuration
 592           file. To appeal to programmers of all kinds, they can be written
 593           in the C, C++, or shell/perl style.
 594         </p>
 595 <div class="sect3" lang="en">
 596 <div class="titlepage"><div><div><h4 class="title">
 597 <a name="id2573357"></a>Syntax</h4></div></div></div>
 598 <p>
 599             </p>
 600 <pre class="programlisting">/* This is a <acronym class="acronym">BIND</acronym> comment as in C */</pre>
 601 <p>
 602             </p>
 603 <pre class="programlisting">// This is a <acronym class="acronym">BIND</acronym> comment as in C++</pre>
 604 <p>
 605             </p>
 606 <pre class="programlisting"># This is a <acronym class="acronym">BIND</acronym> comment as in common UNIX shells
 607 # and perl</pre>
 608 <p>
 609           </p>
 610 </div>
 611 <div class="sect3" lang="en">
 612 <div class="titlepage"><div><div><h4 class="title">
 613 <a name="id2573387"></a>Definition and Usage</h4></div></div></div>
 614 <p>
 615             Comments may appear anywhere that whitespace may appear in
 616             a <acronym class="acronym">BIND</acronym> configuration file.
 617           </p>
 618 <p>
 619             C-style comments start with the two characters /* (slash,
 620             star) and end with */ (star, slash). Because they are completely
 621             delimited with these characters, they can be used to comment only
 622             a portion of a line or to span multiple lines.
 623           </p>
 624 <p>
 625             C-style comments cannot be nested. For example, the following
 626             is not valid because the entire comment ends with the first */:
 627           </p>
 628 <p>
 629
 630 </p>
 631 <pre class="programlisting">/* This is the start of a comment.
 632    This is still part of the comment.
 633 /* This is an incorrect attempt at nesting a comment. */
 634    This is no longer in any comment. */
 635 </pre>
 636 <p>
 637
 638           </p>
 639 <p>
 640             C++-style comments start with the two characters // (slash,
 641             slash) and continue to the end of the physical line. They cannot
 642             be continued across multiple physical lines; to have one logical
 643             comment span multiple lines, each line must use the // pair.
 644             For example:
 645           </p>
 646 <p>
 647
 648 </p>
 649 <pre class="programlisting">// This is the start of a comment.  The next line
 650 // is a new comment, even though it is logically
 651 // part of the previous comment.
 652 </pre>
 653 <p>
 654
 655           </p>
 656 <p>
 657             Shell-style (or perl-style, if you prefer) comments start
 658             with the character <code class="literal">#</code> (number sign)
 659             and continue to the end of the
 660             physical line, as in C++ comments.
 661             For example:
 662           </p>
 663 <p>
 664
 665 </p>
 666 <pre class="programlisting"># This is the start of a comment.  The next line
 667 # is a new comment, even though it is logically
 668 # part of the previous comment.
 669 </pre>
 670 <p>
 671
 672           </p>
 673 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
 674 <h3 class="title">Warning</h3>
 675 <p>
 676               You cannot use the semicolon (`;') character
 677               to start a comment such as you would in a zone file. The
 678               semicolon indicates the end of a configuration
 679               statement.
 680             </p>
 681 </div>
 682 </div>
 683 </div>
 684 </div>
 685 <div class="sect1" lang="en">
 686 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
 687 <a name="Configuration_File_Grammar"></a>Configuration File Grammar</h2></div></div></div>
 688 <p>
 689         A <acronym class="acronym">BIND</acronym> 9 configuration consists of
 690         statements and comments.
 691         Statements end with a semicolon. Statements and comments are the
 692         only elements that can appear without enclosing braces. Many
 693         statements contain a block of sub-statements, which are also
 694         terminated with a semicolon.
 695       </p>
 696 <p>
 697         The following statements are supported:
 698       </p>
 699 <div class="informaltable"><table border="1">
 700 <colgroup>
 701 <col>
 702 <col>
 703 </colgroup>
 704 <tbody>
 705 <tr>
 706 <td>
 707                 <p><span><strong class="command">acl</strong></span></p>
 708               </td>
 709 <td>
 710                 <p>
 711                   defines a named IP address
 712                   matching list, for access control and other uses.
 713                 </p>
 714               </td>
 715 </tr>
 716 <tr>
 717 <td>
 718                 <p><span><strong class="command">controls</strong></span></p>
 719               </td>
 720 <td>
 721                 <p>
 722                   declares control channels to be used
 723                   by the <span><strong class="command">rndc</strong></span> utility.
 724                 </p>
 725               </td>
 726 </tr>
 727 <tr>
 728 <td>
 729                 <p><span><strong class="command">include</strong></span></p>
 730               </td>
 731 <td>
 732                 <p>
 733                   includes a file.
 734                 </p>
 735               </td>
 736 </tr>
 737 <tr>
 738 <td>
 739                 <p><span><strong class="command">key</strong></span></p>
 740               </td>
 741 <td>
 742                 <p>
 743                   specifies key information for use in
 744                   authentication and authorization using TSIG.
 745                 </p>
 746               </td>
 747 </tr>
 748 <tr>
 749 <td>
 750                 <p><span><strong class="command">logging</strong></span></p>
 751               </td>
 752 <td>
 753                 <p>
 754                   specifies what the server logs, and where
 755                   the log messages are sent.
 756                 </p>
 757               </td>
 758 </tr>
 759 <tr>
 760 <td>
 761                 <p><span><strong class="command">lwres</strong></span></p>
 762               </td>
 763 <td>
 764                 <p>
 765                   configures <span><strong class="command">named</strong></span> to
 766                   also act as a light-weight resolver daemon (<span><strong class="command">lwresd</strong></span>).
 767                 </p>
 768               </td>
 769 </tr>
 770 <tr>
 771 <td>
 772                 <p><span><strong class="command">masters</strong></span></p>
 773               </td>
 774 <td>
 775                 <p>
 776                   defines a named masters list for
 777                   inclusion in stub and slave zone masters clauses.
 778                 </p>
 779               </td>
 780 </tr>
 781 <tr>
 782 <td>
 783                 <p><span><strong class="command">options</strong></span></p>
 784               </td>
 785 <td>
 786                 <p>
 787                   controls global server configuration
 788                   options and sets defaults for other statements.
 789                 </p>
 790               </td>
 791 </tr>
 792 <tr>
 793 <td>
 794                 <p><span><strong class="command">server</strong></span></p>
 795               </td>
 796 <td>
 797                 <p>
 798                   sets certain configuration options on
 799                   a per-server basis.
 800                 </p>
 801               </td>
 802 </tr>
 803 <tr>
 804 <td>
 805                 <p><span><strong class="command">statistics-channels</strong></span></p>
 806               </td>
 807 <td>
 808                 <p>
 809                   declares communication channels to get access to
 810                   <span><strong class="command">named</strong></span> statistics.
 811                 </p>
 812               </td>
 813 </tr>
 814 <tr>
 815 <td>
 816                 <p><span><strong class="command">trusted-keys</strong></span></p>
 817               </td>
 818 <td>
 819                 <p>
 820                   defines trusted DNSSEC keys.
 821                 </p>
 822               </td>
 823 </tr>
 824 <tr>
 825 <td>
 826                 <p><span><strong class="command">managed-keys</strong></span></p>
 827               </td>
 828 <td>
 829                 <p>
 830                   lists DNSSEC keys to be kept up to date
 831                   using RFC 5011 trust anchor maintenance.
 832                 </p>
 833               </td>
 834 </tr>
 835 <tr>
 836 <td>
 837                 <p><span><strong class="command">view</strong></span></p>
 838               </td>
 839 <td>
 840                 <p>
 841                   defines a view.
 842                 </p>
 843               </td>
 844 </tr>
 845 <tr>
 846 <td>
 847                 <p><span><strong class="command">zone</strong></span></p>
 848               </td>
 849 <td>
 850                 <p>
 851                   defines a zone.
 852                 </p>
 853               </td>
 854 </tr>
 855 </tbody>
 856 </table></div>
 857 <p>
 858         The <span><strong class="command">logging</strong></span> and
 859         <span><strong class="command">options</strong></span> statements may only occur once
 860         per
 861         configuration.
 862       </p>
 863 <div class="sect2" lang="en">
 864 <div class="titlepage"><div><div><h3 class="title">
 865 <a name="id2573996"></a><span><strong class="command">acl</strong></span> Statement Grammar</h3></div></div></div>
 866 <pre class="programlisting"><span><strong class="command">acl</strong></span> acl-name {
 867     address_match_list
 868 };
 869 </pre>
 870 </div>
 871 <div class="sect2" lang="en">
 872 <div class="titlepage"><div><div><h3 class="title">
 873 <a name="acl"></a><span><strong class="command">acl</strong></span> Statement Definition and
 874           Usage</h3></div></div></div>
 875 <p>
 876           The <span><strong class="command">acl</strong></span> statement assigns a symbolic
 877           name to an address match list. It gets its name from a primary
 878           use of address match lists: Access Control Lists (ACLs).
 879         </p>
 880 <p>
 881           Note that an address match list's name must be defined
 882           with <span><strong class="command">acl</strong></span> before it can be used
 883           elsewhere; no forward references are allowed.
 884         </p>
 885 <p>
 886           The following ACLs are built-in:
 887         </p>
 888 <div class="informaltable"><table border="1">
 889 <colgroup>
 890 <col>
 891 <col>
 892 </colgroup>
 893 <tbody>
 894 <tr>
 895 <td>
 896                   <p><span><strong class="command">any</strong></span></p>
 897                 </td>
 898 <td>
 899                   <p>
 900                     Matches all hosts.
 901                   </p>
 902                 </td>
 903 </tr>
 904 <tr>
 905 <td>
 906                   <p><span><strong class="command">none</strong></span></p>
 907                 </td>
 908 <td>
 909                   <p>
 910                     Matches no hosts.
 911                   </p>
 912                 </td>
 913 </tr>
 914 <tr>
 915 <td>
 916                   <p><span><strong class="command">localhost</strong></span></p>
 917                 </td>
 918 <td>
 919                   <p>
 920                     Matches the IPv4 and IPv6 addresses of all network
 921                     interfaces on the system.
 922                   </p>
 923                 </td>
 924 </tr>
 925 <tr>
 926 <td>
 927                   <p><span><strong class="command">localnets</strong></span></p>
 928                 </td>
 929 <td>
 930                   <p>
 931                     Matches any host on an IPv4 or IPv6 network
 932                     for which the system has an interface.
 933                     Some systems do not provide a way to determine the prefix
 934                     lengths of
 935                     local IPv6 addresses.
 936                     In such a case, <span><strong class="command">localnets</strong></span>
 937                     only matches the local
 938                     IPv6 addresses, just like <span><strong class="command">localhost</strong></span>.
 939                   </p>
 940                 </td>
 941 </tr>
 942 </tbody>
 943 </table></div>
 944 </div>
 945 <div class="sect2" lang="en">
 946 <div class="titlepage"><div><div><h3 class="title">
 947 <a name="id2574186"></a><span><strong class="command">controls</strong></span> Statement Grammar</h3></div></div></div>
 948 <pre class="programlisting"><span><strong class="command">controls</strong></span> {
 949    [ inet ( ip_addr | * ) [ port ip_port ]
 950                 allow { <em class="replaceable"><code> address_match_list </code></em> }
 951                 keys { <em class="replaceable"><code>key_list</code></em> }; ]
 952    [ inet ...; ]
 953    [ unix <em class="replaceable"><code>path</code></em> perm <em class="replaceable"><code>number</code></em> owner <em class="replaceable"><code>number</code></em> group <em class="replaceable"><code>number</code></em>
 954      keys { <em class="replaceable"><code>key_list</code></em> }; ]
 955    [ unix ...; ]
 956 };
 957 </pre>
 958 </div>
 959 <div class="sect2" lang="en">
 960 <div class="titlepage"><div><div><h3 class="title">
 961 <a name="controls_statement_definition_and_usage"></a><span><strong class="command">controls</strong></span> Statement Definition and
 962           Usage</h3></div></div></div>
 963 <p>
 964           The <span><strong class="command">controls</strong></span> statement declares control
 965           channels to be used by system administrators to control the
 966           operation of the name server. These control channels are
 967           used by the <span><strong class="command">rndc</strong></span> utility to send
 968           commands to and retrieve non-DNS results from a name server.
 969         </p>
 970 <p>
 971           An <span><strong class="command">inet</strong></span> control channel is a TCP socket
 972           listening at the specified <span><strong class="command">ip_port</strong></span> on the
 973           specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6
 974           address.  An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is
 975           interpreted as the IPv4 wildcard address; connections will be
 976           accepted on any of the system's IPv4 addresses.
 977           To listen on the IPv6 wildcard address,
 978           use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>.
 979           If you will only use <span><strong class="command">rndc</strong></span> on the local host,
 980           using the loopback address (<code class="literal">127.0.0.1</code>
 981           or <code class="literal">::1</code>) is recommended for maximum security.
 982         </p>
 983 <p>
 984           If no port is specified, port 953 is used. The asterisk
 985           "<code class="literal">*</code>" cannot be used for <span><strong class="command">ip_port</strong></span>.
 986         </p>
 987 <p>
 988           The ability to issue commands over the control channel is
 989           restricted by the <span><strong class="command">allow</strong></span> and
 990           <span><strong class="command">keys</strong></span> clauses.
 991           Connections to the control channel are permitted based on the
 992           <span><strong class="command">address_match_list</strong></span>.  This is for simple
 993           IP address based filtering only; any <span><strong class="command">key_id</strong></span>
 994           elements of the <span><strong class="command">address_match_list</strong></span>
 995           are ignored.
 996         </p>
 997 <p>
 998           A <span><strong class="command">unix</strong></span> control channel is a UNIX domain
 999           socket listening at the specified path in the file system.
1000           Access to the socket is specified by the <span><strong class="command">perm</strong></span>,
1001           <span><strong class="command">owner</strong></span> and <span><strong class="command">group</strong></span> clauses.
1002           Note on some platforms (SunOS and Solaris) the permissions
1003           (<span><strong class="command">perm</strong></span>) are applied to the parent directory
1004           as the permissions on the socket itself are ignored.
1005         </p>
1006 <p>
1007           The primary authorization mechanism of the command
1008           channel is the <span><strong class="command">key_list</strong></span>, which
1009           contains a list of <span><strong class="command">key_id</strong></span>s.
1010           Each <span><strong class="command">key_id</strong></span> in the <span><strong class="command">key_list</strong></span>
1011           is authorized to execute commands over the control channel.
1012           See <a href="Bv9ARM.ch03.html#rndc">Remote Name Daemon Control application</a> in <a href="Bv9ARM.ch03.html#admin_tools" title="Administrative Tools">the section called &#8220;Administrative Tools&#8221;</a>)
1013           for information about configuring keys in <span><strong class="command">rndc</strong></span>.
1014         </p>
1015 <p>
1016           If no <span><strong class="command">controls</strong></span> statement is present,
1017           <span><strong class="command">named</strong></span> will set up a default
1018           control channel listening on the loopback address 127.0.0.1
1019           and its IPv6 counterpart ::1.
1020           In this case, and also when the <span><strong class="command">controls</strong></span> statement
1021           is present but does not have a <span><strong class="command">keys</strong></span> clause,
1022           <span><strong class="command">named</strong></span> will attempt to load the command channel key
1023           from the file <code class="filename">rndc.key</code> in
1024           <code class="filename">/etc</code> (or whatever <code class="varname">sysconfdir</code>
1025           was specified as when <acronym class="acronym">BIND</acronym> was built).
1026           To create a <code class="filename">rndc.key</code> file, run
1027           <strong class="userinput"><code>rndc-confgen -a</code></strong>.
1028         </p>
1029 <p>
1030           The <code class="filename">rndc.key</code> feature was created to
1031           ease the transition of systems from <acronym class="acronym">BIND</acronym> 8,
1032           which did not have digital signatures on its command channel
1033           messages and thus did not have a <span><strong class="command">keys</strong></span> clause.
1034
1035           It makes it possible to use an existing <acronym class="acronym">BIND</acronym> 8
1036           configuration file in <acronym class="acronym">BIND</acronym> 9 unchanged,
1037           and still have <span><strong class="command">rndc</strong></span> work the same way
1038           <span><strong class="command">ndc</strong></span> worked in BIND 8, simply by executing the
1039           command <strong class="userinput"><code>rndc-confgen -a</code></strong> after BIND 9 is
1040           installed.
1041         </p>
1042 <p>
1043           Since the <code class="filename">rndc.key</code> feature
1044           is only intended to allow the backward-compatible usage of
1045           <acronym class="acronym">BIND</acronym> 8 configuration files, this
1046           feature does not
1047           have a high degree of configurability.  You cannot easily change
1048           the key name or the size of the secret, so you should make a
1049           <code class="filename">rndc.conf</code> with your own key if you
1050           wish to change
1051           those things.  The <code class="filename">rndc.key</code> file
1052           also has its
1053           permissions set such that only the owner of the file (the user that
1054           <span><strong class="command">named</strong></span> is running as) can access it.
1055           If you
1056           desire greater flexibility in allowing other users to access
1057           <span><strong class="command">rndc</strong></span> commands, then you need to create
1058           a
1059           <code class="filename">rndc.conf</code> file and make it group
1060           readable by a group
1061           that contains the users who should have access.
1062         </p>
1063 <p>
1064           To disable the command channel, use an empty
1065           <span><strong class="command">controls</strong></span> statement:
1066           <span><strong class="command">controls { };</strong></span>.
1067         </p>
1068 </div>
1069 <div class="sect2" lang="en">
1070 <div class="titlepage"><div><div><h3 class="title">
1071 <a name="id2574614"></a><span><strong class="command">include</strong></span> Statement Grammar</h3></div></div></div>
1072 <pre class="programlisting"><span><strong class="command">include</strong></span> <em class="replaceable"><code>filename</code></em>;</pre>
1073 </div>
1074 <div class="sect2" lang="en">
1075 <div class="titlepage"><div><div><h3 class="title">
1076 <a name="id2574631"></a><span><strong class="command">include</strong></span> Statement Definition and
1077           Usage</h3></div></div></div>
1078 <p>
1079           The <span><strong class="command">include</strong></span> statement inserts the
1080           specified file at the point where the <span><strong class="command">include</strong></span>
1081           statement is encountered. The <span><strong class="command">include</strong></span>
1082                 statement facilitates the administration of configuration
1083           files
1084           by permitting the reading or writing of some things but not
1085           others. For example, the statement could include private keys
1086           that are readable only by the name server.
1087         </p>
1088 </div>
1089 <div class="sect2" lang="en">
1090 <div class="titlepage"><div><div><h3 class="title">
1091 <a name="id2574654"></a><span><strong class="command">key</strong></span> Statement Grammar</h3></div></div></div>
1092 <pre class="programlisting"><span><strong class="command">key</strong></span> <em class="replaceable"><code>key_id</code></em> {
1093     algorithm <em class="replaceable"><code>string</code></em>;
1094     secret <em class="replaceable"><code>string</code></em>;
1095 };
1096 </pre>
1097 </div>
1098 <div class="sect2" lang="en">
1099 <div class="titlepage"><div><div><h3 class="title">
1100 <a name="id2574678"></a><span><strong class="command">key</strong></span> Statement Definition and Usage</h3></div></div></div>
1101 <p>
1102           The <span><strong class="command">key</strong></span> statement defines a shared
1103           secret key for use with TSIG (see <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called &#8220;TSIG&#8221;</a>)
1104           or the command channel
1105           (see <a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and
1106           Usage">the section called &#8220;<span><strong class="command">controls</strong></span> Statement Definition and
1107           Usage&#8221;</a>).
1108         </p>
1109 <p>
1110           The <span><strong class="command">key</strong></span> statement can occur at the
1111           top level
1112           of the configuration file or inside a <span><strong class="command">view</strong></span>
1113           statement.  Keys defined in top-level <span><strong class="command">key</strong></span>
1114           statements can be used in all views.  Keys intended for use in
1115           a <span><strong class="command">controls</strong></span> statement
1116           (see <a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and
1117           Usage">the section called &#8220;<span><strong class="command">controls</strong></span> Statement Definition and
1118           Usage&#8221;</a>)
1119           must be defined at the top level.
1120         </p>
1121 <p>
1122           The <em class="replaceable"><code>key_id</code></em>, also known as the
1123           key name, is a domain name uniquely identifying the key. It can
1124           be used in a <span><strong class="command">server</strong></span>
1125           statement to cause requests sent to that
1126           server to be signed with this key, or in address match lists to
1127           verify that incoming requests have been signed with a key
1128           matching this name, algorithm, and secret.
1129         </p>
1130 <p>
1131           The <em class="replaceable"><code>algorithm_id</code></em> is a string
1132           that specifies a security/authentication algorithm.  Named
1133           supports <code class="literal">hmac-md5</code>,
1134           <code class="literal">hmac-sha1</code>, <code class="literal">hmac-sha224</code>,
1135           <code class="literal">hmac-sha256</code>, <code class="literal">hmac-sha384</code>
1136           and <code class="literal">hmac-sha512</code> TSIG authentication.
1137           Truncated hashes are supported by appending the minimum
1138           number of required bits preceded by a dash, e.g.
1139           <code class="literal">hmac-sha1-80</code>.  The
1140           <em class="replaceable"><code>secret_string</code></em> is the secret
1141           to be used by the algorithm, and is treated as a base-64
1142           encoded string.
1143         </p>
1144 </div>
1145 <div class="sect2" lang="en">
1146 <div class="titlepage"><div><div><h3 class="title">
1147 <a name="id2574769"></a><span><strong class="command">logging</strong></span> Statement Grammar</h3></div></div></div>
1148 <pre class="programlisting"><span><strong class="command">logging</strong></span> {
1149    [ <span><strong class="command">channel</strong></span> <em class="replaceable"><code>channel_name</code></em> {
1150      ( <span><strong class="command">file</strong></span> <em class="replaceable"><code>path_name</code></em>
1151          [ <span><strong class="command">versions</strong></span> ( <em class="replaceable"><code>number</code></em> | <span><strong class="command">unlimited</strong></span> ) ]
1152          [ <span><strong class="command">size</strong></span> <em class="replaceable"><code>size_spec</code></em> ]
1153        | <span><strong class="command">syslog</strong></span> <em class="replaceable"><code>syslog_facility</code></em>
1154        | <span><strong class="command">stderr</strong></span>
1155        | <span><strong class="command">null</strong></span> );
1156      [ <span><strong class="command">severity</strong></span> (<code class="option">critical</code> | <code class="option">error</code> | <code class="option">warning</code> | <code class="option">notice</code> |
1157                  <code class="option">info</code> | <code class="option">debug</code> [ <em class="replaceable"><code>level</code></em> ] | <code class="option">dynamic</code> ); ]
1158      [ <span><strong class="command">print-category</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ]
1159      [ <span><strong class="command">print-severity</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ]
1160      [ <span><strong class="command">print-time</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ]
1161    }; ]
1162    [ <span><strong class="command">category</strong></span> <em class="replaceable"><code>category_name</code></em> {
1163      <em class="replaceable"><code>channel_name</code></em> ; [ <em class="replaceable"><code>channel_name</code></em> ; ... ]
1164    }; ]
1165    ...
1166 };
1167 </pre>
1168 </div>
1169 <div class="sect2" lang="en">
1170 <div class="titlepage"><div><div><h3 class="title">
1171 <a name="id2574963"></a><span><strong class="command">logging</strong></span> Statement Definition and
1172           Usage</h3></div></div></div>
1173 <p>
1174           The <span><strong class="command">logging</strong></span> statement configures a
1175           wide
1176           variety of logging options for the name server. Its <span><strong class="command">channel</strong></span> phrase
1177           associates output methods, format options and severity levels with
1178           a name that can then be used with the <span><strong class="command">category</strong></span> phrase
1179           to select how various classes of messages are logged.
1180         </p>
1181 <p>
1182           Only one <span><strong class="command">logging</strong></span> statement is used to
1183           define
1184           as many channels and categories as are wanted. If there is no <span><strong class="command">logging</strong></span> statement,
1185           the logging configuration will be:
1186         </p>
1187 <pre class="programlisting">logging {
1188      category default { default_syslog; default_debug; };
1189      category unmatched { null; };
1190 };
1191 </pre>
1192 <p>
1193           In <acronym class="acronym">BIND</acronym> 9, the logging configuration
1194           is only established when
1195           the entire configuration file has been parsed.  In <acronym class="acronym">BIND</acronym> 8, it was
1196           established as soon as the <span><strong class="command">logging</strong></span>
1197           statement
1198           was parsed. When the server is starting up, all logging messages
1199           regarding syntax errors in the configuration file go to the default
1200           channels, or to standard error if the "<code class="option">-g</code>" option
1201           was specified.
1202         </p>
1203 <div class="sect3" lang="en">
1204 <div class="titlepage"><div><div><h4 class="title">
1205 <a name="id2575015"></a>The <span><strong class="command">channel</strong></span> Phrase</h4></div></div></div>
1206 <p>
1207             All log output goes to one or more <span class="emphasis"><em>channels</em></span>;
1208             you can make as many of them as you want.
1209           </p>
1210 <p>
1211             Every channel definition must include a destination clause that
1212             says whether messages selected for the channel go to a file, to a
1213             particular syslog facility, to the standard error stream, or are
1214             discarded. It can optionally also limit the message severity level
1215             that will be accepted by the channel (the default is
1216             <span><strong class="command">info</strong></span>), and whether to include a
1217             <span><strong class="command">named</strong></span>-generated time stamp, the
1218             category name
1219             and/or severity level (the default is not to include any).
1220           </p>
1221 <p>
1222             The <span><strong class="command">null</strong></span> destination clause
1223             causes all messages sent to the channel to be discarded;
1224             in that case, other options for the channel are meaningless.
1225           </p>
1226 <p>
1227             The <span><strong class="command">file</strong></span> destination clause directs
1228             the channel
1229             to a disk file.  It can include limitations
1230             both on how large the file is allowed to become, and how many
1231             versions
1232             of the file will be saved each time the file is opened.
1233           </p>
1234 <p>
1235             If you use the <span><strong class="command">versions</strong></span> log file
1236             option, then
1237             <span><strong class="command">named</strong></span> will retain that many backup
1238             versions of the file by
1239             renaming them when opening.  For example, if you choose to keep
1240             three old versions
1241             of the file <code class="filename">lamers.log</code>, then just
1242             before it is opened
1243             <code class="filename">lamers.log.1</code> is renamed to
1244             <code class="filename">lamers.log.2</code>, <code class="filename">lamers.log.0</code> is renamed
1245             to <code class="filename">lamers.log.1</code>, and <code class="filename">lamers.log</code> is
1246             renamed to <code class="filename">lamers.log.0</code>.
1247             You can say <span><strong class="command">versions unlimited</strong></span> to
1248             not limit
1249             the number of versions.
1250             If a <span><strong class="command">size</strong></span> option is associated with
1251             the log file,
1252             then renaming is only done when the file being opened exceeds the
1253             indicated size.  No backup versions are kept by default; any
1254             existing
1255             log file is simply appended.
1256           </p>
1257 <p>
1258             The <span><strong class="command">size</strong></span> option for files is used
1259             to limit log
1260             growth. If the file ever exceeds the size, then <span><strong class="command">named</strong></span> will
1261             stop writing to the file unless it has a <span><strong class="command">versions</strong></span> option
1262             associated with it.  If backup versions are kept, the files are
1263             rolled as
1264             described above and a new one begun.  If there is no
1265             <span><strong class="command">versions</strong></span> option, no more data will
1266             be written to the log
1267             until some out-of-band mechanism removes or truncates the log to
1268             less than the
1269             maximum size.  The default behavior is not to limit the size of
1270             the
1271             file.
1272           </p>
1273 <p>
1274             Example usage of the <span><strong class="command">size</strong></span> and
1275             <span><strong class="command">versions</strong></span> options:
1276           </p>
1277 <pre class="programlisting">channel an_example_channel {
1278     file "example.log" versions 3 size 20m;
1279     print-time yes;
1280     print-category yes;
1281 };
1282 </pre>
1283 <p>
1284             The <span><strong class="command">syslog</strong></span> destination clause
1285             directs the
1286             channel to the system log.  Its argument is a
1287             syslog facility as described in the <span><strong class="command">syslog</strong></span> man
1288             page. Known facilities are <span><strong class="command">kern</strong></span>, <span><strong class="command">user</strong></span>,
1289             <span><strong class="command">mail</strong></span>, <span><strong class="command">daemon</strong></span>, <span><strong class="command">auth</strong></span>,
1290             <span><strong class="command">syslog</strong></span>, <span><strong class="command">lpr</strong></span>, <span><strong class="command">news</strong></span>,
1291             <span><strong class="command">uucp</strong></span>, <span><strong class="command">cron</strong></span>, <span><strong class="command">authpriv</strong></span>,
1292             <span><strong class="command">ftp</strong></span>, <span><strong class="command">local0</strong></span>, <span><strong class="command">local1</strong></span>,
1293             <span><strong class="command">local2</strong></span>, <span><strong class="command">local3</strong></span>, <span><strong class="command">local4</strong></span>,
1294             <span><strong class="command">local5</strong></span>, <span><strong class="command">local6</strong></span> and
1295             <span><strong class="command">local7</strong></span>, however not all facilities
1296             are supported on
1297             all operating systems.
1298             How <span><strong class="command">syslog</strong></span> will handle messages
1299             sent to
1300             this facility is described in the <span><strong class="command">syslog.conf</strong></span> man
1301             page. If you have a system which uses a very old version of <span><strong class="command">syslog</strong></span> that
1302             only uses two arguments to the <span><strong class="command">openlog()</strong></span> function,
1303             then this clause is silently ignored.
1304           </p>
1305 <p>
1306             On Windows machines syslog messages are directed to the EventViewer.
1307           </p>
1308 <p>
1309             The <span><strong class="command">severity</strong></span> clause works like <span><strong class="command">syslog</strong></span>'s
1310             "priorities", except that they can also be used if you are writing
1311             straight to a file rather than using <span><strong class="command">syslog</strong></span>.
1312             Messages which are not at least of the severity level given will
1313             not be selected for the channel; messages of higher severity
1314             levels
1315             will be accepted.
1316           </p>
1317 <p>
1318             If you are using <span><strong class="command">syslog</strong></span>, then the <span><strong class="command">syslog.conf</strong></span> priorities
1319             will also determine what eventually passes through. For example,
1320             defining a channel facility and severity as <span><strong class="command">daemon</strong></span> and <span><strong class="command">debug</strong></span> but
1321             only logging <span><strong class="command">daemon.warning</strong></span> via <span><strong class="command">syslog.conf</strong></span> will
1322             cause messages of severity <span><strong class="command">info</strong></span> and
1323             <span><strong class="command">notice</strong></span> to
1324             be dropped. If the situation were reversed, with <span><strong class="command">named</strong></span> writing
1325             messages of only <span><strong class="command">warning</strong></span> or higher,
1326             then <span><strong class="command">syslogd</strong></span> would
1327             print all messages it received from the channel.
1328           </p>
1329 <p>
1330             The <span><strong class="command">stderr</strong></span> destination clause
1331             directs the
1332             channel to the server's standard error stream.  This is intended
1333             for
1334             use when the server is running as a foreground process, for
1335             example
1336             when debugging a configuration.
1337           </p>
1338 <p>
1339             The server can supply extensive debugging information when
1340             it is in debugging mode. If the server's global debug level is
1341             greater
1342             than zero, then debugging mode will be active. The global debug
1343             level is set either by starting the <span><strong class="command">named</strong></span> server
1344             with the <code class="option">-d</code> flag followed by a positive integer,
1345             or by running <span><strong class="command">rndc trace</strong></span>.
1346             The global debug level
1347             can be set to zero, and debugging mode turned off, by running <span><strong class="command">rndc
1348 notrace</strong></span>. All debugging messages in the server have a debug
1349             level, and higher debug levels give more detailed output. Channels
1350             that specify a specific debug severity, for example:
1351           </p>
1352 <pre class="programlisting">channel specific_debug_level {
1353     file "foo";
1354     severity debug 3;
1355 };
1356 </pre>
1357 <p>
1358             will get debugging output of level 3 or less any time the
1359             server is in debugging mode, regardless of the global debugging
1360             level. Channels with <span><strong class="command">dynamic</strong></span>
1361             severity use the
1362             server's global debug level to determine what messages to print.
1363           </p>
1364 <p>
1365             If <span><strong class="command">print-time</strong></span> has been turned on,
1366             then
1367             the date and time will be logged. <span><strong class="command">print-time</strong></span> may
1368             be specified for a <span><strong class="command">syslog</strong></span> channel,
1369             but is usually
1370             pointless since <span><strong class="command">syslog</strong></span> also logs
1371             the date and
1372             time. If <span><strong class="command">print-category</strong></span> is
1373             requested, then the
1374             category of the message will be logged as well. Finally, if <span><strong class="command">print-severity</strong></span> is
1375             on, then the severity level of the message will be logged. The <span><strong class="command">print-</strong></span> options may
1376             be used in any combination, and will always be printed in the
1377             following
1378             order: time, category, severity. Here is an example where all
1379             three <span><strong class="command">print-</strong></span> options
1380             are on:
1381           </p>
1382 <p>
1383             <code class="computeroutput">28-Feb-2000 15:05:32.863 general: notice: running</code>
1384           </p>
1385 <p>
1386             There are four predefined channels that are used for
1387             <span><strong class="command">named</strong></span>'s default logging as follows.
1388             How they are
1389             used is described in <a href="Bv9ARM.ch06.html#the_category_phrase" title="The category Phrase">the section called &#8220;The <span><strong class="command">category</strong></span> Phrase&#8221;</a>.
1390           </p>
1391 <pre class="programlisting">channel default_syslog {
1392     // send to syslog's daemon facility
1393     syslog daemon;
1394     // only send priority info and higher
1395     severity info;
1396
1397 channel default_debug {
1398     // write to named.run in the working directory
1399     // Note: stderr is used instead of "named.run" if
1400     // the server is started with the '-f' option.
1401     file "named.run";
1402     // log at the server's current debug level
1403     severity dynamic;
1404 };
1405
1406 channel default_stderr {
1407     // writes to stderr
1408     stderr;
1409     // only send priority info and higher
1410     severity info;
1411 };
1412
1413 channel null {
1414    // toss anything sent to this channel
1415    null;
1416 };
1417 </pre>
1418 <p>
1419             The <span><strong class="command">default_debug</strong></span> channel has the
1420             special
1421             property that it only produces output when the server's debug
1422             level is
1423             nonzero.  It normally writes to a file called <code class="filename">named.run</code>
1424             in the server's working directory.
1425           </p>
1426 <p>
1427             For security reasons, when the "<code class="option">-u</code>"
1428             command line option is used, the <code class="filename">named.run</code> file
1429             is created only after <span><strong class="command">named</strong></span> has
1430             changed to the
1431             new UID, and any debug output generated while <span><strong class="command">named</strong></span> is
1432             starting up and still running as root is discarded.  If you need
1433             to capture this output, you must run the server with the "<code class="option">-g</code>"
1434             option and redirect standard error to a file.
1435           </p>
1436 <p>
1437             Once a channel is defined, it cannot be redefined. Thus you
1438             cannot alter the built-in channels directly, but you can modify
1439             the default logging by pointing categories at channels you have
1440             defined.
1441           </p>
1442 </div>
1443 <div class="sect3" lang="en">
1444 <div class="titlepage"><div><div><h4 class="title">
1445 <a name="the_category_phrase"></a>The <span><strong class="command">category</strong></span> Phrase</h4></div></div></div>
1446 <p>
1447             There are many categories, so you can send the logs you want
1448             to see wherever you want, without seeing logs you don't want. If
1449             you don't specify a list of channels for a category, then log
1450             messages
1451             in that category will be sent to the <span><strong class="command">default</strong></span> category
1452             instead. If you don't specify a default category, the following
1453             "default default" is used:
1454           </p>
1455 <pre class="programlisting">category default { default_syslog; default_debug; };
1456 </pre>
1457 <p>
1458             As an example, let's say you want to log security events to
1459             a file, but you also want keep the default logging behavior. You'd
1460             specify the following:
1461           </p>
1462 <pre class="programlisting">channel my_security_channel {
1463     file "my_security_file";
1464     severity info;
1465 };
1466 category security {
1467     my_security_channel;
1468     default_syslog;
1469     default_debug;
1470 };</pre>
1471 <p>
1472             To discard all messages in a category, specify the <span><strong class="command">null</strong></span> channel:
1473           </p>
1474 <pre class="programlisting">category xfer-out { null; };
1475 category notify { null; };
1476 </pre>
1477 <p>
1478             Following are the available categories and brief descriptions
1479             of the types of log information they contain. More
1480             categories may be added in future <acronym class="acronym">BIND</acronym> releases.
1481           </p>
1482 <div class="informaltable"><table border="1">
1483 <colgroup>
1484 <col>
1485 <col>
1486 </colgroup>
1487 <tbody>
1488 <tr>
1489 <td>
1490                     <p><span><strong class="command">default</strong></span></p>
1491                   </td>
1492 <td>
1493                     <p>
1494                       The default category defines the logging
1495                       options for those categories where no specific
1496                       configuration has been
1497                       defined.
1498                     </p>
1499                   </td>
1500 </tr>
1501 <tr>
1502 <td>
1503                     <p><span><strong class="command">general</strong></span></p>
1504                   </td>
1505 <td>
1506                     <p>
1507                       The catch-all. Many things still aren't
1508                       classified into categories, and they all end up here.
1509                     </p>
1510                   </td>
1511 </tr>
1512 <tr>
1513 <td>
1514                     <p><span><strong class="command">database</strong></span></p>
1515                   </td>
1516 <td>
1517                     <p>
1518                       Messages relating to the databases used
1519                       internally by the name server to store zone and cache
1520                       data.
1521                     </p>
1522                   </td>
1523 </tr>
1524 <tr>
1525 <td>
1526                     <p><span><strong class="command">security</strong></span></p>
1527                   </td>
1528 <td>
1529                     <p>
1530                       Approval and denial of requests.
1531                     </p>
1532                   </td>
1533 </tr>
1534 <tr>
1535 <td>
1536                     <p><span><strong class="command">config</strong></span></p>
1537                   </td>
1538 <td>
1539                     <p>
1540                       Configuration file parsing and processing.
1541                     </p>
1542                   </td>
1543 </tr>
1544 <tr>
1545 <td>
1546                     <p><span><strong class="command">resolver</strong></span></p>
1547                   </td>
1548 <td>
1549                     <p>
1550                       DNS resolution, such as the recursive
1551                       lookups performed on behalf of clients by a caching name
1552                       server.
1553                     </p>
1554                   </td>
1555 </tr>
1556 <tr>
1557 <td>
1558                     <p><span><strong class="command">xfer-in</strong></span></p>
1559                   </td>
1560 <td>
1561                     <p>
1562                       Zone transfers the server is receiving.
1563                     </p>
1564                   </td>
1565 </tr>
1566 <tr>
1567 <td>
1568                     <p><span><strong class="command">xfer-out</strong></span></p>
1569                   </td>
1570 <td>
1571                     <p>
1572                       Zone transfers the server is sending.
1573                     </p>
1574                   </td>
1575 </tr>
1576 <tr>
1577 <td>
1578                     <p><span><strong class="command">notify</strong></span></p>
1579                   </td>
1580 <td>
1581                     <p>
1582                       The NOTIFY protocol.
1583                     </p>
1584                   </td>
1585 </tr>
1586 <tr>
1587 <td>
1588                     <p><span><strong class="command">client</strong></span></p>
1589                   </td>
1590 <td>
1591                     <p>
1592                       Processing of client requests.
1593                     </p>
1594                   </td>
1595 </tr>
1596 <tr>
1597 <td>
1598                     <p><span><strong class="command">unmatched</strong></span></p>
1599                   </td>
1600 <td>
1601                     <p>
1602                       Messages that <span><strong class="command">named</strong></span> was unable to determine the
1603                       class of or for which there was no matching <span><strong class="command">view</strong></span>.
1604                       A one line summary is also logged to the <span><strong class="command">client</strong></span> category.
1605                       This category is best sent to a file or stderr, by
1606                       default it is sent to
1607                       the <span><strong class="command">null</strong></span> channel.
1608                     </p>
1609                   </td>
1610 </tr>
1611 <tr>
1612 <td>
1613                     <p><span><strong class="command">network</strong></span></p>
1614                   </td>
1615 <td>
1616                     <p>
1617                       Network operations.
1618                     </p>
1619                   </td>
1620 </tr>
1621 <tr>
1622 <td>
1623                     <p><span><strong class="command">update</strong></span></p>
1624                   </td>
1625 <td>
1626                     <p>
1627                       Dynamic updates.
1628                     </p>
1629                   </td>
1630 </tr>
1631 <tr>
1632 <td>
1633                     <p><span><strong class="command">update-security</strong></span></p>
1634                   </td>
1635 <td>
1636                     <p>
1637                       Approval and denial of update requests.
1638                     </p>
1639                   </td>
1640 </tr>
1641 <tr>
1642 <td>
1643                     <p><span><strong class="command">queries</strong></span></p>
1644                   </td>
1645 <td>
1646                     <p>
1647                       Specify where queries should be logged to.
1648                     </p>
1649                     <p>
1650                       At startup, specifying the category <span><strong class="command">queries</strong></span> will also
1651                       enable query logging unless <span><strong class="command">querylog</strong></span> option has been
1652                       specified.
1653                     </p>
1654
1655                     <p>
1656                       The query log entry reports the client's IP
1657                       address and port number, and the query name,
1658                       class and type.  Next it reports whether the
1659                       Recursion Desired flag was set (+ if set, -
1660                       if not set), if the query was signed (S),
1661                       EDNS was in use (E), if TCP was used (T), if
1662                       DO (DNSSEC Ok) was set (D), or if CD (Checking
1663                       Disabled) was set (C).  After this the
1664                       destination address the query was sent to is
1665                       reported.
1666                     </p>
1667
1668                     <p>
1669                       <code class="computeroutput">client 127.0.0.1#62536: query: www.example.com IN AAAA +SE</code>
1670                     </p>
1671                     <p>
1672                       <code class="computeroutput">client ::1#62537: query: www.example.net IN AAAA -SE</code>
1673                     </p>
1674                   </td>
1675 </tr>
1676 <tr>
1677 <td>
1678                     <p><span><strong class="command">query-errors</strong></span></p>
1679                   </td>
1680 <td>
1681                     <p>
1682                       Information about queries that resulted in some
1683                       failure.
1684                     </p>
1685                   </td>
1686 </tr>
1687 <tr>
1688 <td>
1689                     <p><span><strong class="command">dispatch</strong></span></p>
1690                   </td>
1691 <td>
1692                     <p>
1693                       Dispatching of incoming packets to the
1694                       server modules where they are to be processed.
1695                     </p>
1696                   </td>
1697 </tr>
1698 <tr>
1699 <td>
1700                     <p><span><strong class="command">dnssec</strong></span></p>
1701                   </td>
1702 <td>
1703                     <p>
1704                       DNSSEC and TSIG protocol processing.
1705                     </p>
1706                   </td>
1707 </tr>
1708 <tr>
1709 <td>
1710                     <p><span><strong class="command">lame-servers</strong></span></p>
1711                   </td>
1712 <td>
1713                     <p>
1714                       Lame servers.  These are misconfigurations
1715                       in remote servers, discovered by BIND 9 when trying to
1716                       query those servers during resolution.
1717                     </p>
1718                   </td>
1719 </tr>
1720 <tr>
1721 <td>
1722                     <p><span><strong class="command">delegation-only</strong></span></p>
1723                   </td>
1724 <td>
1725                     <p>
1726                       Delegation only.  Logs queries that have been
1727                       forced to NXDOMAIN as the result of a
1728                       delegation-only zone or a
1729                       <span><strong class="command">delegation-only</strong></span> in a hint
1730                       or stub zone declaration.
1731                     </p>
1732                   </td>
1733 </tr>
1734 <tr>
1735 <td>
1736                     <p><span><strong class="command">edns-disabled</strong></span></p>
1737                   </td>
1738 <td>
1739                     <p>
1740                       Log queries that have been forced to use plain
1741                       DNS due to timeouts.  This is often due to
1742                       the remote servers not being RFC 1034 compliant
1743                       (not always returning FORMERR or similar to
1744                       EDNS queries and other extensions to the DNS
1745                       when they are not understood).  In other words, this is
1746                       targeted at servers that fail to respond to
1747                       DNS queries that they don't understand.
1748                     </p>
1749                     <p>
1750                       Note: the log message can also be due to
1751                       packet loss.  Before reporting servers for
1752                       non-RFC 1034 compliance they should be re-tested
1753                       to determine the nature of the non-compliance.
1754                       This testing should prevent or reduce the
1755                       number of false-positive reports.
1756                     </p>
1757                     <p>
1758                       Note: eventually <span><strong class="command">named</strong></span> will have to stop
1759                       treating such timeouts as due to RFC 1034 non
1760                       compliance and start treating it as plain
1761                       packet loss.  Falsely classifying packet
1762                       loss as due to RFC 1034 non compliance impacts
1763                       on DNSSEC validation which requires EDNS for
1764                       the DNSSEC records to be returned.
1765                     </p>
1766                   </td>
1767 </tr>
1768 <tr>
1769 <td>
1770                     <p><span><strong class="command">RPZ</strong></span></p>
1771                   </td>
1772 <td>
1773                     <p>
1774                       Information about errors in response policy zone files,
1775                       rewritten responses, and at the highest
1776                       <span><strong class="command">debug</strong></span> levels, mere rewriting
1777                       attempts.
1778                     </p>
1779                   </td>
1780 </tr>
1781 </tbody>
1782 </table></div>
1783 </div>
1784 <div class="sect3" lang="en">
1785 <div class="titlepage"><div><div><h4 class="title">
1786 <a name="id2576472"></a>The <span><strong class="command">query-errors</strong></span> Category</h4></div></div></div>
1787 <p>
1788             The <span><strong class="command">query-errors</strong></span> category is
1789             specifically intended for debugging purposes: To identify
1790             why and how specific queries result in responses which
1791             indicate an error.
1792             Messages of this category are therefore only logged
1793             with <span><strong class="command">debug</strong></span> levels.
1794           </p>
1795 <p>
1796             At the debug levels of 1 or higher, each response with the
1797             rcode of SERVFAIL is logged as follows:
1798           </p>
1799 <p>
1800             <code class="computeroutput">client 127.0.0.1#61502: query failed (SERVFAIL) for www.example.com/IN/AAAA at query.c:3880</code>
1801           </p>
1802 <p>
1803             This means an error resulting in SERVFAIL was
1804             detected at line 3880 of source file
1805             <code class="filename">query.c</code>.
1806             Log messages of this level will particularly
1807             help identify the cause of SERVFAIL for an
1808             authoritative server.
1809           </p>
1810 <p>
1811             At the debug levels of 2 or higher, detailed context
1812             information of recursive resolutions that resulted in
1813             SERVFAIL is logged.
1814             The log message will look like as follows:
1815           </p>
1816 <p>
1817
1818             </p>
1819 <pre class="programlisting">
1820 fetch completed at resolver.c:2970 for www.example.com/A
1821 in 30.000183: timed out/success [domain:example.com,
1822 referral:2,restart:7,qrysent:8,timeout:5,lame:0,neterr:0,
1823 badresp:1,adberr:0,findfail:0,valfail:0]
1824             </pre>
1825 <p>
1826           </p>
1827 <p>
1828             The first part before the colon shows that a recursive
1829             resolution for AAAA records of www.example.com completed
1830             in 30.000183 seconds and the final result that led to the
1831             SERVFAIL was determined at line 2970 of source file
1832             <code class="filename">resolver.c</code>.
1833           </p>
1834 <p>
1835             The following part shows the detected final result and the
1836             latest result of DNSSEC validation.
1837             The latter is always success when no validation attempt
1838             is made.
1839             In this example, this query resulted in SERVFAIL probably
1840             because all name servers are down or unreachable, leading
1841             to a timeout in 30 seconds.
1842             DNSSEC validation was probably not attempted.
1843           </p>
1844 <p>
1845             The last part enclosed in square brackets shows statistics
1846             information collected for this particular resolution
1847             attempt.
1848             The <code class="varname">domain</code> field shows the deepest zone
1849             that the resolver reached;
1850             it is the zone where the error was finally detected.
1851             The meaning of the other fields is summarized in the
1852             following table.
1853           </p>
1854 <div class="informaltable"><table border="1">
1855 <colgroup>
1856 <col>
1857 <col>
1858 </colgroup>
1859 <tbody>
1860 <tr>
1861 <td>
1862                     <p><code class="varname">referral</code></p>
1863                   </td>
1864 <td>
1865                     <p>
1866                       The number of referrals the resolver received
1867                       throughout the resolution process.
1868                       In the above example this is 2, which are most
1869                       likely com and example.com.
1870                     </p>
1871                   </td>
1872 </tr>
1873 <tr>
1874 <td>
1875                     <p><code class="varname">restart</code></p>
1876                   </td>
1877 <td>
1878                     <p>
1879                       The number of cycles that the resolver tried
1880                       remote servers at the <code class="varname">domain</code>
1881                       zone.
1882                       In each cycle the resolver sends one query
1883                       (possibly resending it, depending on the response)
1884                       to each known name server of
1885                       the <code class="varname">domain</code> zone.
1886                     </p>
1887                   </td>
1888 </tr>
1889 <tr>
1890 <td>
1891                     <p><code class="varname">qrysent</code></p>
1892                   </td>
1893 <td>
1894                     <p>
1895                       The number of queries the resolver sent at the
1896                       <code class="varname">domain</code> zone.
1897                     </p>
1898                   </td>
1899 </tr>
1900 <tr>
1901 <td>
1902                     <p><code class="varname">timeout</code></p>
1903                   </td>
1904 <td>
1905                     <p>
1906                       The number of timeouts since the resolver
1907                       received the last response.
1908                     </p>
1909                   </td>
1910 </tr>
1911 <tr>
1912 <td>
1913                     <p><code class="varname">lame</code></p>
1914                   </td>
1915 <td>
1916                     <p>
1917                       The number of lame servers the resolver detected
1918                       at the <code class="varname">domain</code> zone.
1919                       A server is detected to be lame either by an
1920                       invalid response or as a result of lookup in
1921                       BIND9's address database (ADB), where lame
1922                       servers are cached.
