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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#id2573609">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#id2574308"><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#id2574498"><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#id2574926"><span><strong class="command">include</strong></span> Statement Grammar</a></span></dt>
  62 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574944"><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#id2574967"><span><strong class="command">key</strong></span> Statement Grammar</a></span></dt>
  65 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574990"><span><strong class="command">key</strong></span> Statement Definition and Usage</a></span></dt>
  66 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575081"><span><strong class="command">logging</strong></span> Statement Grammar</a></span></dt>
  67 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575207"><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#id2577268"><span><strong class="command">lwres</strong></span> Statement Grammar</a></span></dt>
  70 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577341"><span><strong class="command">lwres</strong></span> Statement Definition and Usage</a></span></dt>
  71 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577405"><span><strong class="command">masters</strong></span> Statement Grammar</a></span></dt>
  72 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577449"><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#id2577464"><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#id2586923"><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#id2587078"><span><strong class="command">trusted-keys</strong></span> Statement Grammar</a></span></dt>
  84 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2587129"><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#view_statement_grammar"><span><strong class="command">view</strong></span> Statement Grammar</a></span></dt>
  87 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2587211"><span><strong class="command">view</strong></span> Statement Definition and Usage</a></span></dt>
  88 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#zone_statement_grammar"><span><strong class="command">zone</strong></span>
  89             Statement Grammar</a></span></dt>
  90 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2588616"><span><strong class="command">zone</strong></span> Statement Definition and Usage</a></span></dt>
  91 </dl></dd>
  92 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#id2591300">Zone File</a></span></dt>
  93 <dd><dl>
  94 <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>
  95 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2593530">Discussion of MX Records</a></span></dt>
  96 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#Setting_TTLs">Setting TTLs</a></span></dt>
  97 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2594214">Inverse Mapping in IPv4</a></span></dt>
  98 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2594341">Other Zone File Directives</a></span></dt>
  99 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2594682"><acronym class="acronym">BIND</acronym> Master File Extension: the  <span><strong class="command">$GENERATE</strong></span> Directive</a></span></dt>
 100 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#zonefile_format">Additional File Formats</a></span></dt>
 101 </dl></dd>
 102 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#statistics">BIND9 Statistics</a></span></dt>
 103 <dd><dl><dt><span class="sect2"><a href="Bv9ARM.ch06.html#statistics_counters">Statistics Counters</a></span></dt></dl></dd>
 104 </dl>
 105 </div>
 106 <p>
 107       <acronym class="acronym">BIND</acronym> 9 configuration is broadly similar
 108       to <acronym class="acronym">BIND</acronym> 8; however, there are a few new
 109       areas
 110       of configuration, such as views. <acronym class="acronym">BIND</acronym>
 111       8 configuration files should work with few alterations in <acronym class="acronym">BIND</acronym>
 112       9, although more complex configurations should be reviewed to check
 113       if they can be more efficiently implemented using the new features
 114       found in <acronym class="acronym">BIND</acronym> 9.
 115     </p>
 116 <p>
 117       <acronym class="acronym">BIND</acronym> 4 configuration files can be
 118       converted to the new format
 119       using the shell script
 120       <code class="filename">contrib/named-bootconf/named-bootconf.sh</code>.
 121     </p>
 122 <div class="sect1" lang="en">
 123 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
 124 <a name="configuration_file_elements"></a>Configuration File Elements</h2></div></div></div>
 125 <p>
 126         Following is a list of elements used throughout the <acronym class="acronym">BIND</acronym> configuration
 127         file documentation:
 128       </p>
 129 <div class="informaltable"><table border="1">
 130 <colgroup>
 131 <col>
 132 <col>
 133 </colgroup>
 134 <tbody>
 135 <tr>
 136 <td>
 137                 <p>
 138                   <code class="varname">acl_name</code>
 139                 </p>
 140               </td>
 141 <td>
 142                 <p>
 143                   The name of an <code class="varname">address_match_list</code> as
 144                   defined by the <span><strong class="command">acl</strong></span> statement.
 145                 </p>
 146               </td>
 147 </tr>
 148 <tr>
 149 <td>
 150                 <p>
 151                   <code class="varname">address_match_list</code>
 152                 </p>
 153               </td>
 154 <td>
 155                 <p>
 156                   A list of one or more
 157                   <code class="varname">ip_addr</code>,
 158                   <code class="varname">ip_prefix</code>, <code class="varname">key_id</code>,
 159                   or <code class="varname">acl_name</code> elements, see
 160                   <a href="Bv9ARM.ch06.html#address_match_lists" title="Address Match Lists">the section called &#8220;Address Match Lists&#8221;</a>.
 161                 </p>
 162               </td>
 163 </tr>
 164 <tr>
 165 <td>
 166                 <p>
 167                   <code class="varname">masters_list</code>
 168                 </p>
 169               </td>
 170 <td>
 171                 <p>
 172                   A named list of one or more <code class="varname">ip_addr</code>
 173                   with optional <code class="varname">key_id</code> and/or
 174                   <code class="varname">ip_port</code>.
 175                   A <code class="varname">masters_list</code> may include other
 176                   <code class="varname">masters_lists</code>.
 177                 </p>
 178               </td>
 179 </tr>
 180 <tr>
 181 <td>
 182                 <p>
 183                   <code class="varname">domain_name</code>
 184                 </p>
 185               </td>
 186 <td>
 187                 <p>
 188                   A quoted string which will be used as
 189                   a DNS name, for example "<code class="literal">my.test.domain</code>".
 190                 </p>
 191               </td>
 192 </tr>
 193 <tr>
 194 <td>
 195                 <p>
 196                   <code class="varname">dotted_decimal</code>
 197                 </p>
 198               </td>
 199 <td>
 200                 <p>
 201                   One to four integers valued 0 through
 202                   255 separated by dots (`.'), such as <span><strong class="command">123</strong></span>,
 203                   <span><strong class="command">45.67</strong></span> or <span><strong class="command">89.123.45.67</strong></span>.
 204                 </p>
 205               </td>
 206 </tr>
 207 <tr>
 208 <td>
 209                 <p>
 210                   <code class="varname">ip4_addr</code>
 211                 </p>
 212               </td>
 213 <td>
 214                 <p>
 215                   An IPv4 address with exactly four elements
 216                   in <code class="varname">dotted_decimal</code> notation.
 217                 </p>
 218               </td>
 219 </tr>
 220 <tr>
 221 <td>
 222                 <p>
 223                   <code class="varname">ip6_addr</code>
 224                 </p>
 225               </td>
 226 <td>
 227                 <p>
 228                   An IPv6 address, such as <span><strong class="command">2001:db8::1234</strong></span>.
 229                   IPv6 scoped addresses that have ambiguity on their
 230                   scope zones must be disambiguated by an appropriate
 231                   zone ID with the percent character (`%') as
 232                   delimiter.  It is strongly recommended to use
 233                   string zone names rather than numeric identifiers,
 234                   in order to be robust against system configuration
 235                   changes.  However, since there is no standard
 236                   mapping for such names and identifier values,
 237                   currently only interface names as link identifiers
 238                   are supported, assuming one-to-one mapping between
 239                   interfaces and links.  For example, a link-local
 240                   address <span><strong class="command">fe80::1</strong></span> on the link
 241                   attached to the interface <span><strong class="command">ne0</strong></span>
 242                   can be specified as <span><strong class="command">fe80::1%ne0</strong></span>.
 243                   Note that on most systems link-local addresses
 244                   always have the ambiguity, and need to be
 245                   disambiguated.
 246                 </p>
 247               </td>
 248 </tr>
 249 <tr>
 250 <td>
 251                 <p>
 252                   <code class="varname">ip_addr</code>
 253                 </p>
 254               </td>
 255 <td>
 256                 <p>
 257                   An <code class="varname">ip4_addr</code> or <code class="varname">ip6_addr</code>.
 258                 </p>
 259               </td>
 260 </tr>
 261 <tr>
 262 <td>
 263                 <p>
 264                   <code class="varname">ip_port</code>
 265                 </p>
 266               </td>
 267 <td>
 268                 <p>
 269                   An IP port <code class="varname">number</code>.
 270                   The <code class="varname">number</code> is limited to 0
 271                   through 65535, with values
 272                   below 1024 typically restricted to use by processes running
 273                   as root.
 274                   In some cases, an asterisk (`*') character can be used as a
 275                   placeholder to
 276                   select a random high-numbered port.
 277                 </p>
 278               </td>
 279 </tr>
 280 <tr>
 281 <td>
 282                 <p>
 283                   <code class="varname">ip_prefix</code>
 284                 </p>
 285               </td>
 286 <td>
 287                 <p>
 288                   An IP network specified as an <code class="varname">ip_addr</code>,
 289                   followed by a slash (`/') and then the number of bits in the
 290                   netmask.
 291                   Trailing zeros in a <code class="varname">ip_addr</code>
 292                   may omitted.
 293                   For example, <span><strong class="command">127/8</strong></span> is the
 294                   network <span><strong class="command">127.0.0.0</strong></span> with
 295                   netmask <span><strong class="command">255.0.0.0</strong></span> and <span><strong class="command">1.2.3.0/28</strong></span> is
 296                   network <span><strong class="command">1.2.3.0</strong></span> with netmask <span><strong class="command">255.255.255.240</strong></span>.
 297                 </p>
 298                 <p>
 299                   When specifying a prefix involving a IPv6 scoped address
 300                   the scope may be omitted.  In that case the prefix will
 301                   match packets from any scope.
 302                 </p>
 303               </td>
 304 </tr>
 305 <tr>
 306 <td>
 307                 <p>
 308                   <code class="varname">key_id</code>
 309                 </p>
 310               </td>
 311 <td>
 312                 <p>
 313                   A <code class="varname">domain_name</code> representing
 314                   the name of a shared key, to be used for transaction
 315                   security.
 316                 </p>
 317               </td>
 318 </tr>
 319 <tr>
 320 <td>
 321                 <p>
 322                   <code class="varname">key_list</code>
 323                 </p>
 324               </td>
 325 <td>
 326                 <p>
 327                   A list of one or more
 328                   <code class="varname">key_id</code>s,
 329                   separated by semicolons and ending with a semicolon.
 330                 </p>
 331               </td>
 332 </tr>
 333 <tr>
 334 <td>
 335                 <p>
 336                   <code class="varname">number</code>
 337                 </p>
 338               </td>
 339 <td>
 340                 <p>
 341                   A non-negative 32-bit integer
 342                   (i.e., a number between 0 and 4294967295, inclusive).
 343                   Its acceptable value might further
 344                   be limited by the context in which it is used.
 345                 </p>
 346               </td>
 347 </tr>
 348 <tr>
 349 <td>
 350                 <p>
 351                   <code class="varname">path_name</code>
 352                 </p>
 353               </td>
 354 <td>
 355                 <p>
 356                   A quoted string which will be used as
 357                   a pathname, such as <code class="filename">zones/master/my.test.domain</code>.
 358                 </p>
 359               </td>
 360 </tr>
 361 <tr>
 362 <td>
 363                 <p>
 364                   <code class="varname">port_list</code>
 365                 </p>
 366               </td>
 367 <td>
 368                 <p>
 369                   A list of an <code class="varname">ip_port</code> or a port
 370                   range.
 371                   A port range is specified in the form of
 372                   <strong class="userinput"><code>range</code></strong> followed by
 373                   two <code class="varname">ip_port</code>s,
 374                   <code class="varname">port_low</code> and
 375                   <code class="varname">port_high</code>, which represents
 376                   port numbers from <code class="varname">port_low</code> through
 377                   <code class="varname">port_high</code>, inclusive.
 378                   <code class="varname">port_low</code> must not be larger than
 379                   <code class="varname">port_high</code>.
 380                   For example,
 381                   <strong class="userinput"><code>range 1024 65535</code></strong> represents
 382                   ports from 1024 through 65535.
 383                   In either case an asterisk (`*') character is not
 384                   allowed as a valid <code class="varname">ip_port</code>.
 385                 </p>
 386               </td>
 387 </tr>
 388 <tr>
 389 <td>
 390                 <p>
 391                   <code class="varname">size_spec</code>
 392                 </p>
 393               </td>
 394 <td>
 395                 <p>
 396                   A number, the word <strong class="userinput"><code>unlimited</code></strong>,
 397                   or the word <strong class="userinput"><code>default</code></strong>.
 398                 </p>
 399                 <p>
 400                   An <code class="varname">unlimited</code> <code class="varname">size_spec</code> requests unlimited
 401                   use, or the maximum available amount. A <code class="varname">default size_spec</code> uses
 402                   the limit that was in force when the server was started.
 403                 </p>
 404                 <p>
 405                   A <code class="varname">number</code> can optionally be
 406                   followed by a scaling factor:
 407                   <strong class="userinput"><code>K</code></strong> or <strong class="userinput"><code>k</code></strong>
 408                   for kilobytes,
 409                   <strong class="userinput"><code>M</code></strong> or <strong class="userinput"><code>m</code></strong>
 410                   for megabytes, and
 411                   <strong class="userinput"><code>G</code></strong> or <strong class="userinput"><code>g</code></strong> for gigabytes,
 412                   which scale by 1024, 1024*1024, and 1024*1024*1024
 413                   respectively.
 414                 </p>
 415                 <p>
 416                   The value must be representable as a 64-bit unsigned integer
 417                   (0 to 18446744073709551615, inclusive).
 418                   Using <code class="varname">unlimited</code> is the best
 419                   way
 420                   to safely set a really large number.