1923                     </p>
1924                   </td>
1925 </tr>
1926 <tr>
1927 <td>
1928                     <p><code class="varname">neterr</code></p>
1929                   </td>
1930 <td>
1931                     <p>
1932                       The number of erroneous results that the
1933                       resolver encountered in sending queries
1934                       at the <code class="varname">domain</code> zone.
1935                       One common case is the remote server is
1936                       unreachable and the resolver receives an ICMP
1937                       unreachable error message.
1938                     </p>
1939                   </td>
1940 </tr>
1941 <tr>
1942 <td>
1943                     <p><code class="varname">badresp</code></p>
1944                   </td>
1945 <td>
1946                     <p>
1947                       The number of unexpected responses (other than
1948                       <code class="varname">lame</code>) to queries sent by the
1949                       resolver at the <code class="varname">domain</code> zone.
1950                     </p>
1951                   </td>
1952 </tr>
1953 <tr>
1954 <td>
1955                     <p><code class="varname">adberr</code></p>
1956                   </td>
1957 <td>
1958                     <p>
1959                       Failures in finding remote server addresses
1960                       of the <code class="varname">domain</code> zone in the ADB.
1961                       One common case of this is that the remote
1962                       server's name does not have any address records.
1963                     </p>
1964                   </td>
1965 </tr>
1966 <tr>
1967 <td>
1968                     <p><code class="varname">findfail</code></p>
1969                   </td>
1970 <td>
1971                     <p>
1972                       Failures of resolving remote server addresses.
1973                       This is a total number of failures throughout
1974                       the resolution process.
1975                     </p>
1976                   </td>
1977 </tr>
1978 <tr>
1979 <td>
1980                     <p><code class="varname">valfail</code></p>
1981                   </td>
1982 <td>
1983                     <p>
1984                       Failures of DNSSEC validation.
1985                       Validation failures are counted throughout
1986                       the resolution process (not limited to
1987                       the <code class="varname">domain</code> zone), but should
1988                       only happen in <code class="varname">domain</code>.
1989                     </p>
1990                   </td>
1991 </tr>
1992 </tbody>
1993 </table></div>
1994 <p>
1995             At the debug levels of 3 or higher, the same messages
1996             as those at the debug 1 level are logged for other errors
1997             than SERVFAIL.
1998             Note that negative responses such as NXDOMAIN are not
1999             regarded as errors here.
2000           </p>
2001 <p>
2002             At the debug levels of 4 or higher, the same messages
2003             as those at the debug 2 level are logged for other errors
2004             than SERVFAIL.
2005             Unlike the above case of level 3, messages are logged for
2006             negative responses.
2007             This is because any unexpected results can be difficult to
2008             debug in the recursion case.
2009           </p>
2010 </div>
2011 </div>
2012 <div class="sect2" lang="en">
2013 <div class="titlepage"><div><div><h3 class="title">
2014 <a name="id2577060"></a><span><strong class="command">lwres</strong></span> Statement Grammar</h3></div></div></div>
2015 <p>
2016            This is the grammar of the <span><strong class="command">lwres</strong></span>
2017           statement in the <code class="filename">named.conf</code> file:
2018         </p>
2019 <pre class="programlisting"><span><strong class="command">lwres</strong></span> {
2020     [<span class="optional"> listen-on { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ;
2021                 [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
2022     [<span class="optional"> view <em class="replaceable"><code>view_name</code></em>; </span>]
2023     [<span class="optional"> search { <em class="replaceable"><code>domain_name</code></em> ; [<span class="optional"> <em class="replaceable"><code>domain_name</code></em> ; ... </span>] }; </span>]
2024     [<span class="optional"> ndots <em class="replaceable"><code>number</code></em>; </span>]
2025 };
2026 </pre>
2027 </div>
2028 <div class="sect2" lang="en">
2029 <div class="titlepage"><div><div><h3 class="title">
2030 <a name="id2577133"></a><span><strong class="command">lwres</strong></span> Statement Definition and Usage</h3></div></div></div>
2031 <p>
2032           The <span><strong class="command">lwres</strong></span> statement configures the
2033           name
2034           server to also act as a lightweight resolver server. (See
2035           <a href="Bv9ARM.ch05.html#lwresd" title="Running a Resolver Daemon">the section called &#8220;Running a Resolver Daemon&#8221;</a>.)  There may be multiple
2036           <span><strong class="command">lwres</strong></span> statements configuring
2037           lightweight resolver servers with different properties.
2038         </p>
2039 <p>
2040           The <span><strong class="command">listen-on</strong></span> statement specifies a
2041           list of
2042           addresses (and ports) that this instance of a lightweight resolver
2043           daemon
2044           should accept requests on.  If no port is specified, port 921 is
2045           used.
2046           If this statement is omitted, requests will be accepted on
2047           127.0.0.1,
2048           port 921.
2049         </p>
2050 <p>
2051           The <span><strong class="command">view</strong></span> statement binds this
2052           instance of a
2053           lightweight resolver daemon to a view in the DNS namespace, so that
2054           the
2055           response will be constructed in the same manner as a normal DNS
2056           query
2057           matching this view.  If this statement is omitted, the default view
2058           is
2059           used, and if there is no default view, an error is triggered.
2060         </p>
2061 <p>
2062           The <span><strong class="command">search</strong></span> statement is equivalent to
2063           the
2064           <span><strong class="command">search</strong></span> statement in
2065           <code class="filename">/etc/resolv.conf</code>.  It provides a
2066           list of domains
2067           which are appended to relative names in queries.
2068         </p>
2069 <p>
2070           The <span><strong class="command">ndots</strong></span> statement is equivalent to
2071           the
2072           <span><strong class="command">ndots</strong></span> statement in
2073           <code class="filename">/etc/resolv.conf</code>.  It indicates the
2074           minimum
2075           number of dots in a relative domain name that should result in an
2076           exact match lookup before search path elements are appended.
2077         </p>
2078 </div>
2079 <div class="sect2" lang="en">
2080 <div class="titlepage"><div><div><h3 class="title">
2081 <a name="id2577197"></a><span><strong class="command">masters</strong></span> Statement Grammar</h3></div></div></div>
2082 <pre class="programlisting">
2083 <span><strong class="command">masters</strong></span> <em class="replaceable"><code>name</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { ( <em class="replaceable"><code>masters_list</code></em> |
2084       <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] };
2085 </pre>
2086 </div>
2087 <div class="sect2" lang="en">
2088 <div class="titlepage"><div><div><h3 class="title">
2089 <a name="id2577241"></a><span><strong class="command">masters</strong></span> Statement Definition and
2090           Usage</h3></div></div></div>
2091 <p><span><strong class="command">masters</strong></span>
2092           lists allow for a common set of masters to be easily used by
2093           multiple stub and slave zones.
2094         </p>
2095 </div>
2096 <div class="sect2" lang="en">
2097 <div class="titlepage"><div><div><h3 class="title">
2098 <a name="id2577256"></a><span><strong class="command">options</strong></span> Statement Grammar</h3></div></div></div>
2099 <p>
2100           This is the grammar of the <span><strong class="command">options</strong></span>
2101           statement in the <code class="filename">named.conf</code> file:
2102         </p>
2103 <pre class="programlisting"><span><strong class="command">options</strong></span> {
2104     [<span class="optional"> attach-cache <em class="replaceable"><code>cache_name</code></em>; </span>]
2105     [<span class="optional"> version <em class="replaceable"><code>version_string</code></em>; </span>]
2106     [<span class="optional"> hostname <em class="replaceable"><code>hostname_string</code></em>; </span>]
2107     [<span class="optional"> server-id <em class="replaceable"><code>server_id_string</code></em>; </span>]
2108     [<span class="optional"> directory <em class="replaceable"><code>path_name</code></em>; </span>]
2109     [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>]
2110     [<span class="optional"> managed-keys-directory <em class="replaceable"><code>path_name</code></em>; </span>]
2111     [<span class="optional"> named-xfer <em class="replaceable"><code>path_name</code></em>; </span>]
2112     [<span class="optional"> tkey-gssapi-keytab <em class="replaceable"><code>path_name</code></em>; </span>]
2113     [<span class="optional"> tkey-gssapi-credential <em class="replaceable"><code>principal</code></em>; </span>]
2114     [<span class="optional"> tkey-domain <em class="replaceable"><code>domainname</code></em>; </span>]
2115     [<span class="optional"> tkey-dhkey <em class="replaceable"><code>key_name</code></em> <em class="replaceable"><code>key_tag</code></em>; </span>]
2116     [<span class="optional"> cache-file <em class="replaceable"><code>path_name</code></em>; </span>]
2117     [<span class="optional"> dump-file <em class="replaceable"><code>path_name</code></em>; </span>]
2118     [<span class="optional"> bindkeys-file <em class="replaceable"><code>path_name</code></em>; </span>]
2119     [<span class="optional"> secroots-file <em class="replaceable"><code>path_name</code></em>; </span>]
2120     [<span class="optional"> session-keyfile <em class="replaceable"><code>path_name</code></em>; </span>]
2121     [<span class="optional"> session-keyname <em class="replaceable"><code>key_name</code></em>; </span>]
2122     [<span class="optional"> session-keyalg <em class="replaceable"><code>algorithm_id</code></em>; </span>]
2123     [<span class="optional"> memstatistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2124     [<span class="optional"> memstatistics-file <em class="replaceable"><code>path_name</code></em>; </span>]
2125     [<span class="optional"> pid-file <em class="replaceable"><code>path_name</code></em>; </span>]
2126     [<span class="optional"> recursing-file <em class="replaceable"><code>path_name</code></em>; </span>]
2127     [<span class="optional"> statistics-file <em class="replaceable"><code>path_name</code></em>; </span>]
2128     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2129     [<span class="optional"> auth-nxdomain <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2130     [<span class="optional"> deallocate-on-exit <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2131     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em>; </span>]
2132     [<span class="optional"> fake-iquery <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2133     [<span class="optional"> fetch-glue <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2134     [<span class="optional"> flush-zones-on-shutdown <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2135     [<span class="optional"> has-old-clients <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2136     [<span class="optional"> host-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2137     [<span class="optional"> host-statistics-max <em class="replaceable"><code>number</code></em>; </span>]
2138     [<span class="optional"> minimal-responses <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2139     [<span class="optional"> multiple-cnames <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2140     [<span class="optional"> notify <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>explicit</code></em> | <em class="replaceable"><code>master-only</code></em>; </span>]
2141     [<span class="optional"> recursion <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2142     [<span class="optional"> request-nsid <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2143     [<span class="optional"> rfc2308-type1 <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2144     [<span class="optional"> use-id-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2145     [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2146     [<span class="optional"> ixfr-from-differences (<em class="replaceable"><code>yes_or_no</code></em> | <code class="constant">master</code> | <code class="constant">slave</code>); </span>]
2147     [<span class="optional"> dnssec-enable <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2148     [<span class="optional"> dnssec-validation (<em class="replaceable"><code>yes_or_no</code></em> | <code class="constant">auto</code>); </span>]
2149     [<span class="optional"> dnssec-lookaside ( <em class="replaceable"><code>auto</code></em> |
2150                         <em class="replaceable"><code>no</code></em> |
2151                         <em class="replaceable"><code>domain</code></em> trust-anchor <em class="replaceable"><code>domain</code></em> ); </span>]
2152     [<span class="optional"> dnssec-must-be-secure <em class="replaceable"><code>domain yes_or_no</code></em>; </span>]
2153     [<span class="optional"> dnssec-accept-expired <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2154     [<span class="optional"> forward ( <em class="replaceable"><code>only</code></em> | <em class="replaceable"><code>first</code></em> ); </span>]
2155     [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
2156     [<span class="optional"> dual-stack-servers [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] {
2157         ( <em class="replaceable"><code>domain_name</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] |
2158           <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ) ;
2159         ... }; </span>]
2160     [<span class="optional"> check-names ( <em class="replaceable"><code>master</code></em> | <em class="replaceable"><code>slave</code></em> | <em class="replaceable"><code>response</code></em> )
2161         ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2162     [<span class="optional"> check-dup-records ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2163     [<span class="optional"> check-mx ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2164     [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2165     [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2166     [<span class="optional"> check-mx-cname ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2167     [<span class="optional"> check-srv-cname ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2168     [<span class="optional"> check-sibling <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2169     [<span class="optional"> check-spf ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2170     [<span class="optional"> allow-new-zones { <em class="replaceable"><code>yes_or_no</code></em> }; </span>]
2171     [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2172     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2173     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2174     [<span class="optional"> allow-query-cache { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2175     [<span class="optional"> allow-query-cache-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2176     [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2177     [<span class="optional"> allow-recursion { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2178     [<span class="optional"> allow-recursion-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2179     [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2180     [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2181     [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2182     [<span class="optional"> dnssec-dnskey-kskonly <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2183     [<span class="optional"> dnssec-secure-to-insecure <em class="replaceable"><code>yes_or_no</code></em> ;</span>]
2184     [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2185     [<span class="optional"> allow-v6-synthesis { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2186     [<span class="optional"> blackhole { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2187     [<span class="optional"> use-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2188     [<span class="optional"> avoid-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2189     [<span class="optional"> use-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2190     [<span class="optional"> avoid-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2191     [<span class="optional"> listen-on [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em> </span>] { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2192     [<span class="optional"> listen-on-v6 [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em> </span>] { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2193     [<span class="optional"> query-source ( ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> )
2194         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] |
2195         [<span class="optional"> address ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
2196         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>]
2197     [<span class="optional"> query-source-v6 ( ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> )
2198         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] |
2199         [<span class="optional"> address ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
2200         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>]
2201     [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2202     [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>]
2203     [<span class="optional"> queryport-pool-updateinterval <em class="replaceable"><code>number</code></em>; </span>]
2204     [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em>; </span>]
2205     [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em>; </span>]
2206     [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em>; </span>]
2207     [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em>; </span>]
2208     [<span class="optional"> tcp-clients <em class="replaceable"><code>number</code></em>; </span>]
2209     [<span class="optional"> reserved-sockets <em class="replaceable"><code>number</code></em>; </span>]
2210     [<span class="optional"> recursive-clients <em class="replaceable"><code>number</code></em>; </span>]
2211     [<span class="optional"> serial-query-rate <em class="replaceable"><code>number</code></em>; </span>]
2212     [<span class="optional"> serial-queries <em class="replaceable"><code>number</code></em>; </span>]
2213     [<span class="optional"> tcp-listen-queue <em class="replaceable"><code>number</code></em>; </span>]
2214     [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em>; </span>]
2215     [<span class="optional"> transfers-in  <em class="replaceable"><code>number</code></em>; </span>]
2216     [<span class="optional"> transfers-out <em class="replaceable"><code>number</code></em>; </span>]
2217     [<span class="optional"> transfers-per-ns <em class="replaceable"><code>number</code></em>; </span>]
2218     [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2219     [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2220     [<span class="optional"> alt-transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2221     [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>)
2222                              [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2223     [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2224     [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
2225     [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2226     [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2227     [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2228     [<span class="optional"> also-notify { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ;
2229                   [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
2230     [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em>; </span>]
2231     [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
2232     [<span class="optional"> coresize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2233     [<span class="optional"> datasize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2234     [<span class="optional"> files <em class="replaceable"><code>size_spec</code></em> ; </span>]
2235     [<span class="optional"> stacksize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2236     [<span class="optional"> cleaning-interval <em class="replaceable"><code>number</code></em>; </span>]
2237     [<span class="optional"> heartbeat-interval <em class="replaceable"><code>number</code></em>; </span>]
2238     [<span class="optional"> interface-interval <em class="replaceable"><code>number</code></em>; </span>]
2239     [<span class="optional"> statistics-interval <em class="replaceable"><code>number</code></em>; </span>]
2240     [<span class="optional"> topology { <em class="replaceable"><code>address_match_list</code></em> }</span>];
2241     [<span class="optional"> sortlist { <em class="replaceable"><code>address_match_list</code></em> }</span>];
2242     [<span class="optional"> rrset-order { <em class="replaceable"><code>order_spec</code></em> ; [<span class="optional"> <em class="replaceable"><code>order_spec</code></em> ; ... </span>] </span>] };
2243     [<span class="optional"> lame-ttl <em class="replaceable"><code>number</code></em>; </span>]
2244     [<span class="optional"> max-ncache-ttl <em class="replaceable"><code>number</code></em>; </span>]
2245     [<span class="optional"> max-cache-ttl <em class="replaceable"><code>number</code></em>; </span>]
2246     [<span class="optional"> sig-validity-interval <em class="replaceable"><code>number</code></em> [<span class="optional"><em class="replaceable"><code>number</code></em></span>] ; </span>]
2247     [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>]
2248     [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>]
2249     [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>]
2250     [<span class="optional"> min-roots <em class="replaceable"><code>number</code></em>; </span>]
2251     [<span class="optional"> use-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2252     [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2253     [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2254     [<span class="optional"> treat-cr-as-space <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2255     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
2256     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
2257     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
2258     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
2259     [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em>; </span>]
2260     [<span class="optional"> additional-from-auth <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2261     [<span class="optional"> additional-from-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2262     [<span class="optional"> random-device <em class="replaceable"><code>path_name</code></em> ; </span>]
2263     [<span class="optional"> max-cache-size <em class="replaceable"><code>size_spec</code></em> ; </span>]
2264     [<span class="optional"> match-mapped-addresses <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2265     [<span class="optional"> filter-aaaa-on-v4 ( <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>break-dnssec</code></em> ); </span>]
2266     [<span class="optional"> filter-aaaa { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2267     [<span class="optional"> dns64 <em class="replaceable"><code>IPv6-prefix</code></em> {
2268         [<span class="optional"> clients { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2269         [<span class="optional"> mapped { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2270         [<span class="optional"> exclude { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2271         [<span class="optional"> suffix IPv6-address; </span>]
2272         [<span class="optional"> recursive-only <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2273         [<span class="optional"> break-dnssec <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2274     }; </span>];
2275     [<span class="optional"> dns64-server <em class="replaceable"><code>name</code></em> </span>]
2276     [<span class="optional"> dns64-contact <em class="replaceable"><code>name</code></em> </span>]
2277     [<span class="optional"> preferred-glue ( <em class="replaceable"><code>A</code></em> | <em class="replaceable"><code>AAAA</code></em> | <em class="replaceable"><code>NONE</code></em> ); </span>]
2278     [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em>; </span>]
2279     [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em>; </span>]
2280     [<span class="optional"> root-delegation-only [<span class="optional"> exclude { <em class="replaceable"><code>namelist</code></em> } </span>] ; </span>]
2281     [<span class="optional"> querylog <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2282     [<span class="optional"> disable-algorithms <em class="replaceable"><code>domain</code></em> { <em class="replaceable"><code>algorithm</code></em>;
2283                                 [<span class="optional"> <em class="replaceable"><code>algorithm</code></em>; </span>] }; </span>]
2284     [<span class="optional"> acache-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2285     [<span class="optional"> acache-cleaning-interval <em class="replaceable"><code>number</code></em>; </span>]
2286     [<span class="optional"> max-acache-size <em class="replaceable"><code>size_spec</code></em> ; </span>]
2287     [<span class="optional"> clients-per-query <em class="replaceable"><code>number</code></em> ; </span>]
2288     [<span class="optional"> max-clients-per-query <em class="replaceable"><code>number</code></em> ; </span>]
2289     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
2290     [<span class="optional"> empty-server <em class="replaceable"><code>name</code></em> ; </span>]
2291     [<span class="optional"> empty-contact <em class="replaceable"><code>name</code></em> ; </span>]
2292     [<span class="optional"> empty-zones-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2293     [<span class="optional"> disable-empty-zone <em class="replaceable"><code>zone_name</code></em> ; </span>]
2294     [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2295     [<span class="optional"> zero-no-soa-ttl-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2296     [<span class="optional"> resolver-query-timeout <em class="replaceable"><code>number</code></em> ; </span>]
2297     [<span class="optional"> deny-answer-addresses { <em class="replaceable"><code>address_match_list</code></em> } [<span class="optional"> except-from { <em class="replaceable"><code>namelist</code></em> } </span>];</span>]
2298     [<span class="optional"> deny-answer-aliases { <em class="replaceable"><code>namelist</code></em> } [<span class="optional"> except-from { <em class="replaceable"><code>namelist</code></em> } </span>];</span>]
2299     [<span class="optional"> response-policy { <em class="replaceable"><code>zone_name</code></em>
2300         [<span class="optional"> policy given | disabled | passthru | nxdomain | nodata | cname <em class="replaceable"><code>domain</code></em> </span>]
2301         [<span class="optional"> recursive-only <em class="replaceable"><code>yes_or_no</code></em> </span>] [<span class="optional"> max-policy-ttl <em class="replaceable"><code>number</code></em> </span>] ;
2302     } [<span class="optional"> recursive-only <em class="replaceable"><code>yes_or_no</code></em> </span>] [<span class="optional"> max-policy-ttl <em class="replaceable"><code>number</code></em> </span>]
2303         [<span class="optional"> break-dnssec <em class="replaceable"><code>yes_or_no</code></em> </span>] [<span class="optional"> min-ns-dots <em class="replaceable"><code>number</code></em> </span>] ; </span>]
2304 };
2305 </pre>
2306 </div>
2307 <div class="sect2" lang="en">
2308 <div class="titlepage"><div><div><h3 class="title">
2309 <a name="options"></a><span><strong class="command">options</strong></span> Statement Definition and
2310           Usage</h3></div></div></div>
2311 <p>
2312           The <span><strong class="command">options</strong></span> statement sets up global
2313           options
2314           to be used by <acronym class="acronym">BIND</acronym>. This statement
2315           may appear only
2316           once in a configuration file. If there is no <span><strong class="command">options</strong></span>
2317           statement, an options block with each option set to its default will
2318           be used.
2319         </p>
2320 <div class="variablelist"><dl>
2321 <dt><span class="term"><span><strong class="command">attach-cache</strong></span></span></dt>
2322 <dd>
2323 <p>
2324                   Allows multiple views to share a single cache
2325                   database.
2326                   Each view has its own cache database by default, but
2327                   if multiple views have the same operational policy
2328                   for name resolution and caching, those views can
2329                   share a single cache to save memory and possibly
2330                   improve resolution efficiency by using this option.
2331                 </p>
2332 <p>
2333                   The <span><strong class="command">attach-cache</strong></span> option
2334                   may also be specified in <span><strong class="command">view</strong></span>
2335                   statements, in which case it overrides the
2336                   global <span><strong class="command">attach-cache</strong></span> option.
2337                 </p>
2338 <p>
2339                   The <em class="replaceable"><code>cache_name</code></em> specifies
2340                   the cache to be shared.
2341                   When the <span><strong class="command">named</strong></span> server configures
2342                   views which are supposed to share a cache, it
2343                   creates a cache with the specified name for the
2344                   first view of these sharing views.
2345                   The rest of the views will simply refer to the
2346                   already created cache.
2347                 </p>
2348 <p>
2349                   One common configuration to share a cache would be to
2350                   allow all views to share a single cache.
2351                   This can be done by specifying
2352                   the <span><strong class="command">attach-cache</strong></span> as a global
2353                   option with an arbitrary name.
2354                 </p>
2355 <p>
2356                   Another possible operation is to allow a subset of
2357                   all views to share a cache while the others to
2358                   retain their own caches.
2359                   For example, if there are three views A, B, and C,
2360                   and only A and B should share a cache, specify the
2361                   <span><strong class="command">attach-cache</strong></span> option as a view A (or
2362                   B)'s option, referring to the other view name:
2363                 </p>
2364 <pre class="programlisting">
2365   view "A" {
2366     // this view has its own cache
2367     ...
2368   };
2369   view "B" {
2370     // this view refers to A's cache
2371     attach-cache "A";
2372   };
2373   view "C" {
2374     // this view has its own cache
2375     ...
2376   };
2377 </pre>
2378 <p>
2379                   Views that share a cache must have the same policy
2380                   on configurable parameters that may affect caching.
2381                   The current implementation requires the following
2382                   configurable options be consistent among these
2383                   views:
2384                   <span><strong class="command">check-names</strong></span>,
2385                   <span><strong class="command">cleaning-interval</strong></span>,
2386                   <span><strong class="command">dnssec-accept-expired</strong></span>,
2387                   <span><strong class="command">dnssec-validation</strong></span>,
2388                   <span><strong class="command">max-cache-ttl</strong></span>,
2389                   <span><strong class="command">max-ncache-ttl</strong></span>,
2390                   <span><strong class="command">max-cache-size</strong></span>, and
2391                   <span><strong class="command">zero-no-soa-ttl</strong></span>.
2392                 </p>
2393 <p>
2394                   Note that there may be other parameters that may
2395                   cause confusion if they are inconsistent for
2396                   different views that share a single cache.
2397                   For example, if these views define different sets of
2398                   forwarders that can return different answers for the
2399                   same question, sharing the answer does not make
2400                   sense or could even be harmful.
2401                   It is administrator's responsibility to ensure
2402                   configuration differences in different views do
2403                   not cause disruption with a shared cache.
2404                 </p>
2405 </dd>
2406 <dt><span class="term"><span><strong class="command">directory</strong></span></span></dt>
2407 <dd><p>
2408                 The working directory of the server.
2409                 Any non-absolute pathnames in the configuration file will be
2410                 taken
2411                 as relative to this directory. The default location for most
2412                 server
2413                 output files (e.g. <code class="filename">named.run</code>)
2414                 is this directory.
2415                 If a directory is not specified, the working directory
2416                 defaults to `<code class="filename">.</code>', the directory from
2417                 which the server
2418                 was started. The directory specified should be an absolute
2419                 path.
2420               </p></dd>
2421 <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt>
2422 <dd><p>
2423                 When performing dynamic update of secure zones, the
2424                 directory where the public and private DNSSEC key files
2425                 should be found, if different than the current working
2426                 directory.  (Note that this option has no effect on the
2427                 paths for files containing non-DNSSEC keys such as
2428                 <code class="filename">bind.keys</code>,
2429                 <code class="filename">rndc.key</code> or
2430                 <code class="filename">session.key</code>.)
2431               </p></dd>
2432 <dt><span class="term"><span><strong class="command">managed-keys-directory</strong></span></span></dt>
2433 <dd>
2434 <p>
2435                 Specifies the directory in which to store the files that
2436                 track managed DNSSEC keys.  By default, this is the working
2437                 directory.
2438               </p>
2439 <p>
2440                 If <span><strong class="command">named</strong></span> is not configured to use views,
2441                 then managed keys for the server will be tracked in a single
2442                 file called <code class="filename">managed-keys.bind</code>.
2443                 Otherwise, managed keys will be tracked in separate files,
2444                 one file per view; each file name will be the SHA256 hash
2445                 of the view name, followed by the extension
2446                 <code class="filename">.mkeys</code>.
2447               </p>
2448 </dd>
2449 <dt><span class="term"><span><strong class="command">named-xfer</strong></span></span></dt>
2450 <dd><p>
2451                 <span class="emphasis"><em>This option is obsolete.</em></span> It
2452                 was used in <acronym class="acronym">BIND</acronym> 8 to specify
2453                 the pathname to the <span><strong class="command">named-xfer</strong></span>
2454                 program.  In <acronym class="acronym">BIND</acronym> 9, no separate
2455                 <span><strong class="command">named-xfer</strong></span> program is needed;
2456                 its functionality is built into the name server.
2457               </p></dd>
2458 <dt><span class="term"><span><strong class="command">tkey-gssapi-keytab</strong></span></span></dt>
2459 <dd><p>
2460                 The KRB5 keytab file to use for GSS-TSIG updates. If
2461                 this option is set and tkey-gssapi-credential is not
2462                 set, then updates will be allowed with any key
2463                 matching a principal in the specified keytab.
2464               </p></dd>
2465 <dt><span class="term"><span><strong class="command">tkey-gssapi-credential</strong></span></span></dt>
2466 <dd><p>
2467                 The security credential with which the server should
2468                 authenticate keys requested by the GSS-TSIG protocol.
2469                 Currently only Kerberos 5 authentication is available
2470                 and the credential is a Kerberos principal which the
2471                 server can acquire through the default system key
2472                 file, normally <code class="filename">/etc/krb5.keytab</code>.
2473                 The location keytab file can be overridden using the
2474                 tkey-gssapi-keytab option. Normally this principal is
2475                 of the form "<strong class="userinput"><code>DNS/</code></strong><code class="varname">server.domain</code>".
2476                 To use GSS-TSIG, <span><strong class="command">tkey-domain</strong></span> must
2477                 also be set if a specific keytab is not set with
2478                 tkey-gssapi-keytab.
2479               </p></dd>
2480 <dt><span class="term"><span><strong class="command">tkey-domain</strong></span></span></dt>
2481 <dd><p>
2482                 The domain appended to the names of all shared keys
2483                 generated with <span><strong class="command">TKEY</strong></span>.  When a
2484                 client requests a <span><strong class="command">TKEY</strong></span> exchange,
2485                 it may or may not specify the desired name for the
2486                 key. If present, the name of the shared key will
2487                 be <code class="varname">client specified part</code> +
2488                 <code class="varname">tkey-domain</code>.  Otherwise, the
2489                 name of the shared key will be <code class="varname">random hex
2490                 digits</code> + <code class="varname">tkey-domain</code>.
2491                 In most cases, the <span><strong class="command">domainname</strong></span>
2492                 should be the server's domain name, or an otherwise
2493                 non-existent subdomain like
2494                 "_tkey.<code class="varname">domainname</code>".  If you are
2495                 using GSS-TSIG, this variable must be defined, unless
2496                 you specify a specific keytab using tkey-gssapi-keytab.
2497               </p></dd>
2498 <dt><span class="term"><span><strong class="command">tkey-dhkey</strong></span></span></dt>
2499 <dd><p>
2500                 The Diffie-Hellman key used by the server
2501                 to generate shared keys with clients using the Diffie-Hellman
2502                 mode
2503                 of <span><strong class="command">TKEY</strong></span>. The server must be
2504                 able to load the
2505                 public and private keys from files in the working directory.
2506                 In
2507                 most cases, the keyname should be the server's host name.
2508               </p></dd>
2509 <dt><span class="term"><span><strong class="command">cache-file</strong></span></span></dt>
2510 <dd><p>
2511                 This is for testing only.  Do not use.
2512               </p></dd>
2513 <dt><span class="term"><span><strong class="command">dump-file</strong></span></span></dt>
2514 <dd><p>
2515                 The pathname of the file the server dumps
2516                 the database to when instructed to do so with
2517                 <span><strong class="command">rndc dumpdb</strong></span>.
2518                 If not specified, the default is <code class="filename">named_dump.db</code>.
2519               </p></dd>
2520 <dt><span class="term"><span><strong class="command">memstatistics-file</strong></span></span></dt>
2521 <dd><p>
2522                 The pathname of the file the server writes memory
2523                 usage statistics to on exit. If not specified,
2524                 the default is <code class="filename">named.memstats</code>.
2525               </p></dd>
2526 <dt><span class="term"><span><strong class="command">pid-file</strong></span></span></dt>
2527 <dd><p>
2528                 The pathname of the file the server writes its process ID
2529                 in. If not specified, the default is
2530                 <code class="filename">/var/run/named/named.pid</code>.
2531                 The PID file is used by programs that want to send signals to
2532                 the running
2533                 name server. Specifying <span><strong class="command">pid-file none</strong></span> disables the
2534                 use of a PID file &#8212; no file will be written and any
2535                 existing one will be removed.  Note that <span><strong class="command">none</strong></span>
2536                 is a keyword, not a filename, and therefore is not enclosed
2537                 in
2538                 double quotes.
2539               </p></dd>
2540 <dt><span class="term"><span><strong class="command">recursing-file</strong></span></span></dt>
2541 <dd><p>
2542                 The pathname of the file the server dumps
2543                 the queries that are currently recursing when instructed
2544                 to do so with <span><strong class="command">rndc recursing</strong></span>.
2545                 If not specified, the default is <code class="filename">named.recursing</code>.
2546               </p></dd>
2547 <dt><span class="term"><span><strong class="command">statistics-file</strong></span></span></dt>
2548 <dd><p>
2549                 The pathname of the file the server appends statistics
2550                 to when instructed to do so using <span><strong class="command">rndc stats</strong></span>.
2551                 If not specified, the default is <code class="filename">named.stats</code> in the
2552                 server's current directory.  The format of the file is
2553                 described
2554                 in <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called &#8220;The Statistics File&#8221;</a>.
2555               </p></dd>
2556 <dt><span class="term"><span><strong class="command">bindkeys-file</strong></span></span></dt>
2557 <dd><p>
2558                 The pathname of a file to override the built-in trusted
2559                 keys provided by <span><strong class="command">named</strong></span>.
2560                 See the discussion of <span><strong class="command">dnssec-lookaside</strong></span>
2561                 and <span><strong class="command">dnssec-validation</strong></span> for details.
2562                 If not specified, the default is
2563                 <code class="filename">/etc/bind.keys</code>.
2564               </p></dd>
2565 <dt><span class="term"><span><strong class="command">secroots-file</strong></span></span></dt>
2566 <dd><p>
2567                 The pathname of the file the server dumps
2568                 security roots to when instructed to do so with
2569                 <span><strong class="command">rndc secroots</strong></span>.
2570                 If not specified, the default is
2571                 <code class="filename">named.secroots</code>.
2572               </p></dd>
2573 <dt><span class="term"><span><strong class="command">session-keyfile</strong></span></span></dt>
2574 <dd><p>
2575                 The pathname of the file into which to write a TSIG
2576                 session key generated by <span><strong class="command">named</strong></span> for use by
2577                 <span><strong class="command">nsupdate -l</strong></span>.  If not specified, the
2578                 default is <code class="filename">/var/run/named/session.key</code>.
2579                 (See <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called &#8220;Dynamic Update Policies&#8221;</a>, and in
2580                 particular the discussion of the
2581                 <span><strong class="command">update-policy</strong></span> statement's
2582                 <strong class="userinput"><code>local</code></strong> option for more
2583                 information about this feature.)
2584               </p></dd>
2585 <dt><span class="term"><span><strong class="command">session-keyname</strong></span></span></dt>
2586 <dd><p>
2587                 The key name to use for the TSIG session key.
2588                 If not specified, the default is "local-ddns".
2589               </p></dd>
2590 <dt><span class="term"><span><strong class="command">session-keyalg</strong></span></span></dt>
2591 <dd><p>
2592                 The algorithm to use for the TSIG session key.
2593                 Valid values are hmac-sha1, hmac-sha224, hmac-sha256,
2594                 hmac-sha384, hmac-sha512 and hmac-md5.  If not
2595                 specified, the default is hmac-sha256.
2596               </p></dd>
2597 <dt><span class="term"><span><strong class="command">port</strong></span></span></dt>
2598 <dd><p>
2599                 The UDP/TCP port number the server uses for
2600                 receiving and sending DNS protocol traffic.
2601                 The default is 53.  This option is mainly intended for server
2602                 testing;
2603                 a server using a port other than 53 will not be able to
2604                 communicate with
2605                 the global DNS.
2606               </p></dd>
2607 <dt><span class="term"><span><strong class="command">random-device</strong></span></span></dt>
2608 <dd><p>
2609                 The source of entropy to be used by the server.  Entropy is
2610                 primarily needed
2611                 for DNSSEC operations, such as TKEY transactions and dynamic
2612                 update of signed
2613                 zones.  This options specifies the device (or file) from which
2614                 to read
2615                 entropy.  If this is a file, operations requiring entropy will
2616                 fail when the
2617                 file has been exhausted.  If not specified, the default value
2618                 is
2619                 <code class="filename">/dev/random</code>
2620                 (or equivalent) when present, and none otherwise.  The
2621                 <span><strong class="command">random-device</strong></span> option takes
2622                 effect during
2623                 the initial configuration load at server startup time and
2624                 is ignored on subsequent reloads.
2625               </p></dd>
2626 <dt><span class="term"><span><strong class="command">preferred-glue</strong></span></span></dt>
2627 <dd><p>
2628                 If specified, the listed type (A or AAAA) will be emitted
2629                 before other glue
2630                 in the additional section of a query response.
2631                 The default is not to prefer any type (NONE).
2632               </p></dd>
2633 <dt>
2634 <a name="root_delegation_only"></a><span class="term"><span><strong class="command">root-delegation-only</strong></span></span>
2635 </dt>
2636 <dd>
2637 <p>
2638                 Turn on enforcement of delegation-only in TLDs
2639                 (top level domains) and root zones with an optional
2640                 exclude list.
2641               </p>
2642 <p>
2643                 DS queries are expected to be made to and be answered by
2644                 delegation only zones.  Such queries and responses are
2645                 treated as an exception to delegation-only processing
2646                 and are not converted to NXDOMAIN responses provided
2647                 a CNAME is not discovered at the query name.
2648               </p>
2649 <p>
2650                 If a delegation only zone server also serves a child
2651                 zone it is not always possible to determine whether
2652                 an answer comes from the delegation only zone or the
2653                 child zone.  SOA NS and DNSKEY records are apex
2654                 only records and a matching response that contains
2655                 these records or DS is treated as coming from a
2656                 child zone.  RRSIG records are also examined to see
2657                 if they are signed by a child zone or not.  The
2658                 authority section is also examined to see if there
2659                 is evidence that the answer is from the child zone.
2660                 Answers that are determined to be from a child zone
2661                 are not converted to NXDOMAIN responses.  Despite
2662                 all these checks there is still a possibility of
2663                 false negatives when a child zone is being served.
2664               </p>
2665 <p>
2666                 Similarly false positives can arise from empty nodes
2667                 (no records at the name) in the delegation only zone
2668                 when the query type is not ANY.
2669               </p>
2670 <p>
2671                 Note some TLDs are not delegation only (e.g. "DE", "LV",
2672                 "US" and "MUSEUM").  This list is not exhaustive.
2673               </p>
2674 <pre class="programlisting">
2675 options {
2676         root-delegation-only exclude { "de"; "lv"; "us"; "museum"; };
2677 };
2678 </pre>
2679 </dd>
2680 <dt><span class="term"><span><strong class="command">disable-algorithms</strong></span></span></dt>
2681 <dd><p>
2682                 Disable the specified DNSSEC algorithms at and below the
2683                 specified name.
2684                 Multiple <span><strong class="command">disable-algorithms</strong></span>
2685                 statements are allowed.
2686                 Only the most specific will be applied.
2687               </p></dd>
2688 <dt><span class="term"><span><strong class="command">dnssec-lookaside</strong></span></span></dt>
2689 <dd>
2690 <p>
2691                 When set, <span><strong class="command">dnssec-lookaside</strong></span> provides the
2692                 validator with an alternate method to validate DNSKEY
2693                 records at the top of a zone.  When a DNSKEY is at or
2694                 below a domain specified by the deepest
2695                 <span><strong class="command">dnssec-lookaside</strong></span>, and the normal DNSSEC
2696                 validation has left the key untrusted, the trust-anchor
2697                 will be appended to the key name and a DLV record will be
2698                 looked up to see if it can validate the key.  If the DLV
2699                 record validates a DNSKEY (similarly to the way a DS
2700                 record does) the DNSKEY RRset is deemed to be trusted.
2701               </p>
2702 <p>
2703                 If <span><strong class="command">dnssec-lookaside</strong></span> is set to
2704                 <strong class="userinput"><code>auto</code></strong>, then built-in default
2705                 values for the DLV domain and trust anchor will be
2706                 used, along with a built-in key for validation.
2707               </p>
2708 <p>
2709                 If <span><strong class="command">dnssec-lookaside</strong></span> is set to
2710                 <strong class="userinput"><code>no</code></strong>, then dnssec-lookaside
2711                 is not used.
2712               </p>
2713 <p>
2714                 The default DLV key is stored in the file
2715                 <code class="filename">bind.keys</code>;
2716                 <span><strong class="command">named</strong></span> will load that key at
2717                 startup if <span><strong class="command">dnssec-lookaside</strong></span> is set to
2718                 <code class="constant">auto</code>.  A copy of the file is
2719                 installed along with <acronym class="acronym">BIND</acronym> 9, and is
2720                 current as of the release date.  If the DLV key expires, a
2721                 new copy of <code class="filename">bind.keys</code> can be downloaded
2722                 from <a href="https://www.isc.org/solutions/dlv/" target="_top">https://www.isc.org/solutions/dlv/</a>.
2723               </p>
2724 <p>
2725                 (To prevent problems if <code class="filename">bind.keys</code> is
2726                 not found, the current key is also compiled in to
2727                 <span><strong class="command">named</strong></span>.  Relying on this is not
2728                 recommended, however, as it requires <span><strong class="command">named</strong></span>
2729                 to be recompiled with a new key when the DLV key expires.)
2730               </p>
2731 <p>
2732                 NOTE: <span><strong class="command">named</strong></span> only loads certain specific
2733                 keys from <code class="filename">bind.keys</code>:  those for the
2734                 DLV zone and for the DNS root zone.  The file cannot be
2735                 used to store keys for other zones.
2736               </p>
2737 </dd>
2738 <dt><span class="term"><span><strong class="command">dnssec-must-be-secure</strong></span></span></dt>
2739 <dd><p>
2740                 Specify hierarchies which must be or may not be secure
2741                 (signed and validated).  If <strong class="userinput"><code>yes</code></strong>,
2742                 then <span><strong class="command">named</strong></span> will only accept answers if
2743                 they are secure.  If <strong class="userinput"><code>no</code></strong>, then normal
2744                 DNSSEC validation applies allowing for insecure answers to
2745                 be accepted.  The specified domain must be under a
2746                 <span><strong class="command">trusted-keys</strong></span> or
2747                 <span><strong class="command">managed-keys</strong></span> statement, or
2748                 <span><strong class="command">dnssec-lookaside</strong></span> must be active.
2749               </p></dd>
2750 <dt><span class="term"><span><strong class="command">dns64</strong></span></span></dt>
2751 <dd>
2752 <p>
2753                 This directive instructs <span><strong class="command">named</strong></span> to
2754                 return mapped IPv4 addresses to AAAA queries when
2755                 there are no AAAA records.  It is intended to be
2756                 used in conjunction with a NAT64.  Each
2757                 <span><strong class="command">dns64</strong></span> defines one DNS64 prefix.
2758                 Multiple DNS64 prefixes can be defined.
2759               </p>
2760 <p>
2761                 Compatible IPv6 prefixes have lengths of 32, 40, 48, 56,
2762                 64 and 96 as per RFC 6052.
2763               </p>
2764 <p>
2765                 Additionally a reverse IP6.ARPA zone will be created for
2766                 the prefix to provide a mapping from the IP6.ARPA names
2767                 to the corresponding IN-ADDR.ARPA names using synthesized
2768                 CNAMEs.  <span><strong class="command">dns64-server</strong></span> and
2769                 <span><strong class="command">dns64-contact</strong></span> can be used to specify
2770                 the name of the server and contact for the zones. These
2771                 are settable at the view / options level.  These are
2772                 not settable on a per-prefix basis.
2773               </p>
2774 <p>
2775                 Each <span><strong class="command">dns64</strong></span> supports an optional
2776                 <span><strong class="command">clients</strong></span> ACL that determines which
2777                 clients are affected by this directive.  If not defined,
2778                 it defaults to <strong class="userinput"><code>any;</code></strong>.
2779               </p>
2780 <p>
2781                 Each <span><strong class="command">dns64</strong></span> supports an optional
2782                 <span><strong class="command">mapped</strong></span> ACL that selects which
2783                 IPv4 addresses are to be mapped in the corresponding
2784                 A RRset.  If not defined it defaults to
2785                 <strong class="userinput"><code>any;</code></strong>.
2786               </p>
2787 <p>
2788                 Normally, DNS64 won't apply to a domain name that
2789                 owns one or more AAAA records; these records will
2790                 simply be returned.  The optional
2791                 <span><strong class="command">exclude</strong></span> ACL allows specification
2792                 of a list of IPv6 addresses that will be ignored
2793                 if they appear in a domain name's AAAA records, and
2794                 DNS64 will be applied to any A records the domain
2795                 name owns.  If not defined, <span><strong class="command">exclude</strong></span>
2796                 defaults to none.
2797               </p>
2798 <p>
2799                 A optional <span><strong class="command">suffix</strong></span> can also
2800                 be defined to set the bits trailing the mapped
2801                 IPv4 address bits.  By default these bits are
2802                 set to <strong class="userinput"><code>::</code></strong>.  The bits
2803                 matching the prefix and mapped IPv4 address
2804                 must be zero.
2805               </p>
2806 <p>
2807                 If <span><strong class="command">recursive-only</strong></span> is set to
2808                 <span><strong class="command">yes</strong></span> the DNS64 synthesis will
2809                 only happen for recursive queries.  The default
2810                 is <span><strong class="command">no</strong></span>.
2811               </p>
2812 <p>
2813                 If <span><strong class="command">break-dnssec</strong></span> is set to
2814                 <span><strong class="command">yes</strong></span> the DNS64 synthesis will
2815                 happen even if the result, if validated, would
2816                 cause a DNSSEC validation failure.  If this option
2817                 is set to <span><strong class="command">no</strong></span> (the default), the DO
2818                 is set on the incoming query, and there are RRSIGs on
2819                 the applicable records, then synthesis will not happen.
2820               </p>
2821 <pre class="programlisting">
2822         acl rfc1918 { 10/8; 192.168/16; 172.16/12; };
2823
2824         dns64 64:FF9B::/96 {
2825                 clients { any; };
2826                 mapped { !rfc1918; any; };
2827                 exclude { 64:FF9B::/96; ::ffff:0000:0000/96; };
2828                 suffix ::;
2829         };
2830 </pre>
2831 </dd>
2832 </dl></div>
2833 <div class="sect3" lang="en">
2834 <div class="titlepage"><div><div><h4 class="title">
2835 <a name="boolean_options"></a>Boolean Options</h4></div></div></div>
2836 <div class="variablelist"><dl>
2837 <dt><span class="term"><span><strong class="command">allow-new-zones</strong></span></span></dt>
2838 <dd><p>
2839                   If <strong class="userinput"><code>yes</code></strong>, then zones can be
2840                   added at runtime via <span><strong class="command">rndc addzone</strong></span>
2841                   or deleted via <span><strong class="command">rndc delzone</strong></span>.
2842                   The default is <strong class="userinput"><code>no</code></strong>.
2843                 </p></dd>
2844 <dt><span class="term"><span><strong class="command">auth-nxdomain</strong></span></span></dt>
2845 <dd><p>
2846                   If <strong class="userinput"><code>yes</code></strong>, then the <span><strong class="command">AA</strong></span> bit
2847                   is always set on NXDOMAIN responses, even if the server is
2848                   not actually
2849                   authoritative. The default is <strong class="userinput"><code>no</code></strong>;
2850                   this is
2851                   a change from <acronym class="acronym">BIND</acronym> 8. If you
2852                   are using very old DNS software, you
2853                   may need to set it to <strong class="userinput"><code>yes</code></strong>.
2854                 </p></dd>
2855 <dt><span class="term"><span><strong class="command">deallocate-on-exit</strong></span></span></dt>
2856 <dd><p>
2857                   This option was used in <acronym class="acronym">BIND</acronym>
2858                   8 to enable checking
2859                   for memory leaks on exit. <acronym class="acronym">BIND</acronym> 9 ignores the option and always performs
2860                   the checks.
2861                 </p></dd>
2862 <dt><span class="term"><span><strong class="command">memstatistics</strong></span></span></dt>
2863 <dd><p>
2864                   Write memory statistics to the file specified by
2865                   <span><strong class="command">memstatistics-file</strong></span> at exit.
2866                   The default is <strong class="userinput"><code>no</code></strong> unless
2867                   '-m record' is specified on the command line in
2868                   which case it is <strong class="userinput"><code>yes</code></strong>.
2869                 </p></dd>
2870 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
2871 <dd>
2872 <p>
2873                   If <strong class="userinput"><code>yes</code></strong>, then the
2874                   server treats all zones as if they are doing zone transfers
2875                   across
2876                   a dial-on-demand dialup link, which can be brought up by
2877                   traffic
2878                   originating from this server. This has different effects
2879                   according
2880                   to zone type and concentrates the zone maintenance so that
2881                   it all
2882                   happens in a short interval, once every <span><strong class="command">heartbeat-interval</strong></span> and
2883                   hopefully during the one call. It also suppresses some of
2884                   the normal
2885                   zone maintenance traffic. The default is <strong class="userinput"><code>no</code></strong>.
2886                 </p>
2887 <p>
2888                   The <span><strong class="command">dialup</strong></span> option
2889                   may also be specified in the <span><strong class="command">view</strong></span> and
2890                   <span><strong class="command">zone</strong></span> statements,
2891                   in which case it overrides the global <span><strong class="command">dialup</strong></span>
2892                   option.
2893                 </p>
2894 <p>
2895                   If the zone is a master zone, then the server will send out a
2896                   NOTIFY
2897                   request to all the slaves (default). This should trigger the
2898                   zone serial
2899                   number check in the slave (providing it supports NOTIFY)
2900                   allowing the slave
2901                   to verify the zone while the connection is active.
2902                   The set of servers to which NOTIFY is sent can be controlled
2903                   by
2904                   <span><strong class="command">notify</strong></span> and <span><strong class="command">also-notify</strong></span>.
2905                 </p>
2906 <p>
2907                   If the
2908                   zone is a slave or stub zone, then the server will suppress
2909                   the regular
2910                   "zone up to date" (refresh) queries and only perform them
2911                   when the
2912                   <span><strong class="command">heartbeat-interval</strong></span> expires in
2913                   addition to sending
2914                   NOTIFY requests.
2915                 </p>
2916 <p>
2917                   Finer control can be achieved by using
2918                   <strong class="userinput"><code>notify</code></strong> which only sends NOTIFY
2919                   messages,
2920                   <strong class="userinput"><code>notify-passive</code></strong> which sends NOTIFY
2921                   messages and
2922                   suppresses the normal refresh queries, <strong class="userinput"><code>refresh</code></strong>
2923                   which suppresses normal refresh processing and sends refresh
2924                   queries
2925                   when the <span><strong class="command">heartbeat-interval</strong></span>
2926                   expires, and
2927                   <strong class="userinput"><code>passive</code></strong> which just disables normal
2928                   refresh
2929                   processing.
2930                 </p>
2931 <div class="informaltable"><table border="1">
2932 <colgroup>
2933 <col>
2934 <col>
2935 <col>
2936 <col>
2937 </colgroup>
2938 <tbody>
2939 <tr>
2940 <td>
2941                           <p>
2942                             dialup mode
2943                           </p>
2944                         </td>
2945 <td>
2946                           <p>
2947                             normal refresh
2948                           </p>
2949                         </td>
2950 <td>
2951                           <p>
2952                             heart-beat refresh
2953                           </p>
2954                         </td>
2955 <td>
2956                           <p>
2957                             heart-beat notify
2958                           </p>
2959                         </td>
2960 </tr>
2961 <tr>
2962 <td>
2963                           <p><span><strong class="command">no</strong></span> (default)</p>
2964                         </td>
2965 <td>
2966                           <p>
2967                             yes
2968                           </p>
2969                         </td>
2970 <td>
2971                           <p>
2972                             no
2973                           </p>
2974                         </td>
2975 <td>
2976                           <p>
2977                             no
2978                           </p>
2979                         </td>
2980 </tr>
2981 <tr>
2982 <td>
2983                           <p><span><strong class="command">yes</strong></span></p>
2984                         </td>
2985 <td>
2986                           <p>
2987                             no
2988                           </p>
2989                         </td>
2990 <td>
2991                           <p>
2992                             yes
2993                           </p>
2994                         </td>
2995 <td>
2996                           <p>
2997                             yes
2998                           </p>
2999                         </td>
3000 </tr>
3001 <tr>
3002 <td>
3003                           <p><span><strong class="command">notify</strong></span></p>
3004                         </td>
3005 <td>
3006                           <p>
3007                             yes
3008                           </p>
3009                         </td>
3010 <td>
3011                           <p>
3012                             no
3013                           </p>
3014                         </td>
3015 <td>
3016                           <p>
3017                             yes
3018                           </p>
3019                         </td>
3020 </tr>
3021 <tr>
3022 <td>
3023                           <p><span><strong class="command">refresh</strong></span></p>
3024                         </td>
3025 <td>
3026                           <p>
3027                             no
3028                           </p>
3029                         </td>
3030 <td>
3031                           <p>
3032                             yes
3033                           </p>
3034                         </td>
3035 <td>
3036                           <p>
3037                             no
3038                           </p>
3039                         </td>
3040 </tr>
3041 <tr>
3042 <td>
3043                           <p><span><strong class="command">passive</strong></span></p>
3044                         </td>
3045 <td>
3046                           <p>
3047                             no
3048                           </p>
3049                         </td>
3050 <td>
3051                           <p>
3052                             no
3053                           </p>
3054                         </td>
3055 <td>
3056                           <p>
3057                             no
3058                           </p>
3059                         </td>
3060 </tr>
3061 <tr>
3062 <td>
3063                           <p><span><strong class="command">notify-passive</strong></span></p>
3064                         </td>
3065 <td>
3066                           <p>
3067                             no
3068                           </p>
3069                         </td>
3070 <td>
3071                           <p>
3072                             no
3073                           </p>
3074                         </td>
3075 <td>
3076                           <p>
3077                             yes
3078                           </p>
3079                         </td>
3080 </tr>
3081 </tbody>
3082 </table></div>
3083 <p>
3084                   Note that normal NOTIFY processing is not affected by
3085                   <span><strong class="command">dialup</strong></span>.
3086                 </p>
3087 </dd>
3088 <dt><span class="term"><span><strong class="command">fake-iquery</strong></span></span></dt>
3089 <dd><p>
3090                   In <acronym class="acronym">BIND</acronym> 8, this option
3091                   enabled simulating the obsolete DNS query type
3092                   IQUERY. <acronym class="acronym">BIND</acronym> 9 never does
3093                   IQUERY simulation.
3094                 </p></dd>
3095 <dt><span class="term"><span><strong class="command">fetch-glue</strong></span></span></dt>
3096 <dd><p>
3097                   This option is obsolete.
3098                   In BIND 8, <strong class="userinput"><code>fetch-glue yes</code></strong>
3099                   caused the server to attempt to fetch glue resource records
3100                   it
3101                   didn't have when constructing the additional
3102                   data section of a response.  This is now considered a bad
3103                   idea
3104                   and BIND 9 never does it.
3105                 </p></dd>
3106 <dt><span class="term"><span><strong class="command">flush-zones-on-shutdown</strong></span></span></dt>
3107 <dd><p>
3108                   When the nameserver exits due receiving SIGTERM,
3109                   flush or do not flush any pending zone writes.  The default
3110                   is
3111                   <span><strong class="command">flush-zones-on-shutdown</strong></span> <strong class="userinput"><code>no</code></strong>.
3112                 </p></dd>
3113 <dt><span class="term"><span><strong class="command">has-old-clients</strong></span></span></dt>
3114 <dd><p>
3115                   This option was incorrectly implemented
3116                   in <acronym class="acronym">BIND</acronym> 8, and is ignored by <acronym class="acronym">BIND</acronym> 9.
3117                   To achieve the intended effect
3118                   of
3119                   <span><strong class="command">has-old-clients</strong></span> <strong class="userinput"><code>yes</code></strong>, specify
3120                   the two separate options <span><strong class="command">auth-nxdomain</strong></span> <strong class="userinput"><code>yes</code></strong>
3121                   and <span><strong class="command">rfc2308-type1</strong></span> <strong class="userinput"><code>no</code></strong> instead.
3122                 </p></dd>
3123 <dt><span class="term"><span><strong class="command">host-statistics</strong></span></span></dt>
3124 <dd><p>
3125                   In BIND 8, this enables keeping of
3126                   statistics for every host that the name server interacts
3127                   with.
3128                   Not implemented in BIND 9.
3129                 </p></dd>
3130 <dt><span class="term"><span><strong class="command">maintain-ixfr-base</strong></span></span></dt>
3131 <dd><p>
3132                   <span class="emphasis"><em>This option is obsolete</em></span>.
3133                   It was used in <acronym class="acronym">BIND</acronym> 8 to
3134                   determine whether a transaction log was
3135                   kept for Incremental Zone Transfer. <acronym class="acronym">BIND</acronym> 9 maintains a transaction
3136                   log whenever possible.  If you need to disable outgoing
3137                   incremental zone
3138                   transfers, use <span><strong class="command">provide-ixfr</strong></span> <strong class="userinput"><code>no</code></strong>.
3139                 </p></dd>
3140 <dt><span class="term"><span><strong class="command">minimal-responses</strong></span></span></dt>
3141 <dd><p>
3142                   If <strong class="userinput"><code>yes</code></strong>, then when generating
3143                   responses the server will only add records to the authority
3144                   and additional data sections when they are required (e.g.
3145                   delegations, negative responses).  This may improve the
3146                   performance of the server.
3147                   The default is <strong class="userinput"><code>no</code></strong>.
3148                 </p></dd>
3149 <dt><span class="term"><span><strong class="command">multiple-cnames</strong></span></span></dt>
3150 <dd><p>
3151                   This option was used in <acronym class="acronym">BIND</acronym> 8 to allow
3152                   a domain name to have multiple CNAME records in violation of
3153                   the DNS standards.  <acronym class="acronym">BIND</acronym> 9.2 onwards
3154                   always strictly enforces the CNAME rules both in master
3155                   files and dynamic updates.
3156                 </p></dd>
3157 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
3158 <dd>
3159 <p>
3160                   If <strong class="userinput"><code>yes</code></strong> (the default),
3161                   DNS NOTIFY messages are sent when a zone the server is
3162                   authoritative for
3163                   changes, see <a href="Bv9ARM.ch04.html#notify" title="Notify">the section called &#8220;Notify&#8221;</a>.  The messages are
3164                   sent to the
3165                   servers listed in the zone's NS records (except the master
3166                   server identified
3167                   in the SOA MNAME field), and to any servers listed in the
3168                   <span><strong class="command">also-notify</strong></span> option.
3169                 </p>
3170 <p>
3171                   If <strong class="userinput"><code>master-only</code></strong>, notifies are only
3172                   sent
3173                   for master zones.
3174                   If <strong class="userinput"><code>explicit</code></strong>, notifies are sent only
3175                   to
3176                   servers explicitly listed using <span><strong class="command">also-notify</strong></span>.
3177                   If <strong class="userinput"><code>no</code></strong>, no notifies are sent.
3178                 </p>
3179 <p>
3180                   The <span><strong class="command">notify</strong></span> option may also be
3181                   specified in the <span><strong class="command">zone</strong></span>
3182                   statement,
3183                   in which case it overrides the <span><strong class="command">options notify</strong></span> statement.
3184                   It would only be necessary to turn off this option if it
3185                   caused slaves
3186                   to crash.
3187                 </p>
3188 </dd>
3189 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
3190 <dd><p>
3191                   If <strong class="userinput"><code>yes</code></strong> do not check the nameservers
3192                   in the NS RRset against the SOA MNAME.  Normally a NOTIFY
3193                   message is not sent to the SOA MNAME (SOA ORIGIN) as it is
3194                   supposed to contain the name of the ultimate master.
3195                   Sometimes, however, a slave is listed as the SOA MNAME in
3196                   hidden master configurations and in that case you would
3197                   want the ultimate master to still send NOTIFY messages to
3198                   all the nameservers listed in the NS RRset.
3199                 </p></dd>
3200 <dt><span class="term"><span><strong class="command">recursion</strong></span></span></dt>
3201 <dd><p>
3202                   If <strong class="userinput"><code>yes</code></strong>, and a
3203                   DNS query requests recursion, then the server will attempt
3204                   to do
3205                   all the work required to answer the query. If recursion is
3206                   off
3207                   and the server does not already know the answer, it will
3208                   return a
3209                   referral response. The default is
3210                   <strong class="userinput"><code>yes</code></strong>.
3211                   Note that setting <span><strong class="command">recursion no</strong></span> does not prevent
3212                   clients from getting data from the server's cache; it only
3213                   prevents new data from being cached as an effect of client
3214                   queries.
3215                   Caching may still occur as an effect the server's internal
3216                   operation, such as NOTIFY address lookups.
3217                   See also <span><strong class="command">fetch-glue</strong></span> above.
3218                 </p></dd>
3219 <dt><span class="term"><span><strong class="command">request-nsid</strong></span></span></dt>
3220 <dd><p>
3221                   If <strong class="userinput"><code>yes</code></strong>, then an empty EDNS(0)
3222                   NSID (Name Server Identifier) option is sent with all
3223                   queries to authoritative name servers during iterative
3224                   resolution. If the authoritative server returns an NSID
3225                   option in its response, then its contents are logged in
3226                   the <span><strong class="command">resolver</strong></span> category at level
3227                   <span><strong class="command">info</strong></span>.
3228                   The default is <strong class="userinput"><code>no</code></strong>.
3229                 </p></dd>
3230 <dt><span class="term"><span><strong class="command">rfc2308-type1</strong></span></span></dt>
3231 <dd>
3232 <p>
3233                   Setting this to <strong class="userinput"><code>yes</code></strong> will
3234                   cause the server to send NS records along with the SOA
3235                   record for negative
3236                   answers. The default is <strong class="userinput"><code>no</code></strong>.
3237                 </p>
3238 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3239 <h3 class="title">Note</h3>
3240 <p>
3241                     Not yet implemented in <acronym class="acronym">BIND</acronym>
3242                     9.
3243                   </p>
3244 </div>
3245 </dd>
3246 <dt><span class="term"><span><strong class="command">use-id-pool</strong></span></span></dt>
3247 <dd><p>
3248                   <span class="emphasis"><em>This option is obsolete</em></span>.
3249                   <acronym class="acronym">BIND</acronym> 9 always allocates query
3250                   IDs from a pool.
3251                 </p></dd>
3252 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
3253 <dd><p>
3254                   If <strong class="userinput"><code>yes</code></strong>, the server will collect
3255                   statistical data on all zones (unless specifically turned
3256                   off
3257                   on a per-zone basis by specifying <span><strong class="command">zone-statistics no</strong></span>
3258                   in the <span><strong class="command">zone</strong></span> statement).
3259                   The default is <strong class="userinput"><code>no</code></strong>.
3260                   These statistics may be accessed
3261                   using <span><strong class="command">rndc stats</strong></span>, which will
3262                   dump them to the file listed
3263                   in the <span><strong class="command">statistics-file</strong></span>.  See
3264                   also <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called &#8220;The Statistics File&#8221;</a>.
3265                 </p></dd>
3266 <dt><span class="term"><span><strong class="command">use-ixfr</strong></span></span></dt>
3267 <dd><p>
3268                   <span class="emphasis"><em>This option is obsolete</em></span>.
3269                   If you need to disable IXFR to a particular server or
3270                   servers, see
3271                   the information on the <span><strong class="command">provide-ixfr</strong></span> option
3272                   in <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
3273             Usage">the section called &#8220;<span><strong class="command">server</strong></span> Statement Definition and
3274             Usage&#8221;</a>.
3275                   See also
3276                   <a href="Bv9ARM.ch04.html#incremental_zone_transfers" title="Incremental Zone Transfers (IXFR)">the section called &#8220;Incremental Zone Transfers (IXFR)&#8221;</a>.
3277                 </p></dd>
3278 <dt><span class="term"><span><strong class="command">provide-ixfr</strong></span></span></dt>
3279 <dd><p>
3280                   See the description of
3281                   <span><strong class="command">provide-ixfr</strong></span> in
3282                   <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
3283             Usage">the section called &#8220;<span><strong class="command">server</strong></span> Statement Definition and
3284             Usage&#8221;</a>.
3285                 </p></dd>
3286 <dt><span class="term"><span><strong class="command">request-ixfr</strong></span></span></dt>
3287 <dd><p>
3288                   See the description of
3289                   <span><strong class="command">request-ixfr</strong></span> in
3290                   <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
3291             Usage">the section called &#8220;<span><strong class="command">server</strong></span> Statement Definition and
3292             Usage&#8221;</a>.
3293                 </p></dd>
3294 <dt><span class="term"><span><strong class="command">treat-cr-as-space</strong></span></span></dt>
3295 <dd><p>
3296                   This option was used in <acronym class="acronym">BIND</acronym>
3297                   8 to make
3298                   the server treat carriage return ("<span><strong class="command">\r</strong></span>") characters the same way
3299                   as a space or tab character,
3300                   to facilitate loading of zone files on a UNIX system that
3301                   were generated
3302                   on an NT or DOS machine. In <acronym class="acronym">BIND</acronym> 9, both UNIX "<span><strong class="command">\n</strong></span>"
3303                   and NT/DOS "<span><strong class="command">\r\n</strong></span>" newlines
3304                   are always accepted,
3305                   and the option is ignored.
3306                 </p></dd>
3307 <dt>
3308 <span class="term"><span><strong class="command">additional-from-auth</strong></span>, </span><span class="term"><span><strong class="command">additional-from-cache</strong></span></span>
3309 </dt>
3310 <dd>
3311 <p>
3312                   These options control the behavior of an authoritative
3313                   server when
3314                   answering queries which have additional data, or when
3315                   following CNAME
3316                   and DNAME chains.
3317                 </p>
3318 <p>
3319                   When both of these options are set to <strong class="userinput"><code>yes</code></strong>
3320                   (the default) and a
3321                   query is being answered from authoritative data (a zone
3322                   configured into the server), the additional data section of
3323                   the
3324                   reply will be filled in using data from other authoritative
3325                   zones
3326                   and from the cache.  In some situations this is undesirable,
3327                   such
3328                   as when there is concern over the correctness of the cache,
3329                   or
3330                   in servers where slave zones may be added and modified by
3331                   untrusted third parties.  Also, avoiding
3332                   the search for this additional data will speed up server
3333                   operations
3334                   at the possible expense of additional queries to resolve
3335                   what would
3336                   otherwise be provided in the additional section.
3337                 </p>
3338 <p>
3339                   For example, if a query asks for an MX record for host <code class="literal">foo.example.com</code>,
3340                   and the record found is "<code class="literal">MX 10 mail.example.net</code>", normally the address
3341                   records (A and AAAA) for <code class="literal">mail.example.net</code> will be provided as well,
3342                   if known, even though they are not in the example.com zone.
3343                   Setting these options to <span><strong class="command">no</strong></span>
3344                   disables this behavior and makes
3345                   the server only search for additional data in the zone it
3346                   answers from.
3347                 </p>
3348 <p>
3349                   These options are intended for use in authoritative-only
3350                   servers, or in authoritative-only views.  Attempts to set
3351                   them to <span><strong class="command">no</strong></span> without also
3352                   specifying
3353                   <span><strong class="command">recursion no</strong></span> will cause the
3354                   server to
3355                   ignore the options and log a warning message.
3356                 </p>
3357 <p>
3358                   Specifying <span><strong class="command">additional-from-cache no</strong></span> actually
3359                   disables the use of the cache not only for additional data
3360                   lookups
3361                   but also when looking up the answer.  This is usually the
3362                   desired
3363                   behavior in an authoritative-only server where the
3364                   correctness of
3365                   the cached data is an issue.
3366                 </p>
3367 <p>
3368                   When a name server is non-recursively queried for a name
3369                   that is not
3370                   below the apex of any served zone, it normally answers with
3371                   an
3372                   "upwards referral" to the root servers or the servers of
3373                   some other
3374                   known parent of the query name.  Since the data in an
3375                   upwards referral
3376                   comes from the cache, the server will not be able to provide
3377                   upwards
3378                   referrals when <span><strong class="command">additional-from-cache no</strong></span>
3379                   has been specified.  Instead, it will respond to such
3380                   queries
3381                   with REFUSED.  This should not cause any problems since
3382                   upwards referrals are not required for the resolution
3383                   process.
3384                 </p>
3385 </dd>
3386 <dt><span class="term"><span><strong class="command">match-mapped-addresses</strong></span></span></dt>
3387 <dd>
3388 <p>
3389                   If <strong class="userinput"><code>yes</code></strong>, then an
3390                   IPv4-mapped IPv6 address will match any address match
3391                   list entries that match the corresponding IPv4 address.
3392                 </p>
3393 <p>
3394                   This option was introduced to work around a kernel quirk
3395                   in some operating systems that causes IPv4 TCP
3396                   connections, such as zone transfers, to be accepted on an
3397                   IPv6 socket using mapped addresses.  This caused address
3398                   match lists designed for IPv4 to fail to match.  However,
3399                   <span><strong class="command">named</strong></span> now solves this problem
3400                   internally.  The use of this option is discouraged.
3401                 </p>
3402 </dd>
3403 <dt><span class="term"><span><strong class="command">filter-aaaa-on-v4</strong></span></span></dt>
3404 <dd>
3405 <p>
3406                   This option is only available when
3407                   <acronym class="acronym">BIND</acronym> 9 is compiled with the
3408                   <strong class="userinput"><code>--enable-filter-aaaa</code></strong> option on the
3409                   "configure" command line.  It is intended to help the
3410                   transition from IPv4 to IPv6 by not giving IPv6 addresses
3411                   to DNS clients unless they have connections to the IPv6
3412                   Internet.  This is not recommended unless absolutely
3413                   necessary.  The default is <strong class="userinput"><code>no</code></strong>.
3414                   The <span><strong class="command">filter-aaaa-on-v4</strong></span> option
3415                   may also be specified in <span><strong class="command">view</strong></span> statements
3416                   to override the global <span><strong class="command">filter-aaaa-on-v4</strong></span>
3417                   option.
3418                 </p>
3419 <p>
3420                   If <strong class="userinput"><code>yes</code></strong>,
3421                   the DNS client is at an IPv4 address, in <span><strong class="command">filter-aaaa</strong></span>,
3422                   and if the response does not include DNSSEC signatures,
3423                   then all AAAA records are deleted from the response.
3424                   This filtering applies to all responses and not only
3425                   authoritative responses.
3426                 </p>
3427 <p>
3428                   If <strong class="userinput"><code>break-dnssec</code></strong>,
3429                   then AAAA records are deleted even when dnssec is enabled.
3430                   As suggested by the name, this makes the response not verify,
3431                   because the DNSSEC protocol is designed detect deletions.
3432                 </p>
3433 <p>
3434                   This mechanism can erroneously cause other servers to
3435                   not give AAAA records to their clients.
3436                   A recursing server with both IPv6 and IPv4 network connections
3437                   that queries an authoritative server using this mechanism
3438                   via IPv4 will be denied AAAA records even if its client is
3439                   using IPv6.
3440                 </p>
3441 <p>
3442                   This mechanism is applied to authoritative as well as
3443                   non-authoritative records.
3444                   A client using IPv4 that is not allowed recursion can
3445                   erroneously be given AAAA records because the server is not
3446                   allowed to check for A records.
3447                 </p>
3448 <p>
3449                   Some AAAA records are given to IPv4 clients in glue records.
3450                   IPv4 clients that are servers can then erroneously
3451                   answer requests for AAAA records received via IPv4.
3452                 </p>
3453 </dd>
3454 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
3455 <dd>
3456 <p>
3457                   When <strong class="userinput"><code>yes</code></strong> and the server loads a new version of a master
3458                   zone from its zone file or receives a new version of a slave
3459                   file by a non-incremental zone transfer, it will compare
3460                   the new version to the previous one and calculate a set
3461                   of differences.  The differences are then logged in the
3462                   zone's journal file such that the changes can be transmitted
3463                   to downstream slaves as an incremental zone transfer.
3464                 </p>
3465 <p>
3466                   By allowing incremental zone transfers to be used for
3467                   non-dynamic zones, this option saves bandwidth at the
3468                   expense of increased CPU and memory consumption at the
3469                   master.
3470                   In particular, if the new version of a zone is completely
3471                   different from the previous one, the set of differences
3472                   will be of a size comparable to the combined size of the
3473                   old and new zone version, and the server will need to
3474                   temporarily allocate memory to hold this complete
3475                   difference set.
3476                 </p>
3477 <p><span><strong class="command">ixfr-from-differences</strong></span>
3478                   also accepts <span><strong class="command">master</strong></span> and
3479                   <span><strong class="command">slave</strong></span> at the view and options
3480                   levels which causes
3481                   <span><strong class="command">ixfr-from-differences</strong></span> to be enabled for
3482                   all <span><strong class="command">master</strong></span> or
3483                   <span><strong class="command">slave</strong></span> zones respectively.
3484                   It is off by default.
3485                 </p>
3486 </dd>
3487 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
3488 <dd><p>
3489                   This should be set when you have multiple masters for a zone
3490                   and the
3491                   addresses refer to different machines.  If <strong class="userinput"><code>yes</code></strong>, <span><strong class="command">named</strong></span> will
3492                   not log
3493                   when the serial number on the master is less than what <span><strong class="command">named</strong></span>
3494                   currently
3495                   has.  The default is <strong class="userinput"><code>no</code></strong>.
3496                 </p></dd>
3497 <dt><span class="term"><span><strong class="command">dnssec-enable</strong></span></span></dt>
3498 <dd><p>
3499                   Enable DNSSEC support in <span><strong class="command">named</strong></span>.  Unless set to <strong class="userinput"><code>yes</code></strong>,
3500                   <span><strong class="command">named</strong></span> behaves as if it does not support DNSSEC.
3501                   The default is <strong class="userinput"><code>yes</code></strong>.
3502                 </p></dd>
3503 <dt><span class="term"><span><strong class="command">dnssec-validation</strong></span></span></dt>
3504 <dd><p>
3505                   Enable DNSSEC validation in <span><strong class="command">named</strong></span>.
3506                   Note <span><strong class="command">dnssec-enable</strong></span> also needs to be
3507                   set to <strong class="userinput"><code>yes</code></strong> to be effective.
3508                   If set to <strong class="userinput"><code>no</code></strong>, DNSSEC validation
3509                   is disabled.  If set to <strong class="userinput"><code>auto</code></strong>,
3510                   DNSSEC validation is enabled, and a default
3511                   trust-anchor for the DNS root zone is used.  If set to
3512                   <strong class="userinput"><code>yes</code></strong>, DNSSEC validation is enabled,
3513                   but a trust anchor must be manually configured using
3514                   a <span><strong class="command">trusted-keys</strong></span> or
3515                   <span><strong class="command">managed-keys</strong></span> statement.  The default
3516                   is <strong class="userinput"><code>yes</code></strong>.
3517                 </p></dd>
3518 <dt><span class="term"><span><strong class="command">dnssec-accept-expired</strong></span></span></dt>
3519 <dd><p>
3520                   Accept expired signatures when verifying DNSSEC signatures.
3521                   The default is <strong class="userinput"><code>no</code></strong>.
3522                   Setting this option to <strong class="userinput"><code>yes</code></strong>
3523                   leaves <span><strong class="command">named</strong></span> vulnerable to
3524                   replay attacks.
3525                 </p></dd>
3526 <dt><span class="term"><span><strong class="command">querylog</strong></span></span></dt>
3527 <dd><p>
3528                   Specify whether query logging should be started when <span><strong class="command">named</strong></span>
3529                   starts.
3530                   If <span><strong class="command">querylog</strong></span> is not specified,
3531                   then the query logging
3532                   is determined by the presence of the logging category <span><strong class="command">queries</strong></span>.
3533                 </p></dd>
3534 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
3535 <dd>
3536 <p>
3537                   This option is used to restrict the character set and syntax
3538                   of
3539                   certain domain names in master files and/or DNS responses
3540                   received
3541                   from the network.  The default varies according to usage
3542                   area.  For
3543                   <span><strong class="command">master</strong></span> zones the default is <span><strong class="command">fail</strong></span>.
3544                   For <span><strong class="command">slave</strong></span> zones the default
3545                   is <span><strong class="command">warn</strong></span>.
3546                   For answers received from the network (<span><strong class="command">response</strong></span>)
3547                   the default is <span><strong class="command">ignore</strong></span>.
3548                 </p>
3549 <p>
3550                   The rules for legal hostnames and mail domains are derived
3551                   from RFC 952 and RFC 821 as modified by RFC 1123.
3552                 </p>
3553 <p><span><strong class="command">check-names</strong></span>
3554                   applies to the owner names of A, AAAA and MX records.
3555                   It also applies to the domain names in the RDATA of NS, SOA,
3556                   MX, and SRV records.
3557                   It also applies to the RDATA of PTR records where the owner
3558                   name indicated that it is a reverse lookup of a hostname
3559                   (the owner name ends in IN-ADDR.ARPA, IP6.ARPA, or IP6.INT).
3560                 </p>
3561 </dd>
3562 <dt><span class="term"><span><strong class="command">check-dup-records</strong></span></span></dt>
3563 <dd><p>
3564                   Check master zones for records that are treated as different
3565                   by DNSSEC but are semantically equal in plain DNS.  The
3566                   default is to <span><strong class="command">warn</strong></span>.  Other possible
3567                   values are <span><strong class="command">fail</strong></span> and
3568                   <span><strong class="command">ignore</strong></span>.
3569                 </p></dd>
3570 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
3571 <dd><p>
3572                   Check whether the MX record appears to refer to a IP address.
3573                   The default is to <span><strong class="command">warn</strong></span>.  Other possible
3574                   values are <span><strong class="command">fail</strong></span> and
3575                   <span><strong class="command">ignore</strong></span>.
3576                 </p></dd>
3577 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
3578 <dd><p>
3579                   This option is used to check for non-terminal wildcards.
3580                   The use of non-terminal wildcards is almost always as a
3581                   result of a failure
3582                   to understand the wildcard matching algorithm (RFC 1034).
3583                   This option
3584                   affects master zones.  The default (<span><strong class="command">yes</strong></span>) is to check
3585                   for non-terminal wildcards and issue a warning.
3586                 </p></dd>
3587 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
3588 <dd>
3589 <p>
3590                   Perform post load zone integrity checks on master
3591                   zones.  This checks that MX and SRV records refer
3592                   to address (A or AAAA) records and that glue
3593                   address records exist for delegated zones.  For
3594                   MX and SRV records only in-zone hostnames are
3595                   checked (for out-of-zone hostnames use
3596                   <span><strong class="command">named-checkzone</strong></span>).
3597                   For NS records only names below top of zone are
3598                   checked (for out-of-zone names and glue consistency
3599                   checks use <span><strong class="command">named-checkzone</strong></span>).
3600                   The default is <span><strong class="command">yes</strong></span>.
3601                 </p>
3602 <p>
3603                   Check that the two forms of Sender Policy Framework
3604                   records (TXT records starting with "v=spf1" and SPF) either
3605                   both exist or both don't exist.  Warnings are
3606                   emitted it they don't and be suppressed with
3607                   <span><strong class="command">check-spf</strong></span>.
3608                 </p>
3609 </dd>
3610 <dt><span class="term"><span><strong class="command">check-mx-cname</strong></span></span></dt>
3611 <dd><p>
3612                   If <span><strong class="command">check-integrity</strong></span> is set then
3613                   fail, warn or ignore MX records that refer
3614                   to CNAMES.  The default is to <span><strong class="command">warn</strong></span>.
3615                 </p></dd>
3616 <dt><span class="term"><span><strong class="command">check-srv-cname</strong></span></span></dt>
3617 <dd><p>
3618                   If <span><strong class="command">check-integrity</strong></span> is set then
3619                   fail, warn or ignore SRV records that refer
3620                   to CNAMES.  The default is to <span><strong class="command">warn</strong></span>.
3621                 </p></dd>
3622 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
3623 <dd><p>
3624                   When performing integrity checks, also check that
3625                   sibling glue exists.  The default is <span><strong class="command">yes</strong></span>.
3626                 </p></dd>
3627 <dt><span class="term"><span><strong class="command">check-spf</strong></span></span></dt>
3628 <dd><p>
3629                   When performing integrity checks, check that the
3630                   two forms of Sender Policy Framwork records (TXT
3631                   records starting with "v=spf1" and SPF) both exist
3632                   or both don't exist and issue a warning if not
3633                   met.  The default is <span><strong class="command">warn</strong></span>.
3634                 </p></dd>
3635 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
3636 <dd><p>
3637                   When returning authoritative negative responses to
3638                   SOA queries set the TTL of the SOA record returned in
3639                   the authority section to zero.
3640                   The default is <span><strong class="command">yes</strong></span>.
3641                 </p></dd>
3642 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl-cache</strong></span></span></dt>
3643 <dd><p>
3644                   When caching a negative response to a SOA query
3645                   set the TTL to zero.
3646                   The default is <span><strong class="command">no</strong></span>.
3647                 </p></dd>
3648 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
3649 <dd>
3650 <p>
3651                   When set to the default value of <code class="literal">yes</code>,
3652                   check the KSK bit in each key to determine how the key
3653                   should be used when generating RRSIGs for a secure zone.
3654                 </p>
3655 <p>
3656                   Ordinarily, zone-signing keys (that is, keys without the
3657                   KSK bit set) are used to sign the entire zone, while
3658                   key-signing keys (keys with the KSK bit set) are only
3659                   used to sign the DNSKEY RRset at the zone apex.
3660                   However, if this option is set to <code class="literal">no</code>,
3661                   then the KSK bit is ignored; KSKs are treated as if they
3662                   were ZSKs and are used to sign the entire zone.  This is
3663                   similar to the <span><strong class="command">dnssec-signzone -z</strong></span>
3664                   command line option.
3665                 </p>
3666 <p>
3667                   When this option is set to <code class="literal">yes</code>, there
3668                   must be at least two active keys for every algorithm
3669                   represented in the DNSKEY RRset: at least one KSK and one
3670                   ZSK per algorithm.  If there is any algorithm for which
3671                   this requirement is not met, this option will be ignored
3672                   for that algorithm.
3673                 </p>
3674 </dd>
3675 <dt><span class="term"><span><strong class="command">dnssec-dnskey-kskonly</strong></span></span></dt>
3676 <dd>
3677 <p>
3678                   When this option and <span><strong class="command">update-check-ksk</strong></span>
3679                   are both set to <code class="literal">yes</code>, only key-signing
3680                   keys (that is, keys with the KSK bit set) will be used
3681                   to sign the DNSKEY RRset at the zone apex.  Zone-signing
3682                   keys (keys without the KSK bit set) will be used to sign
3683                   the remainder of the zone, but not the DNSKEY RRset.
3684                   This is similar to the
3685                   <span><strong class="command">dnssec-signzone -x</strong></span> command line option.
3686                 </p>
3687 <p>
3688                   The default is <span><strong class="command">no</strong></span>.  If
3689                   <span><strong class="command">update-check-ksk</strong></span> is set to
3690                   <code class="literal">no</code>, this option is ignored.
3691                 </p>
3692 </dd>
3693 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
3694 <dd><p>
3695                   Try to refresh the zone using TCP if UDP queries fail.
3696                   For BIND 8 compatibility, the default is
3697                   <span><strong class="command">yes</strong></span>.
3698                 </p></dd>
3699 <dt><span class="term"><span><strong class="command">dnssec-secure-to-insecure</strong></span></span></dt>
3700 <dd>
3701 <p>
3702                   Allow a dynamic zone to transition from secure to
3703                   insecure (i.e., signed to unsigned) by deleting all
3704                   of the DNSKEY records.  The default is <span><strong class="command">no</strong></span>.
3705                   If set to <span><strong class="command">yes</strong></span>, and if the DNSKEY RRset
3706                   at the zone apex is deleted, all RRSIG and NSEC records
3707                   will be removed from the zone as well.
3708                 </p>
3709 <p>
3710                   If the zone uses NSEC3, then it is also necessary to
3711                   delete the NSEC3PARAM RRset from the zone apex; this will
3712                   cause the removal of all corresponding NSEC3 records.
3713                   (It is expected that this requirement will be eliminated
3714                   in a future release.)
3715                 </p>
3716 <p>
3717                   Note that if a zone has been configured with
3718                   <span><strong class="command">auto-dnssec maintain</strong></span> and the
3719                   private keys remain accessible in the key repository,
3720                   then the zone will be automatically signed again the
3721                   next time <span><strong class="command">named</strong></span> is started.
3722                 </p>
3723 </dd>
3724 </dl></div>
3725 </div>
3726 <div class="sect3" lang="en">
3727 <div class="titlepage"><div><div><h4 class="title">
3728 <a name="id2582843"></a>Forwarding</h4></div></div></div>
3729 <p>
3730             The forwarding facility can be used to create a large site-wide
3731             cache on a few servers, reducing traffic over links to external
3732             name servers. It can also be used to allow queries by servers that
3733             do not have direct access to the Internet, but wish to look up
3734             exterior
3735             names anyway. Forwarding occurs only on those queries for which
3736             the server is not authoritative and does not have the answer in
3737             its cache.
3738           </p>
3739 <div class="variablelist"><dl>
3740 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
3741 <dd><p>
3742                   This option is only meaningful if the
3743                   forwarders list is not empty. A value of <code class="varname">first</code>,
3744                   the default, causes the server to query the forwarders
3745                   first &#8212; and
3746                   if that doesn't answer the question, the server will then
3747                   look for
3748                   the answer itself. If <code class="varname">only</code> is
3749                   specified, the
3750                   server will only query the forwarders.
3751                 </p></dd>
3752 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
3753 <dd><p>
3754                   Specifies the IP addresses to be used
3755                   for forwarding. The default is the empty list (no
3756                   forwarding).
3757                 </p></dd>
3758 </dl></div>
3759 <p>
3760             Forwarding can also be configured on a per-domain basis, allowing
3761             for the global forwarding options to be overridden in a variety
3762             of ways. You can set particular domains to use different
3763             forwarders,
3764             or have a different <span><strong class="command">forward only/first</strong></span> behavior,
3765             or not forward at all, see <a href="Bv9ARM.ch06.html#zone_statement_grammar" title="zone
3766             Statement Grammar">the section called &#8220;<span><strong class="command">zone</strong></span>
3767             Statement Grammar&#8221;</a>.
3768           </p>
3769 </div>
3770 <div class="sect3" lang="en">
3771 <div class="titlepage"><div><div><h4 class="title">
3772 <a name="id2582970"></a>Dual-stack Servers</h4></div></div></div>
3773 <p>
3774             Dual-stack servers are used as servers of last resort to work
3775             around
3776             problems in reachability due the lack of support for either IPv4
3777             or IPv6
3778             on the host machine.
3779           </p>
3780 <div class="variablelist"><dl>
3781 <dt><span class="term"><span><strong class="command">dual-stack-servers</strong></span></span></dt>
3782 <dd><p>
3783                   Specifies host names or addresses of machines with access to
3784                   both IPv4 and IPv6 transports. If a hostname is used, the
3785                   server must be able
3786                   to resolve the name using only the transport it has.  If the
3787                   machine is dual
3788                   stacked, then the <span><strong class="command">dual-stack-servers</strong></span> have no effect unless
3789                   access to a transport has been disabled on the command line
3790                   (e.g. <span><strong class="command">named -4</strong></span>).
3791                 </p></dd>
3792 </dl></div>
3793 </div>
3794 <div class="sect3" lang="en">
3795 <div class="titlepage"><div><div><h4 class="title">
3796 <a name="access_control"></a>Access Control</h4></div></div></div>
3797 <p>
3798             Access to the server can be restricted based on the IP address
3799             of the requesting system. See <a href="Bv9ARM.ch06.html#address_match_lists" title="Address Match Lists">the section called &#8220;Address Match Lists&#8221;</a> for
3800             details on how to specify IP address lists.
3801           </p>
3802 <div class="variablelist"><dl>
3803 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
3804 <dd><p>
3805                   Specifies which hosts are allowed to
3806                   notify this server, a slave, of zone changes in addition
3807                   to the zone masters.
3808                   <span><strong class="command">allow-notify</strong></span> may also be
3809                   specified in the
3810                   <span><strong class="command">zone</strong></span> statement, in which case
3811                   it overrides the
3812                   <span><strong class="command">options allow-notify</strong></span>
3813                   statement.  It is only meaningful
3814                   for a slave zone.  If not specified, the default is to
3815                   process notify messages
3816                   only from a zone's master.
3817                 </p></dd>
3818 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
3819 <dd>
3820 <p>
3821                   Specifies which hosts are allowed to ask ordinary
3822                   DNS questions. <span><strong class="command">allow-query</strong></span> may
3823                   also be specified in the <span><strong class="command">zone</strong></span>
3824                   statement, in which case it overrides the
3825                   <span><strong class="command">options allow-query</strong></span> statement.
3826                   If not specified, the default is to allow queries
3827                   from all hosts.
3828                 </p>
3829 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3830 <h3 class="title">Note</h3>
3831 <p>
3832                     <span><strong class="command">allow-query-cache</strong></span> is now
3833                     used to specify access to the cache.
3834                   </p>
3835 </div>
3836 </dd>
3837 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
3838 <dd>
3839 <p>
3840                   Specifies which local addresses can accept ordinary
3841                   DNS questions. This makes it possible, for instance,
3842                   to allow queries on internal-facing interfaces but
3843                   disallow them on external-facing ones, without
3844                   necessarily knowing the internal network's addresses.
3845                 </p>
3846 <p>
3847                   Note that <span><strong class="command">allow-query-on</strong></span> is only
3848                   checked for queries that are permitted by
3849                   <span><strong class="command">allow-query</strong></span>.  A query must be
3850                   allowed by both ACLs, or it will be refused.
3851                 </p>
3852 <p>
3853                   <span><strong class="command">allow-query-on</strong></span> may
3854                   also be specified in the <span><strong class="command">zone</strong></span>
3855                   statement, in which case it overrides the
3856                   <span><strong class="command">options allow-query-on</strong></span> statement.
3857                 </p>
3858 <p>
3859                   If not specified, the default is to allow queries
3860                   on all addresses.
3861                 </p>
3862 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3863 <h3 class="title">Note</h3>
3864 <p>
3865                     <span><strong class="command">allow-query-cache</strong></span> is
3866                     used to specify access to the cache.
3867                   </p>
3868 </div>
3869 </dd>
3870 <dt><span class="term"><span><strong class="command">allow-query-cache</strong></span></span></dt>
3871 <dd><p>
3872                   Specifies which hosts are allowed to get answers
3873                   from the cache.  If <span><strong class="command">allow-query-cache</strong></span>
3874                   is not set then <span><strong class="command">allow-recursion</strong></span>
3875                   is used if set, otherwise <span><strong class="command">allow-query</strong></span>
3876                   is used if set unless <span><strong class="command">recursion no;</strong></span> is
3877                   set in which case <span><strong class="command">none;</strong></span> is used,
3878                   otherwise the default (<span><strong class="command">localnets;</strong></span>
3879                   <span><strong class="command">localhost;</strong></span>) is used.
3880                 </p></dd>
3881 <dt><span class="term"><span><strong class="command">allow-query-cache-on</strong></span></span></dt>
3882 <dd><p>
3883                   Specifies which local addresses can give answers
3884                   from the cache.  If not specified, the default is
3885                   to allow cache queries on any address,
3886                   <span><strong class="command">localnets</strong></span> and
3887                   <span><strong class="command">localhost</strong></span>.
3888                 </p></dd>
3889 <dt><span class="term"><span><strong class="command">allow-recursion</strong></span></span></dt>
3890 <dd><p>
3891                   Specifies which hosts are allowed to make recursive
3892                   queries through this server. If
3893                   <span><strong class="command">allow-recursion</strong></span> is not set
3894                   then <span><strong class="command">allow-query-cache</strong></span> is
3895                   used if set, otherwise <span><strong class="command">allow-query</strong></span>
3896                   is used if set, otherwise the default
3897                   (<span><strong class="command">localnets;</strong></span>
3898                   <span><strong class="command">localhost;</strong></span>) is used.
3899                 </p></dd>
3900 <dt><span class="term"><span><strong class="command">allow-recursion-on</strong></span></span></dt>
3901 <dd><p>
3902                   Specifies which local addresses can accept recursive
3903                   queries.  If not specified, the default is to allow
3904                   recursive queries on all addresses.
3905                 </p></dd>
3906 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
3907 <dd><p>
3908                   Specifies which hosts are allowed to
3909                   submit Dynamic DNS updates for master zones. The default is
3910                   to deny
3911                   updates from all hosts.  Note that allowing updates based
3912                   on the requestor's IP address is insecure; see
3913                   <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called &#8220;Dynamic Update Security&#8221;</a> for details.
3914                 </p></dd>
3915 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
3916 <dd>
3917 <p>
3918                   Specifies which hosts are allowed to
3919                   submit Dynamic DNS updates to slave zones to be forwarded to
3920                   the
3921                   master.  The default is <strong class="userinput"><code>{ none; }</code></strong>,
3922                   which
3923                   means that no update forwarding will be performed.  To
3924                   enable
3925                   update forwarding, specify
3926                   <strong class="userinput"><code>allow-update-forwarding { any; };</code></strong>.
3927                   Specifying values other than <strong class="userinput"><code>{ none; }</code></strong> or
3928                   <strong class="userinput"><code>{ any; }</code></strong> is usually
3929                   counterproductive, since
3930                   the responsibility for update access control should rest
3931                   with the
3932                   master server, not the slaves.
3933                 </p>
3934 <p>
3935                   Note that enabling the update forwarding feature on a slave
3936                   server
3937                   may expose master servers relying on insecure IP address
3938                   based
3939                   access control to attacks; see <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called &#8220;Dynamic Update Security&#8221;</a>
3940                   for more details.
3941                 </p>
3942 </dd>
3943 <dt><span class="term"><span><strong class="command">allow-v6-synthesis</strong></span></span></dt>
3944 <dd><p>
3945                   This option was introduced for the smooth transition from
3946                   AAAA
3947                   to A6 and from "nibble labels" to binary labels.
3948                   However, since both A6 and binary labels were then
3949                   deprecated,
3950                   this option was also deprecated.
3951                   It is now ignored with some warning messages.
3952                 </p></dd>
3953 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
3954 <dd><p>
3955                   Specifies which hosts are allowed to
3956                   receive zone transfers from the server. <span><strong class="command">allow-transfer</strong></span> may
3957                   also be specified in the <span><strong class="command">zone</strong></span>
3958                   statement, in which
3959                   case it overrides the <span><strong class="command">options allow-transfer</strong></span> statement.
3960                   If not specified, the default is to allow transfers to all
3961                   hosts.
3962                 </p></dd>
3963 <dt><span class="term"><span><strong class="command">blackhole</strong></span></span></dt>
3964 <dd><p>
3965                   Specifies a list of addresses that the
3966                   server will not accept queries from or use to resolve a
3967                   query. Queries
3968                   from these addresses will not be responded to. The default
3969                   is <strong class="userinput"><code>none</code></strong>.
3970                 </p></dd>
3971 <dt><span class="term"><span><strong class="command">filter-aaaa</strong></span></span></dt>
3972 <dd><p>
3973                   Specifies a list of addresses to which
3974                   <span><strong class="command">filter-aaaa-on-v4</strong></span>
3975                   is applies.  The default is <strong class="userinput"><code>any</code></strong>.
3976                 </p></dd>
3977 <dt><span class="term"><span><strong class="command">resolver-query-timeout</strong></span></span></dt>
3978 <dd><p>
3979                   The amount of time the resolver will spend attempting
3980                   to resolve a recursive query before failing.  The default
3981                   and minimum is <code class="literal">10</code> and the maximum is
3982                   <code class="literal">30</code>.  Setting it to <code class="literal">0</code>
3983                   will result in the default being used.
3984                 </p></dd>
3985 </dl></div>
3986 </div>
3987 <div class="sect3" lang="en">
3988 <div class="titlepage"><div><div><h4 class="title">
3989 <a name="id2583600"></a>Interfaces</h4></div></div></div>
3990 <p>
3991             The interfaces and ports that the server will answer queries
3992             from may be specified using the <span><strong class="command">listen-on</strong></span> option. <span><strong class="command">listen-on</strong></span> takes
3993             an optional port and an <code class="varname">address_match_list</code>.
3994             The server will listen on all interfaces allowed by the address
3995             match list. If a port is not specified, port 53 will be used.
3996           </p>
3997 <p>
3998             Multiple <span><strong class="command">listen-on</strong></span> statements are
3999             allowed.
4000             For example,
4001           </p>
4002 <pre class="programlisting">listen-on { 5.6.7.8; };
4003 listen-on port 1234 { !1.2.3.4; 1.2/16; };
4004 </pre>
4005 <p>
4006             will enable the name server on port 53 for the IP address
4007             5.6.7.8, and on port 1234 of an address on the machine in net
4008             1.2 that is not 1.2.3.4.
4009           </p>
4010 <p>
4011             If no <span><strong class="command">listen-on</strong></span> is specified, the
4012             server will listen on port 53 on all IPv4 interfaces.
4013           </p>
4014 <p>
4015             The <span><strong class="command">listen-on-v6</strong></span> option is used to
4016             specify the interfaces and the ports on which the server will
4017             listen
4018             for incoming queries sent using IPv6.
4019           </p>
4020 <p>
4021             When </p>
4022 <pre class="programlisting">{ any; }</pre>
4023 <p> is
4024             specified
4025             as the <code class="varname">address_match_list</code> for the
4026             <span><strong class="command">listen-on-v6</strong></span> option,
4027             the server does not bind a separate socket to each IPv6 interface
4028             address as it does for IPv4 if the operating system has enough API
4029             support for IPv6 (specifically if it conforms to RFC 3493 and RFC
4030             3542).
4031             Instead, it listens on the IPv6 wildcard address.
4032             If the system only has incomplete API support for IPv6, however,
4033             the behavior is the same as that for IPv4.
4034           </p>
4035 <p>
4036             A list of particular IPv6 addresses can also be specified, in
4037             which case
4038             the server listens on a separate socket for each specified
4039             address,
4040             regardless of whether the desired API is supported by the system.
4041           </p>
4042 <p>
4043             Multiple <span><strong class="command">listen-on-v6</strong></span> options can
4044             be used.
4045             For example,
4046           </p>
4047 <pre class="programlisting">listen-on-v6 { any; };
4048 listen-on-v6 port 1234 { !2001:db8::/32; any; };
4049 </pre>
4050 <p>
4051             will enable the name server on port 53 for any IPv6 addresses
4052             (with a single wildcard socket),
4053             and on port 1234 of IPv6 addresses that is not in the prefix
4054             2001:db8::/32 (with separate sockets for each matched address.)
4055           </p>
4056 <p>
4057             To make the server not listen on any IPv6 address, use
4058           </p>
4059 <pre class="programlisting">listen-on-v6 { none; };
4060 </pre>
4061 <p>
4062             If no <span><strong class="command">listen-on-v6</strong></span> option is
4063             specified, the server will not listen on any IPv6 address
4064             unless <span><strong class="command">-6</strong></span> is specified when <span><strong class="command">named</strong></span> is
4065             invoked.  If <span><strong class="command">-6</strong></span> is specified then
4066             <span><strong class="command">named</strong></span> will listen on port 53 on all IPv6 interfaces by default.
4067           </p>
4068 </div>
4069 <div class="sect3" lang="en">
4070 <div class="titlepage"><div><div><h4 class="title">
4071 <a name="query_address"></a>Query Address</h4></div></div></div>
4072 <p>
4073             If the server doesn't know the answer to a question, it will
4074             query other name servers. <span><strong class="command">query-source</strong></span> specifies
4075             the address and port used for such queries. For queries sent over
4076             IPv6, there is a separate <span><strong class="command">query-source-v6</strong></span> option.
4077             If <span><strong class="command">address</strong></span> is <span><strong class="command">*</strong></span> (asterisk) or is omitted,
4078             a wildcard IP address (<span><strong class="command">INADDR_ANY</strong></span>)
4079             will be used.
4080           </p>
4081 <p>
4082             If <span><strong class="command">port</strong></span> is <span><strong class="command">*</strong></span> or is omitted,
4083             a random port number from a pre-configured
4084             range is picked up and will be used for each query.
4085             The port range(s) is that specified in
4086             the <span><strong class="command">use-v4-udp-ports</strong></span> (for IPv4)
4087             and <span><strong class="command">use-v6-udp-ports</strong></span> (for IPv6)
4088             options, excluding the ranges specified in
4089             the <span><strong class="command">avoid-v4-udp-ports</strong></span>
4090             and <span><strong class="command">avoid-v6-udp-ports</strong></span> options, respectively.
4091           </p>
4092 <p>
4093             The defaults of the <span><strong class="command">query-source</strong></span> and
4094             <span><strong class="command">query-source-v6</strong></span> options
4095             are:
4096           </p>
4097 <pre class="programlisting">query-source address * port *;
4098 query-source-v6 address * port *;
4099 </pre>
4100 <p>
4101             If <span><strong class="command">use-v4-udp-ports</strong></span> or
4102             <span><strong class="command">use-v6-udp-ports</strong></span> is unspecified,
4103             <span><strong class="command">named</strong></span> will check if the operating
4104             system provides a programming interface to retrieve the
4105             system's default range for ephemeral ports.