 421                 </p>
 422               </td>
 423 </tr>
 424 <tr>
 425 <td>
 426                 <p>
 427                   <code class="varname">yes_or_no</code>
 428                 </p>
 429               </td>
 430 <td>
 431                 <p>
 432                   Either <strong class="userinput"><code>yes</code></strong> or <strong class="userinput"><code>no</code></strong>.
 433                   The words <strong class="userinput"><code>true</code></strong> and <strong class="userinput"><code>false</code></strong> are
 434                   also accepted, as are the numbers <strong class="userinput"><code>1</code></strong>
 435                   and <strong class="userinput"><code>0</code></strong>.
 436                 </p>
 437               </td>
 438 </tr>
 439 <tr>
 440 <td>
 441                 <p>
 442                   <code class="varname">dialup_option</code>
 443                 </p>
 444               </td>
 445 <td>
 446                 <p>
 447                   One of <strong class="userinput"><code>yes</code></strong>,
 448                   <strong class="userinput"><code>no</code></strong>, <strong class="userinput"><code>notify</code></strong>,
 449                   <strong class="userinput"><code>notify-passive</code></strong>, <strong class="userinput"><code>refresh</code></strong> or
 450                   <strong class="userinput"><code>passive</code></strong>.
 451                   When used in a zone, <strong class="userinput"><code>notify-passive</code></strong>,
 452                   <strong class="userinput"><code>refresh</code></strong>, and <strong class="userinput"><code>passive</code></strong>
 453                   are restricted to slave and stub zones.
 454                 </p>
 455               </td>
 456 </tr>
 457 </tbody>
 458 </table></div>
 459 <div class="sect2" lang="en">
 460 <div class="titlepage"><div><div><h3 class="title">
 461 <a name="address_match_lists"></a>Address Match Lists</h3></div></div></div>
 462 <div class="sect3" lang="en">
 463 <div class="titlepage"><div><div><h4 class="title">
 464 <a name="id2573376"></a>Syntax</h4></div></div></div>
 465 <pre class="programlisting"><code class="varname">address_match_list</code> = address_match_list_element ;
 466   [<span class="optional"> address_match_list_element; ... </span>]
 467 <code class="varname">address_match_list_element</code> = [<span class="optional"> ! </span>] (ip_address [<span class="optional">/length</span>] |
 468    key key_id | acl_name | { address_match_list } )
 469 </pre>
 470 </div>
 471 <div class="sect3" lang="en">
 472 <div class="titlepage"><div><div><h4 class="title">
 473 <a name="id2573472"></a>Definition and Usage</h4></div></div></div>
 474 <p>
 475             Address match lists are primarily used to determine access
 476             control for various server operations. They are also used in
 477             the <span><strong class="command">listen-on</strong></span> and <span><strong class="command">sortlist</strong></span>
 478             statements. The elements which constitute an address match
 479             list can be any of the following:
 480           </p>
 481 <div class="itemizedlist"><ul type="disc">
 482 <li>an IP address (IPv4 or IPv6)</li>
 483 <li>an IP prefix (in `/' notation)</li>
 484 <li>
 485                 a key ID, as defined by the <span><strong class="command">key</strong></span>
 486                 statement
 487               </li>
 488 <li>the name of an address match list defined with
 489                 the <span><strong class="command">acl</strong></span> statement
 490               </li>
 491 <li>a nested address match list enclosed in braces</li>
 492 </ul></div>
 493 <p>
 494             Elements can be negated with a leading exclamation mark (`!'),
 495             and the match list names "any", "none", "localhost", and
 496             "localnets" are predefined. More information on those names
 497             can be found in the description of the acl statement.
 498           </p>
 499 <p>
 500             The addition of the key clause made the name of this syntactic
 501             element something of a misnomer, since security keys can be used
 502             to validate access without regard to a host or network address.
 503             Nonetheless, the term "address match list" is still used
 504             throughout the documentation.
 505           </p>
 506 <p>
 507             When a given IP address or prefix is compared to an address
 508             match list, the comparison takes place in approximately O(1)
 509             time.  However, key comparisons require that the list of keys
 510             be traversed until a matching key is found, and therefore may
 511             be somewhat slower.
 512           </p>
 513 <p>
 514             The interpretation of a match depends on whether the list is being
 515             used for access control, defining <span><strong class="command">listen-on</strong></span> ports, or in a
 516             <span><strong class="command">sortlist</strong></span>, and whether the element was negated.
 517           </p>
 518 <p>
 519             When used as an access control list, a non-negated match
 520             allows access and a negated match denies access. If
 521             there is no match, access is denied. The clauses
 522             <span><strong class="command">allow-notify</strong></span>,
 523             <span><strong class="command">allow-recursion</strong></span>,
 524             <span><strong class="command">allow-recursion-on</strong></span>,
 525             <span><strong class="command">allow-query</strong></span>,
 526             <span><strong class="command">allow-query-on</strong></span>,
 527             <span><strong class="command">allow-query-cache</strong></span>,
 528             <span><strong class="command">allow-query-cache-on</strong></span>,
 529             <span><strong class="command">allow-transfer</strong></span>,
 530             <span><strong class="command">allow-update</strong></span>,
 531             <span><strong class="command">allow-update-forwarding</strong></span>, and
 532             <span><strong class="command">blackhole</strong></span> all use address match
 533             lists.  Similarly, the <span><strong class="command">listen-on</strong></span> option will cause the
 534             server to refuse queries on any of the machine's
 535             addresses which do not match the list.
 536           </p>
 537 <p>
 538             Order of insertion is significant.  If more than one element
 539             in an ACL is found to match a given IP address or prefix,
 540             preference will be given to the one that came
 541             <span class="emphasis"><em>first</em></span> in the ACL definition.
 542             Because of this first-match behavior, an element that
 543             defines a subset of another element in the list should
 544             come before the broader element, regardless of whether
 545             either is negated. For example, in
 546             <span><strong class="command">1.2.3/24; ! 1.2.3.13;</strong></span>
 547             the 1.2.3.13 element is completely useless because the
 548             algorithm will match any lookup for 1.2.3.13 to the 1.2.3/24
 549             element.  Using <span><strong class="command">! 1.2.3.13; 1.2.3/24</strong></span> fixes
 550             that problem by having 1.2.3.13 blocked by the negation, but
 551             all other 1.2.3.* hosts fall through.
 552           </p>
 553 </div>
 554 </div>
 555 <div class="sect2" lang="en">
 556 <div class="titlepage"><div><div><h3 class="title">
 557 <a name="id2573609"></a>Comment Syntax</h3></div></div></div>
 558 <p>
 559           The <acronym class="acronym">BIND</acronym> 9 comment syntax allows for
 560           comments to appear
 561           anywhere that whitespace may appear in a <acronym class="acronym">BIND</acronym> configuration
 562           file. To appeal to programmers of all kinds, they can be written
 563           in the C, C++, or shell/perl style.