4106             If such an interface is available,
4107             <span><strong class="command">named</strong></span> will use the corresponding system
4108             default range; otherwise, it will use its own defaults:
4109          </p>
4110 <pre class="programlisting">use-v4-udp-ports { range 1024 65535; };
4111 use-v6-udp-ports { range 1024 65535; };
4112 </pre>
4113 <p>
4114             Note: make sure the ranges be sufficiently large for
4115             security.  A desirable size depends on various parameters,
4116             but we generally recommend it contain at least 16384 ports
4117             (14 bits of entropy).
4118             Note also that the system's default range when used may be
4119             too small for this purpose, and that the range may even be
4120             changed while <span><strong class="command">named</strong></span> is running; the new
4121             range will automatically be applied when <span><strong class="command">named</strong></span>
4122             is reloaded.
4123             It is encouraged to
4124             configure <span><strong class="command">use-v4-udp-ports</strong></span> and
4125             <span><strong class="command">use-v6-udp-ports</strong></span> explicitly so that the
4126             ranges are sufficiently large and are reasonably
4127             independent from the ranges used by other applications.
4128           </p>
4129 <p>
4130             Note: the operational configuration
4131             where <span><strong class="command">named</strong></span> runs may prohibit the use
4132             of some ports.  For example, UNIX systems will not allow
4133             <span><strong class="command">named</strong></span> running without a root privilege
4134             to use ports less than 1024.
4135             If such ports are included in the specified (or detected)
4136             set of query ports, the corresponding query attempts will
4137             fail, resulting in resolution failures or delay.
4138             It is therefore important to configure the set of ports
4139             that can be safely used in the expected operational environment.
4140           </p>
4141 <p>
4142             The defaults of the <span><strong class="command">avoid-v4-udp-ports</strong></span> and
4143             <span><strong class="command">avoid-v6-udp-ports</strong></span> options
4144             are:
4145           </p>
4146 <pre class="programlisting">avoid-v4-udp-ports {};
4147 avoid-v6-udp-ports {};
4148 </pre>
4149 <p>
4150             Note: BIND 9.5.0 introduced
4151             the <span><strong class="command">use-queryport-pool</strong></span>
4152             option to support a pool of such random ports, but this
4153             option is now obsolete because reusing the same ports in
4154             the pool may not be sufficiently secure.
4155             For the same reason, it is generally strongly discouraged to
4156             specify a particular port for the
4157             <span><strong class="command">query-source</strong></span> or
4158             <span><strong class="command">query-source-v6</strong></span> options;
4159             it implicitly disables the use of randomized port numbers.
4160           </p>
4161 <div class="variablelist"><dl>
4162 <dt><span class="term"><span><strong class="command">use-queryport-pool</strong></span></span></dt>
4163 <dd><p>
4164                   This option is obsolete.
4165                 </p></dd>
4166 <dt><span class="term"><span><strong class="command">queryport-pool-ports</strong></span></span></dt>
4167 <dd><p>
4168                   This option is obsolete.
4169                 </p></dd>
4170 <dt><span class="term"><span><strong class="command">queryport-pool-updateinterval</strong></span></span></dt>
4171 <dd><p>
4172                   This option is obsolete.
4173                 </p></dd>
4174 </dl></div>
4175 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4176 <h3 class="title">Note</h3>
4177 <p>
4178               The address specified in the <span><strong class="command">query-source</strong></span> option
4179               is used for both UDP and TCP queries, but the port applies only
4180               to UDP queries.  TCP queries always use a random
4181               unprivileged port.
4182             </p>
4183 </div>
4184 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4185 <h3 class="title">Note</h3>
4186 <p>
4187               Solaris 2.5.1 and earlier does not support setting the source
4188               address for TCP sockets.
4189             </p>
4190 </div>
4191 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4192 <h3 class="title">Note</h3>
4193 <p>
4194               See also <span><strong class="command">transfer-source</strong></span> and
4195               <span><strong class="command">notify-source</strong></span>.
4196             </p>
4197 </div>
4198 </div>
4199 <div class="sect3" lang="en">
4200 <div class="titlepage"><div><div><h4 class="title">
4201 <a name="zone_transfers"></a>Zone Transfers</h4></div></div></div>
4202 <p>
4203             <acronym class="acronym">BIND</acronym> has mechanisms in place to
4204             facilitate zone transfers
4205             and set limits on the amount of load that transfers place on the
4206             system. The following options apply to zone transfers.
4207           </p>
4208 <div class="variablelist"><dl>
4209 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
4210 <dd><p>
4211                   Defines a global list of IP addresses of name servers
4212                   that are also sent NOTIFY messages whenever a fresh copy of
4213                   the
4214                   zone is loaded, in addition to the servers listed in the
4215                   zone's NS records.
4216                   This helps to ensure that copies of the zones will
4217                   quickly converge on stealth servers.
4218                   Optionally, a port may be specified with each
4219                   <span><strong class="command">also-notify</strong></span> address to send
4220                   the notify messages to a port other than the
4221                   default of 53.
4222                   If an <span><strong class="command">also-notify</strong></span> list
4223                   is given in a <span><strong class="command">zone</strong></span> statement,
4224                   it will override
4225                   the <span><strong class="command">options also-notify</strong></span>
4226                   statement. When a <span><strong class="command">zone notify</strong></span>
4227                   statement
4228                   is set to <span><strong class="command">no</strong></span>, the IP
4229                   addresses in the global <span><strong class="command">also-notify</strong></span> list will
4230                   not be sent NOTIFY messages for that zone. The default is
4231                   the empty
4232                   list (no global notification list).
4233                 </p></dd>
4234 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
4235 <dd><p>
4236                   Inbound zone transfers running longer than
4237                   this many minutes will be terminated. The default is 120
4238                   minutes
4239                   (2 hours).  The maximum value is 28 days (40320 minutes).
4240                 </p></dd>
4241 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
4242 <dd><p>
4243                   Inbound zone transfers making no progress
4244                   in this many minutes will be terminated. The default is 60
4245                   minutes
4246                   (1 hour).  The maximum value is 28 days (40320 minutes).
4247                 </p></dd>
4248 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
4249 <dd><p>
4250                   Outbound zone transfers running longer than
4251                   this many minutes will be terminated. The default is 120
4252                   minutes
4253                   (2 hours).  The maximum value is 28 days (40320 minutes).
4254                 </p></dd>
4255 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
4256 <dd><p>
4257                   Outbound zone transfers making no progress
4258                   in this many minutes will be terminated.  The default is 60
4259                   minutes (1
4260                   hour).  The maximum value is 28 days (40320 minutes).
4261                 </p></dd>
4262 <dt><span class="term"><span><strong class="command">serial-query-rate</strong></span></span></dt>
4263 <dd>
4264 <p>
4265                   Slave servers will periodically query master
4266                   servers to find out if zone serial numbers have
4267                   changed. Each such query uses a minute amount of
4268                   the slave server's network bandwidth.  To limit
4269                   the amount of bandwidth used, BIND 9 limits the
4270                   rate at which queries are sent.  The value of the
4271                   <span><strong class="command">serial-query-rate</strong></span> option, an
4272                   integer, is the maximum number of queries sent
4273                   per second.  The default is 20.
4274                 </p>
4275 <p>
4276                   In addition to controlling the rate SOA refresh
4277                   queries are issued at
4278                   <span><strong class="command">serial-query-rate</strong></span> also controls
4279                   the rate at which NOTIFY messages are sent from
4280                   both master and slave zones.
4281                 </p>
4282 </dd>
4283 <dt><span class="term"><span><strong class="command">serial-queries</strong></span></span></dt>
4284 <dd><p>
4285                   In BIND 8, the <span><strong class="command">serial-queries</strong></span>
4286                   option
4287                   set the maximum number of concurrent serial number queries
4288                   allowed to be outstanding at any given time.
4289                   BIND 9 does not limit the number of outstanding
4290                   serial queries and ignores the <span><strong class="command">serial-queries</strong></span> option.
4291                   Instead, it limits the rate at which the queries are sent
4292                   as defined using the <span><strong class="command">serial-query-rate</strong></span> option.
4293                 </p></dd>
4294 <dt><span class="term"><span><strong class="command">transfer-format</strong></span></span></dt>
4295 <dd><p>
4296                   Zone transfers can be sent using two different formats,
4297                   <span><strong class="command">one-answer</strong></span> and
4298                   <span><strong class="command">many-answers</strong></span>.
4299                   The <span><strong class="command">transfer-format</strong></span> option is used
4300                   on the master server to determine which format it sends.
4301                   <span><strong class="command">one-answer</strong></span> uses one DNS message per
4302                   resource record transferred.
4303                   <span><strong class="command">many-answers</strong></span> packs as many resource
4304                   records as possible into a message.
4305                   <span><strong class="command">many-answers</strong></span> is more efficient, but is
4306                   only supported by relatively new slave servers,
4307                   such as <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
4308                   8.x and <acronym class="acronym">BIND</acronym> 4.9.5 onwards.
4309                   The <span><strong class="command">many-answers</strong></span> format is also supported by
4310                   recent Microsoft Windows nameservers.
4311                   The default is <span><strong class="command">many-answers</strong></span>.
4312                   <span><strong class="command">transfer-format</strong></span> may be overridden on a
4313                   per-server basis by using the <span><strong class="command">server</strong></span>
4314                   statement.
4315                 </p></dd>
4316 <dt><span class="term"><span><strong class="command">transfers-in</strong></span></span></dt>
4317 <dd><p>
4318                   The maximum number of inbound zone transfers
4319                   that can be running concurrently. The default value is <code class="literal">10</code>.
4320                   Increasing <span><strong class="command">transfers-in</strong></span> may
4321                   speed up the convergence
4322                   of slave zones, but it also may increase the load on the
4323                   local system.
4324                 </p></dd>
4325 <dt><span class="term"><span><strong class="command">transfers-out</strong></span></span></dt>
4326 <dd><p>
4327                   The maximum number of outbound zone transfers
4328                   that can be running concurrently. Zone transfer requests in
4329                   excess
4330                   of the limit will be refused. The default value is <code class="literal">10</code>.
4331                 </p></dd>
4332 <dt><span class="term"><span><strong class="command">transfers-per-ns</strong></span></span></dt>
4333 <dd><p>
4334                   The maximum number of inbound zone transfers
4335                   that can be concurrently transferring from a given remote
4336                   name server.
4337                   The default value is <code class="literal">2</code>.
4338                   Increasing <span><strong class="command">transfers-per-ns</strong></span>
4339                   may
4340                   speed up the convergence of slave zones, but it also may
4341                   increase
4342                   the load on the remote name server. <span><strong class="command">transfers-per-ns</strong></span> may
4343                   be overridden on a per-server basis by using the <span><strong class="command">transfers</strong></span> phrase
4344                   of the <span><strong class="command">server</strong></span> statement.
4345                 </p></dd>
4346 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
4347 <dd>
4348 <p><span><strong class="command">transfer-source</strong></span>
4349                   determines which local address will be bound to IPv4
4350                   TCP connections used to fetch zones transferred
4351                   inbound by the server.  It also determines the
4352                   source IPv4 address, and optionally the UDP port,
4353                   used for the refresh queries and forwarded dynamic
4354                   updates.  If not set, it defaults to a system
4355                   controlled value which will usually be the address
4356                   of the interface "closest to" the remote end. This
4357                   address must appear in the remote end's
4358                   <span><strong class="command">allow-transfer</strong></span> option for the
4359                   zone being transferred, if one is specified. This
4360                   statement sets the
4361                   <span><strong class="command">transfer-source</strong></span> for all zones,
4362                   but can be overridden on a per-view or per-zone
4363                   basis by including a
4364                   <span><strong class="command">transfer-source</strong></span> statement within
4365                   the <span><strong class="command">view</strong></span> or
4366                   <span><strong class="command">zone</strong></span> block in the configuration
4367                   file.
4368                 </p>
4369 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4370 <h3 class="title">Note</h3>
4371 <p>
4372                     Solaris 2.5.1 and earlier does not support setting the
4373                     source address for TCP sockets.
4374                   </p>
4375 </div>
4376 </dd>
4377 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
4378 <dd><p>
4379                   The same as <span><strong class="command">transfer-source</strong></span>,
4380                   except zone transfers are performed using IPv6.
4381                 </p></dd>
4382 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
4383 <dd>
4384 <p>
4385                   An alternate transfer source if the one listed in
4386                   <span><strong class="command">transfer-source</strong></span> fails and
4387                   <span><strong class="command">use-alt-transfer-source</strong></span> is
4388                   set.
4389                 </p>
4390 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4391 <h3 class="title">Note</h3>
4392                   If you do not wish the alternate transfer source
4393                   to be used, you should set
4394                   <span><strong class="command">use-alt-transfer-source</strong></span>
4395                   appropriately and you should not depend upon
4396                   getting an answer back to the first refresh
4397                   query.
4398                 </div>
4399 </dd>
4400 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
4401 <dd><p>
4402                   An alternate transfer source if the one listed in
4403                   <span><strong class="command">transfer-source-v6</strong></span> fails and
4404                   <span><strong class="command">use-alt-transfer-source</strong></span> is
4405                   set.
4406                 </p></dd>
4407 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
4408 <dd><p>
4409                   Use the alternate transfer sources or not.  If views are
4410                   specified this defaults to <span><strong class="command">no</strong></span>
4411                   otherwise it defaults to
4412                   <span><strong class="command">yes</strong></span> (for BIND 8
4413                   compatibility).
4414                 </p></dd>
4415 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
4416 <dd>
4417 <p><span><strong class="command">notify-source</strong></span>
4418                   determines which local source address, and
4419                   optionally UDP port, will be used to send NOTIFY
4420                   messages.  This address must appear in the slave
4421                   server's <span><strong class="command">masters</strong></span> zone clause or
4422                   in an <span><strong class="command">allow-notify</strong></span> clause.  This
4423                   statement sets the <span><strong class="command">notify-source</strong></span>
4424                   for all zones, but can be overridden on a per-zone or
4425                   per-view basis by including a
4426                   <span><strong class="command">notify-source</strong></span> statement within
4427                   the <span><strong class="command">zone</strong></span> or
4428                   <span><strong class="command">view</strong></span> block in the configuration
4429                   file.
4430                 </p>
4431 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4432 <h3 class="title">Note</h3>
4433 <p>
4434                     Solaris 2.5.1 and earlier does not support setting the
4435                     source address for TCP sockets.
4436                   </p>
4437 </div>
4438 </dd>
4439 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
4440 <dd><p>
4441                   Like <span><strong class="command">notify-source</strong></span>,
4442                   but applies to notify messages sent to IPv6 addresses.
4443                 </p></dd>
4444 </dl></div>
4445 </div>
4446 <div class="sect3" lang="en">
4447 <div class="titlepage"><div><div><h4 class="title">
4448 <a name="id2584741"></a>UDP Port Lists</h4></div></div></div>
4449 <p>
4450             <span><strong class="command">use-v4-udp-ports</strong></span>,
4451             <span><strong class="command">avoid-v4-udp-ports</strong></span>,
4452             <span><strong class="command">use-v6-udp-ports</strong></span>, and
4453             <span><strong class="command">avoid-v6-udp-ports</strong></span>
4454             specify a list of IPv4 and IPv6 UDP ports that will be
4455             used or not used as source ports for UDP messages.
4456             See <a href="Bv9ARM.ch06.html#query_address" title="Query Address">the section called &#8220;Query Address&#8221;</a> about how the
4457             available ports are determined.
4458             For example, with the following configuration
4459           </p>
4460 <pre class="programlisting">
4461 use-v6-udp-ports { range 32768 65535; };
4462 avoid-v6-udp-ports { 40000; range 50000 60000; };
4463 </pre>
4464 <p>
4465              UDP ports of IPv6 messages sent
4466              from <span><strong class="command">named</strong></span> will be in one
4467              of the following ranges: 32768 to 39999, 40001 to 49999,
4468              and 60001 to 65535.
4469            </p>
4470 <p>
4471              <span><strong class="command">avoid-v4-udp-ports</strong></span> and
4472              <span><strong class="command">avoid-v6-udp-ports</strong></span> can be used
4473              to prevent <span><strong class="command">named</strong></span> from choosing as its random source port a
4474              port that is blocked by your firewall or a port that is
4475              used by other applications;
4476              if a query went out with a source port blocked by a
4477              firewall, the
4478              answer would not get by the firewall and the name server would
4479              have to query again.
4480              Note: the desired range can also be represented only with
4481              <span><strong class="command">use-v4-udp-ports</strong></span> and
4482              <span><strong class="command">use-v6-udp-ports</strong></span>, and the
4483              <span><strong class="command">avoid-</strong></span> options are redundant in that
4484              sense; they are provided for backward compatibility and
4485              to possibly simplify the port specification.
4486            </p>
4487 </div>
4488 <div class="sect3" lang="en">
4489 <div class="titlepage"><div><div><h4 class="title">
4490 <a name="id2584801"></a>Operating System Resource Limits</h4></div></div></div>
4491 <p>
4492             The server's usage of many system resources can be limited.
4493             Scaled values are allowed when specifying resource limits.  For
4494             example, <span><strong class="command">1G</strong></span> can be used instead of
4495             <span><strong class="command">1073741824</strong></span> to specify a limit of
4496             one
4497             gigabyte. <span><strong class="command">unlimited</strong></span> requests
4498             unlimited use, or the
4499             maximum available amount. <span><strong class="command">default</strong></span>
4500             uses the limit
4501             that was in force when the server was started. See the description
4502             of <span><strong class="command">size_spec</strong></span> in <a href="Bv9ARM.ch06.html#configuration_file_elements" title="Configuration File Elements">the section called &#8220;Configuration File Elements&#8221;</a>.
4503           </p>
4504 <p>
4505             The following options set operating system resource limits for
4506             the name server process.  Some operating systems don't support
4507             some or
4508             any of the limits. On such systems, a warning will be issued if
4509             the
4510             unsupported limit is used.
4511           </p>
4512 <div class="variablelist"><dl>
4513 <dt><span class="term"><span><strong class="command">coresize</strong></span></span></dt>
4514 <dd><p>
4515                   The maximum size of a core dump. The default
4516                   is <code class="literal">default</code>.
4517                 </p></dd>
4518 <dt><span class="term"><span><strong class="command">datasize</strong></span></span></dt>
4519 <dd><p>
4520                   The maximum amount of data memory the server
4521                   may use. The default is <code class="literal">default</code>.
4522                   This is a hard limit on server memory usage.
4523                   If the server attempts to allocate memory in excess of this
4524                   limit, the allocation will fail, which may in turn leave
4525                   the server unable to perform DNS service.  Therefore,
4526                   this option is rarely useful as a way of limiting the
4527                   amount of memory used by the server, but it can be used
4528                   to raise an operating system data size limit that is
4529                   too small by default.  If you wish to limit the amount
4530                   of memory used by the server, use the
4531                   <span><strong class="command">max-cache-size</strong></span> and
4532                   <span><strong class="command">recursive-clients</strong></span>
4533                   options instead.
4534                 </p></dd>
4535 <dt><span class="term"><span><strong class="command">files</strong></span></span></dt>
4536 <dd><p>
4537                   The maximum number of files the server
4538                   may have open concurrently. The default is <code class="literal">unlimited</code>.
4539                 </p></dd>
4540 <dt><span class="term"><span><strong class="command">stacksize</strong></span></span></dt>
4541 <dd><p>
4542                   The maximum amount of stack memory the server
4543                   may use. The default is <code class="literal">default</code>.
4544                 </p></dd>
4545 </dl></div>
4546 </div>
4547 <div class="sect3" lang="en">
4548 <div class="titlepage"><div><div><h4 class="title">
4549 <a name="server_resource_limits"></a>Server  Resource Limits</h4></div></div></div>
4550 <p>
4551             The following options set limits on the server's
4552             resource consumption that are enforced internally by the
4553             server rather than the operating system.
4554           </p>
4555 <div class="variablelist"><dl>
4556 <dt><span class="term"><span><strong class="command">max-ixfr-log-size</strong></span></span></dt>
4557 <dd><p>
4558                   This option is obsolete; it is accepted
4559                   and ignored for BIND 8 compatibility.  The option
4560                   <span><strong class="command">max-journal-size</strong></span> performs a
4561                   similar function in BIND 9.
4562                 </p></dd>
4563 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
4564 <dd><p>
4565                   Sets a maximum size for each journal file
4566                   (see <a href="Bv9ARM.ch04.html#journal" title="The journal file">the section called &#8220;The journal file&#8221;</a>).  When the journal file
4567                   approaches
4568                   the specified size, some of the oldest transactions in the
4569                   journal
4570                   will be automatically removed.  The default is
4571                   <code class="literal">unlimited</code>.
4572                   This may also be set on a per-zone basis.
4573                 </p></dd>
4574 <dt><span class="term"><span><strong class="command">host-statistics-max</strong></span></span></dt>
4575 <dd><p>
4576                   In BIND 8, specifies the maximum number of host statistics
4577                   entries to be kept.
4578                   Not implemented in BIND 9.
4579                 </p></dd>
4580 <dt><span class="term"><span><strong class="command">recursive-clients</strong></span></span></dt>
4581 <dd><p>
4582                   The maximum number of simultaneous recursive lookups
4583                   the server will perform on behalf of clients.  The default
4584                   is
4585                   <code class="literal">1000</code>.  Because each recursing
4586                   client uses a fair
4587                   bit of memory, on the order of 20 kilobytes, the value of
4588                   the
4589                   <span><strong class="command">recursive-clients</strong></span> option may
4590                   have to be decreased
4591                   on hosts with limited memory.
4592                 </p></dd>
4593 <dt><span class="term"><span><strong class="command">tcp-clients</strong></span></span></dt>
4594 <dd><p>
4595                   The maximum number of simultaneous client TCP
4596                   connections that the server will accept.
4597                   The default is <code class="literal">100</code>.
4598                 </p></dd>
4599 <dt><span class="term"><span><strong class="command">reserved-sockets</strong></span></span></dt>
4600 <dd>
4601 <p>
4602                   The number of file descriptors reserved for TCP, stdio,
4603                   etc.  This needs to be big enough to cover the number of
4604                   interfaces <span><strong class="command">named</strong></span> listens on, <span><strong class="command">tcp-clients</strong></span> as well as
4605                   to provide room for outgoing TCP queries and incoming zone
4606                   transfers.  The default is <code class="literal">512</code>.
4607                   The minimum value is <code class="literal">128</code> and the
4608                   maximum value is <code class="literal">128</code> less than
4609                   maxsockets (-S).  This option may be removed in the future.
4610                 </p>
4611 <p>
4612                   This option has little effect on Windows.
4613                 </p>
4614 </dd>
4615 <dt><span class="term"><span><strong class="command">max-cache-size</strong></span></span></dt>
4616 <dd><p>
4617                   The maximum amount of memory to use for the
4618                   server's cache, in bytes.
4619                   When the amount of data in the cache
4620                   reaches this limit, the server will cause records to expire
4621                   prematurely based on an LRU based strategy so that
4622                   the limit is not exceeded.
4623                   A value of 0 is special, meaning that
4624                   records are purged from the cache only when their
4625                   TTLs expire.
4626                   Another special keyword <strong class="userinput"><code>unlimited</code></strong>
4627                   means the maximum value of 32-bit unsigned integers
4628                   (0xffffffff), which may not have the same effect as
4629                   0 on machines that support more than 32 bits of
4630                   memory space.
4631                   Any positive values less than 2MB will be ignored reset
4632                   to 2MB.
4633                   In a server with multiple views, the limit applies
4634                   separately to the cache of each view.
4635                   The default is 0.
4636                 </p></dd>
4637 <dt><span class="term"><span><strong class="command">tcp-listen-queue</strong></span></span></dt>
4638 <dd><p>
4639                   The listen queue depth.  The default and minimum is 10.
4640                   If the kernel supports the accept filter "dataready" this
4641                   also controls how
4642                   many TCP connections that will be queued in kernel space
4643                   waiting for
4644                   some data before being passed to accept.  Nonzero values
4645                   less than 10 will be silently raised. A value of 0 may also
4646                   be used; on most platforms this sets the listen queue
4647                   length to a system-defined default value.
4648                 </p></dd>
4649 </dl></div>
4650 </div>
4651 <div class="sect3" lang="en">
4652 <div class="titlepage"><div><div><h4 class="title">
4653 <a name="id2585155"></a>Periodic Task Intervals</h4></div></div></div>
4654 <div class="variablelist"><dl>
4655 <dt><span class="term"><span><strong class="command">cleaning-interval</strong></span></span></dt>
4656 <dd><p>
4657                   This interval is effectively obsolete.  Previously,
4658                   the server would remove expired resource records
4659                   from the cache every <span><strong class="command">cleaning-interval</strong></span> minutes.
4660                   <acronym class="acronym">BIND</acronym> 9 now manages cache
4661                   memory in a more sophisticated manner and does not
4662                   rely on the periodic cleaning any more.
4663                   Specifying this option therefore has no effect on
4664                   the server's behavior.
4665                 </p></dd>
4666 <dt><span class="term"><span><strong class="command">heartbeat-interval</strong></span></span></dt>
4667 <dd><p>
4668                   The server will perform zone maintenance tasks
4669                   for all zones marked as <span><strong class="command">dialup</strong></span> whenever this
4670                   interval expires. The default is 60 minutes. Reasonable
4671                   values are up
4672                   to 1 day (1440 minutes).  The maximum value is 28 days
4673                   (40320 minutes).
4674                   If set to 0, no zone maintenance for these zones will occur.
4675                 </p></dd>
4676 <dt><span class="term"><span><strong class="command">interface-interval</strong></span></span></dt>
4677 <dd><p>
4678                   The server will scan the network interface list
4679                   every <span><strong class="command">interface-interval</strong></span>
4680                   minutes. The default
4681                   is 60 minutes. The maximum value is 28 days (40320 minutes).
4682                   If set to 0, interface scanning will only occur when
4683                   the configuration file is  loaded. After the scan, the
4684                   server will
4685                   begin listening for queries on any newly discovered
4686                   interfaces (provided they are allowed by the
4687                   <span><strong class="command">listen-on</strong></span> configuration), and
4688                   will
4689                   stop listening on interfaces that have gone away.
4690                 </p></dd>
4691 <dt><span class="term"><span><strong class="command">statistics-interval</strong></span></span></dt>
4692 <dd>
4693 <p>
4694                   Name server statistics will be logged
4695                   every <span><strong class="command">statistics-interval</strong></span>
4696                   minutes. The default is
4697                   60. The maximum value is 28 days (40320 minutes).
4698                   If set to 0, no statistics will be logged.
4699                   </p>
4700 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4701 <h3 class="title">Note</h3>
4702 <p>
4703                     Not yet implemented in
4704                     <acronym class="acronym">BIND</acronym> 9.
4705                   </p>
4706 </div>
4707 </dd>
4708 </dl></div>
4709 </div>
4710 <div class="sect3" lang="en">
4711 <div class="titlepage"><div><div><h4 class="title">
4712 <a name="topology"></a>Topology</h4></div></div></div>
4713 <p>
4714             All other things being equal, when the server chooses a name
4715             server
4716             to query from a list of name servers, it prefers the one that is
4717             topologically closest to itself. The <span><strong class="command">topology</strong></span> statement
4718             takes an <span><strong class="command">address_match_list</strong></span> and
4719             interprets it
4720             in a special way. Each top-level list element is assigned a
4721             distance.
4722             Non-negated elements get a distance based on their position in the
4723             list, where the closer the match is to the start of the list, the
4724             shorter the distance is between it and the server. A negated match
4725             will be assigned the maximum distance from the server. If there
4726             is no match, the address will get a distance which is further than
4727             any non-negated list element, and closer than any negated element.
4728             For example,
4729           </p>
4730 <pre class="programlisting">topology {
4731     10/8;
4732     !1.2.3/24;
4733     { 1.2/16; 3/8; };
4734 };</pre>
4735 <p>
4736             will prefer servers on network 10 the most, followed by hosts
4737             on network 1.2.0.0 (netmask 255.255.0.0) and network 3, with the
4738             exception of hosts on network 1.2.3 (netmask 255.255.255.0), which
4739             is preferred least of all.
4740           </p>
4741 <p>
4742             The default topology is
4743           </p>
4744 <pre class="programlisting">    topology { localhost; localnets; };
4745 </pre>
4746 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4747 <h3 class="title">Note</h3>
4748 <p>
4749               The <span><strong class="command">topology</strong></span> option
4750               is not implemented in <acronym class="acronym">BIND</acronym> 9.
4751             </p>
4752 </div>
4753 </div>
4754 <div class="sect3" lang="en">
4755 <div class="titlepage"><div><div><h4 class="title">
4756 <a name="the_sortlist_statement"></a>The <span><strong class="command">sortlist</strong></span> Statement</h4></div></div></div>
4757 <p>
4758             The response to a DNS query may consist of multiple resource
4759             records (RRs) forming a resource records set (RRset).
4760             The name server will normally return the
4761             RRs within the RRset in an indeterminate order
4762             (but see the <span><strong class="command">rrset-order</strong></span>
4763             statement in <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called &#8220;RRset Ordering&#8221;</a>).
4764             The client resolver code should rearrange the RRs as appropriate,
4765             that is, using any addresses on the local net in preference to
4766             other addresses.
4767             However, not all resolvers can do this or are correctly
4768             configured.
4769             When a client is using a local server, the sorting can be performed
4770             in the server, based on the client's address. This only requires
4771             configuring the name servers, not all the clients.
4772           </p>
4773 <p>
4774             The <span><strong class="command">sortlist</strong></span> statement (see below)
4775             takes
4776             an <span><strong class="command">address_match_list</strong></span> and
4777             interprets it even
4778             more specifically than the <span><strong class="command">topology</strong></span>
4779             statement
4780             does (<a href="Bv9ARM.ch06.html#topology" title="Topology">the section called &#8220;Topology&#8221;</a>).
4781             Each top level statement in the <span><strong class="command">sortlist</strong></span> must
4782             itself be an explicit <span><strong class="command">address_match_list</strong></span> with
4783             one or two elements. The first element (which may be an IP
4784             address,
4785             an IP prefix, an ACL name or a nested <span><strong class="command">address_match_list</strong></span>)
4786             of each top level list is checked against the source address of
4787             the query until a match is found.
4788           </p>
4789 <p>
4790             Once the source address of the query has been matched, if
4791             the top level statement contains only one element, the actual
4792             primitive
4793             element that matched the source address is used to select the
4794             address
4795             in the response to move to the beginning of the response. If the
4796             statement is a list of two elements, then the second element is
4797             treated the same as the <span><strong class="command">address_match_list</strong></span> in
4798             a <span><strong class="command">topology</strong></span> statement. Each top
4799             level element
4800             is assigned a distance and the address in the response with the
4801             minimum
4802             distance is moved to the beginning of the response.
4803           </p>
4804 <p>
4805             In the following example, any queries received from any of
4806             the addresses of the host itself will get responses preferring
4807             addresses
4808             on any of the locally connected networks. Next most preferred are
4809             addresses
4810             on the 192.168.1/24 network, and after that either the
4811             192.168.2/24
4812             or
4813             192.168.3/24 network with no preference shown between these two
4814             networks. Queries received from a host on the 192.168.1/24 network
4815             will prefer other addresses on that network to the 192.168.2/24
4816             and
4817             192.168.3/24 networks. Queries received from a host on the
4818             192.168.4/24
4819             or the 192.168.5/24 network will only prefer other addresses on
4820             their directly connected networks.
4821           </p>
4822 <pre class="programlisting">sortlist {
4823     // IF the local host
4824     // THEN first fit on the following nets
4825     { localhost;
4826         { localnets;
4827             192.168.1/24;
4828             { 192.168.2/24; 192.168.3/24; }; }; };
4829     // IF on class C 192.168.1 THEN use .1, or .2 or .3
4830     { 192.168.1/24;
4831         { 192.168.1/24;
4832             { 192.168.2/24; 192.168.3/24; }; }; };
4833     // IF on class C 192.168.2 THEN use .2, or .1 or .3
4834     { 192.168.2/24;
4835         { 192.168.2/24;
4836             { 192.168.1/24; 192.168.3/24; }; }; };
4837     // IF on class C 192.168.3 THEN use .3, or .1 or .2
4838     { 192.168.3/24;
4839         { 192.168.3/24;
4840             { 192.168.1/24; 192.168.2/24; }; }; };
4841     // IF .4 or .5 THEN prefer that net
4842     { { 192.168.4/24; 192.168.5/24; };
4843     };
4844 };</pre>
4845 <p>
4846             The following example will give reasonable behavior for the
4847             local host and hosts on directly connected networks. It is similar
4848             to the behavior of the address sort in <acronym class="acronym">BIND</acronym> 4.9.x. Responses sent
4849             to queries from the local host will favor any of the directly
4850             connected
4851             networks. Responses sent to queries from any other hosts on a
4852             directly
4853             connected network will prefer addresses on that same network.
4854             Responses
4855             to other queries will not be sorted.
4856           </p>
4857 <pre class="programlisting">sortlist {
4858            { localhost; localnets; };
4859            { localnets; };
4860 };
4861 </pre>
4862 </div>
4863 <div class="sect3" lang="en">
4864 <div class="titlepage"><div><div><h4 class="title">
4865 <a name="rrset_ordering"></a>RRset Ordering</h4></div></div></div>
4866 <p>
4867             When multiple records are returned in an answer it may be
4868             useful to configure the order of the records placed into the
4869             response.
4870             The <span><strong class="command">rrset-order</strong></span> statement permits
4871             configuration
4872             of the ordering of the records in a multiple record response.
4873             See also the <span><strong class="command">sortlist</strong></span> statement,
4874             <a href="Bv9ARM.ch06.html#the_sortlist_statement" title="The sortlist Statement">the section called &#8220;The <span><strong class="command">sortlist</strong></span> Statement&#8221;</a>.
4875           </p>
4876 <p>
4877             An <span><strong class="command">order_spec</strong></span> is defined as
4878             follows:
4879           </p>
4880 <p>
4881             [<span class="optional">class <em class="replaceable"><code>class_name</code></em></span>]
4882             [<span class="optional">type <em class="replaceable"><code>type_name</code></em></span>]
4883             [<span class="optional">name <em class="replaceable"><code>"domain_name"</code></em></span>]
4884             order <em class="replaceable"><code>ordering</code></em>
4885           </p>
4886 <p>
4887             If no class is specified, the default is <span><strong class="command">ANY</strong></span>.
4888             If no type is specified, the default is <span><strong class="command">ANY</strong></span>.
4889             If no name is specified, the default is "<span><strong class="command">*</strong></span>" (asterisk).
4890           </p>
4891 <p>
4892             The legal values for <span><strong class="command">ordering</strong></span> are:
4893           </p>
4894 <div class="informaltable"><table border="1">
4895 <colgroup>
4896 <col>
4897 <col>
4898 </colgroup>
4899 <tbody>
4900 <tr>
4901 <td>
4902                     <p><span><strong class="command">fixed</strong></span></p>
4903                   </td>
4904 <td>
4905                     <p>
4906                       Records are returned in the order they
4907                       are defined in the zone file.
4908                     </p>
4909                   </td>
4910 </tr>
4911 <tr>
4912 <td>
4913                     <p><span><strong class="command">random</strong></span></p>
4914                   </td>
4915 <td>
4916                     <p>
4917                       Records are returned in some random order.
4918                     </p>
4919                   </td>
4920 </tr>
4921 <tr>
4922 <td>
4923                     <p><span><strong class="command">cyclic</strong></span></p>
4924                   </td>
4925 <td>
4926                     <p>
4927                       Records are returned in a cyclic round-robin order.
4928                     </p>
4929                     <p>
4930                       If <acronym class="acronym">BIND</acronym> is configured with the
4931                       "--enable-fixed-rrset" option at compile time, then
4932                       the initial ordering of the RRset will match the
4933                       one specified in the zone file.
4934                     </p>
4935                   </td>
4936 </tr>
4937 </tbody>
4938 </table></div>
4939 <p>
4940             For example:
4941           </p>
4942 <pre class="programlisting">rrset-order {
4943    class IN type A name "host.example.com" order random;
4944    order cyclic;
4945 };
4946 </pre>
4947 <p>
4948             will cause any responses for type A records in class IN that
4949             have "<code class="literal">host.example.com</code>" as a
4950             suffix, to always be returned
4951             in random order. All other records are returned in cyclic order.
4952           </p>
4953 <p>
4954             If multiple <span><strong class="command">rrset-order</strong></span> statements
4955             appear,
4956             they are not combined &#8212; the last one applies.
4957           </p>
4958 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4959 <h3 class="title">Note</h3>
4960 <p>
4961               In this release of <acronym class="acronym">BIND</acronym> 9, the
4962               <span><strong class="command">rrset-order</strong></span> statement does not support
4963               "fixed" ordering by default.  Fixed ordering can be enabled
4964               at compile time by specifying "--enable-fixed-rrset" on
4965               the "configure" command line.
4966             </p>
4967 </div>
4968 </div>
4969 <div class="sect3" lang="en">
4970 <div class="titlepage"><div><div><h4 class="title">
4971 <a name="tuning"></a>Tuning</h4></div></div></div>
4972 <div class="variablelist"><dl>
4973 <dt><span class="term"><span><strong class="command">lame-ttl</strong></span></span></dt>
4974 <dd>
4975 <p>
4976                   Sets the number of seconds to cache a
4977                   lame server indication. 0 disables caching. (This is
4978                   <span class="bold"><strong>NOT</strong></span> recommended.)
4979                   The default is <code class="literal">600</code> (10 minutes) and the
4980                   maximum value is
4981                   <code class="literal">1800</code> (30 minutes).
4982                 </p>
4983 <p>
4984                   Lame-ttl also controls the amount of time DNSSEC
4985                   validation failures are cached.  There is a minimum
4986                   of 30 seconds applied to bad cache entries if the
4987                   lame-ttl is set to less than 30 seconds.
4988                 </p>
4989 </dd>
4990 <dt><span class="term"><span><strong class="command">max-ncache-ttl</strong></span></span></dt>
4991 <dd><p>
4992                   To reduce network traffic and increase performance,
4993                   the server stores negative answers. <span><strong class="command">max-ncache-ttl</strong></span> is
4994                   used to set a maximum retention time for these answers in
4995                   the server
4996                   in seconds. The default
4997                   <span><strong class="command">max-ncache-ttl</strong></span> is <code class="literal">10800</code> seconds (3 hours).
4998                   <span><strong class="command">max-ncache-ttl</strong></span> cannot exceed
4999                   7 days and will
5000                   be silently truncated to 7 days if set to a greater value.
5001                 </p></dd>
5002 <dt><span class="term"><span><strong class="command">max-cache-ttl</strong></span></span></dt>
5003 <dd><p>
5004                   Sets the maximum time for which the server will
5005                   cache ordinary (positive) answers. The default is
5006                   one week (7 days).
5007                   A value of zero may cause all queries to return
5008                   SERVFAIL, because of lost caches of intermediate
5009                   RRsets (such as NS and glue AAAA/A records) in the
5010                   resolution process.
5011                 </p></dd>
5012 <dt><span class="term"><span><strong class="command">min-roots</strong></span></span></dt>
5013 <dd>
5014 <p>
5015                   The minimum number of root servers that
5016                   is required for a request for the root servers to be
5017                   accepted. The default
5018                   is <strong class="userinput"><code>2</code></strong>.
5019                 </p>
5020 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
5021 <h3 class="title">Note</h3>
5022 <p>
5023                     Not implemented in <acronym class="acronym">BIND</acronym> 9.
5024                   </p>
5025 </div>
5026 </dd>
5027 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
5028 <dd>
5029 <p>
5030                   Specifies the number of days into the future when
5031                   DNSSEC signatures automatically generated as a
5032                   result of dynamic updates (<a href="Bv9ARM.ch04.html#dynamic_update" title="Dynamic Update">the section called &#8220;Dynamic Update&#8221;</a>) will expire.  There
5033                   is an optional second field which specifies how
5034                   long before expiry that the signatures will be
5035                   regenerated.  If not specified, the signatures will
5036                   be regenerated at 1/4 of base interval.  The second
5037                   field is specified in days if the base interval is
5038                   greater than 7 days otherwise it is specified in hours.
5039                   The default base interval is <code class="literal">30</code> days
5040                   giving a re-signing interval of 7 1/2 days.  The maximum
5041                   values are 10 years (3660 days).
5042                 </p>
5043 <p>
5044                   The signature inception time is unconditionally
5045                   set to one hour before the current time to allow
5046                   for a limited amount of clock skew.
5047                 </p>
5048 <p>
5049                   The <span><strong class="command">sig-validity-interval</strong></span>
5050                   should be, at least, several multiples of the SOA
5051                   expire interval to allow for reasonable interaction
5052                   between the various timer and expiry dates.
5053                 </p>
5054 </dd>
5055 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
5056 <dd><p>
5057                   Specify the maximum number of nodes to be
5058                   examined in each quantum when signing a zone with
5059                   a new DNSKEY. The default is
5060                   <code class="literal">100</code>.
5061                 </p></dd>
5062 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
5063 <dd><p>
5064                   Specify a threshold number of signatures that
5065                   will terminate processing a quantum when signing
5066                   a zone with a new DNSKEY.  The default is
5067                   <code class="literal">10</code>.
5068                 </p></dd>
5069 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
5070 <dd>
5071 <p>
5072                   Specify a private RDATA type to be used when generating
5073                   key signing records.  The default is
5074                   <code class="literal">65534</code>.
5075                 </p>
5076 <p>
5077                   It is expected that this parameter may be removed
5078                   in a future version once there is a standard type.
5079                 </p>
5080 </dd>
5081 <dt>
5082 <span class="term"><span><strong class="command">min-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">max-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">min-retry-time</strong></span>, </span><span class="term"><span><strong class="command">max-retry-time</strong></span></span>
5083 </dt>
5084 <dd>
5085 <p>
5086                   These options control the server's behavior on refreshing a
5087                   zone
5088                   (querying for SOA changes) or retrying failed transfers.
5089                   Usually the SOA values for the zone are used, but these
5090                   values
5091                   are set by the master, giving slave server administrators
5092                   little
5093                   control over their contents.
5094                 </p>
5095 <p>
5096                   These options allow the administrator to set a minimum and
5097                   maximum
5098                   refresh and retry time either per-zone, per-view, or
5099                   globally.
5100                   These options are valid for slave and stub zones,
5101                   and clamp the SOA refresh and retry times to the specified
5102                   values.
5103                 </p>
5104 <p>
5105                   The following defaults apply.
5106                   <span><strong class="command">min-refresh-time</strong></span> 300 seconds,
5107                   <span><strong class="command">max-refresh-time</strong></span> 2419200 seconds
5108                   (4 weeks), <span><strong class="command">min-retry-time</strong></span> 500 seconds,
5109                   and <span><strong class="command">max-retry-time</strong></span> 1209600 seconds
5110                   (2 weeks).
5111                 </p>
5112 </dd>
5113 <dt><span class="term"><span><strong class="command">edns-udp-size</strong></span></span></dt>
5114 <dd>
5115 <p>
5116                   Sets the advertised EDNS UDP buffer size in bytes
5117                   to control the size of packets received.
5118                   Valid values are 512 to 4096 (values outside this range
5119                   will be silently adjusted).  The default value
5120                   is 4096.  The usual reason for setting
5121                   <span><strong class="command">edns-udp-size</strong></span> to a non-default
5122                   value is to get UDP answers to pass through broken
5123                   firewalls that block fragmented packets and/or
5124                   block UDP packets that are greater than 512 bytes.
5125                 </p>
5126 <p>
5127                   <span><strong class="command">named</strong></span> will fallback to using 512 bytes
5128                   if it get a series of timeout at the initial value.  512
5129                   bytes is not being offered to encourage sites to fix their
5130                   firewalls.  Small EDNS UDP sizes will result in the
5131                   excessive use of TCP.
5132                 </p>
5133 </dd>
5134 <dt><span class="term"><span><strong class="command">max-udp-size</strong></span></span></dt>
5135 <dd>
5136 <p>
5137                   Sets the maximum EDNS UDP message size
5138                   <span><strong class="command">named</strong></span> will send in bytes.
5139                   Valid values are 512 to 4096 (values outside this
5140                   range will be silently adjusted).  The default
5141                   value is 4096.  The usual reason for setting
5142                   <span><strong class="command">max-udp-size</strong></span> to a non-default
5143                   value is to get UDP answers to pass through broken
5144                   firewalls that block fragmented packets and/or
5145                   block UDP packets that are greater than 512 bytes.
5146                   This is independent of the advertised receive
5147                   buffer (<span><strong class="command">edns-udp-size</strong></span>).
5148                 </p>
5149 <p>
5150                   Setting this to a low value will encourage additional
5151                   TCP traffic to the nameserver.
5152                 </p>
5153 </dd>
5154 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
5155 <dd><p>Specifies
5156                   the file format of zone files (see
5157                   <a href="Bv9ARM.ch06.html#zonefile_format" title="Additional File Formats">the section called &#8220;Additional File Formats&#8221;</a>).
5158                   The default value is <code class="constant">text</code>, which is the
5159                   standard textual representation.  Files in other formats
5160                   than <code class="constant">text</code> are typically expected
5161                   to be generated by the <span><strong class="command">named-compilezone</strong></span> tool.
5162                   Note that when a zone file in a different format than
5163                   <code class="constant">text</code> is loaded, <span><strong class="command">named</strong></span>
5164                   may omit some of the checks which would be performed for a
5165                   file in the <code class="constant">text</code> format.  In particular,
5166                   <span><strong class="command">check-names</strong></span> checks do not apply
5167                   for the <code class="constant">raw</code> format.  This means
5168                   a zone file in the <code class="constant">raw</code> format
5169                   must be generated with the same check level as that
5170                   specified in the <span><strong class="command">named</strong></span> configuration
5171                   file.  This statement sets the
5172                   <span><strong class="command">masterfile-format</strong></span> for all zones,
5173                   but can be overridden on a per-zone or per-view basis
5174                   by including a <span><strong class="command">masterfile-format</strong></span>
5175                   statement within the <span><strong class="command">zone</strong></span> or
5176                   <span><strong class="command">view</strong></span> block in the configuration
5177                   file.
5178                 </p></dd>
5179 <dt>
5180 <a name="clients-per-query"></a><span class="term"><span><strong class="command">clients-per-query</strong></span>, </span><span class="term"><span><strong class="command">max-clients-per-query</strong></span></span>
5181 </dt>
5182 <dd>
5183 <p>These set the
5184                   initial value (minimum) and maximum number of recursive
5185                   simultaneous clients for any given query
5186                   (&lt;qname,qtype,qclass&gt;) that the server will accept
5187                   before dropping additional clients.  <span><strong class="command">named</strong></span> will attempt to
5188                   self tune this value and changes will be logged.  The
5189                   default values are 10 and 100.
5190                 </p>
5191 <p>
5192                   This value should reflect how many queries come in for
5193                   a given name in the time it takes to resolve that name.
5194                   If the number of queries exceed this value, <span><strong class="command">named</strong></span> will
5195                   assume that it is dealing with a non-responsive zone
5196                   and will drop additional queries.  If it gets a response
5197                   after dropping queries, it will raise the estimate.  The
5198                   estimate will then be lowered in 20 minutes if it has
5199                   remained unchanged.
5200                 </p>
5201 <p>
5202                   If <span><strong class="command">clients-per-query</strong></span> is set to zero,
5203                   then there is no limit on the number of clients per query
5204                   and no queries will be dropped.
5205                 </p>
5206 <p>
5207                   If <span><strong class="command">max-clients-per-query</strong></span> is set to zero,
5208                   then there is no upper bound other than imposed by
5209                   <span><strong class="command">recursive-clients</strong></span>.
5210                 </p>
5211 </dd>
5212 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
5213 <dd>
5214 <p>
5215                   The delay, in seconds, between sending sets of notify
5216                   messages for a zone.  The default is five (5) seconds.
5217                 </p>
5218 <p>
5219                   The overall rate that NOTIFY messages are sent for all
5220                   zones is controlled by <span><strong class="command">serial-query-rate</strong></span>.
5221                 </p>
5222 </dd>
5223 </dl></div>
5224 </div>
5225 <div class="sect3" lang="en">
5226 <div class="titlepage"><div><div><h4 class="title">
5227 <a name="builtin"></a>Built-in server information zones</h4></div></div></div>
5228 <p>
5229             The server provides some helpful diagnostic information
5230             through a number of built-in zones under the
5231             pseudo-top-level-domain <code class="literal">bind</code> in the
5232             <span><strong class="command">CHAOS</strong></span> class.  These zones are part
5233             of a
5234             built-in view (see <a href="Bv9ARM.ch06.html#view_statement_grammar" title="view Statement Grammar">the section called &#8220;<span><strong class="command">view</strong></span> Statement Grammar&#8221;</a>) of
5235             class
5236             <span><strong class="command">CHAOS</strong></span> which is separate from the
5237             default view of class <span><strong class="command">IN</strong></span>. Most global
5238             configuration options (<span><strong class="command">allow-query</strong></span>,
5239             etc) will apply to this view, but some are locally
5240             overridden: <span><strong class="command">notify</strong></span>,
5241             <span><strong class="command">recursion</strong></span> and
5242             <span><strong class="command">allow-new-zones</strong></span> are
5243             always set to <strong class="userinput"><code>no</code></strong>.
5244           </p>
5245 <p>
5246             If you need to disable these zones, use the options
5247             below, or hide the built-in <span><strong class="command">CHAOS</strong></span>
5248             view by
5249             defining an explicit view of class <span><strong class="command">CHAOS</strong></span>
5250             that matches all clients.
5251           </p>
5252 <div class="variablelist"><dl>
5253 <dt><span class="term"><span><strong class="command">version</strong></span></span></dt>
5254 <dd><p>
5255                   The version the server should report
5256                   via a query of the name <code class="literal">version.bind</code>
5257                   with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
5258                   The default is the real version number of this server.
5259                   Specifying <span><strong class="command">version none</strong></span>
5260                   disables processing of the queries.
5261                 </p></dd>
5262 <dt><span class="term"><span><strong class="command">hostname</strong></span></span></dt>
5263 <dd><p>
5264                   The hostname the server should report via a query of
5265                   the name <code class="filename">hostname.bind</code>
5266                   with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
5267                   This defaults to the hostname of the machine hosting the
5268                   name server as
5269                   found by the gethostname() function.  The primary purpose of such queries
5270                   is to
5271                   identify which of a group of anycast servers is actually
5272                   answering your queries.  Specifying <span><strong class="command">hostname none;</strong></span>
5273                   disables processing of the queries.
5274                 </p></dd>
5275 <dt><span class="term"><span><strong class="command">server-id</strong></span></span></dt>
5276 <dd><p>
5277                   The ID the server should report when receiving a Name
5278                   Server Identifier (NSID) query, or a query of the name
5279                   <code class="filename">ID.SERVER</code> with type
5280                   <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
5281                   The primary purpose of such queries is to
5282                   identify which of a group of anycast servers is actually
5283                   answering your queries.  Specifying <span><strong class="command">server-id none;</strong></span>
5284                   disables processing of the queries.
5285                   Specifying <span><strong class="command">server-id hostname;</strong></span> will cause <span><strong class="command">named</strong></span> to
5286                   use the hostname as found by the gethostname() function.
5287                   The default <span><strong class="command">server-id</strong></span> is <span><strong class="command">none</strong></span>.
5288                 </p></dd>
5289 </dl></div>
5290 </div>
5291 <div class="sect3" lang="en">
5292 <div class="titlepage"><div><div><h4 class="title">
5293 <a name="empty"></a>Built-in Empty Zones</h4></div></div></div>
5294 <p>
5295             Named has some built-in empty zones (SOA and NS records only).
5296             These are for zones that should normally be answered locally
5297             and which queries should not be sent to the Internet's root
5298             servers.  The official servers which cover these namespaces
5299             return NXDOMAIN responses to these queries.  In particular,
5300             these cover the reverse namespaces for addresses from
5301             RFC 1918, RFC 4193, RFC 5737 and RFC 6598.  They also include the
5302             reverse namespace for IPv6 local address (locally assigned),
5303             IPv6 link local addresses, the IPv6 loopback address and the
5304             IPv6 unknown address.
5305           </p>
5306 <p>
5307             Named will attempt to determine if a built-in zone already exists
5308             or is active (covered by a forward-only forwarding declaration)
5309             and will not create an empty zone in that case.
5310           </p>
5311 <p>
5312             The current list of empty zones is:
5313             </p>
5314 <div class="itemizedlist"><ul type="disc">
5315 <li>10.IN-ADDR.ARPA</li>
5316 <li>16.172.IN-ADDR.ARPA</li>
5317 <li>17.172.IN-ADDR.ARPA</li>
5318 <li>18.172.IN-ADDR.ARPA</li>
5319 <li>19.172.IN-ADDR.ARPA</li>
5320 <li>20.172.IN-ADDR.ARPA</li>
5321 <li>21.172.IN-ADDR.ARPA</li>
5322 <li>22.172.IN-ADDR.ARPA</li>
5323 <li>23.172.IN-ADDR.ARPA</li>
5324 <li>24.172.IN-ADDR.ARPA</li>
5325 <li>25.172.IN-ADDR.ARPA</li>
5326 <li>26.172.IN-ADDR.ARPA</li>
5327 <li>27.172.IN-ADDR.ARPA</li>
5328 <li>28.172.IN-ADDR.ARPA</li>
5329 <li>29.172.IN-ADDR.ARPA</li>
5330 <li>30.172.IN-ADDR.ARPA</li>
5331 <li>31.172.IN-ADDR.ARPA</li>
5332 <li>168.192.IN-ADDR.ARPA</li>
5333 <li>64.100.IN-ADDR.ARPA</li>
5334 <li>65.100.IN-ADDR.ARPA</li>
5335 <li>66.100.IN-ADDR.ARPA</li>
5336 <li>67.100.IN-ADDR.ARPA</li>
5337 <li>68.100.IN-ADDR.ARPA</li>
5338 <li>69.100.IN-ADDR.ARPA</li>
5339 <li>70.100.IN-ADDR.ARPA</li>
5340 <li>71.100.IN-ADDR.ARPA</li>
5341 <li>72.100.IN-ADDR.ARPA</li>
5342 <li>73.100.IN-ADDR.ARPA</li>
5343 <li>74.100.IN-ADDR.ARPA</li>
5344 <li>75.100.IN-ADDR.ARPA</li>
5345 <li>76.100.IN-ADDR.ARPA</li>
5346 <li>77.100.IN-ADDR.ARPA</li>
5347 <li>78.100.IN-ADDR.ARPA</li>
5348 <li>79.100.IN-ADDR.ARPA</li>
5349 <li>80.100.IN-ADDR.ARPA</li>
5350 <li>81.100.IN-ADDR.ARPA</li>
5351 <li>82.100.IN-ADDR.ARPA</li>
5352 <li>83.100.IN-ADDR.ARPA</li>
5353 <li>84.100.IN-ADDR.ARPA</li>
5354 <li>85.100.IN-ADDR.ARPA</li>
5355 <li>86.100.IN-ADDR.ARPA</li>
5356 <li>87.100.IN-ADDR.ARPA</li>
5357 <li>88.100.IN-ADDR.ARPA</li>
5358 <li>89.100.IN-ADDR.ARPA</li>
5359 <li>90.100.IN-ADDR.ARPA</li>
5360 <li>91.100.IN-ADDR.ARPA</li>
5361 <li>92.100.IN-ADDR.ARPA</li>
5362 <li>93.100.IN-ADDR.ARPA</li>
5363 <li>94.100.IN-ADDR.ARPA</li>
5364 <li>95.100.IN-ADDR.ARPA</li>
5365 <li>96.100.IN-ADDR.ARPA</li>
5366 <li>97.100.IN-ADDR.ARPA</li>
5367 <li>98.100.IN-ADDR.ARPA</li>
5368 <li>99.100.IN-ADDR.ARPA</li>
5369 <li>100.100.IN-ADDR.ARPA</li>
5370 <li>101.100.IN-ADDR.ARPA</li>
5371 <li>102.100.IN-ADDR.ARPA</li>
5372 <li>103.100.IN-ADDR.ARPA</li>
5373 <li>104.100.IN-ADDR.ARPA</li>
5374 <li>105.100.IN-ADDR.ARPA</li>
5375 <li>106.100.IN-ADDR.ARPA</li>
5376 <li>107.100.IN-ADDR.ARPA</li>
5377 <li>108.100.IN-ADDR.ARPA</li>
5378 <li>109.100.IN-ADDR.ARPA</li>
5379 <li>110.100.IN-ADDR.ARPA</li>
5380 <li>111.100.IN-ADDR.ARPA</li>
5381 <li>112.100.IN-ADDR.ARPA</li>
5382 <li>113.100.IN-ADDR.ARPA</li>
5383 <li>114.100.IN-ADDR.ARPA</li>
5384 <li>115.100.IN-ADDR.ARPA</li>
5385 <li>116.100.IN-ADDR.ARPA</li>
5386 <li>117.100.IN-ADDR.ARPA</li>
5387 <li>118.100.IN-ADDR.ARPA</li>
5388 <li>119.100.IN-ADDR.ARPA</li>
5389 <li>120.100.IN-ADDR.ARPA</li>
5390 <li>121.100.IN-ADDR.ARPA</li>
5391 <li>122.100.IN-ADDR.ARPA</li>
5392 <li>123.100.IN-ADDR.ARPA</li>
5393 <li>124.100.IN-ADDR.ARPA</li>
5394 <li>125.100.IN-ADDR.ARPA</li>
5395 <li>126.100.IN-ADDR.ARPA</li>
5396 <li>127.100.IN-ADDR.ARPA</li>
5397 <li>0.IN-ADDR.ARPA</li>
5398 <li>127.IN-ADDR.ARPA</li>
5399 <li>254.169.IN-ADDR.ARPA</li>
5400 <li>2.0.192.IN-ADDR.ARPA</li>
5401 <li>100.51.198.IN-ADDR.ARPA</li>
5402 <li>113.0.203.IN-ADDR.ARPA</li>
5403 <li>255.255.255.255.IN-ADDR.ARPA</li>
5404 <li>0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA</li>
5405 <li>1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA</li>
5406 <li>8.B.D.0.1.0.0.2.IP6.ARPA</li>
5407 <li>D.F.IP6.ARPA</li>
5408 <li>8.E.F.IP6.ARPA</li>
5409 <li>9.E.F.IP6.ARPA</li>
5410 <li>A.E.F.IP6.ARPA</li>
5411 <li>B.E.F.IP6.ARPA</li>
5412 </ul></div>
5413 <p>
5414           </p>
5415 <p>
5416             Empty zones are settable at the view level and only apply to
5417             views of class IN.  Disabled empty zones are only inherited
5418             from options if there are no disabled empty zones specified
5419             at the view level.  To override the options list of disabled
5420             zones, you can disable the root zone at the view level, for example:
5421 </p>
5422 <pre class="programlisting">
5423             disable-empty-zone ".";
5424 </pre>
5425 <p>
5426           </p>
5427 <p>
5428             If you are using the address ranges covered here, you should
5429             already have reverse zones covering the addresses you use.
5430             In practice this appears to not be the case with many queries
5431             being made to the infrastructure servers for names in these
5432             spaces.  So many in fact that sacrificial servers were needed
5433             to be deployed to channel the query load away from the
5434             infrastructure servers.
5435           </p>
5436 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
5437 <h3 class="title">Note</h3>
5438             The real parent servers for these zones should disable all
5439             empty zone under the parent zone they serve.  For the real
5440             root servers, this is all built-in empty zones.  This will
5441             enable them to return referrals to deeper in the tree.
5442           </div>
5443 <div class="variablelist"><dl>
5444 <dt><span class="term"><span><strong class="command">empty-server</strong></span></span></dt>
5445 <dd><p>
5446                   Specify what server name will appear in the returned
5447                   SOA record for empty zones.  If none is specified, then
5448                   the zone's name will be used.
5449                 </p></dd>
5450 <dt><span class="term"><span><strong class="command">empty-contact</strong></span></span></dt>
5451 <dd><p>
5452                   Specify what contact name will appear in the returned
5453                   SOA record for empty zones.  If none is specified, then
5454                   "." will be used.
5455                 </p></dd>
5456 <dt><span class="term"><span><strong class="command">empty-zones-enable</strong></span></span></dt>
5457 <dd><p>
5458                   Enable or disable all empty zones.  By default, they
5459                   are enabled.
5460                 </p></dd>
5461 <dt><span class="term"><span><strong class="command">disable-empty-zone</strong></span></span></dt>
5462 <dd><p>
5463                   Disable individual empty zones.  By default, none are
5464                   disabled.  This option can be specified multiple times.
5465                 </p></dd>
5466 </dl></div>
5467 </div>
5468 <div class="sect3" lang="en">
5469 <div class="titlepage"><div><div><h4 class="title">
5470 <a name="acache"></a>Additional Section Caching</h4></div></div></div>
5471 <p>
5472             The additional section cache, also called <span><strong class="command">acache</strong></span>,
5473             is an internal cache to improve the response performance of BIND 9.
5474             When additional section caching is enabled, BIND 9 will
5475             cache an internal short-cut to the additional section content for
5476             each answer RR.
5477             Note that <span><strong class="command">acache</strong></span> is an internal caching
5478             mechanism of BIND 9, and is not related to the DNS caching
5479             server function.
5480           </p>
5481 <p>
5482             Additional section caching does not change the
5483             response content (except the RRsets ordering of the additional
5484             section, see below), but can improve the response performance
5485             significantly.
5486             It is particularly effective when BIND 9 acts as an authoritative
5487             server for a zone that has many delegations with many glue RRs.
5488           </p>
5489 <p>
5490             In order to obtain the maximum performance improvement
5491             from additional section caching, setting
5492             <span><strong class="command">additional-from-cache</strong></span>
5493             to <span><strong class="command">no</strong></span> is recommended, since the current
5494             implementation of <span><strong class="command">acache</strong></span>
5495             does not short-cut of additional section information from the
5496             DNS cache data.
5497           </p>
5498 <p>
5499             One obvious disadvantage of <span><strong class="command">acache</strong></span> is
5500             that it requires much more
5501             memory for the internal cached data.
5502             Thus, if the response performance does not matter and memory
5503             consumption is much more critical, the
5504             <span><strong class="command">acache</strong></span> mechanism can be
5505             disabled by setting <span><strong class="command">acache-enable</strong></span> to
5506             <span><strong class="command">no</strong></span>.
5507             It is also possible to specify the upper limit of memory
5508             consumption
5509             for acache by using <span><strong class="command">max-acache-size</strong></span>.
5510           </p>
5511 <p>
5512             Additional section caching also has a minor effect on the
5513             RRset ordering in the additional section.
5514             Without <span><strong class="command">acache</strong></span>,
5515             <span><strong class="command">cyclic</strong></span> order is effective for the additional
5516             section as well as the answer and authority sections.
5517             However, additional section caching fixes the ordering when it
5518             first caches an RRset for the additional section, and the same
5519             ordering will be kept in succeeding responses, regardless of the
5520             setting of <span><strong class="command">rrset-order</strong></span>.
5521             The effect of this should be minor, however, since an
5522             RRset in the additional section
5523             typically only contains a small number of RRs (and in many cases
5524             it only contains a single RR), in which case the
5525             ordering does not matter much.
5526           </p>
5527 <p>
5528             The following is a summary of options related to
5529             <span><strong class="command">acache</strong></span>.
5530           </p>
5531 <div class="variablelist"><dl>
5532 <dt><span class="term"><span><strong class="command">acache-enable</strong></span></span></dt>
5533 <dd><p>
5534                   If <span><strong class="command">yes</strong></span>, additional section caching is
5535                   enabled.  The default value is <span><strong class="command">no</strong></span>.
5536                 </p></dd>
5537 <dt><span class="term"><span><strong class="command">acache-cleaning-interval</strong></span></span></dt>
5538 <dd><p>
5539                   The server will remove stale cache entries, based on an LRU
5540                   based
5541                   algorithm, every <span><strong class="command">acache-cleaning-interval</strong></span> minutes.
5542                   The default is 60 minutes.
5543                   If set to 0, no periodic cleaning will occur.
5544                 </p></dd>
5545 <dt><span class="term"><span><strong class="command">max-acache-size</strong></span></span></dt>
5546 <dd><p>
5547                   The maximum amount of memory in bytes to use for the server's acache.
5548                   When the amount of data in the acache reaches this limit,
5549                   the server
5550                   will clean more aggressively so that the limit is not
5551                   exceeded.
5552                   In a server with multiple views, the limit applies
5553                   separately to the
5554                   acache of each view.
5555                   The default is <code class="literal">16M</code>.
5556                 </p></dd>
5557 </dl></div>
5558 </div>
5559 <div class="sect3" lang="en">
5560 <div class="titlepage"><div><div><h4 class="title">
5561 <a name="id2587621"></a>Content Filtering</h4></div></div></div>
5562 <p>
5563             <acronym class="acronym">BIND</acronym> 9 provides the ability to filter
5564             out DNS responses from external DNS servers containing
5565             certain types of data in the answer section.
5566             Specifically, it can reject address (A or AAAA) records if
5567             the corresponding IPv4 or IPv6 addresses match the given
5568             <code class="varname">address_match_list</code> of the
5569             <span><strong class="command">deny-answer-addresses</strong></span> option.
5570             It can also reject CNAME or DNAME records if the "alias"
5571             name (i.e., the CNAME alias or the substituted query name
5572             due to DNAME) matches the
5573             given <code class="varname">namelist</code> of the
5574             <span><strong class="command">deny-answer-aliases</strong></span> option, where
5575             "match" means the alias name is a subdomain of one of
5576             the <code class="varname">name_list</code> elements.
5577             If the optional <code class="varname">namelist</code> is specified
5578             with <span><strong class="command">except-from</strong></span>, records whose query name
5579             matches the list will be accepted regardless of the filter
5580             setting.
5581             Likewise, if the alias name is a subdomain of the
5582             corresponding zone, the <span><strong class="command">deny-answer-aliases</strong></span>
5583             filter will not apply;
5584             for example, even if "example.com" is specified for
5585             <span><strong class="command">deny-answer-aliases</strong></span>,
5586           </p>
5587 <pre class="programlisting">www.example.com. CNAME xxx.example.com.</pre>
5588 <p>
5589             returned by an "example.com" server will be accepted.
5590           </p>
5591 <p>
5592             In the <code class="varname">address_match_list</code> of the
5593             <span><strong class="command">deny-answer-addresses</strong></span> option, only
5594             <code class="varname">ip_addr</code>
5595             and <code class="varname">ip_prefix</code>
5596             are meaningful;
5597             any <code class="varname">key_id</code> will be silently ignored.
5598           </p>
5599 <p>
5600             If a response message is rejected due to the filtering,
5601             the entire message is discarded without being cached, and
5602             a SERVFAIL error will be returned to the client.
5603           </p>
5604 <p>
5605             This filtering is intended to prevent "DNS rebinding attacks," in
5606             which an attacker, in response to a query for a domain name the
5607             attacker controls, returns an IP address within your own network or
5608             an alias name within your own domain.
5609             A naive web browser or script could then serve as an
5610             unintended proxy, allowing the attacker
5611             to get access to an internal node of your local network
5612             that couldn't be externally accessed otherwise.
5613             See the paper available at
5614             <a href="http://portal.acm.org/citation.cfm?id=1315245.1315298" target="_top">
5615             http://portal.acm.org/citation.cfm?id=1315245.1315298
5616             </a>
5617             for more details about the attacks.
5618           </p>
5619 <p>
5620             For example, if you own a domain named "example.net" and
5621             your internal network uses an IPv4 prefix 192.0.2.0/24,
5622             you might specify the following rules:
5623           </p>
5624 <pre class="programlisting">deny-answer-addresses { 192.0.2.0/24; } except-from { "example.net"; };
5625 deny-answer-aliases { "example.net"; };
5626 </pre>
5627 <p>
5628             If an external attacker lets a web browser in your local
5629             network look up an IPv4 address of "attacker.example.com",
5630             the attacker's DNS server would return a response like this:
5631           </p>
5632 <pre class="programlisting">attacker.example.com. A 192.0.2.1</pre>
5633 <p>
5634             in the answer section.
5635             Since the rdata of this record (the IPv4 address) matches
5636             the specified prefix 192.0.2.0/24, this response will be
5637             ignored.
5638           </p>
5639 <p>
5640             On the other hand, if the browser looks up a legitimate
5641             internal web server "www.example.net" and the
5642             following response is returned to
5643             the <acronym class="acronym">BIND</acronym> 9 server
5644           </p>
5645 <pre class="programlisting">www.example.net. A 192.0.2.2</pre>
5646 <p>
5647             it will be accepted since the owner name "www.example.net"
5648             matches the <span><strong class="command">except-from</strong></span> element,
5649             "example.net".
5650           </p>
5651 <p>
5652             Note that this is not really an attack on the DNS per se.
5653             In fact, there is nothing wrong for an "external" name to
5654             be mapped to your "internal" IP address or domain name
5655             from the DNS point of view.
5656             It might actually be provided for a legitimate purpose,
5657             such as for debugging.
5658             As long as the mapping is provided by the correct owner,
5659             it is not possible or does not make sense to detect
5660             whether the intent of the mapping is legitimate or not
5661             within the DNS.
5662             The "rebinding" attack must primarily be protected at the
5663             application that uses the DNS.
5664             For a large site, however, it may be difficult to protect
5665             all possible applications at once.
5666             This filtering feature is provided only to help such an
5667             operational environment;
5668             it is generally discouraged to turn it on unless you are
5669             very sure you have no other choice and the attack is a
5670             real threat for your applications.
5671           </p>
5672 <p>
5673             Care should be particularly taken if you want to use this
5674             option for addresses within 127.0.0.0/8.
5675             These addresses are obviously "internal", but many
5676             applications conventionally rely on a DNS mapping from
5677             some name to such an address.
5678             Filtering out DNS records containing this address
5679             spuriously can break such applications.
5680           </p>
5681 </div>
5682 <div class="sect3" lang="en">
5683 <div class="titlepage"><div><div><h4 class="title">
5684 <a name="id2587883"></a>Response Policy Zone (RPZ) Rewriting</h4></div></div></div>
5685 <p>
5686             <acronym class="acronym">BIND</acronym> 9 includes a limited
5687             mechanism to modify DNS responses for requests
5688             analogous to email anti-spam DNS blacklists.
5689             Responses can be changed to deny the existence of domains(NXDOMAIN),
5690             deny the existence of IP addresses for domains (NODATA),
5691             or contain other IP addresses or data.
5692           </p>
5693 <p>
5694             Response policy zones are named in the
5695             <span><strong class="command">response-policy</strong></span> option for the view or among the
5696             global options if there is no response-policy option for the view.
5697             RPZs are ordinary DNS zones containing RRsets
5698             that can be queried normally if allowed.
5699             It is usually best to restrict those queries with something like
5700             <span><strong class="command">allow-query { localhost; };</strong></span>.
5701           </p>
5702 <p>
5703             Four policy triggers are encoded in RPZ records, QNAME, IP, NSIP,
5704             and NSDNAME.
5705             QNAME RPZ records triggered by query names of requests and targets
5706             of CNAME records resolved to generate the response.
5707             The owner name of a QNAME RPZ record is the query name relativized
5708             to the RPZ.
5709           </p>
5710 <p>
5711             The second kind of RPZ trigger is an IP address in an A and AAAA
5712             record in the ANSWER section of a response.
5713             IP address triggers are encoded in records that have owner names
5714             that are subdomains of <strong class="userinput"><code>rpz-ip</code></strong> relativized
5715             to the RPZ origin name and encode an IP address or address block.
5716             IPv4 trigger addresses are represented as
5717             <strong class="userinput"><code>prefixlength.B4.B3.B2.B1.rpz-ip</code></strong>.
5718             The prefix length must be between 1 and 32.
5719             All four bytes, B4, B3, B2, and B1, must be present.
5720             B4 is the decimal value of the least significant byte of the
5721             IPv4 address as in IN-ADDR.ARPA.
5722             IPv6 addresses are encoded in a format similar to the standard
5723             IPv6 text representation,
5724             <strong class="userinput"><code>prefixlength.W8.W7.W6.W5.W4.W3.W2.W1.rpz-ip</code></strong>.
5725             Each of W8,...,W1 is a one to four digit hexadecimal number
5726             representing 16 bits of the IPv6 address as in the standard text
5727             representation of IPv6 addresses, but reversed as in IN-ADDR.ARPA.
5728             All 8 words must be present except when consecutive
5729             zero words are replaced with <strong class="userinput"><code>.zz.</code></strong>
5730             analogous to double colons (::) in standard IPv6 text encodings.
5731             The prefix length must be between 1 and 128.
5732           </p>
5733 <p>
5734             NSDNAME triggers match names of authoritative servers
5735             for the query name, a parent of the query name, a CNAME for
5736             query name, or a parent of a CNAME.
5737             They are encoded as subdomains of
5738             <strong class="userinput"><code>rpz-nsdomain</code></strong> relativized
5739             to the RPZ origin name.
5740             NSIP triggers match IP addresses in A and
5741             AAAA RRsets for domains that can be checked against NSDNAME
5742             policy records.
5743             NSIP triggers are encoded like IP triggers except as subdomains of
5744             <strong class="userinput"><code>rpz-nsip</code></strong>.
5745             NSDNAME and NSIP triggers are checked only for names with at
5746             least <span><strong class="command">min-ns-dots</strong></span> dots.
5747             The default value of <span><strong class="command">min-ns-dots</strong></span> is 1 to
5748             exclude top level domains.
5749           </p>
5750 <p>
5751             The query response is checked against all RPZs, so
5752             two or more policy records can be triggered by a response.
5753             Because DNS responses can be rewritten according to at most one
5754             policy record, a single record encoding an action (other than
5755             <span><strong class="command">DISABLED</strong></span> actions) must be chosen.
5756             Triggers or the records that encode them are chosen in
5757             the following order:
5758             </p>
5759 <div class="itemizedlist"><ul type="disc">
5760 <li>Choose the triggered record in the zone that appears
5761                 first in the response-policy option.
5762               </li>
5763 <li>Prefer QNAME to IP to NSDNAME to NSIP triggers
5764                 in a single zone.
5765               </li>
5766 <li>Among NSDNAME triggers, prefer the
5767                 trigger that matches the smallest name under the DNSSEC ordering.
5768               </li>
5769 <li>Among IP or NSIP triggers, prefer the trigger
5770                 with the longest prefix.
5771               </li>
5772 <li>Among triggers with the same prefex length,
5773                 prefer the IP or NSIP trigger that matches
5774                 the smallest IP address.
5775               </li>
5776 </ul></div>
5777 <p>
5778           </p>
5779 <p>
5780             When the processing of a response is restarted to resolve
5781             DNAME or CNAME records and a policy record set has
5782             not been triggered,
5783             all RPZs are again consulted for the DNAME or CNAME names
5784             and addresses.
5785           </p>
5786 <p>
5787             RPZ record sets are sets of any types of DNS record except
5788             DNAME or DNSSEC that encode actions or responses to queries.
5789             </p>
5790 <div class="itemizedlist"><ul type="disc">
5791 <li>The <span><strong class="command">NXDOMAIN</strong></span> response is encoded
5792                 by a CNAME whose target is the root domain (.)
5793               </li>
5794 <li>A CNAME whose target is the wildcard top-level
5795                 domain (*.) specifies the <span><strong class="command">NODATA</strong></span> action,
5796                 which rewrites the response to NODATA or ANCOUNT=1.
5797               </li>
5798 <li>The <span><strong class="command">Local Data</strong></span> action is
5799                 represented by a set ordinary DNS records that are used
5800                 to answer queries.  Queries for record types not the
5801                 set are answered with NODATA.
5802
5803                 A special form of local data is a CNAME whose target is a
5804                 wildcard such as *.example.com.
5805                 It is used as if were an ordinary CNAME after the astrisk (*)
5806                 has been replaced with the query name.
5807                 The purpose for this special form is query logging in the
5808                 walled garden's authority DNS server.
5809               </li>
5810 <li>The <span><strong class="command">PASSTHRU</strong></span> policy is specified
5811                 by a CNAME whose target is <span><strong class="command">rpz-passthru.</strong></span>
5812                 It causes the response to not be rewritten
5813                 and is most often used to "poke holes" in policies for
5814                 CIDR blocks.
5815                 (A CNAME whose target is the variable part of its owner name
5816                 is an obsolete specification of the PASSTHRU policy.)
5817               </li>
5818 </ul></div>
5819 <p>
5820           </p>
5821 <p>
5822             The actions specified in an RPZ can be overridden with a
5823             <span><strong class="command">policy</strong></span> clause in the
5824             <span><strong class="command">response-policy</strong></span> option.
5825             An organization using an RPZ provided by another organization might
5826             use this mechanism to redirect domains to its own walled garden.
5827             </p>
5828 <div class="itemizedlist"><ul type="disc">
5829 <li>
5830 <span><strong class="command">GIVEN</strong></span> says "do not override but
5831                 perform the action specified in the zone."
5832               </li>
5833 <li>
5834 <span><strong class="command">DISABLED</strong></span> causes policy records to do
5835                 nothing but log what they might have done.
5836                 The response to the DNS query will be written according to
5837                 any triggered policy records that are not disabled.
5838                 Disabled policy zones should appear first,
5839                 because they will often not be logged
5840                 if a higher precedence trigger is found first.
5841               </li>
5842 <li>
5843 <span><strong class="command">PASSTHRU</strong></span> causes all policy records
5844                 to act as if they were CNAME records with targets the variable
5845                 part of their owner name.  They protect the response from
5846                 being changed.
5847               </li>
5848 <li>
5849 <span><strong class="command">NXDOMAIN</strong></span> causes all RPZ records
5850                 to specify NXDOMAIN policies.
5851               </li>
5852 <li>
5853 <span><strong class="command">NODATA</strong></span> overrides with the
5854                 NODATA policy
5855               </li>
5856 <li>
5857 <span><strong class="command">CNAME domain</strong></span> causes all RPZ
5858                 policy records to act as if they were "cname domain" records.
5859               </li>
5860 </ul></div>
5861 <p>
5862           </p>
5863 <p>
5864             By default, the actions encoded in an RPZ are applied
5865             only to queries that ask for recursion (RD=1).
5866             That default can be changed for a single RPZ or all RPZs in a view
5867             with a <span><strong class="command">recursive-only no</strong></span> clause.
5868             This feature is useful for serving the same zone files
5869             both inside and outside an RFC 1918 cloud and using RPZ to
5870             delete answers that would otherwise contain RFC 1918 values
5871             on the externally visible name server or view.
5872           </p>
5873 <p>
5874             Also by default, RPZ actions are applied only to DNS requests that
5875             either do not request DNSSEC metadata (DO=0) or when no DNSSEC
5876             records are available for request name in the original zone (not
5877             the response policy zone).
5878             This default can be changed for all RPZs in a view with a
5879             <span><strong class="command">break-dnssec yes</strong></span> clause.
5880             In that case, RPZ actions are applied regardless of DNSSEC.
5881             The name of the clause option reflects the fact that results
5882             rewritten by RPZ actions cannot verify.
5883           </p>
5884 <p>
5885             The TTL of a record modified by RPZ policies is set from the
5886             TTL of the relevant record in policy zone.  It is then limited
5887             to a maximum value.
5888             The <span><strong class="command">max-policy-ttl</strong></span> clause changes that
5889             maximum from its default of 5.
5890           </p>
5891 <p>
5892             For example, you might use this option statement
5893           </p>
5894 <pre class="programlisting">    response-policy { zone "badlist"; };</pre>
5895 <p>
5896             and this zone statement
5897           </p>
5898 <pre class="programlisting">    zone "badlist" {type master; file "master/badlist"; allow-query {none;}; };</pre>
5899 <p>
5900             with this zone file
5901           </p>
5902 <pre class="programlisting">$TTL 1H
5903 @                       SOA LOCALHOST. named-mgr.example.com (1 1h 15m 30d 2h)
5904                         NS  LOCALHOST.
5905
5906 ; QNAME policy records.  There are no periods (.) after the owner names.
5907 nxdomain.domain.com     CNAME   .               ; NXDOMAIN policy
5908 nodata.domain.com       CNAME   *.              ; NODATA policy
5909 bad.domain.com          A       10.0.0.1        ; redirect to a walled garden
5910                         AAAA    2001:2::1
5911
5912 ; do not rewrite (PASSTHRU) OK.DOMAIN.COM
5913 ok.domain.com           CNAME   rpz-passthru.
5914
5915 bzone.domain.com        CNAME   garden.example.com.
5916
5917 ; redirect x.bzone.domain.com to x.bzone.domain.com.garden.example.com
5918 *.bzone.domain.com      CNAME   *.garden.example.com.
5919
5920
5921 ; IP policy records that rewrite all answers for 127/8 except 127.0.0.1
5922 8.0.0.0.127.rpz-ip      CNAME   .
5923 32.1.0.0.127.rpz-ip     CNAME   rpz-passthru.
5924
5925 ; NSDNAME and NSIP policy records
5926 ns.domain.com.rpz-nsdname   CNAME   .
5927 48.zz.2.2001.rpz-nsip       CNAME   .
5928 </pre>
5929 <p>
5930             RPZ can affect server performance.
5931             Each configured response policy zone requires the server to
5932             perform one to four additional database lookups before a
5933             query can be answered.
5934             For example, a DNS server with four policy zones, each with all
5935             four kinds of response triggers, QNAME, IP, NSIP, and
5936             NSDNAME, requires a total of 17 times as many database
5937             lookups as a similar DNS server with no response policy zones.
5938             A <acronym class="acronym">BIND9</acronym> server with adequate memory and one
5939             response policy zone with QNAME and IP triggers might achieve a
5940             maximum queries-per-second rate about 20% lower.
5941             A server with four response policy zones with QNAME and IP
5942             triggers might have a maximum QPS rate about 50% lower.
5943           </p>
5944 <p>
5945             Responses rewritten by RPZ are counted in the
5946             <span><strong class="command">RPZRewrites</strong></span> statistics.
5947           </p>
5948 </div>
5949 </div>
5950 <div class="sect2" lang="en">
5951 <div class="titlepage"><div><div><h3 class="title">
5952 <a name="server_statement_grammar"></a><span><strong class="command">server</strong></span> Statement Grammar</h3></div></div></div>
5953 <pre class="programlisting"><span><strong class="command">server</strong></span> <em class="replaceable"><code>ip_addr[/prefixlen]</code></em> {
5954     [<span class="optional"> bogus <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5955     [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5956     [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5957     [<span class="optional"> edns <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5958     [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
5959     [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
5960     [<span class="optional"> transfers <em class="replaceable"><code>number</code></em> ; </span>]
5961     [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em> ; ]</span>]
5962     [<span class="optional"> keys <em class="replaceable"><code>{ string ; [<span class="optional"> string ; [<span class="optional">...</span>]</span>] }</code></em> ; </span>]
5963     [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
5964     [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
5965     [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
5966     [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
5967     [<span class="optional"> query-source [<span class="optional"> address ( <em class="replaceable"><code>ip_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
5968                   [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>]
5969     [<span class="optional"> query-source-v6 [<span class="optional"> address ( <em class="replaceable"><code>ip_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
5970                      [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>]
5971     [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5972     [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>]
5973     [<span class="optional"> queryport-pool-updateinterval <em class="replaceable"><code>number</code></em>; </span>]
5974 };
5975 </pre>
5976 </div>
5977 <div class="sect2" lang="en">
5978 <div class="titlepage"><div><div><h3 class="title">
5979 <a name="server_statement_definition_and_usage"></a><span><strong class="command">server</strong></span> Statement Definition and
5980             Usage</h3></div></div></div>
5981 <p>
5982             The <span><strong class="command">server</strong></span> statement defines
5983             characteristics
5984             to be associated with a remote name server.  If a prefix length is
5985             specified, then a range of servers is covered.  Only the most
5986             specific
5987             server clause applies regardless of the order in
5988             <code class="filename">named.conf</code>.
5989           </p>
5990 <p>
5991             The <span><strong class="command">server</strong></span> statement can occur at
5992             the top level of the
5993             configuration file or inside a <span><strong class="command">view</strong></span>
5994             statement.
5995             If a <span><strong class="command">view</strong></span> statement contains
5996             one or more <span><strong class="command">server</strong></span> statements, only
5997             those
5998             apply to the view and any top-level ones are ignored.
5999             If a view contains no <span><strong class="command">server</strong></span>
6000             statements,
6001             any top-level <span><strong class="command">server</strong></span> statements are
6002             used as
6003             defaults.
6004           </p>
6005 <p>
6006             If you discover that a remote server is giving out bad data,
6007             marking it as bogus will prevent further queries to it. The
6008             default
6009             value of <span><strong class="command">bogus</strong></span> is <span><strong class="command">no</strong></span>.
6010           </p>
6011 <p>
6012             The <span><strong class="command">provide-ixfr</strong></span> clause determines
6013             whether
6014             the local server, acting as master, will respond with an
6015             incremental
6016             zone transfer when the given remote server, a slave, requests it.
6017             If set to <span><strong class="command">yes</strong></span>, incremental transfer
6018             will be provided
6019             whenever possible. If set to <span><strong class="command">no</strong></span>,
6020             all transfers
6021             to the remote server will be non-incremental. If not set, the
6022             value
6023             of the <span><strong class="command">provide-ixfr</strong></span> option in the
6024             view or
6025             global options block is used as a default.
6026           </p>
6027 <p>
6028             The <span><strong class="command">request-ixfr</strong></span> clause determines
6029             whether
6030             the local server, acting as a slave, will request incremental zone
6031             transfers from the given remote server, a master. If not set, the
6032             value of the <span><strong class="command">request-ixfr</strong></span> option in
6033             the view or
6034             global options block is used as a default.
6035           </p>
6036 <p>
6037             IXFR requests to servers that do not support IXFR will
6038             automatically
6039             fall back to AXFR.  Therefore, there is no need to manually list
6040             which servers support IXFR and which ones do not; the global
6041             default
6042             of <span><strong class="command">yes</strong></span> should always work.
6043             The purpose of the <span><strong class="command">provide-ixfr</strong></span> and
6044             <span><strong class="command">request-ixfr</strong></span> clauses is
6045             to make it possible to disable the use of IXFR even when both
6046             master
6047             and slave claim to support it, for example if one of the servers
6048             is buggy and crashes or corrupts data when IXFR is used.
6049           </p>
6050 <p>
6051             The <span><strong class="command">edns</strong></span> clause determines whether
6052             the local server will attempt to use EDNS when communicating
6053             with the remote server.  The default is <span><strong class="command">yes</strong></span>.
6054           </p>
6055 <p>
6056             The <span><strong class="command">edns-udp-size</strong></span> option sets the EDNS UDP size
6057             that is advertised by <span><strong class="command">named</strong></span> when querying the remote server.
6058             Valid values are 512 to 4096 bytes (values outside this range will be
6059             silently adjusted).  This option is useful when you wish to
6060             advertises a different value to this server than the value you
6061             advertise globally, for example, when there is a firewall at the
6062             remote site that is blocking large replies.
6063           </p>
6064 <p>
6065             The <span><strong class="command">max-udp-size</strong></span> option sets the
6066             maximum EDNS UDP message size <span><strong class="command">named</strong></span> will send.  Valid
6067             values are 512 to 4096 bytes (values outside this range will
6068             be silently adjusted).  This option is useful when you
6069             know that there is a firewall that is blocking large
6070             replies from <span><strong class="command">named</strong></span>.
6071           </p>
6072 <p>
6073             The server supports two zone transfer methods. The first, <span><strong class="command">one-answer</strong></span>,
6074             uses one DNS message per resource record transferred. <span><strong class="command">many-answers</strong></span> packs
6075             as many resource records as possible into a message. <span><strong class="command">many-answers</strong></span> is
6076             more efficient, but is only known to be understood by <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
6077             8.x, and patched versions of <acronym class="acronym">BIND</acronym>
6078             4.9.5. You can specify which method
6079             to use for a server with the <span><strong class="command">transfer-format</strong></span> option.
6080             If <span><strong class="command">transfer-format</strong></span> is not
6081             specified, the <span><strong class="command">transfer-format</strong></span>
6082             specified
6083             by the <span><strong class="command">options</strong></span> statement will be
6084             used.
6085           </p>
6086 <p><span><strong class="command">transfers</strong></span>
6087             is used to limit the number of concurrent inbound zone
6088             transfers from the specified server. If no
6089             <span><strong class="command">transfers</strong></span> clause is specified, the
6090             limit is set according to the
6091             <span><strong class="command">transfers-per-ns</strong></span> option.
6092           </p>
6093 <p>
6094             The <span><strong class="command">keys</strong></span> clause identifies a
6095             <span><strong class="command">key_id</strong></span> defined by the <span><strong class="command">key</strong></span> statement,
6096             to be used for transaction security (TSIG, <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called &#8220;TSIG&#8221;</a>)
6097             when talking to the remote server.
6098             When a request is sent to the remote server, a request signature
6099             will be generated using the key specified here and appended to the
6100             message. A request originating from the remote server is not
6101             required
6102             to be signed by this key.
6103           </p>
6104 <p>
6105             Although the grammar of the <span><strong class="command">keys</strong></span>
6106             clause
6107             allows for multiple keys, only a single key per server is
6108             currently
6109             supported.
6110           </p>
6111 <p>
6112             The <span><strong class="command">transfer-source</strong></span> and
6113             <span><strong class="command">transfer-source-v6</strong></span> clauses specify
6114             the IPv4 and IPv6 source
6115             address to be used for zone transfer with the remote server,
6116             respectively.
6117             For an IPv4 remote server, only <span><strong class="command">transfer-source</strong></span> can
6118             be specified.
6119             Similarly, for an IPv6 remote server, only
6120             <span><strong class="command">transfer-source-v6</strong></span> can be
6121             specified.
6122             For more details, see the description of
6123             <span><strong class="command">transfer-source</strong></span> and
6124             <span><strong class="command">transfer-source-v6</strong></span> in
6125             <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
6126           </p>
6127 <p>
6128             The <span><strong class="command">notify-source</strong></span> and
6129             <span><strong class="command">notify-source-v6</strong></span> clauses specify the
6130             IPv4 and IPv6 source address to be used for notify
6131             messages sent to remote servers, respectively.  For an
6132             IPv4 remote server, only <span><strong class="command">notify-source</strong></span>
6133             can be specified.  Similarly, for an IPv6 remote server,
6134             only <span><strong class="command">notify-source-v6</strong></span> can be specified.
6135           </p>
6136 <p>
6137             The <span><strong class="command">query-source</strong></span> and
6138             <span><strong class="command">query-source-v6</strong></span> clauses specify the
6139             IPv4 and IPv6 source address to be used for queries
6140             sent to remote servers, respectively.  For an IPv4
6141             remote server, only <span><strong class="command">query-source</strong></span> can
6142             be specified.  Similarly, for an IPv6 remote server,
6143             only <span><strong class="command">query-source-v6</strong></span> can be specified.
6144           </p>
6145 </div>
6146 <div class="sect2" lang="en">
6147 <div class="titlepage"><div><div><h3 class="title">
6148 <a name="statschannels"></a><span><strong class="command">statistics-channels</strong></span> Statement Grammar</h3></div></div></div>
6149 <pre class="programlisting"><span><strong class="command">statistics-channels</strong></span> {
6150    [ inet ( ip_addr | * ) [ port ip_port ]
6151    [ allow { <em class="replaceable"><code> address_match_list </code></em> } ]; ]
6152    [ inet ...; ]
6153 };
6154 </pre>
6155 </div>
6156 <div class="sect2" lang="en">
6157 <div class="titlepage"><div><div><h3 class="title">
6158 <a name="id2589011"></a><span><strong class="command">statistics-channels</strong></span> Statement Definition and
6159             Usage</h3></div></div></div>
6160 <p>
6161           The <span><strong class="command">statistics-channels</strong></span> statement
6162           declares communication channels to be used by system
6163           administrators to get access to statistics information of
6164           the name server.
6165         </p>
6166 <p>
6167           This statement intends to be flexible to support multiple
6168           communication protocols in the future, but currently only
6169           HTTP access is supported.
6170           It requires that BIND 9 be compiled with libxml2;
6171           the <span><strong class="command">statistics-channels</strong></span> statement is
6172           still accepted even if it is built without the library,
6173           but any HTTP access will fail with an error.
6174         </p>
6175 <p>
6176           An <span><strong class="command">inet</strong></span> control channel is a TCP socket
6177           listening at the specified <span><strong class="command">ip_port</strong></span> on the
6178           specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6
6179           address.  An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is
6180           interpreted as the IPv4 wildcard address; connections will be
6181           accepted on any of the system's IPv4 addresses.
6182           To listen on the IPv6 wildcard address,
6183           use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>.
6184         </p>
6185 <p>
6186           If no port is specified, port 80 is used for HTTP channels.
6187           The asterisk "<code class="literal">*</code>" cannot be used for
6188           <span><strong class="command">ip_port</strong></span>.
6189         </p>
6190 <p>
6191           The attempt of opening a statistics channel is
6192           restricted by the optional <span><strong class="command">allow</strong></span> clause.
6193           Connections to the statistics channel are permitted based on the
6194           <span><strong class="command">address_match_list</strong></span>.
6195           If no <span><strong class="command">allow</strong></span> clause is present,
6196           <span><strong class="command">named</strong></span> accepts connection
6197           attempts from any address; since the statistics may
6198           contain sensitive internal information, it is highly
6199           recommended to restrict the source of connection requests
6200           appropriately.
6201         </p>
6202 <p>
6203           If no <span><strong class="command">statistics-channels</strong></span> statement is present,
6204           <span><strong class="command">named</strong></span> will not open any communication channels.
6205         </p>
6206 </div>
6207 <div class="sect2" lang="en">
6208 <div class="titlepage"><div><div><h3 class="title">
6209 <a name="trusted-keys"></a><span><strong class="command">trusted-keys</strong></span> Statement Grammar</h3></div></div></div>
6210 <pre class="programlisting"><span><strong class="command">trusted-keys</strong></span> {
6211     <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ;
6212     [<span class="optional"> <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; [<span class="optional">...</span>]</span>]
6213 };
6214 </pre>
6215 </div>
6216 <div class="sect2" lang="en">
6217 <div class="titlepage"><div><div><h3 class="title">
6218 <a name="id2589219"></a><span><strong class="command">trusted-keys</strong></span> Statement Definition
6219             and Usage</h3></div></div></div>
6220 <p>
6221             The <span><strong class="command">trusted-keys</strong></span> statement defines
6222             DNSSEC security roots. DNSSEC is described in <a href="Bv9ARM.ch04.html#DNSSEC" title="DNSSEC">the section called &#8220;DNSSEC&#8221;</a>. A security root is defined when the
6223             public key for a non-authoritative zone is known, but
6224             cannot be securely obtained through DNS, either because
6225             it is the DNS root zone or because its parent zone is
6226             unsigned.  Once a key has been configured as a trusted
6227             key, it is treated as if it had been validated and
6228             proven secure. The resolver attempts DNSSEC validation
6229             on all DNS data in subdomains of a security root.
6230           </p>
6231 <p>
6232             All keys (and corresponding zones) listed in
6233             <span><strong class="command">trusted-keys</strong></span> are deemed to exist regardless
6234             of what parent zones say.  Similarly for all keys listed in
6235             <span><strong class="command">trusted-keys</strong></span> only those keys are
6236             used to validate the DNSKEY RRset.  The parent's DS RRset
6237             will not be used.
6238           </p>
6239 <p>
6240             The <span><strong class="command">trusted-keys</strong></span> statement can contain
6241             multiple key entries, each consisting of the key's
6242             domain name, flags, protocol, algorithm, and the Base-64
6243             representation of the key data.
6244             Spaces, tabs, newlines and carriage returns are ignored
6245             in the key data, so the configuration may be split up into
6246             multiple lines.
6247           </p>
6248 <p>
6249             <span><strong class="command">trusted-keys</strong></span> may be set at the top level
6250             of <code class="filename">named.conf</code> or within a view.  If it is
6251             set in both places, they are additive: keys defined at the top
6252             level are inherited by all views, but keys defined in a view
6253             are only used within that view.
6254           </p>
6255 </div>
6256 <div class="sect2" lang="en">
6257 <div class="titlepage"><div><div><h3 class="title">
6258 <a name="id2589266"></a><span><strong class="command">managed-keys</strong></span> Statement Grammar</h3></div></div></div>
6259 <pre class="programlisting"><span><strong class="command">managed-keys</strong></span> {
6260     <em class="replaceable"><code>name</code></em> <code class="literal">initial-key</code> <em class="replaceable"><code>flags</code></em> <em class="replaceable"><code>protocol</code></em> <em class="replaceable"><code>algorithm</code></em> <em class="replaceable"><code>key-data</code></em> ;
6261     [<span class="optional"> <em class="replaceable"><code>name</code></em> <code class="literal">initial-key</code> <em class="replaceable"><code>flags</code></em> <em class="replaceable"><code>protocol</code></em> <em class="replaceable"><code>algorithm</code></em> <em class="replaceable"><code>key-data</code></em> ; [<span class="optional">...</span>]</span>]
6262 };
6263 </pre>
6264 </div>
6265 <div class="sect2" lang="en">
6266 <div class="titlepage"><div><div><h3 class="title">
6267 <a name="managed-keys"></a><span><strong class="command">managed-keys</strong></span> Statement Definition
6268             and Usage</h3></div></div></div>
6269 <p>
6270             The <span><strong class="command">managed-keys</strong></span> statement, like
6271             <span><strong class="command">trusted-keys</strong></span>, defines DNSSEC
6272             security roots.  The difference is that
6273             <span><strong class="command">managed-keys</strong></span> can be kept up to date
6274             automatically, without intervention from the resolver
6275             operator.
6276           </p>
6277 <p>
6278             Suppose, for example, that a zone's key-signing
6279             key was compromised, and the zone owner had to revoke and
6280             replace the key.  A resolver which had the old key in a
6281             <span><strong class="command">trusted-keys</strong></span> statement would be
6282             unable to validate this zone any longer; it would
6283             reply with a SERVFAIL response code.  This would
6284             continue until the resolver operator had updated the
6285             <span><strong class="command">trusted-keys</strong></span> statement with the new key.
6286           </p>
6287 <p>
6288             If, however, the zone were listed in a
6289             <span><strong class="command">managed-keys</strong></span> statement instead, then the
6290             zone owner could add a "stand-by" key to the zone in advance.
6291             <span><strong class="command">named</strong></span> would store the stand-by key, and
6292             when the original key was revoked, <span><strong class="command">named</strong></span>
6293             would be able to transition smoothly to the new key.  It would
6294             also recognize that the old key had been revoked, and cease
6295             using that key to validate answers, minimizing the damage that
6296             the compromised key could do.
6297           </p>
6298 <p>
6299             A <span><strong class="command">managed-keys</strong></span> statement contains a list of
6300             the keys to be managed, along with information about how the
6301             keys are to be initialized for the first time.  The only
6302             initialization method currently supported (as of
6303             <acronym class="acronym">BIND</acronym> 9.7.0) is <code class="literal">initial-key</code>.
6304             This means the <span><strong class="command">managed-keys</strong></span> statement must
6305             contain a copy of the initializing key.  (Future releases may
6306             allow keys to be initialized by other methods, eliminating this
6307             requirement.)
6308           </p>
6309 <p>
6310             Consequently, a <span><strong class="command">managed-keys</strong></span> statement
6311             appears similar to a <span><strong class="command">trusted-keys</strong></span>, differing
6312             in the presence of the second field, containing the keyword
6313             <code class="literal">initial-key</code>.  The difference is, whereas the
6314             keys listed in a <span><strong class="command">trusted-keys</strong></span> continue to be
6315             trusted until they are removed from
6316             <code class="filename">named.conf</code>, an initializing key listed
6317             in a <span><strong class="command">managed-keys</strong></span> statement is only trusted
6318             <span class="emphasis"><em>once</em></span>: for as long as it takes to load the
6319             managed key database and start the RFC 5011 key maintenance
6320             process.