 564         </p>
 565 <div class="sect3" lang="en">
 566 <div class="titlepage"><div><div><h4 class="title">
 567 <a name="id2573624"></a>Syntax</h4></div></div></div>
 568 <p>
 569             </p>
 570 <pre class="programlisting">/* This is a <acronym class="acronym">BIND</acronym> comment as in C */</pre>
 571 <p>
 572             </p>
 573 <pre class="programlisting">// This is a <acronym class="acronym">BIND</acronym> comment as in C++</pre>
 574 <p>
 575             </p>
 576 <pre class="programlisting"># This is a <acronym class="acronym">BIND</acronym> comment as in common UNIX shells and perl</pre>
 577 <p>
 578           </p>
 579 </div>
 580 <div class="sect3" lang="en">
 581 <div class="titlepage"><div><div><h4 class="title">
 582 <a name="id2573790"></a>Definition and Usage</h4></div></div></div>
 583 <p>
 584             Comments may appear anywhere that whitespace may appear in
 585             a <acronym class="acronym">BIND</acronym> configuration file.
 586           </p>
 587 <p>
 588             C-style comments start with the two characters /* (slash,
 589             star) and end with */ (star, slash). Because they are completely
 590             delimited with these characters, they can be used to comment only
 591             a portion of a line or to span multiple lines.
 592           </p>
 593 <p>
 594             C-style comments cannot be nested. For example, the following
 595             is not valid because the entire comment ends with the first */:
 596           </p>
 597 <p>
 598
 599 </p>
 600 <pre class="programlisting">/* This is the start of a comment.
 601    This is still part of the comment.
 602 /* This is an incorrect attempt at nesting a comment. */
 603    This is no longer in any comment. */
 604 </pre>
 605 <p>
 606
 607           </p>
 608 <p>
 609             C++-style comments start with the two characters // (slash,
 610             slash) and continue to the end of the physical line. They cannot
 611             be continued across multiple physical lines; to have one logical
 612             comment span multiple lines, each line must use the // pair.
 613             For example:
 614           </p>
 615 <p>
 616
 617 </p>
 618 <pre class="programlisting">// This is the start of a comment.  The next line
 619 // is a new comment, even though it is logically
 620 // part of the previous comment.
 621 </pre>
 622 <p>
 623
 624           </p>
 625 <p>
 626             Shell-style (or perl-style, if you prefer) comments start
 627             with the character <code class="literal">#</code> (number sign)
 628             and continue to the end of the
 629             physical line, as in C++ comments.
 630             For example:
 631           </p>
 632 <p>
 633
 634 </p>
 635 <pre class="programlisting"># This is the start of a comment.  The next line
 636 # is a new comment, even though it is logically
 637 # part of the previous comment.
 638 </pre>
 639 <p>
 640
 641           </p>
 642 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
 643 <h3 class="title">Warning</h3>
 644 <p>
 645               You cannot use the semicolon (`;') character
 646               to start a comment such as you would in a zone file. The
 647               semicolon indicates the end of a configuration
 648               statement.
 649             </p>
 650 </div>
 651 </div>
 652 </div>
 653 </div>
 654 <div class="sect1" lang="en">
 655 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
 656 <a name="Configuration_File_Grammar"></a>Configuration File Grammar</h2></div></div></div>
 657 <p>
 658         A <acronym class="acronym">BIND</acronym> 9 configuration consists of
 659         statements and comments.
 660         Statements end with a semicolon. Statements and comments are the
 661         only elements that can appear without enclosing braces. Many
 662         statements contain a block of sub-statements, which are also
 663         terminated with a semicolon.
 664       </p>
 665 <p>
 666         The following statements are supported:
 667       </p>
 668 <div class="informaltable"><table border="1">
 669 <colgroup>
 670 <col>
 671 <col>
 672 </colgroup>
 673 <tbody>
 674 <tr>
 675 <td>
 676                 <p><span><strong class="command">acl</strong></span></p>
 677               </td>
 678 <td>
 679                 <p>
 680                   defines a named IP address
 681                   matching list, for access control and other uses.
 682                 </p>
 683               </td>
 684 </tr>
 685 <tr>
 686 <td>
 687                 <p><span><strong class="command">controls</strong></span></p>
 688               </td>
 689 <td>
 690                 <p>
 691                   declares control channels to be used
 692                   by the <span><strong class="command">rndc</strong></span> utility.
 693                 </p>
 694               </td>
 695 </tr>
 696 <tr>
 697 <td>
 698                 <p><span><strong class="command">include</strong></span></p>
 699               </td>
 700 <td>
 701                 <p>
 702                   includes a file.
 703                 </p>
 704               </td>
 705 </tr>
 706 <tr>
 707 <td>
 708                 <p><span><strong class="command">key</strong></span></p>
 709               </td>
 710 <td>
 711                 <p>
 712                   specifies key information for use in
 713                   authentication and authorization using TSIG.
 714                 </p>
 715               </td>
 716 </tr>
 717 <tr>
 718 <td>
 719                 <p><span><strong class="command">logging</strong></span></p>
 720               </td>
 721 <td>
 722                 <p>
 723                   specifies what the server logs, and where
 724                   the log messages are sent.
 725                 </p>
 726               </td>
 727 </tr>
 728 <tr>
 729 <td>
 730                 <p><span><strong class="command">lwres</strong></span></p>
 731               </td>
 732 <td>
 733                 <p>
 734                   configures <span><strong class="command">named</strong></span> to
 735                   also act as a light-weight resolver daemon (<span><strong class="command">lwresd</strong></span>).
 736                 </p>
 737               </td>
 738 </tr>
 739 <tr>
 740 <td>
 741                 <p><span><strong class="command">masters</strong></span></p>
 742               </td>
 743 <td>
 744                 <p>
 745                   defines a named masters list for
 746                   inclusion in stub and slave zone masters clauses.
 747                 </p>
 748               </td>
 749 </tr>
 750 <tr>
 751 <td>
 752                 <p><span><strong class="command">options</strong></span></p>
 753               </td>
 754 <td>
 755                 <p>
 756                   controls global server configuration
 757                   options and sets defaults for other statements.
 758                 </p>
 759               </td>
 760 </tr>
 761 <tr>
 762 <td>
 763                 <p><span><strong class="command">server</strong></span></p>
 764               </td>
 765 <td>
 766                 <p>
 767                   sets certain configuration options on
 768                   a per-server basis.
 769                 </p>
 770               </td>
 771 </tr>
 772 <tr>
 773 <td>
 774                 <p><span><strong class="command">statistics-channels</strong></span></p>
 775               </td>
 776 <td>
 777                 <p>
 778                   declares communication channels to get access to
 779                   <span><strong class="command">named</strong></span> statistics.
 780                 </p>
 781               </td>
 782 </tr>
 783 <tr>
 784 <td>
 785                 <p><span><strong class="command">trusted-keys</strong></span></p>
 786               </td>
 787 <td>
 788                 <p>
 789                   defines trusted DNSSEC keys.
 790                 </p>
 791               </td>
 792 </tr>
 793 <tr>
 794 <td>
 795                 <p><span><strong class="command">view</strong></span></p>
 796               </td>
 797 <td>
 798                 <p>
 799                   defines a view.
 800                 </p>
 801               </td>
 802 </tr>
 803 <tr>
 804 <td>
 805                 <p><span><strong class="command">zone</strong></span></p>
 806               </td>
 807 <td>
 808                 <p>
 809                   defines a zone.
 810                 </p>
 811               </td>
 812 </tr>
 813 </tbody>
 814 </table></div>
 815 <p>
 816         The <span><strong class="command">logging</strong></span> and
 817         <span><strong class="command">options</strong></span> statements may only occur once
 818         per
 819         configuration.
 820       </p>
 821 <div class="sect2" lang="en">
 822 <div class="titlepage"><div><div><h3 class="title">
 823 <a name="id2574308"></a><span><strong class="command">acl</strong></span> Statement Grammar</h3></div></div></div>
 824 <pre class="programlisting"><span><strong class="command">acl</strong></span> acl-name {
 825     address_match_list
 826 };
 827 </pre>
 828 </div>
 829 <div class="sect2" lang="en">
 830 <div class="titlepage"><div><div><h3 class="title">
 831 <a name="acl"></a><span><strong class="command">acl</strong></span> Statement Definition and
 832           Usage</h3></div></div></div>
 833 <p>
 834           The <span><strong class="command">acl</strong></span> statement assigns a symbolic
 835           name to an address match list. It gets its name from a primary
 836           use of address match lists: Access Control Lists (ACLs).
 837         </p>
 838 <p>
 839           Note that an address match list's name must be defined
 840           with <span><strong class="command">acl</strong></span> before it can be used
 841           elsewhere; no forward references are allowed.
 842         </p>
 843 <p>
 844           The following ACLs are built-in:
 845         </p>
 846 <div class="informaltable"><table border="1">
 847 <colgroup>
 848 <col>
 849 <col>
 850 </colgroup>
 851 <tbody>
 852 <tr>
 853 <td>
 854                   <p><span><strong class="command">any</strong></span></p>
 855                 </td>
 856 <td>
 857                   <p>
 858                     Matches all hosts.
 859                   </p>
 860                 </td>
 861 </tr>
 862 <tr>
 863 <td>
 864                   <p><span><strong class="command">none</strong></span></p>
 865                 </td>
 866 <td>
 867                   <p>
 868                     Matches no hosts.
 869                   </p>
 870                 </td>
 871 </tr>
 872 <tr>
 873 <td>
 874                   <p><span><strong class="command">localhost</strong></span></p>
 875                 </td>
 876 <td>
 877                   <p>
 878                     Matches the IPv4 and IPv6 addresses of all network
 879                     interfaces on the system.
 880                   </p>
 881                 </td>
 882 </tr>
 883 <tr>
 884 <td>
 885                   <p><span><strong class="command">localnets</strong></span></p>
 886                 </td>
 887 <td>
 888                   <p>
 889                     Matches any host on an IPv4 or IPv6 network
 890                     for which the system has an interface.
 891                     Some systems do not provide a way to determine the prefix
 892                     lengths of
 893                     local IPv6 addresses.
 894                     In such a case, <span><strong class="command">localnets</strong></span>
 895                     only matches the local
 896                     IPv6 addresses, just like <span><strong class="command">localhost</strong></span>.
 897                   </p>
 898                 </td>
 899 </tr>
 900 </tbody>
 901 </table></div>
 902 </div>
 903 <div class="sect2" lang="en">
 904 <div class="titlepage"><div><div><h3 class="title">
 905 <a name="id2574498"></a><span><strong class="command">controls</strong></span> Statement Grammar</h3></div></div></div>
 906 <pre class="programlisting"><span><strong class="command">controls</strong></span> {
 907    [ inet ( ip_addr | * ) [ port ip_port ] allow { <em class="replaceable"><code> address_match_list </code></em> }
 908                 keys { <em class="replaceable"><code>key_list</code></em> }; ]
 909    [ inet ...; ]
 910    [ 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> keys { <em class="replaceable"><code>key_list</code></em> }; ]
 911    [ unix ...; ]
 912 };
 913 </pre>
 914 </div>
 915 <div class="sect2" lang="en">
 916 <div class="titlepage"><div><div><h3 class="title">
 917 <a name="controls_statement_definition_and_usage"></a><span><strong class="command">controls</strong></span> Statement Definition and
 918           Usage</h3></div></div></div>
 919 <p>
 920           The <span><strong class="command">controls</strong></span> statement declares control
 921           channels to be used by system administrators to control the
 922           operation of the name server. These control channels are
 923           used by the <span><strong class="command">rndc</strong></span> utility to send
 924           commands to and retrieve non-DNS results from a name server.
 925         </p>
 926 <p>
 927           An <span><strong class="command">inet</strong></span> control channel is a TCP socket
 928           listening at the specified <span><strong class="command">ip_port</strong></span> on the
 929           specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6
 930           address.  An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is
 931           interpreted as the IPv4 wildcard address; connections will be
 932           accepted on any of the system's IPv4 addresses.
 933           To listen on the IPv6 wildcard address,
 934           use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>.
 935           If you will only use <span><strong class="command">rndc</strong></span> on the local host,
 936           using the loopback address (<code class="literal">127.0.0.1</code>
 937           or <code class="literal">::1</code>) is recommended for maximum security.
 938         </p>
 939 <p>
 940           If no port is specified, port 953 is used. The asterisk
 941           "<code class="literal">*</code>" cannot be used for <span><strong class="command">ip_port</strong></span>.
 942         </p>
 943 <p>
 944           The ability to issue commands over the control channel is
 945           restricted by the <span><strong class="command">allow</strong></span> and
 946           <span><strong class="command">keys</strong></span> clauses.
 947           Connections to the control channel are permitted based on the
 948           <span><strong class="command">address_match_list</strong></span>.  This is for simple
 949           IP address based filtering only; any <span><strong class="command">key_id</strong></span>
 950           elements of the <span><strong class="command">address_match_list</strong></span>
 951           are ignored.
 952         </p>
 953 <p>
 954           A <span><strong class="command">unix</strong></span> control channel is a UNIX domain
 955           socket listening at the specified path in the file system.
 956           Access to the socket is specified by the <span><strong class="command">perm</strong></span>,
 957           <span><strong class="command">owner</strong></span> and <span><strong class="command">group</strong></span> clauses.