6321           </p>
6322 <p>
6323             The first time <span><strong class="command">named</strong></span> runs with a managed key
6324             configured in <code class="filename">named.conf</code>, it fetches the
6325             DNSKEY RRset directly from the zone apex, and validates it
6326             using the key specified in the <span><strong class="command">managed-keys</strong></span>
6327             statement.  If the DNSKEY RRset is validly signed, then it is
6328             used as the basis for a new managed keys database.
6329           </p>
6330 <p>
6331             From that point on, whenever <span><strong class="command">named</strong></span> runs, it
6332             sees the <span><strong class="command">managed-keys</strong></span> statement, checks to
6333             make sure RFC 5011 key maintenance has already been initialized
6334             for the specified domain, and if so, it simply moves on.  The
6335             key specified in the <span><strong class="command">managed-keys</strong></span> is not
6336             used to validate answers; it has been superseded by the key or
6337             keys stored in the managed keys database.
6338           </p>
6339 <p>
6340             The next time <span><strong class="command">named</strong></span> runs after a name
6341             has been <span class="emphasis"><em>removed</em></span> from the
6342             <span><strong class="command">managed-keys</strong></span> statement, the corresponding
6343             zone will be removed from the managed keys database,
6344             and RFC 5011 key maintenance will no longer be used for that
6345             domain.
6346           </p>
6347 <p>
6348             <span><strong class="command">named</strong></span> only maintains a single managed keys
6349             database; consequently, unlike <span><strong class="command">trusted-keys</strong></span>,
6350             <span><strong class="command">managed-keys</strong></span> may only be set at the top
6351             level of <code class="filename">named.conf</code>, not within a view.
6352           </p>
6353 <p>
6354             In the current implementation, the managed keys database is
6355             stored as a master-format zone file called
6356             <code class="filename">managed-keys.bind</code>.  When the key database
6357             is changed, the zone is updated.  As with any other dynamic
6358             zone, changes will be written into a journal file,
6359             <code class="filename">managed-keys.bind.jnl</code>.  They are committed
6360             to the master file as soon as possible afterward; in the case
6361             of the managed key database, this will usually occur within 30
6362             seconds.  So, whenever <span><strong class="command">named</strong></span> is using
6363             automatic key maintenance, those two files can be expected to
6364             exist in the working directory.  (For this reason among others,
6365             the working directory should be always be writable by
6366             <span><strong class="command">named</strong></span>.)
6367           </p>
6368 <p>
6369             If the <span><strong class="command">dnssec-validation</strong></span> option is
6370             set to <strong class="userinput"><code>auto</code></strong>, <span><strong class="command">named</strong></span>
6371             will automatically initialize a managed key for the
6372             root zone.  Similarly, if the <span><strong class="command">dnssec-lookaside</strong></span>
6373             option is set to <strong class="userinput"><code>auto</code></strong>,
6374             <span><strong class="command">named</strong></span> will automatically initialize
6375             a managed key for the zone <code class="literal">dlv.isc.org</code>.
6376             In both cases, the key that is used to initialize the key
6377             maintenance process is built into <span><strong class="command">named</strong></span>,
6378             and can be overridden from <span><strong class="command">bindkeys-file</strong></span>.
6379           </p>
6380 </div>
6381 <div class="sect2" lang="en">
6382 <div class="titlepage"><div><div><h3 class="title">
6383 <a name="view_statement_grammar"></a><span><strong class="command">view</strong></span> Statement Grammar</h3></div></div></div>
6384 <pre class="programlisting"><span><strong class="command">view</strong></span> <em class="replaceable"><code>view_name</code></em>
6385       [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6386       match-clients { <em class="replaceable"><code>address_match_list</code></em> };
6387       match-destinations { <em class="replaceable"><code>address_match_list</code></em> };
6388       match-recursive-only <em class="replaceable"><code>yes_or_no</code></em> ;
6389       [<span class="optional"> <em class="replaceable"><code>view_option</code></em>; ...</span>]
6390       [<span class="optional"> <em class="replaceable"><code>zone_statement</code></em>; ...</span>]
6391 };
6392 </pre>
6393 </div>
6394 <div class="sect2" lang="en">
6395 <div class="titlepage"><div><div><h3 class="title">
6396 <a name="id2589844"></a><span><strong class="command">view</strong></span> Statement Definition and Usage</h3></div></div></div>
6397 <p>
6398             The <span><strong class="command">view</strong></span> statement is a powerful
6399             feature
6400             of <acronym class="acronym">BIND</acronym> 9 that lets a name server
6401             answer a DNS query differently
6402             depending on who is asking. It is particularly useful for
6403             implementing
6404             split DNS setups without having to run multiple servers.
6405           </p>
6406 <p>
6407             Each <span><strong class="command">view</strong></span> statement defines a view
6408             of the
6409             DNS namespace that will be seen by a subset of clients.  A client
6410             matches
6411             a view if its source IP address matches the
6412             <code class="varname">address_match_list</code> of the view's
6413             <span><strong class="command">match-clients</strong></span> clause and its
6414             destination IP address matches
6415             the <code class="varname">address_match_list</code> of the
6416             view's
6417             <span><strong class="command">match-destinations</strong></span> clause.  If not
6418             specified, both
6419             <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
6420             default to matching all addresses.  In addition to checking IP
6421             addresses
6422             <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
6423             can also take <span><strong class="command">keys</strong></span> which provide an
6424             mechanism for the
6425             client to select the view.  A view can also be specified
6426             as <span><strong class="command">match-recursive-only</strong></span>, which
6427             means that only recursive
6428             requests from matching clients will match that view.
6429             The order of the <span><strong class="command">view</strong></span> statements is
6430             significant &#8212;
6431             a client request will be resolved in the context of the first
6432             <span><strong class="command">view</strong></span> that it matches.
6433           </p>
6434 <p>
6435             Zones defined within a <span><strong class="command">view</strong></span>
6436             statement will
6437             only be accessible to clients that match the <span><strong class="command">view</strong></span>.
6438             By defining a zone of the same name in multiple views, different
6439             zone data can be given to different clients, for example,
6440             "internal"
6441             and "external" clients in a split DNS setup.
6442           </p>
6443 <p>
6444             Many of the options given in the <span><strong class="command">options</strong></span> statement
6445             can also be used within a <span><strong class="command">view</strong></span>
6446             statement, and then
6447             apply only when resolving queries with that view.  When no
6448             view-specific
6449             value is given, the value in the <span><strong class="command">options</strong></span> statement
6450             is used as a default.  Also, zone options can have default values
6451             specified
6452             in the <span><strong class="command">view</strong></span> statement; these
6453             view-specific defaults
6454             take precedence over those in the <span><strong class="command">options</strong></span> statement.
6455           </p>
6456 <p>
6457             Views are class specific.  If no class is given, class IN
6458             is assumed.  Note that all non-IN views must contain a hint zone,
6459             since only the IN class has compiled-in default hints.
6460           </p>
6461 <p>
6462             If there are no <span><strong class="command">view</strong></span> statements in
6463             the config
6464             file, a default view that matches any client is automatically
6465             created
6466             in class IN. Any <span><strong class="command">zone</strong></span> statements
6467             specified on
6468             the top level of the configuration file are considered to be part
6469             of
6470             this default view, and the <span><strong class="command">options</strong></span>
6471             statement will
6472             apply to the default view. If any explicit <span><strong class="command">view</strong></span>
6473             statements are present, all <span><strong class="command">zone</strong></span>
6474             statements must
6475             occur inside <span><strong class="command">view</strong></span> statements.
6476           </p>
6477 <p>
6478             Here is an example of a typical split DNS setup implemented
6479             using <span><strong class="command">view</strong></span> statements:
6480           </p>
6481 <pre class="programlisting">view "internal" {
6482       // This should match our internal networks.
6483       match-clients { 10.0.0.0/8; };
6484
6485       // Provide recursive service to internal
6486       // clients only.
6487       recursion yes;
6488
6489       // Provide a complete view of the example.com
6490       // zone including addresses of internal hosts.
6491       zone "example.com" {
6492             type master;
6493             file "example-internal.db";
6494       };
6495 };
6496
6497 view "external" {
6498       // Match all clients not matched by the
6499       // previous view.
6500       match-clients { any; };
6501
6502       // Refuse recursive service to external clients.
6503       recursion no;
6504
6505       // Provide a restricted view of the example.com
6506       // zone containing only publicly accessible hosts.
6507       zone "example.com" {
6508            type master;
6509            file "example-external.db";
6510       };
6511 };
6512 </pre>
6513 </div>
6514 <div class="sect2" lang="en">
6515 <div class="titlepage"><div><div><h3 class="title">
6516 <a name="zone_statement_grammar"></a><span><strong class="command">zone</strong></span>
6517             Statement Grammar</h3></div></div></div>
6518 <pre class="programlisting"><span><strong class="command">zone</strong></span> <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6519     type master;
6520     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6521     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6522     [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6523     [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6524     [<span class="optional"> update-policy <em class="replaceable"><code>local</code></em> | { <em class="replaceable"><code>update_policy_rule</code></em> [<span class="optional">...</span>] }; </span>]
6525     [<span class="optional"> also-notify { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ;
6526                   [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
6527     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6528     [<span class="optional"> check-mx (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6529     [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6530     [<span class="optional"> check-spf ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
6531     [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6532     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
6533     [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
6534     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
6535     [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>]
6536     [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
6537     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
6538     [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
6539     [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>]
6540     [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6541     [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>]
6542     [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6543     [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
6544     [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
6545     [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
6546     [<span class="optional"> notify <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>explicit</code></em> | <em class="replaceable"><code>master-only</code></em> ; </span>]
6547     [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
6548     [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6549     [<span class="optional"> pubkey <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; </span>]
6550     [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6551     [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6552     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6553     [<span class="optional"> sig-validity-interval <em class="replaceable"><code>number</code></em> [<span class="optional"><em class="replaceable"><code>number</code></em></span>] ; </span>]
6554     [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>]
6555     [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>]
6556     [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>]
6557     [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
6558     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6559     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6560     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6561     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6562     [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>]
6563     [<span class="optional"> auto-dnssec <code class="constant">allow</code>|<code class="constant">maintain</code>|<code class="constant">off</code>; </span>]
6564     [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6565 };
6566
6567 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6568     type slave;
6569     [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6570     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6571     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6572     [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6573     [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6574     [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6575     [<span class="optional"> dnssec-update-mode ( <em class="replaceable"><code>maintain</code></em> | <em class="replaceable"><code>no-resign</code></em> ); </span>]
6576     [<span class="optional"> dnssec-dnskey-kskonly <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6577     [<span class="optional"> dnssec-secure-to-insecure <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6578     [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6579     [<span class="optional"> also-notify { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ;
6580                   [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
6581     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6582     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
6583     [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
6584     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
6585     [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>]
6586     [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
6587     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
6588     [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
6589     [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>]
6590     [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6591     [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>]
6592     [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6593     [<span class="optional"> masters [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { ( <em class="replaceable"><code>masters_list</code></em> | <em class="replaceable"><code>ip_addr</code></em>
6594                               [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>]
6595                               [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] }; </span>]
6596     [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
6597     [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
6598     [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
6599     [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
6600     [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
6601     [<span class="optional"> notify <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>explicit</code></em> | <em class="replaceable"><code>master-only</code></em> ; </span>]
6602     [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
6603     [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6604     [<span class="optional"> pubkey <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; </span>]
6605     [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6606     [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6607     [<span class="optional"> alt-transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6608     [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>)
6609                              [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6610     [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6611     [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6612     [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6613     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6614     [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
6615     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6616     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6617     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6618     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6619     [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6620     [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6621 };
6622
6623 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6624     type hint;
6625     file <em class="replaceable"><code>string</code></em> ;
6626     [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6627     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>] // Not Implemented.
6628 };
6629
6630 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6631     type stub;
6632     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6633     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6634     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6635     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
6636     [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6637     [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
6638     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
6639     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
6640     [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
6641     [<span class="optional"> masters [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { ( <em class="replaceable"><code>masters_list</code></em> | <em class="replaceable"><code>ip_addr</code></em>
6642                               [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>]
6643                               [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] }; </span>]
6644     [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
6645     [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
6646     [<span class="optional"> pubkey <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; </span>]
6647     [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6648     [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>)
6649                          [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6650     [<span class="optional"> alt-transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6651     [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>)
6652                             [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6653     [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6654     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6655     [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
6656     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6657     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6658     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6659     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6660     [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6661 };
6662
6663 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6664     type static-stub;
6665     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6666     [<span class="optional"> server-addresses { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> ; ... </span>] }; </span>]
6667     [<span class="optional"> server-names { [<span class="optional"> <em class="replaceable"><code>namelist</code></em> </span>] }; </span>]
6668     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6669 };
6670
6671 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6672     type forward;
6673     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
6674     [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
6675     [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6676 };
6677
6678 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6679     type delegation-only;
6680 };
6681
6682 </pre>
6683 </div>
6684 <div class="sect2" lang="en">
6685 <div class="titlepage"><div><div><h3 class="title">
6686 <a name="id2591339"></a><span><strong class="command">zone</strong></span> Statement Definition and Usage</h3></div></div></div>
6687 <div class="sect3" lang="en">
6688 <div class="titlepage"><div><div><h4 class="title">
6689 <a name="id2591347"></a>Zone Types</h4></div></div></div>
6690 <div class="informaltable"><table border="1">
6691 <colgroup>
6692 <col>
6693 <col>
6694 </colgroup>
6695 <tbody>
6696 <tr>
6697 <td>
6698                       <p>
6699                         <code class="varname">master</code>
6700                       </p>
6701                     </td>
6702 <td>
6703                       <p>
6704                         The server has a master copy of the data
6705                         for the zone and will be able to provide authoritative
6706                         answers for
6707                         it.
6708                       </p>
6709                     </td>
6710 </tr>
6711 <tr>
6712 <td>
6713                       <p>
6714                         <code class="varname">slave</code>
6715                       </p>
6716                     </td>
6717 <td>
6718                       <p>
6719                         A slave zone is a replica of a master
6720                         zone. The <span><strong class="command">masters</strong></span> list
6721                         specifies one or more IP addresses
6722                         of master servers that the slave contacts to update
6723                         its copy of the zone.
6724                         Masters list elements can also be names of other
6725                         masters lists.
6726                         By default, transfers are made from port 53 on the
6727                         servers; this can
6728                         be changed for all servers by specifying a port number
6729                         before the
6730                         list of IP addresses, or on a per-server basis after
6731                         the IP address.
6732                         Authentication to the master can also be done with
6733                         per-server TSIG keys.
6734                         If a file is specified, then the
6735                         replica will be written to this file whenever the zone
6736                         is changed,
6737                         and reloaded from this file on a server restart. Use
6738                         of a file is
6739                         recommended, since it often speeds server startup and
6740                         eliminates
6741                         a needless waste of bandwidth. Note that for large
6742                         numbers (in the
6743                         tens or hundreds of thousands) of zones per server, it
6744                         is best to
6745                         use a two-level naming scheme for zone filenames. For
6746                         example,
6747                         a slave server for the zone <code class="literal">example.com</code> might place
6748                         the zone contents into a file called
6749                         <code class="filename">ex/example.com</code> where <code class="filename">ex/</code> is
6750                         just the first two letters of the zone name. (Most
6751                         operating systems
6752                         behave very slowly if you put 100000 files into
6753                         a single directory.)
6754                       </p>
6755                     </td>
6756 </tr>
6757 <tr>
6758 <td>
6759                       <p>
6760                         <code class="varname">stub</code>
6761                       </p>
6762                     </td>
6763 <td>
6764                       <p>
6765                         A stub zone is similar to a slave zone,
6766                         except that it replicates only the NS records of a
6767                         master zone instead
6768                         of the entire zone. Stub zones are not a standard part
6769                         of the DNS;
6770                         they are a feature specific to the <acronym class="acronym">BIND</acronym> implementation.
6771                       </p>
6772
6773                       <p>
6774                         Stub zones can be used to eliminate the need for glue
6775                         NS record
6776                         in a parent zone at the expense of maintaining a stub
6777                         zone entry and
6778                         a set of name server addresses in <code class="filename">named.conf</code>.
6779                         This usage is not recommended for new configurations,
6780                         and BIND 9
6781                         supports it only in a limited way.
6782                         In <acronym class="acronym">BIND</acronym> 4/8, zone
6783                         transfers of a parent zone
6784                         included the NS records from stub children of that
6785                         zone. This meant
6786                         that, in some cases, users could get away with
6787                         configuring child stubs
6788                         only in the master server for the parent zone. <acronym class="acronym">BIND</acronym>
6789                         9 never mixes together zone data from different zones
6790                         in this
6791                         way. Therefore, if a <acronym class="acronym">BIND</acronym> 9 master serving a parent
6792                         zone has child stub zones configured, all the slave
6793                         servers for the
6794                         parent zone also need to have the same child stub
6795                         zones
6796                         configured.
6797                       </p>
6798
6799                       <p>
6800                         Stub zones can also be used as a way of forcing the
6801                         resolution
6802                         of a given domain to use a particular set of
6803                         authoritative servers.
6804                         For example, the caching name servers on a private
6805                         network using
6806                         RFC1918 addressing may be configured with stub zones
6807                         for
6808                         <code class="literal">10.in-addr.arpa</code>
6809                         to use a set of internal name servers as the
6810                         authoritative
6811                         servers for that domain.
6812                       </p>
6813                     </td>
6814 </tr>
6815 <tr>
6816 <td>
6817                       <p>
6818                         <code class="varname">static-stub</code>
6819                       </p>
6820                     </td>
6821 <td>
6822                       <p>
6823                         A static-stub zone is similar to a stub zone
6824                         with the following exceptions:
6825                         the zone data is statically configured, rather
6826                         than transferred from a master server;
6827                         when recursion is necessary for a query that
6828                         matches a static-stub zone, the locally
6829                         configured data (nameserver names and glue addresses)
6830                         is always used even if different authoritative
6831                         information is cached.
6832                       </p>
6833                       <p>
6834                         Zone data is configured via the
6835                         <span><strong class="command">server-addresses</strong></span> and
6836                         <span><strong class="command">server-names</strong></span> zone options.
6837                       </p>
6838                       <p>
6839                         The zone data is maintained in the form of NS
6840                         and (if necessary) glue A or AAAA RRs
6841                         internally, which can be seen by dumping zone
6842                         databases by <span><strong class="command">rndc dumpdb -all</strong></span>.
6843                         The configured RRs are considered local configuration
6844                         parameters rather than public data.
6845                         Non recursive queries (i.e., those with the RD
6846                         bit off) to a static-stub zone are therefore
6847                         prohibited and will be responded with REFUSED.
6848                       </p>
6849                       <p>
6850                         Since the data is statically configured, no
6851                         zone maintenance action takes place for a static-stub
6852                         zone.
6853                         For example, there is no periodic refresh
6854                         attempt, and an incoming notify message
6855                         will be rejected with an rcode of NOTAUTH.
6856                       </p>
6857                       <p>
6858                         Each static-stub zone is configured with
6859                         internally generated NS and (if necessary)
6860                         glue A or AAAA RRs
6861                       </p>
6862                     </td>
6863 </tr>
6864 <tr>
6865 <td>
6866                       <p>
6867                         <code class="varname">forward</code>
6868                       </p>
6869                     </td>
6870 <td>
6871                       <p>
6872                         A "forward zone" is a way to configure
6873                         forwarding on a per-domain basis.  A <span><strong class="command">zone</strong></span> statement
6874                         of type <span><strong class="command">forward</strong></span> can
6875                         contain a <span><strong class="command">forward</strong></span>
6876                         and/or <span><strong class="command">forwarders</strong></span>
6877                         statement,
6878                         which will apply to queries within the domain given by
6879                         the zone
6880                         name. If no <span><strong class="command">forwarders</strong></span>
6881                         statement is present or
6882                         an empty list for <span><strong class="command">forwarders</strong></span> is given, then no
6883                         forwarding will be done for the domain, canceling the
6884                         effects of
6885                         any forwarders in the <span><strong class="command">options</strong></span> statement. Thus
6886                         if you want to use this type of zone to change the
6887                         behavior of the
6888                         global <span><strong class="command">forward</strong></span> option
6889                         (that is, "forward first"
6890                         to, then "forward only", or vice versa, but want to
6891                         use the same
6892                         servers as set globally) you need to re-specify the
6893                         global forwarders.
6894                       </p>
6895                     </td>
6896 </tr>
6897 <tr>
6898 <td>
6899                       <p>
6900                         <code class="varname">hint</code>
6901                       </p>
6902                     </td>
6903 <td>
6904                       <p>
6905                         The initial set of root name servers is
6906                         specified using a "hint zone". When the server starts
6907                         up, it uses
6908                         the root hints to find a root name server and get the
6909                         most recent
6910                         list of root name servers. If no hint zone is
6911                         specified for class
6912                         IN, the server uses a compiled-in default set of root
6913                         servers hints.
6914                         Classes other than IN have no built-in defaults hints.
6915                       </p>
6916                     </td>
6917 </tr>
6918 <tr>
6919 <td>
6920                       <p>
6921                         <code class="varname">delegation-only</code>
6922                       </p>
6923                     </td>
6924 <td>
6925                       <p>
6926                         This is used to enforce the delegation-only
6927                         status of infrastructure zones (e.g. COM,
6928                         NET, ORG).  Any answer that is received
6929                         without an explicit or implicit delegation
6930                         in the authority section will be treated
6931                         as NXDOMAIN.  This does not apply to the
6932                         zone apex.  This should not be applied to
6933                         leaf zones.
6934                       </p>
6935                       <p>
6936                         <code class="varname">delegation-only</code> has no
6937                         effect on answers received from forwarders.
6938                       </p>
6939                       <p>
6940                         See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>.
6941                       </p>
6942                     </td>
6943 </tr>
6944 </tbody>
6945 </table></div>
6946 </div>
6947 <div class="sect3" lang="en">
6948 <div class="titlepage"><div><div><h4 class="title">
6949 <a name="id2591892"></a>Class</h4></div></div></div>
6950 <p>
6951               The zone's name may optionally be followed by a class. If
6952               a class is not specified, class <code class="literal">IN</code> (for <code class="varname">Internet</code>),
6953               is assumed. This is correct for the vast majority of cases.
6954             </p>
6955 <p>
6956               The <code class="literal">hesiod</code> class is
6957               named for an information service from MIT's Project Athena. It
6958               is
6959               used to share information about various systems databases, such
6960               as users, groups, printers and so on. The keyword
6961               <code class="literal">HS</code> is
6962               a synonym for hesiod.
6963             </p>
6964 <p>
6965               Another MIT development is Chaosnet, a LAN protocol created
6966               in the mid-1970s. Zone data for it can be specified with the <code class="literal">CHAOS</code> class.
6967             </p>
6968 </div>
6969 <div class="sect3" lang="en">
6970 <div class="titlepage"><div><div><h4 class="title">
6971 <a name="id2591925"></a>Zone Options</h4></div></div></div>
6972 <div class="variablelist"><dl>
6973 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
6974 <dd><p>
6975                     See the description of
6976                     <span><strong class="command">allow-notify</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
6977                   </p></dd>
6978 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
6979 <dd><p>
6980                     See the description of
6981                     <span><strong class="command">allow-query</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
6982                   </p></dd>
6983 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
6984 <dd><p>
6985                     See the description of
6986                     <span><strong class="command">allow-query-on</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
6987                   </p></dd>
6988 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
6989 <dd><p>
6990                     See the description of <span><strong class="command">allow-transfer</strong></span>
6991                     in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
6992                   </p></dd>
6993 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
6994 <dd><p>
6995                     See the description of <span><strong class="command">allow-update</strong></span>
6996                     in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
6997                   </p></dd>
6998 <dt><span class="term"><span><strong class="command">update-policy</strong></span></span></dt>
6999 <dd><p>
7000                     Specifies a "Simple Secure Update" policy. See
7001                     <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called &#8220;Dynamic Update Policies&#8221;</a>.
7002                   </p></dd>
7003 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
7004 <dd><p>
7005                     See the description of <span><strong class="command">allow-update-forwarding</strong></span>
7006                     in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
7007                   </p></dd>
7008 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
7009 <dd><p>
7010                     Only meaningful if <span><strong class="command">notify</strong></span>
7011                     is
7012                     active for this zone. The set of machines that will
7013                     receive a
7014                     <code class="literal">DNS NOTIFY</code> message
7015                     for this zone is made up of all the listed name servers
7016                     (other than
7017                     the primary master) for the zone plus any IP addresses
7018                     specified
7019                     with <span><strong class="command">also-notify</strong></span>. A port
7020                     may be specified
7021                     with each <span><strong class="command">also-notify</strong></span>
7022                     address to send the notify
7023                     messages to a port other than the default of 53.
7024                     <span><strong class="command">also-notify</strong></span> is not
7025                     meaningful for stub zones.
7026                     The default is the empty list.
7027                   </p></dd>
7028 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
7029 <dd><p>
7030                     This option is used to restrict the character set and
7031                     syntax of
7032                     certain domain names in master files and/or DNS responses
7033                     received from the
7034                     network.  The default varies according to zone type.  For <span><strong class="command">master</strong></span> zones the default is <span><strong class="command">fail</strong></span>.  For <span><strong class="command">slave</strong></span>
7035                     zones the default is <span><strong class="command">warn</strong></span>.
7036                     It is not implemented for <span><strong class="command">hint</strong></span> zones.
7037                   </p></dd>
7038 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
7039 <dd><p>
7040                     See the description of
7041                     <span><strong class="command">check-mx</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7042                   </p></dd>
7043 <dt><span class="term"><span><strong class="command">check-spf</strong></span></span></dt>
7044 <dd><p>
7045                     See the description of
7046                     <span><strong class="command">check-spf</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7047                   </p></dd>
7048 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
7049 <dd><p>
7050                     See the description of
7051                     <span><strong class="command">check-wildcard</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7052                   </p></dd>
7053 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
7054 <dd><p>
7055                     See the description of
7056                     <span><strong class="command">check-integrity</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7057                   </p></dd>
7058 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
7059 <dd><p>
7060                     See the description of
7061                     <span><strong class="command">check-sibling</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7062                   </p></dd>
7063 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
7064 <dd><p>
7065                     See the description of
7066                     <span><strong class="command">zero-no-soa-ttl</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7067                   </p></dd>
7068 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
7069 <dd><p>
7070                     See the description of
7071                     <span><strong class="command">update-check-ksk</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7072                   </p></dd>
7073 <dt><span class="term"><span><strong class="command">dnssec-dnskey-kskonly</strong></span></span></dt>
7074 <dd><p>
7075                     See the description of
7076                     <span><strong class="command">dnssec-dnskey-kskonly</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7077                   </p></dd>
7078 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
7079 <dd><p>
7080                     See the description of
7081                     <span><strong class="command">try-tcp-refresh</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7082                   </p></dd>
7083 <dt><span class="term"><span><strong class="command">database</strong></span></span></dt>
7084 <dd>
7085 <p>
7086                     Specify the type of database to be used for storing the
7087                     zone data.  The string following the <span><strong class="command">database</strong></span> keyword
7088                     is interpreted as a list of whitespace-delimited words.
7089                     The first word
7090                     identifies the database type, and any subsequent words are
7091                     passed
7092                     as arguments to the database to be interpreted in a way
7093                     specific
7094                     to the database type.
7095                   </p>
7096 <p>
7097                     The default is <strong class="userinput"><code>"rbt"</code></strong>, BIND 9's
7098                     native in-memory
7099                     red-black-tree database.  This database does not take
7100                     arguments.
7101                   </p>
7102 <p>
7103                     Other values are possible if additional database drivers
7104                     have been linked into the server.  Some sample drivers are
7105                     included
7106                     with the distribution but none are linked in by default.
7107                   </p>
7108 </dd>
7109 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
7110 <dd><p>
7111                     See the description of
7112                     <span><strong class="command">dialup</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7113                   </p></dd>
7114 <dt><span class="term"><span><strong class="command">delegation-only</strong></span></span></dt>
7115 <dd>
7116 <p>
7117                     The flag only applies to hint and stub zones.  If set
7118                     to <strong class="userinput"><code>yes</code></strong>, then the zone will also be
7119                     treated as if it is also a delegation-only type zone.
7120                   </p>
7121 <p>
7122                     See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>.
7123                   </p>
7124 </dd>
7125 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
7126 <dd><p>
7127                     Only meaningful if the zone has a forwarders
7128                     list. The <span><strong class="command">only</strong></span> value causes
7129                     the lookup to fail
7130                     after trying the forwarders and getting no answer, while <span><strong class="command">first</strong></span> would
7131                     allow a normal lookup to be tried.
7132                   </p></dd>
7133 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
7134 <dd><p>
7135                     Used to override the list of global forwarders.
7136                     If it is not specified in a zone of type <span><strong class="command">forward</strong></span>,
7137                     no forwarding is done for the zone and the global options are
7138                     not used.
7139                   </p></dd>
7140 <dt><span class="term"><span><strong class="command">ixfr-base</strong></span></span></dt>
7141 <dd><p>
7142                     Was used in <acronym class="acronym">BIND</acronym> 8 to
7143                     specify the name
7144                     of the transaction log (journal) file for dynamic update
7145                     and IXFR.
7146                     <acronym class="acronym">BIND</acronym> 9 ignores the option
7147                     and constructs the name of the journal
7148                     file by appending "<code class="filename">.jnl</code>"
7149                     to the name of the
7150                     zone file.
7151                   </p></dd>
7152 <dt><span class="term"><span><strong class="command">ixfr-tmp-file</strong></span></span></dt>
7153 <dd><p>
7154                     Was an undocumented option in <acronym class="acronym">BIND</acronym> 8.
7155                     Ignored in <acronym class="acronym">BIND</acronym> 9.
7156                   </p></dd>
7157 <dt><span class="term"><span><strong class="command">journal</strong></span></span></dt>
7158 <dd><p>
7159                     Allow the default journal's filename to be overridden.
7160                     The default is the zone's filename with "<code class="filename">.jnl</code>" appended.
7161                     This is applicable to <span><strong class="command">master</strong></span> and <span><strong class="command">slave</strong></span> zones.
7162                   </p></dd>
7163 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
7164 <dd><p>
7165                     See the description of
7166                     <span><strong class="command">max-journal-size</strong></span> in <a href="Bv9ARM.ch06.html#server_resource_limits" title="Server  Resource Limits">the section called &#8220;Server  Resource Limits&#8221;</a>.
7167                   </p></dd>
7168 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
7169 <dd><p>
7170                     See the description of
7171                     <span><strong class="command">max-transfer-time-in</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
7172                   </p></dd>
7173 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
7174 <dd><p>
7175                     See the description of
7176                     <span><strong class="command">max-transfer-idle-in</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
7177                   </p></dd>
7178 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
7179 <dd><p>
7180                     See the description of
7181                     <span><strong class="command">max-transfer-time-out</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
7182                   </p></dd>
7183 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
7184 <dd><p>
7185                     See the description of
7186                     <span><strong class="command">max-transfer-idle-out</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
7187                   </p></dd>
7188 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
7189 <dd><p>
7190                     See the description of
7191                     <span><strong class="command">notify</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7192                   </p></dd>
7193 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
7194 <dd><p>
7195                     See the description of
7196                     <span><strong class="command">notify-delay</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
7197                   </p></dd>
7198 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
7199 <dd><p>
7200                     See the description of
7201                     <span><strong class="command">notify-to-soa</strong></span> in
7202                     <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7203                   </p></dd>
7204 <dt><span class="term"><span><strong class="command">pubkey</strong></span></span></dt>
7205 <dd><p>
7206                     In <acronym class="acronym">BIND</acronym> 8, this option was
7207                     intended for specifying
7208                     a public zone key for verification of signatures in DNSSEC
7209                     signed
7210                     zones when they are loaded from disk. <acronym class="acronym">BIND</acronym> 9 does not verify signatures
7211                     on load and ignores the option.
7212                   </p></dd>
7213 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
7214 <dd><p>
7215                     If <strong class="userinput"><code>yes</code></strong>, the server will keep
7216                     statistical
7217                     information for this zone, which can be dumped to the
7218                     <span><strong class="command">statistics-file</strong></span> defined in
7219                     the server options.
7220                   </p></dd>
7221 <dt><span class="term"><span><strong class="command">server-addresses</strong></span></span></dt>
7222 <dd>
7223 <p>
7224                     Only meaningful for static-stub zones.
7225                     This is a list of IP addresses to which queries
7226                     should be sent in recursive resolution for the
7227                     zone.
7228                     A non empty list for this option will internally
7229                     configure the apex NS RR with associated glue A or
7230                     AAAA RRs.
7231                   </p>
7232 <p>
7233                     For example, if "example.com" is configured as a
7234                     static-stub zone with 192.0.2.1 and 2001:db8::1234
7235                     in a <span><strong class="command">server-addresses</strong></span> option,
7236                     the following RRs will be internally configured.
7237                   </p>
7238 <pre class="programlisting">example.com. NS example.com.
7239 example.com. A 192.0.2.1
7240 example.com. AAAA 2001:db8::1234</pre>
7241 <p>
7242                     These records are internally used to resolve
7243                     names under the static-stub zone.
7244                     For instance, if the server receives a query for
7245                     "www.example.com" with the RD bit on, the server
7246                     will initiate recursive resolution and send
7247                     queries to 192.0.2.1 and/or 2001:db8::1234.
7248                   </p>
7249 </dd>
7250 <dt><span class="term"><span><strong class="command">server-names</strong></span></span></dt>
7251 <dd>
7252 <p>
7253                     Only meaningful for static-stub zones.
7254                     This is a list of domain names of nameservers that
7255                     act as authoritative servers of the static-stub
7256                     zone.
7257                     These names will be resolved to IP addresses when
7258                     <span><strong class="command">named</strong></span> needs to send queries to
7259                     these servers.
7260                     To make this supplemental resolution successful,
7261                     these names must not be a subdomain of the origin
7262                     name of static-stub zone.
7263                     That is, when "example.net" is the origin of a
7264                     static-stub zone, "ns.example" and
7265                     "master.example.com" can be specified in the
7266                     <span><strong class="command">server-names</strong></span> option, but
7267                     "ns.example.net" cannot, and will be rejected by
7268                     the configuration parser.
7269                   </p>
7270 <p>
7271                     A non empty list for this option will internally
7272                     configure the apex NS RR with the specified names.
7273                     For example, if "example.com" is configured as a
7274                     static-stub zone with "ns1.example.net" and
7275                     "ns2.example.net"
7276                     in a <span><strong class="command">server-names</strong></span> option,
7277                     the following RRs will be internally configured.
7278                   </p>
7279 <pre class="programlisting">example.com. NS ns1.example.net.
7280 example.com. NS ns2.example.net.
7281 </pre>
7282 <p>
7283                     These records are internally used to resolve
7284                     names under the static-stub zone.
7285                     For instance, if the server receives a query for
7286                     "www.example.com" with the RD bit on, the server
7287                     initiate recursive resolution,
7288                     resolve "ns1.example.net" and/or
7289                     "ns2.example.net" to IP addresses, and then send
7290                     queries to (one or more of) these addresses.
7291                   </p>
7292 </dd>
7293 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
7294 <dd><p>
7295                     See the description of
7296                     <span><strong class="command">sig-validity-interval</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
7297                   </p></dd>
7298 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
7299 <dd><p>
7300                     See the description of
7301                     <span><strong class="command">sig-signing-nodes</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
7302                   </p></dd>
7303 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
7304 <dd><p>
7305                     See the description of
7306                     <span><strong class="command">sig-signing-signatures</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
7307                   </p></dd>
7308 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
7309 <dd><p>
7310                     See the description of
7311                     <span><strong class="command">sig-signing-type</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
7312                   </p></dd>
7313 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
7314 <dd><p>
7315                     See the description of
7316                     <span><strong class="command">transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
7317                   </p></dd>
7318 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
7319 <dd><p>
7320                     See the description of
7321                     <span><strong class="command">transfer-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
7322                   </p></dd>
7323 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
7324 <dd><p>
7325                     See the description of
7326                     <span><strong class="command">alt-transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
7327                   </p></dd>
7328 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
7329 <dd><p>
7330                     See the description of
7331                     <span><strong class="command">alt-transfer-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
7332                   </p></dd>
7333 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
7334 <dd><p>
7335                     See the description of
7336                     <span><strong class="command">use-alt-transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
7337                   </p></dd>
7338 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
7339 <dd><p>
7340                     See the description of
7341                     <span><strong class="command">notify-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
7342                   </p></dd>
7343 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
7344 <dd><p>
7345                     See the description of
7346                     <span><strong class="command">notify-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
7347                   </p></dd>
7348 <dt>
7349 <span class="term"><span><strong class="command">min-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">max-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">min-retry-time</strong></span>, </span><span class="term"><span><strong class="command">max-retry-time</strong></span></span>
7350 </dt>
7351 <dd><p>
7352                     See the description in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
7353                   </p></dd>
7354 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
7355 <dd><p>
7356                     See the description of
7357                     <span><strong class="command">ixfr-from-differences</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7358                     (Note that the <span><strong class="command">ixfr-from-differences</strong></span>
7359                     <strong class="userinput"><code>master</code></strong> and
7360                     <strong class="userinput"><code>slave</code></strong> choices are not
7361                     available at the zone level.)
7362                   </p></dd>
7363 <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt>
7364 <dd><p>
7365                     See the description of
7366                     <span><strong class="command">key-directory</strong></span> in <a href="Bv9ARM.ch06.html#options" title="options Statement Definition and
7367           Usage">the section called &#8220;<span><strong class="command">options</strong></span> Statement Definition and
7368           Usage&#8221;</a>.
7369                   </p></dd>
7370 <dt><span class="term"><span><strong class="command">auto-dnssec</strong></span></span></dt>
7371 <dd>
7372 <p>
7373                     Zones configured for dynamic DNS may also use this
7374                     option to allow varying levels of automatic DNSSEC key
7375                     management. There are three possible settings:
7376                   </p>
7377 <p>
7378                     <span><strong class="command">auto-dnssec allow;</strong></span> permits
7379                     keys to be updated and the zone fully re-signed
7380                     whenever the user issues the command <span><strong class="command">rndc sign
7381                     <em class="replaceable"><code>zonename</code></em></strong></span>.
7382                   </p>
7383 <p>
7384                     <span><strong class="command">auto-dnssec maintain;</strong></span> includes the
7385                     above, but also automatically adjusts the zone's DNSSEC
7386                     keys on schedule, according to the keys' timing metadata
7387                     (see <a href="man.dnssec-keygen.html" title="dnssec-keygen"><span class="refentrytitle"><span class="application">dnssec-keygen</span></span>(8)</a> and
7388                     <a href="man.dnssec-settime.html" title="dnssec-settime"><span class="refentrytitle"><span class="application">dnssec-settime</span></span>(8)</a>).  The command
7389                     <span><strong class="command">rndc sign
7390                     <em class="replaceable"><code>zonename</code></em></strong></span> causes
7391                     <span><strong class="command">named</strong></span> to load keys from the key
7392                     repository and sign the zone with all keys that are
7393                     active.
7394                     <span><strong class="command">rndc loadkeys
7395                     <em class="replaceable"><code>zonename</code></em></strong></span> causes
7396                     <span><strong class="command">named</strong></span> to load keys from the key
7397                     repository and schedule key maintenance events to occur
7398                     in the future, but it does not sign the full zone
7399                     immediately.  Note: once keys have been loaded for a
7400                     zone the first time, the repository will be searched
7401                     for changes periodically, regardless of whether
7402                     <span><strong class="command">rndc loadkeys</strong></span> is used.  The recheck
7403                     interval is hard-coded to
7404                     one hour.
7405                   </p>
7406 <p>
7407                     <span><strong class="command">auto-dnssec create;</strong></span> includes the
7408                     above, but also allows <span><strong class="command">named</strong></span>
7409                     to create new keys in the key repository when needed.
7410                     (NOTE: This option is not yet implemented; the syntax is
7411                     being reserved for future use.)
7412                   </p>
7413 <p>
7414                     The default setting is <span><strong class="command">auto-dnssec off</strong></span>.
7415                   </p>
7416 </dd>
7417 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
7418 <dd><p>
7419                     See the description of <span><strong class="command">multi-master</strong></span> in
7420                     <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7421                   </p></dd>
7422 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
7423 <dd><p>
7424                     See the description of <span><strong class="command">masterfile-format</strong></span>
7425                     in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
7426                   </p></dd>
7427 <dt><span class="term"><span><strong class="command">dnssec-secure-to-insecure</strong></span></span></dt>
7428 <dd><p>
7429                     See the description of
7430                     <span><strong class="command">dnssec-secure-to-insecure</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
7431                   </p></dd>
7432 </dl></div>
7433 </div>
7434 <div class="sect3" lang="en">
7435 <div class="titlepage"><div><div><h4 class="title">
7436 <a name="dynamic_update_policies"></a>Dynamic Update Policies</h4></div></div></div>
7437 <p><acronym class="acronym">BIND</acronym> 9 supports two alternative
7438               methods of granting clients the right to perform
7439               dynamic updates to a zone, configured by the
7440               <span><strong class="command">allow-update</strong></span> and
7441               <span><strong class="command">update-policy</strong></span> option, respectively.
7442             </p>
7443 <p>
7444               The <span><strong class="command">allow-update</strong></span> clause works the
7445               same way as in previous versions of <acronym class="acronym">BIND</acronym>.
7446               It grants given clients the permission to update any
7447               record of any name in the zone.
7448             </p>
7449 <p>
7450               The <span><strong class="command">update-policy</strong></span> clause
7451               allows more fine-grained control over what updates are
7452               allowed.  A set of rules is specified, where each rule
7453               either grants or denies permissions for one or more
7454               names to be updated by one or more identities.  If
7455               the dynamic update request message is signed (that is,
7456               it includes either a TSIG or SIG(0) record), the
7457               identity of the signer can be determined.
7458             </p>
7459 <p>
7460               Rules are specified in the <span><strong class="command">update-policy</strong></span>
7461               zone option, and are only meaningful for master zones.
7462               When the <span><strong class="command">update-policy</strong></span> statement
7463               is present, it is a configuration error for the
7464               <span><strong class="command">allow-update</strong></span> statement to be
7465               present.  The <span><strong class="command">update-policy</strong></span> statement
7466               only examines the signer of a message; the source
7467               address is not relevant.
7468             </p>
7469 <p>
7470               There is a pre-defined <span><strong class="command">update-policy</strong></span>
7471               rule which can be switched on with the command
7472               <span><strong class="command">update-policy local;</strong></span>.
7473               Switching on this rule in a zone causes
7474               <span><strong class="command">named</strong></span> to generate a TSIG session
7475               key and place it in a file, and to allow that key
7476               to update the zone.  (By default, the file is
7477               <code class="filename">/var/run/named/session.key</code>, the key
7478               name is "local-ddns" and the key algorithm is HMAC-SHA256,
7479               but these values are configurable with the
7480               <span><strong class="command">session-keyfile</strong></span>,
7481               <span><strong class="command">session-keyname</strong></span> and
7482               <span><strong class="command">session-keyalg</strong></span> options, respectively).
7483             </p>
7484 <p>
7485               A client running on the local system, and with appropriate
7486               permissions, may read that file and use the key to sign update
7487               requests.  The zone's update policy will be set to allow that
7488               key to change any record within the zone.  Assuming the
7489               key name is "local-ddns", this policy is equivalent to:
7490             </p>
7491 <pre class="programlisting">update-policy { grant local-ddns zonesub any; };
7492             </pre>
7493 <p>
7494               The command <span><strong class="command">nsupdate -l</strong></span> sends update
7495               requests to localhost, and signs them using the session key.
7496             </p>
7497 <p>
7498               Other rule definitions look like this:
7499             </p>
7500 <pre class="programlisting">
7501 ( <span><strong class="command">grant</strong></span> | <span><strong class="command">deny</strong></span> ) <em class="replaceable"><code>identity</code></em> <em class="replaceable"><code>nametype</code></em> [<span class="optional"> <em class="replaceable"><code>name</code></em> </span>] [<span class="optional"> <em class="replaceable"><code>types</code></em> </span>]
7502 </pre>
7503 <p>
7504               Each rule grants or denies privileges.  Once a message has
7505               successfully matched a rule, the operation is immediately
7506               granted or denied and no further rules are examined.  A rule
7507               is matched when the signer matches the identity field, the
7508               name matches the name field in accordance with the nametype
7509               field, and the type matches the types specified in the type
7510               field.
7511             </p>
7512 <p>
7513               No signer is required for <em class="replaceable"><code>tcp-self</code></em>
7514               or <em class="replaceable"><code>6to4-self</code></em> however the standard
7515               reverse mapping / prefix conversion must match the identity
7516               field.
7517             </p>
7518 <p>
7519               The identity field specifies a name or a wildcard
7520               name.  Normally, this is the name of the TSIG or
7521               SIG(0) key used to sign the update request.  When a
7522               TKEY exchange has been used to create a shared secret,
7523               the identity of the shared secret is the same as the
7524               identity of the key used to authenticate the TKEY
7525               exchange.  TKEY is also the negotiation method used
7526               by GSS-TSIG, which establishes an identity that is
7527               the Kerberos principal of the client, such as
7528               <strong class="userinput"><code>"user@host.domain"</code></strong>.  When the
7529               <em class="replaceable"><code>identity</code></em> field specifies
7530               a wildcard name, it is subject to DNS wildcard
7531               expansion, so the rule will apply to multiple identities.
7532               The <em class="replaceable"><code>identity</code></em> field must
7533               contain a fully-qualified domain name.
7534             </p>
7535 <p>
7536               For nametypes <code class="varname">krb5-self</code>,
7537               <code class="varname">ms-self</code>, <code class="varname">krb5-subdomain</code>,
7538               and <code class="varname">ms-subdomain</code> the
7539               <em class="replaceable"><code>identity</code></em> field specifies
7540               the Windows or Kerberos realm of the machine belongs to.
7541             </p>
7542 <p>
7543               The <em class="replaceable"><code>nametype</code></em> field has 13
7544               values:
7545               <code class="varname">name</code>, <code class="varname">subdomain</code>,
7546               <code class="varname">wildcard</code>, <code class="varname">self</code>,
7547               <code class="varname">selfsub</code>, <code class="varname">selfwild</code>,
7548               <code class="varname">krb5-self</code>, <code class="varname">ms-self</code>,
7549               <code class="varname">krb5-subdomain</code>,
7550               <code class="varname">ms-subdomain</code>,
7551               <code class="varname">tcp-self</code>, <code class="varname">6to4-self</code>,
7552               <code class="varname">zonesub</code>, and <code class="varname">external</code>.
7553             </p>
7554 <div class="informaltable"><table border="1">
7555 <colgroup>
7556 <col>
7557 <col>
7558 </colgroup>
7559 <tbody>
7560 <tr>
7561 <td>
7562                       <p>
7563                         <code class="varname">name</code>
7564                       </p>
7565                     </td>
7566 <td>
7567                       <p>
7568                         Exact-match semantics.  This rule matches
7569                         when the name being updated is identical
7570                         to the contents of the
7571                         <em class="replaceable"><code>name</code></em> field.
7572                       </p>
7573                     </td>
7574 </tr>
7575 <tr>
7576 <td>
7577                       <p>
7578                         <code class="varname">subdomain</code>
7579                       </p>
7580                     </td>
7581 <td>
7582                       <p>
7583                         This rule matches when the name being updated
7584                         is a subdomain of, or identical to, the
7585                         contents of the <em class="replaceable"><code>name</code></em>
7586                         field.
7587                       </p>
7588                     </td>
7589 </tr>
7590 <tr>
7591 <td>
7592                       <p>
7593                         <code class="varname">zonesub</code>
7594                       </p>
7595                     </td>
7596 <td>
7597                       <p>
7598                         This rule is similar to subdomain, except that
7599                         it matches when the name being updated is a
7600                         subdomain of the zone in which the
7601                         <span><strong class="command">update-policy</strong></span> statement
7602                         appears.  This obviates the need to type the zone
7603                         name twice, and enables the use of a standard
7604                         <span><strong class="command">update-policy</strong></span> statement in
7605                         multiple zones without modification.
7606                       </p>
7607                       <p>
7608                         When this rule is used, the
7609                         <em class="replaceable"><code>name</code></em> field is omitted.
7610                       </p>
7611                     </td>
7612 </tr>
7613 <tr>
7614 <td>
7615                       <p>
7616                         <code class="varname">wildcard</code>
7617                       </p>
7618                     </td>
7619 <td>
7620                       <p>
7621                         The <em class="replaceable"><code>name</code></em> field
7622                         is subject to DNS wildcard expansion, and
7623                         this rule matches when the name being updated
7624                         name is a valid expansion of the wildcard.
7625                       </p>
7626                     </td>
7627 </tr>
7628 <tr>
7629 <td>
7630                       <p>
7631                         <code class="varname">self</code>
7632                       </p>
7633                     </td>
7634 <td>
7635                       <p>
7636                         This rule matches when the name being updated
7637                         matches the contents of the
7638                         <em class="replaceable"><code>identity</code></em> field.
7639                         The <em class="replaceable"><code>name</code></em> field
7640                         is ignored, but should be the same as the
7641                         <em class="replaceable"><code>identity</code></em> field.
7642                         The <code class="varname">self</code> nametype is
7643                         most useful when allowing using one key per
7644                         name to update, where the key has the same
7645                         name as the name to be updated.  The
7646                         <em class="replaceable"><code>identity</code></em> would
7647                         be specified as <code class="constant">*</code> (an asterisk) in
7648                         this case.
7649                       </p>
7650                     </td>
7651 </tr>
7652 <tr>
7653 <td>
7654                       <p>
7655                         <code class="varname">selfsub</code>
7656                       </p>
7657                     </td>
7658 <td>
7659                       <p>
7660                         This rule is similar to <code class="varname">self</code>
7661                         except that subdomains of <code class="varname">self</code>
7662                         can also be updated.
7663                       </p>
7664                     </td>
7665 </tr>
7666 <tr>
7667 <td>
7668                       <p>
7669                         <code class="varname">selfwild</code>
7670                       </p>
7671                     </td>
7672 <td>
7673                       <p>
7674                         This rule is similar to <code class="varname">self</code>
7675                         except that only subdomains of
7676                         <code class="varname">self</code> can be updated.