 958           Note on some platforms (SunOS and Solaris) the permissions
 959           (<span><strong class="command">perm</strong></span>) are applied to the parent directory
 960           as the permissions on the socket itself are ignored.
 961         </p>
 962 <p>
 963           The primary authorization mechanism of the command
 964           channel is the <span><strong class="command">key_list</strong></span>, which
 965           contains a list of <span><strong class="command">key_id</strong></span>s.
 966           Each <span><strong class="command">key_id</strong></span> in the <span><strong class="command">key_list</strong></span>
 967           is authorized to execute commands over the control channel.
 968           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>)
 969           for information about configuring keys in <span><strong class="command">rndc</strong></span>.
 970         </p>
 971 <p>
 972           If no <span><strong class="command">controls</strong></span> statement is present,
 973           <span><strong class="command">named</strong></span> will set up a default
 974           control channel listening on the loopback address 127.0.0.1
 975           and its IPv6 counterpart ::1.
 976           In this case, and also when the <span><strong class="command">controls</strong></span> statement
 977           is present but does not have a <span><strong class="command">keys</strong></span> clause,
 978           <span><strong class="command">named</strong></span> will attempt to load the command channel key
 979           from the file <code class="filename">rndc.key</code> in
 980           <code class="filename">/etc</code> (or whatever <code class="varname">sysconfdir</code>
 981           was specified as when <acronym class="acronym">BIND</acronym> was built).
 982           To create a <code class="filename">rndc.key</code> file, run
 983           <strong class="userinput"><code>rndc-confgen -a</code></strong>.
 984         </p>
 985 <p>
 986           The <code class="filename">rndc.key</code> feature was created to
 987           ease the transition of systems from <acronym class="acronym">BIND</acronym> 8,
 988           which did not have digital signatures on its command channel
 989           messages and thus did not have a <span><strong class="command">keys</strong></span> clause.
 990
 991           It makes it possible to use an existing <acronym class="acronym">BIND</acronym> 8
 992           configuration file in <acronym class="acronym">BIND</acronym> 9 unchanged,
 993           and still have <span><strong class="command">rndc</strong></span> work the same way
 994           <span><strong class="command">ndc</strong></span> worked in BIND 8, simply by executing the
 995           command <strong class="userinput"><code>rndc-confgen -a</code></strong> after BIND 9 is
 996           installed.
 997         </p>
 998 <p>
 999           Since the <code class="filename">rndc.key</code> feature
1000           is only intended to allow the backward-compatible usage of
1001           <acronym class="acronym">BIND</acronym> 8 configuration files, this
1002           feature does not
1003           have a high degree of configurability.  You cannot easily change
1004           the key name or the size of the secret, so you should make a
1005           <code class="filename">rndc.conf</code> with your own key if you
1006           wish to change
1007           those things.  The <code class="filename">rndc.key</code> file
1008           also has its
1009           permissions set such that only the owner of the file (the user that
1010           <span><strong class="command">named</strong></span> is running as) can access it.
1011           If you
1012           desire greater flexibility in allowing other users to access
1013           <span><strong class="command">rndc</strong></span> commands, then you need to create
1014           a
1015           <code class="filename">rndc.conf</code> file and make it group
1016           readable by a group
1017           that contains the users who should have access.
1018         </p>
1019 <p>
1020           To disable the command channel, use an empty
1021           <span><strong class="command">controls</strong></span> statement:
1022           <span><strong class="command">controls { };</strong></span>.
1023         </p>
1024 </div>
1025 <div class="sect2" lang="en">
1026 <div class="titlepage"><div><div><h3 class="title">
1027 <a name="id2574926"></a><span><strong class="command">include</strong></span> Statement Grammar</h3></div></div></div>
1028 <pre class="programlisting"><span><strong class="command">include</strong></span> <em class="replaceable"><code>filename</code></em>;</pre>
1029 </div>
1030 <div class="sect2" lang="en">
1031 <div class="titlepage"><div><div><h3 class="title">
1032 <a name="id2574944"></a><span><strong class="command">include</strong></span> Statement Definition and
1033           Usage</h3></div></div></div>
1034 <p>
1035           The <span><strong class="command">include</strong></span> statement inserts the
1036           specified file at the point where the <span><strong class="command">include</strong></span>
1037           statement is encountered. The <span><strong class="command">include</strong></span>
1038                 statement facilitates the administration of configuration
1039           files
1040           by permitting the reading or writing of some things but not
1041           others. For example, the statement could include private keys
1042           that are readable only by the name server.
1043         </p>
1044 </div>
1045 <div class="sect2" lang="en">
1046 <div class="titlepage"><div><div><h3 class="title">
1047 <a name="id2574967"></a><span><strong class="command">key</strong></span> Statement Grammar</h3></div></div></div>
1048 <pre class="programlisting"><span><strong class="command">key</strong></span> <em class="replaceable"><code>key_id</code></em> {
1049     algorithm <em class="replaceable"><code>string</code></em>;
1050     secret <em class="replaceable"><code>string</code></em>;
1051 };
1052 </pre>
1053 </div>
1054 <div class="sect2" lang="en">
1055 <div class="titlepage"><div><div><h3 class="title">
1056 <a name="id2574990"></a><span><strong class="command">key</strong></span> Statement Definition and Usage</h3></div></div></div>
1057 <p>
1058           The <span><strong class="command">key</strong></span> statement defines a shared
1059           secret key for use with TSIG (see <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called &#8220;TSIG&#8221;</a>)
1060           or the command channel
1061           (see <a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and
1062           Usage">the section called &#8220;<span><strong class="command">controls</strong></span> Statement Definition and
1063           Usage&#8221;</a>).
1064         </p>
1065 <p>
1066           The <span><strong class="command">key</strong></span> statement can occur at the
1067           top level
1068           of the configuration file or inside a <span><strong class="command">view</strong></span>
1069           statement.  Keys defined in top-level <span><strong class="command">key</strong></span>
1070           statements can be used in all views.  Keys intended for use in
1071           a <span><strong class="command">controls</strong></span> statement
1072           (see <a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and
1073           Usage">the section called &#8220;<span><strong class="command">controls</strong></span> Statement Definition and
1074           Usage&#8221;</a>)
1075           must be defined at the top level.
1076         </p>
1077 <p>
1078           The <em class="replaceable"><code>key_id</code></em>, also known as the
1079           key name, is a domain name uniquely identifying the key. It can
1080           be used in a <span><strong class="command">server</strong></span>
1081           statement to cause requests sent to that
1082           server to be signed with this key, or in address match lists to
1083           verify that incoming requests have been signed with a key
1084           matching this name, algorithm, and secret.
1085         </p>
1086 <p>
1087           The <em class="replaceable"><code>algorithm_id</code></em> is a string
1088           that specifies a security/authentication algorithm.  Named
1089           supports <code class="literal">hmac-md5</code>,
1090           <code class="literal">hmac-sha1</code>, <code class="literal">hmac-sha224</code>,
1091           <code class="literal">hmac-sha256</code>, <code class="literal">hmac-sha384</code>
1092           and <code class="literal">hmac-sha512</code> TSIG authentication.
1093           Truncated hashes are supported by appending the minimum
1094           number of required bits preceded by a dash, e.g.
1095           <code class="literal">hmac-sha1-80</code>.  The
1096           <em class="replaceable"><code>secret_string</code></em> is the secret
1097           to be used by the algorithm, and is treated as a base-64
1098           encoded string.
1099         </p>
1100 </div>
1101 <div class="sect2" lang="en">
1102 <div class="titlepage"><div><div><h3 class="title">
1103 <a name="id2575081"></a><span><strong class="command">logging</strong></span> Statement Grammar</h3></div></div></div>
1104 <pre class="programlisting"><span><strong class="command">logging</strong></span> {
1105    [ <span><strong class="command">channel</strong></span> <em class="replaceable"><code>channel_name</code></em> {
1106      ( <span><strong class="command">file</strong></span> <em class="replaceable"><code>path_name</code></em>
1107          [ <span><strong class="command">versions</strong></span> ( <em class="replaceable"><code>number</code></em> | <span><strong class="command">unlimited</strong></span> ) ]
1108          [ <span><strong class="command">size</strong></span> <em class="replaceable"><code>size spec</code></em> ]
1109        | <span><strong class="command">syslog</strong></span> <em class="replaceable"><code>syslog_facility</code></em>
1110        | <span><strong class="command">stderr</strong></span>
1111        | <span><strong class="command">null</strong></span> );
1112      [ <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> |
1113                  <code class="option">info</code> | <code class="option">debug</code> [ <em class="replaceable"><code>level</code></em> ] | <code class="option">dynamic</code> ); ]
1114      [ <span><strong class="command">print-category</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ]
1115      [ <span><strong class="command">print-severity</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ]
1116      [ <span><strong class="command">print-time</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ]
1117    }; ]
1118    [ <span><strong class="command">category</strong></span> <em class="replaceable"><code>category_name</code></em> {
1119      <em class="replaceable"><code>channel_name</code></em> ; [ <em class="replaceable"><code>channel_name</code></em> ; ... ]
1120    }; ]
1121    ...
1122 };
1123 </pre>
1124 </div>
1125 <div class="sect2" lang="en">
1126 <div class="titlepage"><div><div><h3 class="title">
1127 <a name="id2575207"></a><span><strong class="command">logging</strong></span> Statement Definition and
1128           Usage</h3></div></div></div>
1129 <p>
1130           The <span><strong class="command">logging</strong></span> statement configures a
1131           wide
1132           variety of logging options for the name server. Its <span><strong class="command">channel</strong></span> phrase
1133           associates output methods, format options and severity levels with
1134           a name that can then be used with the <span><strong class="command">category</strong></span> phrase
1135           to select how various classes of messages are logged.
1136         </p>
1137 <p>
1138           Only one <span><strong class="command">logging</strong></span> statement is used to
1139           define
1140           as many channels and categories as are wanted. If there is no <span><strong class="command">logging</strong></span> statement,
1141           the logging configuration will be:
1142         </p>
1143 <pre class="programlisting">logging {
1144      category default { default_syslog; default_debug; };
1145      category unmatched { null; };
1146 };
1147 </pre>
1148 <p>
1149           In <acronym class="acronym">BIND</acronym> 9, the logging configuration
1150           is only established when
1151           the entire configuration file has been parsed.  In <acronym class="acronym">BIND</acronym> 8, it was
1152           established as soon as the <span><strong class="command">logging</strong></span>
1153           statement
1154           was parsed. When the server is starting up, all logging messages
1155           regarding syntax errors in the configuration file go to the default
1156           channels, or to standard error if the "<code class="option">-g</code>" option
1157           was specified.
1158         </p>
1159 <div class="sect3" lang="en">
1160 <div class="titlepage"><div><div><h4 class="title">
1161 <a name="id2575259"></a>The <span><strong class="command">channel</strong></span> Phrase</h4></div></div></div>
1162 <p>
1163             All log output goes to one or more <span class="emphasis"><em>channels</em></span>;
1164             you can make as many of them as you want.
1165           </p>
1166 <p>
1167             Every channel definition must include a destination clause that
1168             says whether messages selected for the channel go to a file, to a
1169             particular syslog facility, to the standard error stream, or are
1170             discarded. It can optionally also limit the message severity level
1171             that will be accepted by the channel (the default is
1172             <span><strong class="command">info</strong></span>), and whether to include a
1173             <span><strong class="command">named</strong></span>-generated time stamp, the
1174             category name
1175             and/or severity level (the default is not to include any).
1176           </p>
1177 <p>
1178             The <span><strong class="command">null</strong></span> destination clause
1179             causes all messages sent to the channel to be discarded;
1180             in that case, other options for the channel are meaningless.
1181           </p>
1182 <p>
1183             The <span><strong class="command">file</strong></span> destination clause directs
1184             the channel
1185             to a disk file.  It can include limitations
1186             both on how large the file is allowed to become, and how many
1187             versions
1188             of the file will be saved each time the file is opened.
1189           </p>
1190 <p>
1191             If you use the <span><strong class="command">versions</strong></span> log file
1192             option, then
1193             <span><strong class="command">named</strong></span> will retain that many backup
1194             versions of the file by
1195             renaming them when opening.  For example, if you choose to keep
1196             three old versions
1197             of the file <code class="filename">lamers.log</code>, then just
1198             before it is opened
1199             <code class="filename">lamers.log.1</code> is renamed to
1200             <code class="filename">lamers.log.2</code>, <code class="filename">lamers.log.0</code> is renamed
1201             to <code class="filename">lamers.log.1</code>, and <code class="filename">lamers.log</code> is
1202             renamed to <code class="filename">lamers.log.0</code>.
1203             You can say <span><strong class="command">versions unlimited</strong></span> to
1204             not limit
1205             the number of versions.
1206             If a <span><strong class="command">size</strong></span> option is associated with
1207             the log file,
1208             then renaming is only done when the file being opened exceeds the
1209             indicated size.  No backup versions are kept by default; any
1210             existing
1211             log file is simply appended.
1212           </p>
1213 <p>
1214             The <span><strong class="command">size</strong></span> option for files is used
1215             to limit log
1216             growth. If the file ever exceeds the size, then <span><strong class="command">named</strong></span> will
1217             stop writing to the file unless it has a <span><strong class="command">versions</strong></span> option
1218             associated with it.  If backup versions are kept, the files are
1219             rolled as
1220             described above and a new one begun.  If there is no
1221             <span><strong class="command">versions</strong></span> option, no more data will
1222             be written to the log
1223             until some out-of-band mechanism removes or truncates the log to
1224             less than the
1225             maximum size.  The default behavior is not to limit the size of
1226             the
1227             file.