7677                       </p>
7678                     </td>
7679 </tr>
7680 <tr>
7681 <td>
7682                       <p>
7683                         <code class="varname">ms-self</code>
7684                       </p>
7685                     </td>
7686 <td>
7687                       <p>
7688                         This rule takes a Windows machine principal
7689                         (machine$@REALM) for machine in REALM and
7690                         and converts it machine.realm allowing the machine
7691                         to update machine.realm.  The REALM to be matched
7692                         is specified in the <em class="replaceable"><code>identity</code></em>
7693                         field.
7694                       </p>
7695                     </td>
7696 </tr>
7697 <tr>
7698 <td>
7699                       <p>
7700                         <code class="varname">ms-subdomain</code>
7701                       </p>
7702                     </td>
7703 <td>
7704                       <p>
7705                         This rule takes a Windows machine principal
7706                         (machine$@REALM) for machine in REALM and
7707                         converts it to machine.realm allowing the machine
7708                         to update subdomains of machine.realm.  The REALM
7709                         to be matched is specified in the
7710                         <em class="replaceable"><code>identity</code></em> field.
7711                       </p>
7712                     </td>
7713 </tr>
7714 <tr>
7715 <td>
7716                       <p>
7717                         <code class="varname">krb5-self</code>
7718                       </p>
7719                     </td>
7720 <td>
7721                       <p>
7722                         This rule takes a Kerberos machine principal
7723                         (host/machine@REALM) for machine in REALM and
7724                         and converts it machine.realm allowing the machine
7725                         to update machine.realm.  The REALM to be matched
7726                         is specified in the <em class="replaceable"><code>identity</code></em>
7727                         field.
7728                       </p>
7729                     </td>
7730 </tr>
7731 <tr>
7732 <td>
7733                       <p>
7734                         <code class="varname">krb5-subdomain</code>
7735                       </p>
7736                     </td>
7737 <td>
7738                       <p>
7739                         This rule takes a Kerberos machine principal
7740                         (host/machine@REALM) for machine in REALM and
7741                         converts it to machine.realm allowing the machine
7742                         to update subdomains of machine.realm.  The REALM
7743                         to be matched is specified in the
7744                         <em class="replaceable"><code>identity</code></em> field.
7745                       </p>
7746                     </td>
7747 </tr>
7748 <tr>
7749 <td>
7750                       <p>
7751                         <code class="varname">tcp-self</code>
7752                       </p>
7753                     </td>
7754 <td>
7755                       <p>
7756                         Allow updates that have been sent via TCP and
7757                         for which the standard mapping from the initiating
7758                         IP address into the IN-ADDR.ARPA and IP6.ARPA
7759                         namespaces match the name to be updated.
7760                       </p>
7761                       <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7762 <h3 class="title">Note</h3>
7763                         It is theoretically possible to spoof these TCP
7764                         sessions.
7765                       </div>
7766                     </td>
7767 </tr>
7768 <tr>
7769 <td>
7770                       <p>
7771                         <code class="varname">6to4-self</code>
7772                       </p>
7773                     </td>
7774 <td>
7775                       <p>
7776                         Allow the 6to4 prefix to be update by any TCP
7777                         connection from the 6to4 network or from the
7778                         corresponding IPv4 address.  This is intended
7779                         to allow NS or DNAME RRsets to be added to the
7780                         reverse tree.
7781                       </p>
7782                       <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7783 <h3 class="title">Note</h3>
7784                         It is theoretically possible to spoof these TCP
7785                         sessions.
7786                       </div>
7787                     </td>
7788 </tr>
7789 <tr>
7790 <td>
7791                       <p>
7792                         <code class="varname">external</code>
7793                       </p>
7794                     </td>
7795 <td>
7796                       <p>
7797                         This rule allows <span><strong class="command">named</strong></span>
7798                         to defer the decision of whether to allow a
7799                         given update to an external daemon.
7800                       </p>
7801                       <p>
7802                         The method of communicating with the daemon is
7803                         specified in the <em class="replaceable"><code>identity</code></em>
7804                         field, the format of which is
7805                         "<code class="constant">local:</code><em class="replaceable"><code>path</code></em>",
7806                         where <em class="replaceable"><code>path</code></em> is the location
7807                         of a UNIX-domain socket.  (Currently, "local" is the
7808                         only supported mechanism.)
7809                       </p>
7810                       <p>
7811                         Requests to the external daemon are sent over the
7812                         UNIX-domain socket as datagrams with the following
7813                         format:
7814                       </p>
7815                       <pre class="programlisting">
7816    Protocol version number (4 bytes, network byte order, currently 1)
7817    Request length (4 bytes, network byte order)
7818    Signer (null-terminated string)
7819    Name (null-terminated string)
7820    TCP source address (null-terminated string)
7821    Rdata type (null-terminated string)
7822    Key (null-terminated string)
7823    TKEY token length (4 bytes, network byte order)
7824    TKEY token (remainder of packet)</pre>
7825                       <p>
7826                         The daemon replies with a four-byte value in
7827                         network byte order, containing either 0 or 1; 0
7828                         indicates that the specified update is not
7829                         permitted, and 1 indicates that it is.
7830                       </p>
7831                     </td>
7832 </tr>
7833 </tbody>
7834 </table></div>
7835 <p>
7836               In all cases, the <em class="replaceable"><code>name</code></em>
7837               field must specify a fully-qualified domain name.
7838             </p>
7839 <p>
7840               If no types are explicitly specified, this rule matches
7841               all types except RRSIG, NS, SOA, NSEC and NSEC3. Types
7842               may be specified by name, including "ANY" (ANY matches
7843               all types except NSEC and NSEC3, which can never be
7844               updated).  Note that when an attempt is made to delete
7845               all records associated with a name, the rules are
7846               checked for each existing record type.
7847             </p>
7848 </div>
7849 </div>
7850 </div>
7851 <div class="sect1" lang="en">
7852 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
7853 <a name="id2594764"></a>Zone File</h2></div></div></div>
7854 <div class="sect2" lang="en">
7855 <div class="titlepage"><div><div><h3 class="title">
7856 <a name="types_of_resource_records_and_when_to_use_them"></a>Types of Resource Records and When to Use Them</h3></div></div></div>
7857 <p>
7858             This section, largely borrowed from RFC 1034, describes the
7859             concept of a Resource Record (RR) and explains when each is used.
7860             Since the publication of RFC 1034, several new RRs have been
7861             identified
7862             and implemented in the DNS. These are also included.
7863           </p>
7864 <div class="sect3" lang="en">
7865 <div class="titlepage"><div><div><h4 class="title">
7866 <a name="id2594782"></a>Resource Records</h4></div></div></div>
7867 <p>
7868               A domain name identifies a node.  Each node has a set of
7869               resource information, which may be empty.  The set of resource
7870               information associated with a particular name is composed of
7871               separate RRs. The order of RRs in a set is not significant and
7872               need not be preserved by name servers, resolvers, or other
7873               parts of the DNS. However, sorting of multiple RRs is
7874               permitted for optimization purposes, for example, to specify
7875               that a particular nearby server be tried first. See <a href="Bv9ARM.ch06.html#the_sortlist_statement" title="The sortlist Statement">the section called &#8220;The <span><strong class="command">sortlist</strong></span> Statement&#8221;</a> and <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called &#8220;RRset Ordering&#8221;</a>.
7876             </p>
7877 <p>
7878               The components of a Resource Record are:
7879             </p>
7880 <div class="informaltable"><table border="1">
7881 <colgroup>
7882 <col>
7883 <col>
7884 </colgroup>
7885 <tbody>
7886 <tr>
7887 <td>
7888                       <p>
7889                         owner name
7890                       </p>
7891                     </td>
7892 <td>
7893                       <p>
7894                         The domain name where the RR is found.
7895                       </p>
7896                     </td>
7897 </tr>
7898 <tr>
7899 <td>
7900                       <p>
7901                         type
7902                       </p>
7903                     </td>
7904 <td>
7905                       <p>
7906                         An encoded 16-bit value that specifies
7907                         the type of the resource record.
7908                       </p>
7909                     </td>
7910 </tr>
7911 <tr>
7912 <td>
7913                       <p>
7914                         TTL
7915                       </p>
7916                     </td>
7917 <td>
7918                       <p>
7919                         The time-to-live of the RR. This field
7920                         is a 32-bit integer in units of seconds, and is
7921                         primarily used by
7922                         resolvers when they cache RRs. The TTL describes how
7923                         long a RR can
7924                         be cached before it should be discarded.
7925                       </p>
7926                     </td>
7927 </tr>
7928 <tr>
7929 <td>
7930                       <p>
7931                         class
7932                       </p>
7933                     </td>
7934 <td>
7935                       <p>
7936                         An encoded 16-bit value that identifies
7937                         a protocol family or instance of a protocol.
7938                       </p>
7939                     </td>
7940 </tr>
7941 <tr>
7942 <td>
7943                       <p>
7944                         RDATA
7945                       </p>
7946                     </td>
7947 <td>
7948                       <p>
7949                         The resource data.  The format of the
7950                         data is type (and sometimes class) specific.
7951                       </p>
7952                     </td>
7953 </tr>
7954 </tbody>
7955 </table></div>
7956 <p>
7957               The following are <span class="emphasis"><em>types</em></span> of valid RRs:
7958             </p>
7959 <div class="informaltable"><table border="1">
7960 <colgroup>
7961 <col>
7962 <col>
7963 </colgroup>
7964 <tbody>
7965 <tr>
7966 <td>
7967                       <p>
7968                         A
7969                       </p>
7970                     </td>
7971 <td>
7972                       <p>
7973                         A host address.  In the IN class, this is a
7974                         32-bit IP address.  Described in RFC 1035.
7975                       </p>
7976                     </td>
7977 </tr>
7978 <tr>
7979 <td>
7980                       <p>
7981                         AAAA
7982                       </p>
7983                     </td>
7984 <td>
7985                       <p>
7986                         IPv6 address.  Described in RFC 1886.
7987                       </p>
7988                     </td>
7989 </tr>
7990 <tr>
7991 <td>
7992                       <p>
7993                         A6
7994                       </p>
7995                     </td>
7996 <td>
7997                       <p>
7998                         IPv6 address.  This can be a partial
7999                         address (a suffix) and an indirection to the name
8000                         where the rest of the
8001                         address (the prefix) can be found.  Experimental.
8002                         Described in RFC 2874.
8003                       </p>
8004                     </td>
8005 </tr>
8006 <tr>
8007 <td>
8008                       <p>
8009                         AFSDB
8010                       </p>
8011                     </td>
8012 <td>
8013                       <p>
8014                         Location of AFS database servers.
8015                         Experimental.  Described in RFC 1183.
8016                       </p>
8017                     </td>
8018 </tr>
8019 <tr>
8020 <td>
8021                       <p>
8022                         APL
8023                       </p>
8024                     </td>
8025 <td>
8026                       <p>
8027                         Address prefix list.  Experimental.
8028                         Described in RFC 3123.
8029                       </p>
8030                     </td>
8031 </tr>
8032 <tr>
8033 <td>
8034                       <p>
8035                         CERT
8036                       </p>
8037                     </td>
8038 <td>
8039                       <p>
8040                         Holds a digital certificate.
8041                         Described in RFC 2538.
8042                       </p>
8043                     </td>
8044 </tr>
8045 <tr>
8046 <td>
8047                       <p>
8048                         CNAME
8049                       </p>
8050                     </td>
8051 <td>
8052                       <p>
8053                         Identifies the canonical name of an alias.
8054                         Described in RFC 1035.
8055                       </p>
8056                     </td>
8057 </tr>
8058 <tr>
8059 <td>
8060                       <p>
8061                         DHCID
8062                       </p>
8063                     </td>
8064 <td>
8065                       <p>
8066                         Is used for identifying which DHCP client is
8067                         associated with this name.  Described in RFC 4701.
8068                       </p>
8069                     </td>
8070 </tr>
8071 <tr>
8072 <td>
8073                       <p>
8074                         DNAME
8075                       </p>
8076                     </td>
8077 <td>
8078                       <p>
8079                         Replaces the domain name specified with
8080                         another name to be looked up, effectively aliasing an
8081                         entire
8082                         subtree of the domain name space rather than a single
8083                         record
8084                         as in the case of the CNAME RR.
8085                         Described in RFC 2672.
8086                       </p>
8087                     </td>
8088 </tr>
8089 <tr>
8090 <td>
8091                       <p>
8092                         DNSKEY
8093                       </p>
8094                     </td>
8095 <td>
8096                       <p>
8097                         Stores a public key associated with a signed
8098                         DNS zone.  Described in RFC 4034.
8099                       </p>
8100                     </td>
8101 </tr>
8102 <tr>
8103 <td>
8104                       <p>
8105                         DS
8106                       </p>
8107                     </td>
8108 <td>
8109                       <p>
8110                         Stores the hash of a public key associated with a
8111                         signed DNS zone.  Described in RFC 4034.
8112                       </p>
8113                     </td>
8114 </tr>
8115 <tr>
8116 <td>
8117                       <p>
8118                         GPOS
8119                       </p>
8120                     </td>
8121 <td>
8122                       <p>
8123                         Specifies the global position.  Superseded by LOC.
8124                       </p>
8125                     </td>
8126 </tr>
8127 <tr>
8128 <td>
8129                       <p>
8130                         HINFO
8131                       </p>
8132                     </td>
8133 <td>
8134                       <p>
8135                         Identifies the CPU and OS used by a host.
8136                         Described in RFC 1035.
8137                       </p>
8138                     </td>
8139 </tr>
8140 <tr>
8141 <td>
8142                       <p>
8143                         IPSECKEY
8144                       </p>
8145                     </td>
8146 <td>
8147                       <p>
8148                         Provides a method for storing IPsec keying material in
8149                         DNS.  Described in RFC 4025.
8150                       </p>
8151                     </td>
8152 </tr>
8153 <tr>
8154 <td>
8155                       <p>
8156                         ISDN
8157                       </p>
8158                     </td>
8159 <td>
8160                       <p>
8161                         Representation of ISDN addresses.
8162                         Experimental.  Described in RFC 1183.
8163                       </p>
8164                     </td>
8165 </tr>
8166 <tr>
8167 <td>
8168                       <p>
8169                         KEY
8170                       </p>
8171                     </td>
8172 <td>
8173                       <p>
8174                         Stores a public key associated with a
8175                         DNS name.  Used in original DNSSEC; replaced
8176                         by DNSKEY in DNSSECbis, but still used with
8177                         SIG(0).  Described in RFCs 2535 and 2931.
8178                       </p>
8179                     </td>
8180 </tr>
8181 <tr>
8182 <td>
8183                       <p>
8184                         KX
8185                       </p>
8186                     </td>
8187 <td>
8188                       <p>
8189                         Identifies a key exchanger for this
8190                         DNS name.  Described in RFC 2230.
8191                       </p>
8192                     </td>
8193 </tr>
8194 <tr>
8195 <td>
8196                       <p>
8197                         LOC
8198                       </p>
8199                     </td>
8200 <td>
8201                       <p>
8202                         For storing GPS info.  Described in RFC 1876.
8203                         Experimental.
8204                       </p>
8205                     </td>
8206 </tr>
8207 <tr>
8208 <td>
8209                       <p>
8210                         MX
8211                       </p>
8212                     </td>
8213 <td>
8214                       <p>
8215                         Identifies a mail exchange for the domain with
8216                         a 16-bit preference value (lower is better)
8217                         followed by the host name of the mail exchange.
8218                         Described in RFC 974, RFC 1035.
8219                       </p>
8220                     </td>
8221 </tr>
8222 <tr>
8223 <td>
8224                       <p>
8225                         NAPTR
8226                       </p>
8227                     </td>
8228 <td>
8229                       <p>
8230                         Name authority pointer.  Described in RFC 2915.
8231                       </p>
8232                     </td>
8233 </tr>
8234 <tr>
8235 <td>
8236                       <p>
8237                         NSAP
8238                       </p>
8239                     </td>
8240 <td>
8241                       <p>
8242                         A network service access point.
8243                         Described in RFC 1706.
8244                       </p>
8245                     </td>
8246 </tr>
8247 <tr>
8248 <td>
8249                       <p>
8250                         NS
8251                       </p>
8252                     </td>
8253 <td>
8254                       <p>
8255                         The authoritative name server for the
8256                         domain.  Described in RFC 1035.
8257                       </p>
8258                     </td>
8259 </tr>
8260 <tr>
8261 <td>
8262                       <p>
8263                         NSEC
8264                       </p>
8265                     </td>
8266 <td>
8267                       <p>
8268                         Used in DNSSECbis to securely indicate that
8269                         RRs with an owner name in a certain name interval do
8270                         not exist in
8271                         a zone and indicate what RR types are present for an
8272                         existing name.
8273                         Described in RFC 4034.
8274                       </p>
8275                     </td>
8276 </tr>
8277 <tr>
8278 <td>
8279                       <p>
8280                         NSEC3
8281                       </p>
8282                     </td>
8283 <td>
8284                       <p>
8285                         Used in DNSSECbis to securely indicate that
8286                         RRs with an owner name in a certain name
8287                         interval do not exist in a zone and indicate
8288                         what RR types are present for an existing
8289                         name.  NSEC3 differs from NSEC in that it
8290                         prevents zone enumeration but is more
8291                         computationally expensive on both the server
8292                         and the client than NSEC.  Described in RFC
8293                         5155.
8294                       </p>
8295                     </td>
8296 </tr>
8297 <tr>
8298 <td>
8299                       <p>
8300                         NSEC3PARAM
8301                       </p>
8302                     </td>
8303 <td>
8304                       <p>
8305                         Used in DNSSECbis to tell the authoritative
8306                         server which NSEC3 chains are available to use.
8307                         Described in RFC 5155.
8308                       </p>
8309                     </td>
8310 </tr>
8311 <tr>
8312 <td>
8313                       <p>
8314                         NXT
8315                       </p>
8316                     </td>
8317 <td>
8318                       <p>
8319                         Used in DNSSEC to securely indicate that
8320                         RRs with an owner name in a certain name interval do
8321                         not exist in
8322                         a zone and indicate what RR types are present for an
8323                         existing name.
8324                         Used in original DNSSEC; replaced by NSEC in
8325                         DNSSECbis.
8326                         Described in RFC 2535.
8327                       </p>
8328                     </td>
8329 </tr>
8330 <tr>
8331 <td>
8332                       <p>
8333                         PTR
8334                       </p>
8335                     </td>
8336 <td>
8337                       <p>
8338                         A pointer to another part of the domain
8339                         name space.  Described in RFC 1035.
8340                       </p>
8341                     </td>
8342 </tr>
8343 <tr>
8344 <td>
8345                       <p>
8346                         PX
8347                       </p>
8348                     </td>
8349 <td>
8350                       <p>
8351                         Provides mappings between RFC 822 and X.400
8352                         addresses.  Described in RFC 2163.
8353                       </p>
8354                     </td>
8355 </tr>
8356 <tr>
8357 <td>
8358                       <p>
8359                         RP
8360                       </p>
8361                     </td>
8362 <td>
8363                       <p>
8364                         Information on persons responsible
8365                         for the domain.  Experimental.  Described in RFC 1183.
8366                       </p>
8367                     </td>
8368 </tr>
8369 <tr>
8370 <td>
8371                       <p>
8372                         RRSIG
8373                       </p>
8374                     </td>
8375 <td>
8376                       <p>
8377                         Contains DNSSECbis signature data.  Described
8378                         in RFC 4034.
8379                       </p>
8380                     </td>
8381 </tr>
8382 <tr>
8383 <td>
8384                       <p>
8385                         RT
8386                       </p>
8387                     </td>
8388 <td>
8389                       <p>
8390                         Route-through binding for hosts that
8391                         do not have their own direct wide area network
8392                         addresses.
8393                         Experimental.  Described in RFC 1183.
8394                       </p>
8395                     </td>
8396 </tr>
8397 <tr>
8398 <td>
8399                       <p>
8400                         SIG
8401                       </p>
8402                     </td>
8403 <td>
8404                       <p>
8405                         Contains DNSSEC signature data.  Used in
8406                         original DNSSEC; replaced by RRSIG in
8407                         DNSSECbis, but still used for SIG(0).
8408                         Described in RFCs 2535 and 2931.
8409                       </p>
8410                     </td>
8411 </tr>
8412 <tr>
8413 <td>
8414                       <p>
8415                         SOA
8416                       </p>
8417                     </td>
8418 <td>
8419                       <p>
8420                         Identifies the start of a zone of authority.
8421                         Described in RFC 1035.
8422                       </p>
8423                     </td>
8424 </tr>
8425 <tr>
8426 <td>
8427                       <p>
8428                         SPF
8429                       </p>
8430                     </td>
8431 <td>
8432                       <p>
8433                         Contains the Sender Policy Framework information
8434                         for a given email domain.  Described in RFC 4408.
8435                       </p>
8436                     </td>
8437 </tr>
8438 <tr>
8439 <td>
8440                       <p>
8441                         SRV
8442                       </p>
8443                     </td>
8444 <td>
8445                       <p>
8446                         Information about well known network
8447                         services (replaces WKS).  Described in RFC 2782.
8448                       </p>
8449                     </td>
8450 </tr>
8451 <tr>
8452 <td>
8453                       <p>
8454                         SSHFP
8455                       </p>
8456                     </td>
8457 <td>
8458                       <p>
8459                         Provides a way to securely publish a secure shell key's
8460                         fingerprint.  Described in RFC 4255.
8461                       </p>
8462                     </td>
8463 </tr>
8464 <tr>
8465 <td>
8466                       <p>
8467                         TXT
8468                       </p>
8469                     </td>
8470 <td>
8471                       <p>
8472                         Text records.  Described in RFC 1035.
8473                       </p>
8474                     </td>
8475 </tr>
8476 <tr>
8477 <td>
8478                       <p>
8479                         WKS
8480                       </p>
8481                     </td>
8482 <td>
8483                       <p>
8484                         Information about which well known
8485                         network services, such as SMTP, that a domain
8486                         supports. Historical.
8487                       </p>
8488                     </td>
8489 </tr>
8490 <tr>
8491 <td>
8492                       <p>
8493                         X25
8494                       </p>
8495                     </td>
8496 <td>
8497                       <p>
8498                         Representation of X.25 network addresses.
8499                         Experimental.  Described in RFC 1183.
8500                       </p>
8501                     </td>
8502 </tr>
8503 </tbody>
8504 </table></div>
8505 <p>
8506               The following <span class="emphasis"><em>classes</em></span> of resource records
8507               are currently valid in the DNS:
8508             </p>
8509 <div class="informaltable"><table border="1">
8510 <colgroup>
8511 <col>
8512 <col>
8513 </colgroup>
8514 <tbody>
8515 <tr>
8516 <td>
8517                       <p>
8518                         IN
8519                       </p>
8520                     </td>
8521 <td>
8522                       <p>
8523                         The Internet.
8524                       </p>
8525                     </td>
8526 </tr>
8527 <tr>
8528 <td>
8529                       <p>
8530                         CH
8531                       </p>
8532                     </td>
8533 <td>
8534                       <p>
8535                         Chaosnet, a LAN protocol created at MIT in the
8536                         mid-1970s.
8537                         Rarely used for its historical purpose, but reused for
8538                         BIND's
8539                         built-in server information zones, e.g.,
8540                         <code class="literal">version.bind</code>.
8541                       </p>
8542                     </td>
8543 </tr>
8544 <tr>
8545 <td>
8546                       <p>
8547                         HS
8548                       </p>
8549                     </td>
8550 <td>
8551                       <p>
8552                         Hesiod, an information service
8553                         developed by MIT's Project Athena. It is used to share
8554                         information
8555                         about various systems databases, such as users,
8556                         groups, printers
8557                         and so on.
8558                       </p>
8559                     </td>
8560 </tr>
8561 </tbody>
8562 </table></div>
8563 <p>
8564               The owner name is often implicit, rather than forming an
8565               integral
8566               part of the RR.  For example, many name servers internally form
8567               tree
8568               or hash structures for the name space, and chain RRs off nodes.
8569               The remaining RR parts are the fixed header (type, class, TTL)
8570               which is consistent for all RRs, and a variable part (RDATA)
8571               that
8572               fits the needs of the resource being described.
8573             </p>
8574 <p>
8575               The meaning of the TTL field is a time limit on how long an
8576               RR can be kept in a cache.  This limit does not apply to
8577               authoritative
8578               data in zones; it is also timed out, but by the refreshing
8579               policies
8580               for the zone.  The TTL is assigned by the administrator for the
8581               zone where the data originates.  While short TTLs can be used to
8582               minimize caching, and a zero TTL prohibits caching, the
8583               realities
8584               of Internet performance suggest that these times should be on
8585               the
8586               order of days for the typical host.  If a change can be
8587               anticipated,
8588               the TTL can be reduced prior to the change to minimize
8589               inconsistency
8590               during the change, and then increased back to its former value
8591               following
8592               the change.
8593             </p>
8594 <p>
8595               The data in the RDATA section of RRs is carried as a combination
8596               of binary strings and domain names.  The domain names are
8597               frequently
8598               used as "pointers" to other data in the DNS.
8599             </p>
8600 </div>
8601 <div class="sect3" lang="en">
8602 <div class="titlepage"><div><div><h4 class="title">
8603 <a name="id2596406"></a>Textual expression of RRs</h4></div></div></div>
8604 <p>
8605               RRs are represented in binary form in the packets of the DNS
8606               protocol, and are usually represented in highly encoded form
8607               when
8608               stored in a name server or resolver.  In the examples provided
8609               in
8610               RFC 1034, a style similar to that used in master files was
8611               employed
8612               in order to show the contents of RRs.  In this format, most RRs
8613               are shown on a single line, although continuation lines are
8614               possible
8615               using parentheses.
8616             </p>
8617 <p>
8618               The start of the line gives the owner of the RR.  If a line
8619               begins with a blank, then the owner is assumed to be the same as
8620               that of the previous RR.  Blank lines are often included for
8621               readability.
8622             </p>
8623 <p>
8624               Following the owner, we list the TTL, type, and class of the
8625               RR.  Class and type use the mnemonics defined above, and TTL is
8626               an integer before the type field.  In order to avoid ambiguity
8627               in
8628               parsing, type and class mnemonics are disjoint, TTLs are
8629               integers,
8630               and the type mnemonic is always last. The IN class and TTL
8631               values
8632               are often omitted from examples in the interests of clarity.
8633             </p>
8634 <p>
8635               The resource data or RDATA section of the RR are given using
8636               knowledge of the typical representation for the data.
8637             </p>
8638 <p>
8639               For example, we might show the RRs carried in a message as:
8640             </p>
8641 <div class="informaltable"><table border="1">
8642 <colgroup>
8643 <col>
8644 <col>
8645 <col>
8646 </colgroup>
8647 <tbody>
8648 <tr>
8649 <td>
8650                       <p>
8651                         <code class="literal">ISI.EDU.</code>
8652                       </p>
8653                     </td>
8654 <td>
8655                       <p>
8656                         <code class="literal">MX</code>
8657                       </p>
8658                     </td>
8659 <td>
8660                       <p>
8661                         <code class="literal">10 VENERA.ISI.EDU.</code>
8662                       </p>
8663                     </td>
8664 </tr>
8665 <tr>
8666 <td>
8667                       <p></p>
8668                     </td>
8669 <td>
8670                       <p>
8671                         <code class="literal">MX</code>
8672                       </p>
8673                     </td>
8674 <td>
8675                       <p>
8676                         <code class="literal">10 VAXA.ISI.EDU</code>
8677                       </p>
8678                     </td>
8679 </tr>
8680 <tr>
8681 <td>
8682                       <p>
8683                         <code class="literal">VENERA.ISI.EDU</code>
8684                       </p>
8685                     </td>
8686 <td>
8687                       <p>
8688                         <code class="literal">A</code>
8689                       </p>
8690                     </td>
8691 <td>
8692                       <p>
8693                         <code class="literal">128.9.0.32</code>
8694                       </p>
8695                     </td>
8696 </tr>
8697 <tr>
8698 <td>
8699                       <p></p>
8700                     </td>
8701 <td>
8702                       <p>
8703                         <code class="literal">A</code>
8704                       </p>
8705                     </td>
8706 <td>
8707                       <p>
8708                         <code class="literal">10.1.0.52</code>
8709                       </p>
8710                     </td>
8711 </tr>
8712 <tr>
8713 <td>
8714                       <p>
8715                         <code class="literal">VAXA.ISI.EDU</code>
8716                       </p>
8717                     </td>
8718 <td>
8719                       <p>
8720                         <code class="literal">A</code>
8721                       </p>
8722                     </td>
8723 <td>
8724                       <p>
8725                         <code class="literal">10.2.0.27</code>
8726                       </p>
8727                     </td>
8728 </tr>
8729 <tr>
8730 <td>
8731                       <p></p>
8732                     </td>
8733 <td>
8734                       <p>
8735                         <code class="literal">A</code>
8736                       </p>
8737                     </td>
8738 <td>
8739                       <p>
8740                         <code class="literal">128.9.0.33</code>
8741                       </p>
8742                     </td>
8743 </tr>
8744 </tbody>
8745 </table></div>
8746 <p>
8747               The MX RRs have an RDATA section which consists of a 16-bit
8748               number followed by a domain name.  The address RRs use a
8749               standard
8750               IP address format to contain a 32-bit internet address.
8751             </p>
8752 <p>
8753               The above example shows six RRs, with two RRs at each of three
8754               domain names.
8755             </p>
8756 <p>
8757               Similarly we might see:
8758             </p>
8759 <div class="informaltable"><table border="1">
8760 <colgroup>
8761 <col>
8762 <col>
8763 <col>
8764 </colgroup>
8765 <tbody>
8766 <tr>
8767 <td>
8768                       <p>
8769                         <code class="literal">XX.LCS.MIT.EDU.</code>
8770                       </p>
8771                     </td>
8772 <td>
8773                       <p>
8774                         <code class="literal">IN A</code>
8775                       </p>
8776                     </td>
8777 <td>
8778                       <p>
8779                         <code class="literal">10.0.0.44</code>
8780                       </p>
8781                     </td>
8782 </tr>
8783 <tr>
8784 <td> </td>
8785 <td>
8786                       <p>
8787                         <code class="literal">CH A</code>
8788                       </p>
8789                     </td>
8790 <td>
8791                       <p>
8792                         <code class="literal">MIT.EDU. 2420</code>
8793                       </p>
8794                     </td>
8795 </tr>
8796 </tbody>
8797 </table></div>
8798 <p>
8799               This example shows two addresses for
8800               <code class="literal">XX.LCS.MIT.EDU</code>, each of a different class.
8801             </p>
8802 </div>
8803 </div>
8804 <div class="sect2" lang="en">
8805 <div class="titlepage"><div><div><h3 class="title">
8806 <a name="id2596926"></a>Discussion of MX Records</h3></div></div></div>
8807 <p>
8808             As described above, domain servers store information as a
8809             series of resource records, each of which contains a particular
8810             piece of information about a given domain name (which is usually,
8811             but not always, a host). The simplest way to think of a RR is as
8812             a typed pair of data, a domain name matched with a relevant datum,
8813             and stored with some additional type information to help systems
8814             determine when the RR is relevant.
8815           </p>
8816 <p>
8817             MX records are used to control delivery of email. The data
8818             specified in the record is a priority and a domain name. The
8819             priority
8820             controls the order in which email delivery is attempted, with the
8821             lowest number first. If two priorities are the same, a server is
8822             chosen randomly. If no servers at a given priority are responding,
8823             the mail transport agent will fall back to the next largest
8824             priority.
8825             Priority numbers do not have any absolute meaning &#8212; they are
8826             relevant
8827             only respective to other MX records for that domain name. The
8828             domain
8829             name given is the machine to which the mail will be delivered.
8830             It <span class="emphasis"><em>must</em></span> have an associated address record
8831             (A or AAAA) &#8212; CNAME is not sufficient.
8832           </p>
8833 <p>
8834             For a given domain, if there is both a CNAME record and an
8835             MX record, the MX record is in error, and will be ignored.
8836             Instead,
8837             the mail will be delivered to the server specified in the MX
8838             record
8839             pointed to by the CNAME.
8840             For example:
8841           </p>
8842 <div class="informaltable"><table border="1">
8843 <colgroup>
8844 <col>
8845 <col>
8846 <col>
8847 <col>
8848 <col>
8849 </colgroup>
8850 <tbody>
8851 <tr>
8852 <td>
8853                     <p>
8854                       <code class="literal">example.com.</code>
8855                     </p>
8856                   </td>
8857 <td>
8858                     <p>
8859                       <code class="literal">IN</code>
8860                     </p>
8861                   </td>
8862 <td>
8863                     <p>
8864                       <code class="literal">MX</code>
8865                     </p>
8866                   </td>
8867 <td>
8868                     <p>
8869                       <code class="literal">10</code>
8870                     </p>
8871                   </td>
8872 <td>
8873                     <p>
8874                       <code class="literal">mail.example.com.</code>
8875                     </p>
8876                   </td>
8877 </tr>
8878 <tr>
8879 <td>
8880                     <p></p>
8881                   </td>
8882 <td>
8883                     <p>
8884                       <code class="literal">IN</code>
8885                     </p>
8886                   </td>
8887 <td>
8888                     <p>
8889                       <code class="literal">MX</code>
8890                     </p>
8891                   </td>
8892 <td>
8893                     <p>
8894                       <code class="literal">10</code>
8895                     </p>
8896                   </td>
8897 <td>
8898                     <p>
8899                       <code class="literal">mail2.example.com.</code>
8900                     </p>
8901                   </td>
8902 </tr>
8903 <tr>
8904 <td>
8905                     <p></p>
8906                   </td>
8907 <td>
8908                     <p>
8909                       <code class="literal">IN</code>
8910                     </p>
8911                   </td>
8912 <td>
8913                     <p>
8914                       <code class="literal">MX</code>
8915                     </p>
8916                   </td>
8917 <td>
8918                     <p>
8919                       <code class="literal">20</code>
8920                     </p>
8921                   </td>
8922 <td>
8923                     <p>
8924                       <code class="literal">mail.backup.org.</code>
8925                     </p>
8926                   </td>
8927 </tr>
8928 <tr>
8929 <td>
8930                     <p>
8931                       <code class="literal">mail.example.com.</code>
8932                     </p>
8933                   </td>
8934 <td>
8935                     <p>
8936                       <code class="literal">IN</code>
8937                     </p>
8938                   </td>
8939 <td>
8940                     <p>
8941                       <code class="literal">A</code>
8942                     </p>
8943                   </td>
8944 <td>
8945                     <p>
8946                       <code class="literal">10.0.0.1</code>
8947                     </p>
8948                   </td>
8949 <td>
8950                     <p></p>
8951                   </td>
8952 </tr>
8953 <tr>
8954 <td>
8955                     <p>
8956                       <code class="literal">mail2.example.com.</code>
8957                     </p>
8958                   </td>
8959 <td>
8960                     <p>
8961                       <code class="literal">IN</code>
8962                     </p>
8963                   </td>
8964 <td>
8965                     <p>
8966                       <code class="literal">A</code>
8967                     </p>
8968                   </td>
8969 <td>
8970                     <p>
8971                       <code class="literal">10.0.0.2</code>
8972                     </p>
8973                   </td>
8974 <td>
8975                     <p></p>
8976                   </td>
8977 </tr>
8978 </tbody>
8979 </table></div>
8980 <p>
8981             Mail delivery will be attempted to <code class="literal">mail.example.com</code> and
8982             <code class="literal">mail2.example.com</code> (in
8983             any order), and if neither of those succeed, delivery to <code class="literal">mail.backup.org</code> will
8984             be attempted.
8985           </p>
8986 </div>
8987 <div class="sect2" lang="en">
8988 <div class="titlepage"><div><div><h3 class="title">
8989 <a name="Setting_TTLs"></a>Setting TTLs</h3></div></div></div>
8990 <p>
8991             The time-to-live of the RR field is a 32-bit integer represented
8992             in units of seconds, and is primarily used by resolvers when they
8993             cache RRs. The TTL describes how long a RR can be cached before it
8994             should be discarded. The following three types of TTL are
8995             currently
8996             used in a zone file.
8997           </p>
8998 <div class="informaltable"><table border="1">
8999 <colgroup>
9000 <col>
9001 <col>
9002 </colgroup>
9003 <tbody>
9004 <tr>
9005 <td>
9006                     <p>
9007                       SOA
9008                     </p>
9009                   </td>
9010 <td>
9011                     <p>
9012                       The last field in the SOA is the negative
9013                       caching TTL. This controls how long other servers will
9014                       cache no-such-domain
9015                       (NXDOMAIN) responses from you.
9016                     </p>
9017                     <p>
9018                       The maximum time for
9019                       negative caching is 3 hours (3h).
9020                     </p>
9021                   </td>
9022 </tr>
9023 <tr>
9024 <td>
9025                     <p>
9026                       $TTL
9027                     </p>
9028                   </td>
9029 <td>
9030                     <p>
9031                       The $TTL directive at the top of the
9032                       zone file (before the SOA) gives a default TTL for every
9033                       RR without
9034                       a specific TTL set.
9035                     </p>
9036                   </td>
9037 </tr>
9038 <tr>
9039 <td>
9040                     <p>
9041                       RR TTLs
9042                     </p>
9043                   </td>
9044 <td>
9045                     <p>
9046                       Each RR can have a TTL as the second
9047                       field in the RR, which will control how long other
9048                       servers can cache
9049                       the it.
9050                     </p>
9051                   </td>
9052 </tr>
9053 </tbody>
9054 </table></div>
9055 <p>
9056             All of these TTLs default to units of seconds, though units
9057             can be explicitly specified, for example, <code class="literal">1h30m</code>.
9058           </p>
9059 </div>
9060 <div class="sect2" lang="en">
9061 <div class="titlepage"><div><div><h3 class="title">
9062 <a name="id2597542"></a>Inverse Mapping in IPv4</h3></div></div></div>
9063 <p>
9064             Reverse name resolution (that is, translation from IP address
9065             to name) is achieved by means of the <span class="emphasis"><em>in-addr.arpa</em></span> domain
9066             and PTR records. Entries in the in-addr.arpa domain are made in
9067             least-to-most significant order, read left to right. This is the
9068             opposite order to the way IP addresses are usually written. Thus,
9069             a machine with an IP address of 10.1.2.3 would have a
9070             corresponding
9071             in-addr.arpa name of
9072             3.2.1.10.in-addr.arpa. This name should have a PTR resource record
9073             whose data field is the name of the machine or, optionally,
9074             multiple
9075             PTR records if the machine has more than one name. For example,
9076             in the [<span class="optional">example.com</span>] domain:
9077           </p>
9078 <div class="informaltable"><table border="1">
9079 <colgroup>
9080 <col>
9081 <col>
9082 </colgroup>
9083 <tbody>
9084 <tr>
9085 <td>
9086                     <p>
9087                       <code class="literal">$ORIGIN</code>
9088                     </p>
9089                   </td>
9090 <td>
9091                     <p>
9092                       <code class="literal">2.1.10.in-addr.arpa</code>
9093                     </p>
9094                   </td>
9095 </tr>
9096 <tr>
9097 <td>
9098                     <p>
9099                       <code class="literal">3</code>
9100                     </p>
9101                   </td>
9102 <td>
9103                     <p>
9104                       <code class="literal">IN PTR foo.example.com.</code>
9105                     </p>
9106                   </td>
9107 </tr>
9108 </tbody>
9109 </table></div>
9110 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
9111 <h3 class="title">Note</h3>
9112 <p>
9113               The <span><strong class="command">$ORIGIN</strong></span> lines in the examples
9114               are for providing context to the examples only &#8212; they do not
9115               necessarily
9116               appear in the actual usage. They are only used here to indicate
9117               that the example is relative to the listed origin.
9118             </p>
9119 </div>
9120 </div>
9121 <div class="sect2" lang="en">
9122 <div class="titlepage"><div><div><h3 class="title">
9123 <a name="id2597669"></a>Other Zone File Directives</h3></div></div></div>
9124 <p>
9125             The Master File Format was initially defined in RFC 1035 and
9126             has subsequently been extended. While the Master File Format
9127             itself
9128             is class independent all records in a Master File must be of the
9129             same
9130             class.
9131           </p>
9132 <p>
9133             Master File Directives include <span><strong class="command">$ORIGIN</strong></span>, <span><strong class="command">$INCLUDE</strong></span>,
9134             and <span><strong class="command">$TTL.</strong></span>
9135           </p>
9136 <div class="sect3" lang="en">
9137 <div class="titlepage"><div><div><h4 class="title">
9138 <a name="id2597760"></a>The <span><strong class="command">@</strong></span> (at-sign)</h4></div></div></div>
9139 <p>
9140               When used in the label (or name) field, the asperand or
9141               at-sign (@) symbol represents the current origin.
9142               At the start of the zone file, it is the
9143               &lt;<code class="varname">zone_name</code>&gt; (followed by
9144               trailing dot).
9145             </p>
9146 </div>
9147 <div class="sect3" lang="en">
9148 <div class="titlepage"><div><div><h4 class="title">
9149 <a name="id2597776"></a>The <span><strong class="command">$ORIGIN</strong></span> Directive</h4></div></div></div>
9150 <p>
9151               Syntax: <span><strong class="command">$ORIGIN</strong></span>
9152               <em class="replaceable"><code>domain-name</code></em>
9153               [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
9154             </p>
9155 <p><span><strong class="command">$ORIGIN</strong></span>
9156               sets the domain name that will be appended to any
9157               unqualified records. When a zone is first read in there
9158               is an implicit <span><strong class="command">$ORIGIN</strong></span>
9159               &lt;<code class="varname">zone_name</code>&gt;<span><strong class="command">.</strong></span>
9160               (followed by trailing dot).
9161               The current <span><strong class="command">$ORIGIN</strong></span> is appended to
9162               the domain specified in the <span><strong class="command">$ORIGIN</strong></span>
9163               argument if it is not absolute.
9164             </p>
9165 <pre class="programlisting">
9166 $ORIGIN example.com.
9167 WWW     CNAME   MAIN-SERVER
9168 </pre>
9169 <p>
9170               is equivalent to
9171             </p>
9172 <pre class="programlisting">
9173 WWW.EXAMPLE.COM. CNAME MAIN-SERVER.EXAMPLE.COM.
9174 </pre>
9175 </div>
9176 <div class="sect3" lang="en">
9177 <div class="titlepage"><div><div><h4 class="title">
9178 <a name="id2597836"></a>The <span><strong class="command">$INCLUDE</strong></span> Directive</h4></div></div></div>
9179 <p>
9180               Syntax: <span><strong class="command">$INCLUDE</strong></span>
9181               <em class="replaceable"><code>filename</code></em>
9182               [<span class="optional">
9183 <em class="replaceable"><code>origin</code></em> </span>]
9184               [<span class="optional"> <em class="replaceable"><code>comment</code></em> </span>]
9185             </p>
9186 <p>
9187               Read and process the file <code class="filename">filename</code> as
9188               if it were included into the file at this point.  If <span><strong class="command">origin</strong></span> is
9189               specified the file is processed with <span><strong class="command">$ORIGIN</strong></span> set
9190               to that value, otherwise the current <span><strong class="command">$ORIGIN</strong></span> is
9191               used.
9192             </p>
9193 <p>
9194               The origin and the current domain name
9195               revert to the values they had prior to the <span><strong class="command">$INCLUDE</strong></span> once
9196               the file has been read.
9197             </p>
9198 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
9199 <h3 class="title">Note</h3>
9200 <p>
9201                 RFC 1035 specifies that the current origin should be restored
9202                 after
9203                 an <span><strong class="command">$INCLUDE</strong></span>, but it is silent
9204                 on whether the current
9205                 domain name should also be restored.  BIND 9 restores both of
9206                 them.
9207                 This could be construed as a deviation from RFC 1035, a
9208                 feature, or both.
9209               </p>
9210 </div>
9211 </div>
9212 <div class="sect3" lang="en">
9213 <div class="titlepage"><div><div><h4 class="title">
9214 <a name="id2597906"></a>The <span><strong class="command">$TTL</strong></span> Directive</h4></div></div></div>
9215 <p>
9216               Syntax: <span><strong class="command">$TTL</strong></span>
9217               <em class="replaceable"><code>default-ttl</code></em>
9218               [<span class="optional">
9219 <em class="replaceable"><code>comment</code></em> </span>]
9220             </p>
9221 <p>
9222               Set the default Time To Live (TTL) for subsequent records
9223               with undefined TTLs. Valid TTLs are of the range 0-2147483647
9224               seconds.
9225             </p>
9226 <p><span><strong class="command">$TTL</strong></span>
9227                is defined in RFC 2308.
9228             </p>
9229 </div>
9230 </div>
9231 <div class="sect2" lang="en">
9232 <div class="titlepage"><div><div><h3 class="title">
9233 <a name="id2597942"></a><acronym class="acronym">BIND</acronym> Master File Extension: the  <span><strong class="command">$GENERATE</strong></span> Directive</h3></div></div></div>
9234 <p>
9235             Syntax: <span><strong class="command">$GENERATE</strong></span>
9236             <em class="replaceable"><code>range</code></em>
9237             <em class="replaceable"><code>lhs</code></em>
9238             [<span class="optional"><em class="replaceable"><code>ttl</code></em></span>]
9239             [<span class="optional"><em class="replaceable"><code>class</code></em></span>]
9240             <em class="replaceable"><code>type</code></em>
9241             <em class="replaceable"><code>rhs</code></em>
9242             [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
9243           </p>
9244 <p><span><strong class="command">$GENERATE</strong></span>
9245             is used to create a series of resource records that only
9246             differ from each other by an
9247             iterator. <span><strong class="command">$GENERATE</strong></span> can be used to
9248             easily generate the sets of records required to support
9249             sub /24 reverse delegations described in RFC 2317:
9250             Classless IN-ADDR.ARPA delegation.
9251           </p>
9252 <pre class="programlisting">$ORIGIN 0.0.192.IN-ADDR.ARPA.
9253 $GENERATE 1-2 @ NS SERVER$.EXAMPLE.
9254 $GENERATE 1-127 $ CNAME $.0</pre>
9255 <p>
9256             is equivalent to
9257           </p>
9258 <pre class="programlisting">0.0.0.192.IN-ADDR.ARPA. NS SERVER1.EXAMPLE.
9259 0.0.0.192.IN-ADDR.ARPA. NS SERVER2.EXAMPLE.
9260 1.0.0.192.IN-ADDR.ARPA. CNAME 1.0.0.0.192.IN-ADDR.ARPA.
9261 2.0.0.192.IN-ADDR.ARPA. CNAME 2.0.0.0.192.IN-ADDR.ARPA.
9262 ...
9263 127.0.0.192.IN-ADDR.ARPA. CNAME 127.0.0.0.192.IN-ADDR.ARPA.
9264 </pre>
9265 <p>
9266             Generate a set of A and MX records.  Note the MX's right hand
9267             side is a quoted string.  The quotes will be stripped when the
9268             right hand side is processed.
9269            </p>
9270 <pre class="programlisting">
9271 $ORIGIN EXAMPLE.
9272 $GENERATE 1-127 HOST-$ A 1.2.3.$
9273 $GENERATE 1-127 HOST-$ MX "0 ."</pre>
9274 <p>
9275             is equivalent to
9276           </p>
9277 <pre class="programlisting">HOST-1.EXAMPLE.   A  1.2.3.1
9278 HOST-1.EXAMPLE.   MX 0 .
9279 HOST-2.EXAMPLE.   A  1.2.3.2
9280 HOST-2.EXAMPLE.   MX 0 .
9281 HOST-3.EXAMPLE.   A  1.2.3.3
9282 HOST-3.EXAMPLE.   MX 0 .
9283 ...
9284 HOST-127.EXAMPLE. A  1.2.3.127
9285 HOST-127.EXAMPLE. MX 0 .
9286 </pre>
9287 <div class="informaltable"><table border="1">
9288 <colgroup>
9289 <col>
9290 <col>
9291 </colgroup>
9292 <tbody>
9293 <tr>
9294 <td>
9295                     <p><span><strong class="command">range</strong></span></p>
9296                   </td>
9297 <td>
9298                     <p>
9299                       This can be one of two forms: start-stop
9300                       or start-stop/step. If the first form is used, then step
9301                       is set to
9302                       1. All of start, stop and step must be positive.
9303                     </p>
9304                   </td>
9305 </tr>
9306 <tr>
9307 <td>
9308                     <p><span><strong class="command">lhs</strong></span></p>
9309                   </td>
9310 <td>
9311                     <p>This
9312                       describes the owner name of the resource records
9313                       to be created.  Any single <span><strong class="command">$</strong></span>
9314                       (dollar sign)
9315                       symbols within the <span><strong class="command">lhs</strong></span> string
9316                       are replaced by the iterator value.
9317
9318                       To get a $ in the output, you need to escape the
9319                       <span><strong class="command">$</strong></span> using a backslash
9320                       <span><strong class="command">\</strong></span>,
9321                       e.g. <span><strong class="command">\$</strong></span>. The
9322                       <span><strong class="command">$</strong></span> may optionally be followed
9323                       by modifiers which change the offset from the
9324                       iterator, field width and base.
9325
9326                       Modifiers are introduced by a
9327                       <span><strong class="command">{</strong></span> (left brace) immediately following the
9328                       <span><strong class="command">$</strong></span> as
9329                       <span><strong class="command">${offset[,width[,base]]}</strong></span>.
9330                       For example, <span><strong class="command">${-20,3,d}</strong></span>
9331                       subtracts 20 from the current value, prints the
9332                       result as a decimal in a zero-padded field of
9333                       width 3.
9334
9335                       Available output forms are decimal
9336                       (<span><strong class="command">d</strong></span>), octal
9337                       (<span><strong class="command">o</strong></span>), hexadecimal
9338                       (<span><strong class="command">x</strong></span> or <span><strong class="command">X</strong></span>
9339                       for uppercase) and nibble
9340                       (<span><strong class="command">n</strong></span> or <span><strong class="command">N</strong></span>\
9341                       for uppercase).  The default modifier is
9342                       <span><strong class="command">${0,0,d}</strong></span>.  If the
9343                       <span><strong class="command">lhs</strong></span> is not absolute, the
9344                       current <span><strong class="command">$ORIGIN</strong></span> is appended
9345                       to the name.
9346                     </p>
9347                     <p>
9348                       In nibble mode the value will be treated as
9349                       if it was a reversed hexadecimal string
9350                       with each hexadecimal digit as a separate
9351                       label.  The width field includes the label
9352                       separator.
9353                     </p>
9354                     <p>
9355                       For compatibility with earlier versions,
9356                       <span><strong class="command">$$</strong></span> is still recognized as
9357                       indicating a literal $ in the output.
9358                     </p>
9359                   </td>
9360 </tr>
9361 <tr>
9362 <td>
9363                     <p><span><strong class="command">ttl</strong></span></p>
9364                   </td>
9365 <td>
9366                     <p>
9367                       Specifies the time-to-live of the generated records. If
9368                       not specified this will be inherited using the
9369                       normal TTL inheritance rules.
9370                     </p>
9371                     <p><span><strong class="command">class</strong></span>
9372                       and <span><strong class="command">ttl</strong></span> can be
9373                       entered in either order.
9374                     </p>
9375                   </td>
9376 </tr>
9377 <tr>
9378 <td>
9379                     <p><span><strong class="command">class</strong></span></p>
9380                   </td>
9381 <td>
9382                     <p>
9383                       Specifies the class of the generated records.
9384                       This must match the zone class if it is
9385                       specified.
9386                     </p>
9387                     <p><span><strong class="command">class</strong></span>
9388                       and <span><strong class="command">ttl</strong></span> can be
9389                       entered in either order.
9390                     </p>
9391                   </td>
9392 </tr>
9393 <tr>
9394 <td>
9395                     <p><span><strong class="command">type</strong></span></p>
9396                   </td>
9397 <td>
9398                     <p>
9399                       Any valid type.
9400                     </p>
9401                   </td>
9402 </tr>
9403 <tr>
9404 <td>
9405                     <p><span><strong class="command">rhs</strong></span></p>
9406                   </td>
9407 <td>
9408                     <p>
9409                       <span><strong class="command">rhs</strong></span>, optionally, quoted string.
9410                     </p>
9411                   </td>
9412 </tr>
9413 </tbody>
9414 </table></div>
9415 <p>
9416             The <span><strong class="command">$GENERATE</strong></span> directive is a <acronym class="acronym">BIND</acronym> extension
9417             and not part of the standard zone file format.
9418           </p>
9419 <p>
9420             BIND 8 does not support the optional TTL and CLASS fields.
9421           </p>
9422 </div>
9423 <div class="sect2" lang="en">
9424 <div class="titlepage"><div><div><h3 class="title">
9425 <a name="zonefile_format"></a>Additional File Formats</h3></div></div></div>
9426 <p>
9427             In addition to the standard textual format, BIND 9
9428             supports the ability to read or dump to zone files in
9429             other formats.  The <code class="constant">raw</code> format is
9430             currently available as an additional format.  It is a
9431             binary format representing BIND 9's internal data
9432             structure directly, thereby remarkably improving the
9433             loading time.
9434           </p>
9435 <p>
9436             For a primary server, a zone file in the
9437             <code class="constant">raw</code> format is expected to be
9438             generated from a textual zone file by the
9439             <span><strong class="command">named-compilezone</strong></span> command.  For a
9440             secondary server or for a dynamic zone, it is automatically
9441             generated (if this format is specified by the
9442             <span><strong class="command">masterfile-format</strong></span> option) when
9443             <span><strong class="command">named</strong></span> dumps the zone contents after
9444             zone transfer or when applying prior updates.
9445           </p>
9446 <p>
9447             If a zone file in a binary format needs manual modification,
9448             it first must be converted to a textual form by the
9449             <span><strong class="command">named-compilezone</strong></span> command.  All
9450             necessary modification should go to the text file, which
9451             should then be converted to the binary form by the
9452             <span><strong class="command">named-compilezone</strong></span> command again.
9453           </p>
9454 <p>
9455              Although the <code class="constant">raw</code> format uses the
9456              network byte order and avoids architecture-dependent
9457              data alignment so that it is as much portable as
9458              possible, it is primarily expected to be used inside
9459              the same single system.  In order to export a zone
9460              file in the <code class="constant">raw</code> format or make a
9461              portable backup of the file, it is recommended to
9462              convert the file to the standard textual representation.
9463           </p>
9464 </div>
9465 </div>
9466 <div class="sect1" lang="en">
9467 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
9468 <a name="statistics"></a>BIND9 Statistics</h2></div></div></div>
9469 <p>
9470           <acronym class="acronym">BIND</acronym> 9 maintains lots of statistics
9471           information and provides several interfaces for users to
9472           get access to the statistics.
9473           The available statistics include all statistics counters
9474           that were available in <acronym class="acronym">BIND</acronym> 8 and
9475           are meaningful in <acronym class="acronym">BIND</acronym> 9,
9476           and other information that is considered useful.
9477         </p>
9478 <p>
9479           The statistics information is categorized into the following
9480           sections.
9481         </p>
9482 <div class="informaltable"><table border="1">
9483 <colgroup>
9484 <col>
9485 <col>
9486 </colgroup>
9487 <tbody>
9488 <tr>
9489 <td>
9490                   <p>Incoming Requests</p>
9491                 </td>
9492 <td>
9493                   <p>
9494                     The number of incoming DNS requests for each OPCODE.
9495                   </p>
9496                 </td>
9497 </tr>
9498 <tr>
9499 <td>
9500                   <p>Incoming Queries</p>
9501                 </td>
9502 <td>
9503                   <p>
9504                     The number of incoming queries for each RR type.
9505                   </p>
9506                 </td>
9507 </tr>
9508 <tr>
9509 <td>
9510                   <p>Outgoing Queries</p>
9511                 </td>
9512 <td>
9513                   <p>
9514                     The number of outgoing queries for each RR
9515                     type sent from the internal resolver.
9516                     Maintained per view.
9517                   </p>
9518                 </td>
9519 </tr>
9520 <tr>
9521 <td>
9522                   <p>Name Server Statistics</p>
9523                 </td>
9524 <td>
9525                   <p>
9526                     Statistics counters about incoming request processing.
9527                   </p>
9528                 </td>
9529 </tr>
9530 <tr>
9531 <td>
9532                   <p>Zone Maintenance Statistics</p>
9533                 </td>
9534 <td>
9535                   <p>
9536                     Statistics counters regarding zone maintenance
9537                     operations such as zone transfers.
9538                   </p>
9539                 </td>
9540 </tr>
9541 <tr>
9542 <td>
9543                   <p>Resolver Statistics</p>
9544                 </td>
9545 <td>
9546                   <p>
9547                     Statistics counters about name resolution
9548                     performed in the internal resolver.
9549                     Maintained per view.
9550                   </p>
9551                 </td>
9552 </tr>
9553 <tr>
9554 <td>
9555                   <p>Cache DB RRsets</p>
9556                 </td>
9557 <td>
9558                   <p>
9559                     The number of RRsets per RR type and nonexistent
9560                     names stored in the cache database.
9561                     If the exclamation mark (!) is printed for a RR
9562                     type, it means that particular type of RRset is
9563                     known to be nonexistent (this is also known as
9564                     "NXRRSET").
9565                     Maintained per view.
9566                   </p>
9567                 </td>
9568 </tr>
9569 <tr>
9570 <td>
9571                   <p>Socket I/O Statistics</p>
9572                 </td>
9573 <td>
9574                   <p>
9575                     Statistics counters about network related events.
9576                   </p>
9577                 </td>
9578 </tr>
9579 </tbody>
9580 </table></div>
9581 <p>
9582           A subset of Name Server Statistics is collected and shown
9583           per zone for which the server has the authority when
9584           <span><strong class="command">zone-statistics</strong></span> is set to
9585           <strong class="userinput"><code>yes</code></strong>.
9586           These statistics counters are shown with their zone and view
9587           names.
9588           In some cases the view names are omitted for the default view.
9589         </p>
9590 <p>
9591           There are currently two user interfaces to get access to the
9592           statistics.
9593           One is in the plain text format dumped to the file specified
9594           by the <span><strong class="command">statistics-file</strong></span> configuration option.
9595           The other is remotely accessible via a statistics channel
9596           when the <span><strong class="command">statistics-channels</strong></span> statement
9597           is specified in the configuration file
9598           (see <a href="Bv9ARM.ch06.html#statschannels" title="statistics-channels Statement Grammar">the section called &#8220;<span><strong class="command">statistics-channels</strong></span> Statement Grammar&#8221;</a>.)
9599         </p>
9600 <div class="sect3" lang="en">
9601 <div class="titlepage"><div><div><h4 class="title">
9602 <a name="statsfile"></a>The Statistics File</h4></div></div></div>
9603 <p>
9604             The text format statistics dump begins with a line, like:
9605           </p>
9606 <p>
9607             <span><strong class="command">+++ Statistics Dump +++ (973798949)</strong></span>
9608           </p>
9609 <p>
9610             The number in parentheses is a standard
9611             Unix-style timestamp, measured as seconds since January 1, 1970.
9612
9613             Following
9614             that line is a set of statistics information, which is categorized
9615             as described above.
9616             Each section begins with a line, like:
9617           </p>
9618 <p>
9619             <span><strong class="command">++ Name Server Statistics ++</strong></span>
9620           </p>
9621 <p>
9622             Each section consists of lines, each containing the statistics
9623             counter value followed by its textual description.
9624             See below for available counters.
9625             For brevity, counters that have a value of 0 are not shown
9626             in the statistics file.
9627           </p>
9628 <p>
9629             The statistics dump ends with the line where the
9630             number is identical to the number in the beginning line; for example:
9631           </p>
9632 <p>
9633             <span><strong class="command">--- Statistics Dump --- (973798949)</strong></span>
9634           </p>
9635 </div>
9636 <div class="sect2" lang="en">
9637 <div class="titlepage"><div><div><h3 class="title">
9638 <a name="statistics_counters"></a>Statistics Counters</h3></div></div></div>
9639 <p>
9640             The following tables summarize statistics counters that
9641             <acronym class="acronym">BIND</acronym> 9 provides.
9642             For each row of the tables, the leftmost column is the
9643             abbreviated symbol name of that counter.
9644             These symbols are shown in the statistics information
9645             accessed via an HTTP statistics channel.
9646             The rightmost column gives the description of the counter,
9647             which is also shown in the statistics file
9648             (but, in this document, possibly with slight modification
9649             for better readability).
9650             Additional notes may also be provided in this column.
9651             When a middle column exists between these two columns,
9652             it gives the corresponding counter name of the
9653             <acronym class="acronym">BIND</acronym> 8 statistics, if applicable.
9654           </p>
9655 <div class="sect3" lang="en">
9656 <div class="titlepage"><div><div><h4 class="title">
9657 <a name="id2598964"></a>Name Server Statistics Counters</h4></div></div></div>
9658 <div class="informaltable"><table border="1">
9659 <colgroup>
9660 <col>
9661 <col>
9662 <col>
9663 </colgroup>
9664 <tbody>
9665 <tr>
9666 <td>
9667                       <p>
9668                         <span class="emphasis"><em>Symbol</em></span>
9669                       </p>
9670                     </td>
9671 <td>
9672                       <p>
9673                         <span class="emphasis"><em>BIND8 Symbol</em></span>
9674                       </p>
9675                     </td>
9676 <td>
9677                       <p>
9678                         <span class="emphasis"><em>Description</em></span>
9679                       </p>
9680                     </td>
9681 </tr>
9682 <tr>
9683 <td>
9684                       <p><span><strong class="command">Requestv4</strong></span></p>
9685                     </td>
9686 <td>
9687                       <p><span><strong class="command">RQ</strong></span></p>
9688                     </td>
9689 <td>
9690                       <p>
9691                         IPv4 requests received.
9692                         Note: this also counts non query requests.
9693                       </p>
9694                     </td>
9695 </tr>
9696 <tr>
9697 <td>
9698                       <p><span><strong class="command">Requestv6</strong></span></p>
9699                     </td>
9700 <td>
9701                       <p><span><strong class="command">RQ</strong></span></p>
9702                     </td>
9703 <td>
9704                       <p>
9705                         IPv6 requests received.
9706                         Note: this also counts non query requests.
9707                       </p>
9708                     </td>
9709 </tr>
9710 <tr>
9711 <td>
9712                       <p><span><strong class="command">ReqEdns0</strong></span></p>
9713                     </td>
9714 <td>
9715                       <p><span><strong class="command"></strong></span></p>
9716                     </td>
9717 <td>
9718                       <p>
9719                         Requests with EDNS(0) received.
9720                       </p>
9721                     </td>
9722 </tr>
9723 <tr>
9724 <td>
9725                       <p><span><strong class="command">ReqBadEDNSVer</strong></span></p>
9726                     </td>
9727 <td>
9728                       <p><span><strong class="command"></strong></span></p>
9729                     </td>
9730 <td>
9731                       <p>
9732                         Requests with unsupported EDNS version received.
9733                       </p>
9734                     </td>
9735 </tr>
9736 <tr>
9737 <td>
9738                       <p><span><strong class="command">ReqTSIG</strong></span></p>
9739                     </td>
9740 <td>
9741                       <p><span><strong class="command"></strong></span></p>
9742                     </td>
9743 <td>
9744                       <p>
9745                         Requests with TSIG received.
9746                       </p>
9747                     </td>
9748 </tr>
9749 <tr>
9750 <td>
9751                       <p><span><strong class="command">ReqSIG0</strong></span></p>
9752                     </td>
9753 <td>
9754                       <p><span><strong class="command"></strong></span></p>
9755                     </td>
9756 <td>
9757                       <p>
9758                         Requests with SIG(0) received.
9759                       </p>
9760                     </td>
9761 </tr>
9762 <tr>
9763 <td>
9764                       <p><span><strong class="command">ReqBadSIG</strong></span></p>
9765                     </td>
9766 <td>
9767                       <p><span><strong class="command"></strong></span></p>
9768                     </td>
9769 <td>
9770                       <p>
9771                         Requests with invalid (TSIG or SIG(0)) signature.
9772                       </p>
9773                     </td>
9774 </tr>
9775 <tr>
9776 <td>
9777                       <p><span><strong class="command">ReqTCP</strong></span></p>
9778                     </td>
9779 <td>
9780                       <p><span><strong class="command">RTCP</strong></span></p>
9781                     </td>
9782 <td>
9783                       <p>
9784                         TCP requests received.
9785                       </p>
9786                     </td>
9787 </tr>
9788 <tr>
9789 <td>
9790                       <p><span><strong class="command">AuthQryRej</strong></span></p>
9791                     </td>
9792 <td>
9793                       <p><span><strong class="command">RUQ</strong></span></p>
9794                     </td>
9795 <td>
9796                       <p>
9797                         Authoritative (non recursive) queries rejected.
9798                       </p>
9799                     </td>
9800 </tr>
9801 <tr>
9802 <td>
9803                       <p><span><strong class="command">RecQryRej</strong></span></p>
9804                     </td>
9805 <td>
9806                       <p><span><strong class="command">RURQ</strong></span></p>
9807                     </td>
9808 <td>
9809                       <p>
9810                         Recursive queries rejected.
9811                       </p>
9812                     </td>
9813 </tr>
9814 <tr>
9815 <td>
9816                       <p><span><strong class="command">XfrRej</strong></span></p>
9817                     </td>
9818 <td>
9819                       <p><span><strong class="command">RUXFR</strong></span></p>
9820                     </td>
9821 <td>
9822                       <p>
9823                         Zone transfer requests rejected.
9824                       </p>
9825                     </td>
9826 </tr>
9827 <tr>
9828 <td>
9829                       <p><span><strong class="command">UpdateRej</strong></span></p>
9830                     </td>
9831 <td>
9832                       <p><span><strong class="command">RUUpd</strong></span></p>
9833                     </td>
9834 <td>
9835                       <p>
9836                         Dynamic update requests rejected.
9837                       </p>
9838                     </td>
9839 </tr>
9840 <tr>
9841 <td>
9842                       <p><span><strong class="command">Response</strong></span></p>
9843                     </td>
9844 <td>
9845                       <p><span><strong class="command">SAns</strong></span></p>
9846                     </td>
9847 <td>
9848                       <p>
9849                         Responses sent.
9850                       </p>
9851                     </td>
9852 </tr>
9853 <tr>
9854 <td>
9855                       <p><span><strong class="command">RespTruncated</strong></span></p>
9856                     </td>
9857 <td>
9858                       <p><span><strong class="command"></strong></span></p>
9859                     </td>
9860 <td>
9861                       <p>
9862                         Truncated responses sent.
9863                       </p>
9864                     </td>
9865 </tr>
9866 <tr>
9867 <td>
9868                       <p><span><strong class="command">RespEDNS0</strong></span></p>
9869                     </td>
9870 <td>
9871                       <p><span><strong class="command"></strong></span></p>
9872                     </td>
9873 <td>
9874                       <p>
9875                         Responses with EDNS(0) sent.
9876                       </p>
9877                     </td>
9878 </tr>
9879 <tr>
9880 <td>
9881                       <p><span><strong class="command">RespTSIG</strong></span></p>
9882                     </td>
9883 <td>
9884                       <p><span><strong class="command"></strong></span></p>
9885                     </td>
9886 <td>
9887                       <p>
9888                         Responses with TSIG sent.
9889                       </p>
9890                     </td>
9891 </tr>
9892 <tr>
9893 <td>
9894                       <p><span><strong class="command">RespSIG0</strong></span></p>
9895                     </td>
9896 <td>
9897                       <p><span><strong class="command"></strong></span></p>
9898                     </td>
9899 <td>
9900                       <p>
9901                         Responses with SIG(0) sent.
9902                       </p>
9903                     </td>
9904 </tr>
9905 <tr>
9906 <td>
9907                       <p><span><strong class="command">QrySuccess</strong></span></p>
9908                     </td>
9909 <td>
9910                       <p><span><strong class="command"></strong></span></p>
9911                     </td>
9912 <td>
9913                       <p>
9914                         Queries resulted in a successful answer.
9915                         This means the query which returns a NOERROR response
9916                         with at least one answer RR.
9917                         This corresponds to the
9918                         <span><strong class="command">success</strong></span> counter
9919                         of previous versions of
9920                         <acronym class="acronym">BIND</acronym> 9.
9921                       </p>
9922                     </td>
9923 </tr>
9924 <tr>
9925 <td>
9926                       <p><span><strong class="command">QryAuthAns</strong></span></p>
9927                     </td>
9928 <td>
9929                       <p><span><strong class="command"></strong></span></p>
9930                     </td>
9931 <td>
9932                       <p>
9933                         Queries resulted in authoritative answer.
9934                       </p>
9935                     </td>
9936 </tr>
9937 <tr>
9938 <td>
9939                       <p><span><strong class="command">QryNoauthAns</strong></span></p>
9940                     </td>
9941 <td>
9942                       <p><span><strong class="command">SNaAns</strong></span></p>
9943                     </td>
9944 <td>
9945                       <p>
9946                         Queries resulted in non authoritative answer.
9947                       </p>
9948                     </td>
9949 </tr>
9950 <tr>
9951 <td>
9952                       <p><span><strong class="command">QryReferral</strong></span></p>
9953                     </td>
9954 <td>
9955                       <p><span><strong class="command"></strong></span></p>
9956                     </td>
9957 <td>
9958                       <p>
9959                         Queries resulted in referral answer.
9960                         This corresponds to the
9961                         <span><strong class="command">referral</strong></span> counter
9962                         of previous versions of
9963                         <acronym class="acronym">BIND</acronym> 9.
9964                       </p>
9965                     </td>
9966 </tr>
9967 <tr>
9968 <td>
9969                       <p><span><strong class="command">QryNxrrset</strong></span></p>
9970                     </td>
9971 <td>
9972                       <p><span><strong class="command"></strong></span></p>
9973                     </td>
9974 <td>
9975                       <p>
9976                         Queries resulted in NOERROR responses with no data.
9977                         This corresponds to the
9978                         <span><strong class="command">nxrrset</strong></span> counter
9979                         of previous versions of
9980                         <acronym class="acronym">BIND</acronym> 9.
9981                       </p>
9982                     </td>
9983 </tr>
9984 <tr>
9985 <td>
9986                       <p><span><strong class="command">QrySERVFAIL</strong></span></p>
9987                     </td>
9988 <td>
9989                       <p><span><strong class="command">SFail</strong></span></p>
9990                     </td>
9991 <td>
9992                       <p>
9993                         Queries resulted in SERVFAIL.
9994                       </p>
9995                     </td>
9996 </tr>
9997 <tr>
9998 <td>
9999                       <p><span><strong class="command">QryFORMERR</strong></span></p>
10000                     </td>
10001 <td>
10002                       <p><span><strong class="command">SFErr</strong></span></p>
10003                     </td>
10004 <td>
10005                       <p>
10006                         Queries resulted in FORMERR.
10007                       </p>
10008                     </td>
10009 </tr>
10010 <tr>
10011 <td>
10012                       <p><span><strong class="command">QryNXDOMAIN</strong></span></p>
10013                     </td>
10014 <td>
10015                       <p><span><strong class="command">SNXD</strong></span></p>
10016                     </td>
10017 <td>
10018                       <p>
10019                         Queries resulted in NXDOMAIN.
10020                         This corresponds to the
10021                         <span><strong class="command">nxdomain</strong></span> counter
10022                         of previous versions of
10023                         <acronym class="acronym">BIND</acronym> 9.
10024                       </p>
10025                     </td>
10026 </tr>
10027 <tr>
10028 <td>
10029                       <p><span><strong class="command">QryRecursion</strong></span></p>
10030                     </td>
10031 <td>
10032                       <p><span><strong class="command">RFwdQ</strong></span></p>
10033                     </td>
10034 <td>
10035                       <p>
10036                         Queries which caused the server
10037                         to perform recursion in order to find the final answer.
10038                         This corresponds to the
10039                         <span><strong class="command">recursion</strong></span> counter
10040                         of previous versions of
10041                         <acronym class="acronym">BIND</acronym> 9.
10042                       </p>
10043                     </td>
10044 </tr>
10045 <tr>
10046 <td>
10047                       <p><span><strong class="command">QryDuplicate</strong></span></p>
10048                     </td>
10049 <td>
10050                       <p><span><strong class="command">RDupQ</strong></span></p>
10051                     </td>
10052 <td>
10053                       <p>
10054                         Queries which the server attempted to
10055                         recurse but discovered an existing query with the same
10056                         IP address, port, query ID, name, type and class
10057                         already being processed.
10058                         This corresponds to the
10059                         <span><strong class="command">duplicate</strong></span> counter
10060                         of previous versions of
10061                         <acronym class="acronym">BIND</acronym> 9.
10062                       </p>
10063                     </td>
10064 </tr>
10065 <tr>
10066 <td>
10067                       <p><span><strong class="command">QryDropped</strong></span></p>
10068                     </td>
10069 <td>
10070                       <p><span><strong class="command"></strong></span></p>
10071                     </td>
10072 <td>
10073                       <p>
10074                         Recursive queries for which the server
10075                         discovered an excessive number of existing
10076                         recursive queries for the same name, type and
10077                         class and were subsequently dropped.
10078                         This is the number of dropped queries due to
10079                         the reason explained with the
10080                         <span><strong class="command">clients-per-query</strong></span>
10081                         and
10082                         <span><strong class="command">max-clients-per-query</strong></span>
10083                         options
10084                         (see the description about
10085                         <a href="Bv9ARM.ch06.html#clients-per-query"><span><strong class="command">clients-per-query</strong></span></a>.)
10086                         This corresponds to the
10087                         <span><strong class="command">dropped</strong></span> counter
10088                         of previous versions of
10089                         <acronym class="acronym">BIND</acronym> 9.
10090                       </p>
10091                     </td>
10092 </tr>
10093 <tr>
10094 <td>
10095                       <p><span><strong class="command">QryFailure</strong></span></p>
10096                     </td>
10097 <td>
10098                       <p><span><strong class="command"></strong></span></p>
10099                     </td>
10100 <td>
10101                       <p>
10102                         Other query failures.
10103                         This corresponds to the
10104                         <span><strong class="command">failure</strong></span> counter
10105                         of previous versions of
10106                         <acronym class="acronym">BIND</acronym> 9.
10107                         Note: this counter is provided mainly for
10108                         backward compatibility with the previous versions.
10109                         Normally a more fine-grained counters such as
10110                         <span><strong class="command">AuthQryRej</strong></span> and
10111                         <span><strong class="command">RecQryRej</strong></span>
10112                         that would also fall into this counter are provided,
10113                         and so this counter would not be of much
10114                         interest in practice.
10115                       </p>
10116                     </td>
10117 </tr>
10118 <tr>
10119 <td>
10120                       <p><span><strong class="command">XfrReqDone</strong></span></p>
10121                     </td>
10122 <td>
10123                       <p><span><strong class="command"></strong></span></p>
10124                     </td>
10125 <td>
10126                       <p>
10127                         Requested zone transfers completed.
10128                       </p>
10129                     </td>
10130 </tr>
10131 <tr>
10132 <td>
10133                       <p><span><strong class="command">UpdateReqFwd</strong></span></p>
10134                     </td>
10135 <td>
10136                       <p><span><strong class="command"></strong></span></p>
10137                     </td>
10138 <td>
10139                       <p>
10140                         Update requests forwarded.
10141                       </p>
10142                     </td>
10143 </tr>
10144 <tr>
10145 <td>
10146                       <p><span><strong class="command">UpdateRespFwd</strong></span></p>
10147                     </td>
10148 <td>
10149                       <p><span><strong class="command"></strong></span></p>
10150                     </td>
10151 <td>
10152                       <p>
10153                         Update responses forwarded.
10154                       </p>
10155                     </td>
10156 </tr>
10157 <tr>
10158 <td>
10159                       <p><span><strong class="command">UpdateFwdFail</strong></span></p>
10160                     </td>
10161 <td>
10162                       <p><span><strong class="command"></strong></span></p>
10163                     </td>
10164 <td>
10165                       <p>
10166                         Dynamic update forward failed.
10167                       </p>
10168                     </td>
10169 </tr>
10170 <tr>
10171 <td>
10172                       <p><span><strong class="command">UpdateDone</strong></span></p>
10173                     </td>
10174 <td>
10175                       <p><span><strong class="command"></strong></span></p>
10176                     </td>
10177 <td>
10178                       <p>
10179                         Dynamic updates completed.
10180                       </p>
10181                     </td>
10182 </tr>
10183 <tr>
10184 <td>
10185                       <p><span><strong class="command">UpdateFail</strong></span></p>
10186                     </td>
10187 <td>
10188                       <p><span><strong class="command"></strong></span></p>
10189                     </td>
10190 <td>
10191                       <p>
10192                         Dynamic updates failed.
10193                       </p>
10194                     </td>
10195 </tr>
10196 <tr>
10197 <td>
10198                       <p><span><strong class="command">UpdateBadPrereq</strong></span></p>
10199                     </td>
10200 <td>
10201                       <p><span><strong class="command"></strong></span></p>
10202                     </td>
10203 <td>
10204                       <p>
10205                         Dynamic updates rejected due to prerequisite failure.
10206                       </p>
10207                     </td>
10208 </tr>
10209 <tr>
10210 <td>
10211                       <p><span><strong class="command">RPZRewrites</strong></span></p>
10212                     </td>
10213 <td>
10214                       <p><span><strong class="command"></strong></span></p>
10215                     </td>
10216 <td>
10217                       <p>
10218                         Response policy zone rewrites.
10219                       </p>
10220                     </td>
10221 </tr>
10222 </tbody>
10223 </table></div>
10224 </div>
10225 <div class="sect3" lang="en">
10226 <div class="titlepage"><div><div><h4 class="title">
10227 <a name="id2600537"></a>Zone Maintenance Statistics Counters</h4></div></div></div>
10228 <div class="informaltable"><table border="1">
10229 <colgroup>
10230 <col>
10231 <col>
10232 </colgroup>
10233 <tbody>
10234 <tr>
10235 <td>
10236                       <p>
10237                         <span class="emphasis"><em>Symbol</em></span>
10238                       </p>
10239                     </td>
10240 <td>
10241                       <p>
10242                         <span class="emphasis"><em>Description</em></span>
10243                       </p>
10244                     </td>
10245 </tr>
10246 <tr>
10247 <td>
10248                       <p><span><strong class="command">NotifyOutv4</strong></span></p>
10249                     </td>
10250 <td>
10251                       <p>
10252                         IPv4 notifies sent.
10253                       </p>
10254                     </td>
10255 </tr>
10256 <tr>
10257 <td>
10258                       <p><span><strong class="command">NotifyOutv6</strong></span></p>
10259                     </td>
10260 <td>
10261                       <p>
10262                         IPv6 notifies sent.
10263                       </p>
10264                     </td>
10265 </tr>
10266 <tr>
10267 <td>
10268                       <p><span><strong class="command">NotifyInv4</strong></span></p>
10269                     </td>
10270 <td>
10271                       <p>
10272                         IPv4 notifies received.
10273                       </p>
10274                     </td>
10275 </tr>
10276 <tr>
10277 <td>
10278                       <p><span><strong class="command">NotifyInv6</strong></span></p>
10279                     </td>
10280 <td>
10281                       <p>
10282                         IPv6 notifies received.
10283                       </p>
10284                     </td>
10285 </tr>
10286 <tr>
10287 <td>
10288                       <p><span><strong class="command">NotifyRej</strong></span></p>
10289                     </td>
10290 <td>
10291                       <p>
10292                         Incoming notifies rejected.
10293                       </p>
10294                     </td>
10295 </tr>
10296 <tr>
10297 <td>
10298                       <p><span><strong class="command">SOAOutv4</strong></span></p>
10299                     </td>
10300 <td>
10301                       <p>
10302                         IPv4 SOA queries sent.
10303                       </p>
10304                     </td>
10305 </tr>
10306 <tr>
10307 <td>
10308                       <p><span><strong class="command">SOAOutv6</strong></span></p>
10309                     </td>
10310 <td>
10311                       <p>
10312                         IPv6 SOA queries sent.
10313                       </p>
10314                     </td>
10315 </tr>
10316 <tr>
10317 <td>
10318                       <p><span><strong class="command">AXFRReqv4</strong></span></p>
10319                     </td>
10320 <td>
10321                       <p>
10322                         IPv4 AXFR requested.
10323                       </p>
10324                     </td>
10325 </tr>
10326 <tr>
10327 <td>
10328                       <p><span><strong class="command">AXFRReqv6</strong></span></p>
10329                     </td>
10330 <td>
10331                       <p>
10332                         IPv6 AXFR requested.
10333                       </p>
10334                     </td>
10335 </tr>
10336 <tr>
10337 <td>
10338                       <p><span><strong class="command">IXFRReqv4</strong></span></p>
10339                     </td>
10340 <td>
10341                       <p>
10342                         IPv4 IXFR requested.
10343                       </p>
10344                     </td>
10345 </tr>
10346 <tr>
10347 <td>
10348                       <p><span><strong class="command">IXFRReqv6</strong></span></p>
10349                     </td>
10350 <td>
10351                       <p>
10352                         IPv6 IXFR requested.
10353                       </p>
10354                     </td>
10355 </tr>
10356 <tr>
10357 <td>
10358                       <p><span><strong class="command">XfrSuccess</strong></span></p>
10359                     </td>
10360 <td>
10361                       <p>
10362                         Zone transfer requests succeeded.
10363                       </p>
10364                     </td>
10365 </tr>
10366 <tr>
10367 <td>
10368                       <p><span><strong class="command">XfrFail</strong></span></p>
10369                     </td>
10370 <td>
10371                       <p>
10372                         Zone transfer requests failed.
10373                       </p>
10374                     </td>
10375 </tr>
10376 </tbody>
10377 </table></div>
10378 </div>
10379 <div class="sect3" lang="en">
10380 <div class="titlepage"><div><div><h4 class="title">
10381 <a name="id2600988"></a>Resolver Statistics Counters</h4></div></div></div>
10382 <div class="informaltable"><table border="1">
10383 <colgroup>
10384 <col>
10385 <col>
10386 <col>
10387 </colgroup>
10388 <tbody>
10389 <tr>
10390 <td>
10391                       <p>
10392                         <span class="emphasis"><em>Symbol</em></span>
10393                       </p>
10394                     </td>
10395 <td>
10396                       <p>
10397                         <span class="emphasis"><em>BIND8 Symbol</em></span>
10398                       </p>
10399                     </td>
10400 <td>
10401                       <p>
10402                         <span class="emphasis"><em>Description</em></span>
10403                       </p>
10404                     </td>
10405 </tr>
10406 <tr>
10407 <td>
10408                       <p><span><strong class="command">Queryv4</strong></span></p>
10409                     </td>
10410 <td>
10411                       <p><span><strong class="command">SFwdQ</strong></span></p>
10412                     </td>
10413 <td>
10414                       <p>
10415                         IPv4 queries sent.
10416                       </p>
10417                     </td>
10418 </tr>
10419 <tr>
10420 <td>
10421                       <p><span><strong class="command">Queryv6</strong></span></p>
10422                     </td>
10423 <td>
10424                       <p><span><strong class="command">SFwdQ</strong></span></p>
10425                     </td>
10426 <td>
10427                       <p>
10428                         IPv6 queries sent.
10429                       </p>
10430                     </td>
10431 </tr>
10432 <tr>
10433 <td>
10434                       <p><span><strong class="command">Responsev4</strong></span></p>
10435                     </td>
10436 <td>
10437                       <p><span><strong class="command">RR</strong></span></p>
10438                     </td>
10439 <td>
10440                       <p>
10441                         IPv4 responses received.
10442                       </p>
10443                     </td>
10444 </tr>
10445 <tr>
10446 <td>
10447                       <p><span><strong class="command">Responsev6</strong></span></p>
10448                     </td>
10449 <td>
10450                       <p><span><strong class="command">RR</strong></span></p>
10451                     </td>
10452 <td>
10453                       <p>
10454                         IPv6 responses received.
10455                       </p>
10456                     </td>
10457 </tr>
10458 <tr>
10459 <td>
10460                       <p><span><strong class="command">NXDOMAIN</strong></span></p>
10461                     </td>
10462 <td>
10463                       <p><span><strong class="command">RNXD</strong></span></p>
10464                     </td>
10465 <td>
10466                       <p>
10467                         NXDOMAIN received.
10468                       </p>
10469                     </td>
10470 </tr>
10471 <tr>
10472 <td>
10473                       <p><span><strong class="command">SERVFAIL</strong></span></p>
10474                     </td>
10475 <td>
10476                       <p><span><strong class="command">RFail</strong></span></p>
10477                     </td>
10478 <td>
10479                       <p>
10480                         SERVFAIL received.
10481                       </p>
10482                     </td>
10483 </tr>
10484 <tr>
10485 <td>
10486                       <p><span><strong class="command">FORMERR</strong></span></p>
10487                     </td>
10488 <td>
10489                       <p><span><strong class="command">RFErr</strong></span></p>
10490                     </td>
10491 <td>
10492                       <p>
10493                         FORMERR received.
10494                       </p>
10495                     </td>
10496 </tr>
10497 <tr>
10498 <td>
10499                       <p><span><strong class="command">OtherError</strong></span></p>
10500                     </td>
10501 <td>
10502                       <p><span><strong class="command">RErr</strong></span></p>
10503                     </td>
10504 <td>
10505                       <p>
10506                         Other errors received.
10507                       </p>
10508                     </td>
10509 </tr>
10510 <tr>
10511 <td>
10512                       <p><span><strong class="command">EDNS0Fail</strong></span></p>
10513                                                  </td>
10514 <td>
10515                       <p><span><strong class="command"></strong></span></p>
10516                     </td>
10517 <td>
10518                       <p>
10519                         EDNS(0) query failures.
10520                       </p>
10521                     </td>
10522 </tr>
10523 <tr>
10524 <td>
10525                       <p><span><strong class="command">Mismatch</strong></span></p>
10526                     </td>
10527 <td>
10528                       <p><span><strong class="command">RDupR</strong></span></p>
10529                     </td>
10530 <td>
10531                       <p>
10532                         Mismatch responses received.
10533                         The DNS ID, response's source address,
10534                         and/or the response's source port does not
10535                         match what was expected.
10536                         (The port must be 53 or as defined by
10537                         the <span><strong class="command">port</strong></span> option.)
10538                         This may be an indication of a cache
10539                         poisoning attempt.
10540                       </p>
10541                     </td>
10542 </tr>
10543 <tr>
10544 <td>
10545                       <p><span><strong class="command">Truncated</strong></span></p>
10546                     </td>
10547 <td>
10548                       <p><span><strong class="command"></strong></span></p>
10549                     </td>
10550 <td>
10551                       <p>
10552                         Truncated responses received.
10553                       </p>
10554                     </td>
10555 </tr>
10556 <tr>
10557 <td>
10558                       <p><span><strong class="command">Lame</strong></span></p>
10559                     </td>
10560 <td>
10561                       <p><span><strong class="command">RLame</strong></span></p>
10562                     </td>
10563 <td>
10564                       <p>
10565                         Lame delegations received.
10566                       </p>
10567                     </td>
10568 </tr>
10569 <tr>
10570 <td>
10571                       <p><span><strong class="command">Retry</strong></span></p>
10572                     </td>
10573 <td>
10574                       <p><span><strong class="command">SDupQ</strong></span></p>
10575                     </td>
10576 <td>
10577                       <p>
10578                         Query retries performed.
10579                       </p>
10580                     </td>
10581 </tr>
10582 <tr>
10583 <td>
10584                       <p><span><strong class="command">QueryAbort</strong></span></p>
10585                     </td>
10586 <td>
10587                       <p><span><strong class="command"></strong></span></p>
10588                     </td>
10589 <td>
10590                       <p>
10591                         Queries aborted due to quota control.
10592                       </p>
10593                     </td>
10594 </tr>
10595 <tr>
10596 <td>
10597                       <p><span><strong class="command">QuerySockFail</strong></span></p>
10598                     </td>
10599 <td>
10600                       <p><span><strong class="command"></strong></span></p>
10601                     </td>
10602 <td>
10603                       <p>
10604                         Failures in opening query sockets.
10605                         One common reason for such failures is a
10606                         failure of opening a new socket due to a
10607                         limitation on file descriptors.
10608                       </p>
10609                     </td>
10610 </tr>
10611 <tr>
10612 <td>
10613                       <p><span><strong class="command">QueryTimeout</strong></span></p>
10614                     </td>
10615 <td>
10616                       <p><span><strong class="command"></strong></span></p>
10617                     </td>
10618 <td>
10619                       <p>
10620                         Query timeouts.
10621                       </p>
10622                     </td>
10623 </tr>
10624 <tr>
10625 <td>
10626                       <p><span><strong class="command">GlueFetchv4</strong></span></p>
10627                     </td>
10628 <td>
10629                       <p><span><strong class="command">SSysQ</strong></span></p>
10630                     </td>
10631 <td>
10632                       <p>
10633                         IPv4 NS address fetches invoked.
10634                       </p>
10635                     </td>
10636 </tr>
10637 <tr>
10638 <td>
10639                       <p><span><strong class="command">GlueFetchv6</strong></span></p>
10640                     </td>
10641 <td>
10642                       <p><span><strong class="command">SSysQ</strong></span></p>
10643                     </td>
10644 <td>
10645                       <p>
10646                         IPv6 NS address fetches invoked.
10647                       </p>
10648                     </td>
10649 </tr>
10650 <tr>
10651 <td>
10652                       <p><span><strong class="command">GlueFetchv4Fail</strong></span></p>
10653                     </td>
10654 <td>
10655                       <p><span><strong class="command"></strong></span></p>
10656                     </td>
10657 <td>
10658                       <p>
10659                         IPv4 NS address fetch failed.
10660                       </p>
10661                     </td>
10662 </tr>
10663 <tr>
10664 <td>
10665                       <p><span><strong class="command">GlueFetchv6Fail</strong></span></p>
10666                     </td>
10667 <td>
10668                       <p><span><strong class="command"></strong></span></p>
10669                     </td>
10670 <td>
10671                       <p>
10672                         IPv6 NS address fetch failed.
10673                       </p>
10674                     </td>
10675 </tr>
10676 <tr>
10677 <td>
10678                       <p><span><strong class="command">ValAttempt</strong></span></p>
10679                     </td>
10680 <td>
10681                       <p><span><strong class="command"></strong></span></p>
10682                     </td>
10683 <td>
10684                       <p>
10685                         DNSSEC validation attempted.
10686                       </p>
10687                     </td>
10688 </tr>
10689 <tr>
10690 <td>
10691                       <p><span><strong class="command">ValOk</strong></span></p>
10692                     </td>
10693 <td>
10694                       <p><span><strong class="command"></strong></span></p>
10695                     </td>
10696 <td>
10697                       <p>
10698                         DNSSEC validation succeeded.
10699                       </p>
10700                     </td>
10701 </tr>
10702 <tr>
10703 <td>
10704                       <p><span><strong class="command">ValNegOk</strong></span></p>
10705                     </td>
10706 <td>
10707                       <p><span><strong class="command"></strong></span></p>
10708                     </td>
10709 <td>
10710                       <p>
10711                         DNSSEC validation on negative information succeeded.
10712                       </p>
10713                     </td>
10714 </tr>
10715 <tr>
10716 <td>
10717                       <p><span><strong class="command">ValFail</strong></span></p>
10718                     </td>
10719 <td>
10720                       <p><span><strong class="command"></strong></span></p>
10721                     </td>
10722 <td>
10723                       <p>
10724                         DNSSEC validation failed.
10725                       </p>
10726                     </td>
10727 </tr>
10728 <tr>
10729 <td>
10730                       <p><span><strong class="command">QryRTTnn</strong></span></p>
10731                     </td>
10732 <td>
10733                       <p><span><strong class="command"></strong></span></p>
10734                     </td>
10735 <td>
10736                       <p>
10737                         Frequency table on round trip times (RTTs) of
10738                         queries.
10739                         Each <span><strong class="command">nn</strong></span> specifies the corresponding
10740                         frequency.
10741                         In the sequence of
10742                         <span><strong class="command">nn_1</strong></span>,
10743                         <span><strong class="command">nn_2</strong></span>,
10744                         ...,
10745                         <span><strong class="command">nn_m</strong></span>,
10746                         the value of <span><strong class="command">nn_i</strong></span> is the
10747                         number of queries whose RTTs are between
10748                         <span><strong class="command">nn_(i-1)</strong></span> (inclusive) and
10749                         <span><strong class="command">nn_i</strong></span> (exclusive) milliseconds.
10750                         For the sake of convenience we define
10751                         <span><strong class="command">nn_0</strong></span> to be 0.
10752                         The last entry should be represented as
10753                         <span><strong class="command">nn_m+</strong></span>, which means the
10754                         number of queries whose RTTs are equal to or over
10755                         <span><strong class="command">nn_m</strong></span> milliseconds.
10756                       </p>
10757                     </td>
10758 </tr>
10759 </tbody>
10760 </table></div>
10761 </div>
10762 <div class="sect3" lang="en">
10763 <div class="titlepage"><div><div><h4 class="title">
10764 <a name="id2601942"></a>Socket I/O Statistics Counters</h4></div></div></div>
10765 <p>
10766               Socket I/O statistics counters are defined per socket
10767               types, which are
10768               <span><strong class="command">UDP4</strong></span> (UDP/IPv4),
10769               <span><strong class="command">UDP6</strong></span> (UDP/IPv6),
10770               <span><strong class="command">TCP4</strong></span> (TCP/IPv4),
10771               <span><strong class="command">TCP6</strong></span> (TCP/IPv6),
10772               <span><strong class="command">Unix</strong></span> (Unix Domain), and
10773               <span><strong class="command">FDwatch</strong></span> (sockets opened outside the
10774               socket module).
10775               In the following table <span><strong class="command">&lt;TYPE&gt;</strong></span>
10776               represents a socket type.
10777               Not all counters are available for all socket types;
10778               exceptions are noted in the description field.
10779             </p>
10780 <div class="informaltable"><table border="1">
10781 <colgroup>
10782 <col>
10783 <col>
10784 </colgroup>
10785 <tbody>
10786 <tr>
10787 <td>
10788                       <p>
10789                         <span class="emphasis"><em>Symbol</em></span>
10790                       </p>
10791                     </td>
10792 <td>
10793                       <p>
10794                         <span class="emphasis"><em>Description</em></span>
10795                       </p>
10796                     </td>
10797 </tr>
10798 <tr>
10799 <td>
10800                       <p><span><strong class="command">&lt;TYPE&gt;Open</strong></span></p>
10801                     </td>
10802 <td>
10803                       <p>
10804                         Sockets opened successfully.
10805                         This counter is not applicable to the
10806                         <span><strong class="command">FDwatch</strong></span> type.
10807                       </p>
10808                     </td>
10809 </tr>
10810 <tr>
10811 <td>
10812                       <p><span><strong class="command">&lt;TYPE&gt;OpenFail</strong></span></p>
10813                     </td>
10814 <td>
10815                       <p>
10816                         Failures of opening sockets.
10817                         This counter is not applicable to the
10818                         <span><strong class="command">FDwatch</strong></span> type.
10819                       </p>
10820                     </td>
10821 </tr>
10822 <tr>
10823 <td>
10824                       <p><span><strong class="command">&lt;TYPE&gt;Close</strong></span></p>
10825                     </td>
10826 <td>
10827                       <p>
10828                         Sockets closed.
10829                       </p>
10830                     </td>
10831 </tr>
10832 <tr>
10833 <td>
10834                       <p><span><strong class="command">&lt;TYPE&gt;BindFail</strong></span></p>
10835                     </td>
10836 <td>
10837                       <p>
10838                         Failures of binding sockets.
10839                       </p>
10840                     </td>
10841 </tr>
10842 <tr>
10843 <td>
10844                       <p><span><strong class="command">&lt;TYPE&gt;ConnFail</strong></span></p>
10845                     </td>
10846 <td>
10847                       <p>
10848                         Failures of connecting sockets.
10849                       </p>
10850                     </td>
10851 </tr>
10852 <tr>
10853 <td>
10854                       <p><span><strong class="command">&lt;TYPE&gt;Conn</strong></span></p>
10855                     </td>
10856 <td>
10857                       <p>
10858                         Connections established successfully.
10859                       </p>
10860                     </td>
10861 </tr>
10862 <tr>
10863 <td>
10864                       <p><span><strong class="command">&lt;TYPE&gt;AcceptFail</strong></span></p>
10865                     </td>
10866 <td>
10867                       <p>
10868                         Failures of accepting incoming connection requests.
10869                         This counter is not applicable to the
10870                         <span><strong class="command">UDP</strong></span> and
10871                         <span><strong class="command">FDwatch</strong></span> types.
10872                       </p>
10873                     </td>
10874 </tr>
10875 <tr>
10876 <td>
10877                       <p><span><strong class="command">&lt;TYPE&gt;Accept</strong></span></p>
10878                     </td>
10879 <td>
10880                       <p>
10881                         Incoming connections successfully accepted.
10882                         This counter is not applicable to the
10883                         <span><strong class="command">UDP</strong></span> and
10884                         <span><strong class="command">FDwatch</strong></span> types.
10885                       </p>
10886                     </td>
10887 </tr>
10888 <tr>
10889 <td>
10890                       <p><span><strong class="command">&lt;TYPE&gt;SendErr</strong></span></p>
10891                     </td>
10892 <td>
10893                       <p>
10894                         Errors in socket send operations.
10895                         This counter corresponds
10896                         to <span><strong class="command">SErr</strong></span> counter of
10897                         <span><strong class="command">BIND</strong></span> 8.
10898                       </p>
10899                     </td>
10900 </tr>
10901 <tr>
10902 <td>
10903                       <p><span><strong class="command">&lt;TYPE&gt;RecvErr</strong></span></p>
10904                     </td>
10905 <td>
10906                       <p>
10907                         Errors in socket receive operations.
10908                         This includes errors of send operations on a
10909                         connected UDP socket notified by an ICMP error
10910                         message.
10911                       </p>
10912                     </td>
10913 </tr>
10914 </tbody>
10915 </table></div>
10916 </div>
10917 <div class="sect3" lang="en">
10918 <div class="titlepage"><div><div><h4 class="title">
10919 <a name="id2602520"></a>Compatibility with <span class="emphasis"><em>BIND</em></span> 8 Counters</h4></div></div></div>
10920 <p>
10921               Most statistics counters that were available
10922               in <span><strong class="command">BIND</strong></span> 8 are also supported in
10923               <span><strong class="command">BIND</strong></span> 9 as shown in the above tables.
10924               Here are notes about other counters that do not appear
10925               in these tables.
10926             </p>
10927 <div class="variablelist"><dl>
10928 <dt><span class="term"><span><strong class="command">RFwdR,SFwdR</strong></span></span></dt>
10929 <dd><p>
10930                     These counters are not supported
10931                     because <span><strong class="command">BIND</strong></span> 9 does not adopt
10932                     the notion of <span class="emphasis"><em>forwarding</em></span>
10933                     as <span><strong class="command">BIND</strong></span> 8 did.
10934                   </p></dd>
10935 <dt><span class="term"><span><strong class="command">RAXFR</strong></span></span></dt>
10936 <dd><p>
10937                     This counter is accessible in the Incoming Queries section.
10938                   </p></dd>
10939 <dt><span class="term"><span><strong class="command">RIQ</strong></span></span></dt>
10940 <dd><p>
10941                     This counter is accessible in the Incoming Requests section.
10942                   </p></dd>
10943 <dt><span class="term"><span><strong class="command">ROpts</strong></span></span></dt>
10944 <dd><p>
10945                     This counter is not supported
10946                     because <span><strong class="command">BIND</strong></span> 9 does not care
10947                     about IP options in the first place.
10948                   </p></dd>
10949 </dl></div>
10950 </div>
10951 </div>
10952 </div>
10953 </div>
10954 <div class="navfooter">
10955 <hr>
10956 <table width="100%" summary="Navigation footer">
10957 <tr>
10958 <td width="40%" align="left">
10959 <a accesskey="p" href="Bv9ARM.ch05.html">Prev</a> </td>
10960 <td width="20%" align="center"> </td>
10961 <td width="40%" align="right"> <a accesskey="n" href="Bv9ARM.ch07.html">Next</a>
10962 </td>
10963 </tr>
10964 <tr>
10965 <td width="40%" align="left" valign="top">Chapter 5. The <acronym class="acronym">BIND</acronym> 9 Lightweight Resolver </td>
10966 <td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td>
10967 <td width="40%" align="right" valign="top"> Chapter 7. <acronym class="acronym">BIND</acronym> 9 Security Considerations</td>
10968 </tr>
10969 </table>
10970 </div>
10971 </body>
10972 </html>