1228           </p>
1229 <p>
1230             Example usage of the <span><strong class="command">size</strong></span> and
1231             <span><strong class="command">versions</strong></span> options:
1232           </p>
1233 <pre class="programlisting">channel an_example_channel {
1234     file "example.log" versions 3 size 20m;
1235     print-time yes;
1236     print-category yes;
1237 };
1238 </pre>
1239 <p>
1240             The <span><strong class="command">syslog</strong></span> destination clause
1241             directs the
1242             channel to the system log.  Its argument is a
1243             syslog facility as described in the <span><strong class="command">syslog</strong></span> man
1244             page. Known facilities are <span><strong class="command">kern</strong></span>, <span><strong class="command">user</strong></span>,
1245             <span><strong class="command">mail</strong></span>, <span><strong class="command">daemon</strong></span>, <span><strong class="command">auth</strong></span>,
1246             <span><strong class="command">syslog</strong></span>, <span><strong class="command">lpr</strong></span>, <span><strong class="command">news</strong></span>,
1247             <span><strong class="command">uucp</strong></span>, <span><strong class="command">cron</strong></span>, <span><strong class="command">authpriv</strong></span>,
1248             <span><strong class="command">ftp</strong></span>, <span><strong class="command">local0</strong></span>, <span><strong class="command">local1</strong></span>,
1249             <span><strong class="command">local2</strong></span>, <span><strong class="command">local3</strong></span>, <span><strong class="command">local4</strong></span>,
1250             <span><strong class="command">local5</strong></span>, <span><strong class="command">local6</strong></span> and
1251             <span><strong class="command">local7</strong></span>, however not all facilities
1252             are supported on
1253             all operating systems.
1254             How <span><strong class="command">syslog</strong></span> will handle messages
1255             sent to
1256             this facility is described in the <span><strong class="command">syslog.conf</strong></span> man
1257             page. If you have a system which uses a very old version of <span><strong class="command">syslog</strong></span> that
1258             only uses two arguments to the <span><strong class="command">openlog()</strong></span> function,
1259             then this clause is silently ignored.
1260           </p>
1261 <p>
1262             The <span><strong class="command">severity</strong></span> clause works like <span><strong class="command">syslog</strong></span>'s
1263             "priorities", except that they can also be used if you are writing
1264             straight to a file rather than using <span><strong class="command">syslog</strong></span>.
1265             Messages which are not at least of the severity level given will
1266             not be selected for the channel; messages of higher severity
1267             levels
1268             will be accepted.
1269           </p>
1270 <p>
1271             If you are using <span><strong class="command">syslog</strong></span>, then the <span><strong class="command">syslog.conf</strong></span> priorities
1272             will also determine what eventually passes through. For example,
1273             defining a channel facility and severity as <span><strong class="command">daemon</strong></span> and <span><strong class="command">debug</strong></span> but
1274             only logging <span><strong class="command">daemon.warning</strong></span> via <span><strong class="command">syslog.conf</strong></span> will
1275             cause messages of severity <span><strong class="command">info</strong></span> and
1276             <span><strong class="command">notice</strong></span> to
1277             be dropped. If the situation were reversed, with <span><strong class="command">named</strong></span> writing
1278             messages of only <span><strong class="command">warning</strong></span> or higher,
1279             then <span><strong class="command">syslogd</strong></span> would
1280             print all messages it received from the channel.
1281           </p>
1282 <p>
1283             The <span><strong class="command">stderr</strong></span> destination clause
1284             directs the
1285             channel to the server's standard error stream.  This is intended
1286             for
1287             use when the server is running as a foreground process, for
1288             example
1289             when debugging a configuration.
1290           </p>
1291 <p>
1292             The server can supply extensive debugging information when
1293             it is in debugging mode. If the server's global debug level is
1294             greater
1295             than zero, then debugging mode will be active. The global debug
1296             level is set either by starting the <span><strong class="command">named</strong></span> server
1297             with the <code class="option">-d</code> flag followed by a positive integer,
1298             or by running <span><strong class="command">rndc trace</strong></span>.
1299             The global debug level
1300             can be set to zero, and debugging mode turned off, by running <span><strong class="command">rndc
1301 notrace</strong></span>. All debugging messages in the server have a debug
1302             level, and higher debug levels give more detailed output. Channels
1303             that specify a specific debug severity, for example:
1304           </p>
1305 <pre class="programlisting">channel specific_debug_level {
1306     file "foo";
1307     severity debug 3;
1308 };
1309 </pre>
1310 <p>
1311             will get debugging output of level 3 or less any time the
1312             server is in debugging mode, regardless of the global debugging
1313             level. Channels with <span><strong class="command">dynamic</strong></span>
1314             severity use the
1315             server's global debug level to determine what messages to print.
1316           </p>
1317 <p>
1318             If <span><strong class="command">print-time</strong></span> has been turned on,
1319             then
1320             the date and time will be logged. <span><strong class="command">print-time</strong></span> may
1321             be specified for a <span><strong class="command">syslog</strong></span> channel,
1322             but is usually
1323             pointless since <span><strong class="command">syslog</strong></span> also logs
1324             the date and
1325             time. If <span><strong class="command">print-category</strong></span> is
1326             requested, then the
1327             category of the message will be logged as well. Finally, if <span><strong class="command">print-severity</strong></span> is
1328             on, then the severity level of the message will be logged. The <span><strong class="command">print-</strong></span> options may
1329             be used in any combination, and will always be printed in the
1330             following
1331             order: time, category, severity. Here is an example where all
1332             three <span><strong class="command">print-</strong></span> options
1333             are on:
1334           </p>
1335 <p>
1336             <code class="computeroutput">28-Feb-2000 15:05:32.863 general: notice: running</code>
1337           </p>
1338 <p>
1339             There are four predefined channels that are used for
1340             <span><strong class="command">named</strong></span>'s default logging as follows.
1341             How they are
1342             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>.
1343           </p>
1344 <pre class="programlisting">channel default_syslog {
1345     syslog daemon;                      // send to syslog's daemon
1346                                         // facility
1347     severity info;                      // only send priority info
1348                                         // and higher
1349 };
1350
1351 channel default_debug {
1352     file "named.run";                   // write to named.run in
1353                                         // the working directory
1354                                         // Note: stderr is used instead
1355                                         // of "named.run"
1356                                         // if the server is started
1357                                         // with the '-f' option.
1358     severity dynamic;                   // log at the server's
1359                                         // current debug level
1360 };
1361
1362 channel default_stderr {
1363     stderr;                             // writes to stderr
1364     severity info;                      // only send priority info
1365                                         // and higher
1366 };
1367
1368 channel null {
1369    null;                                // toss anything sent to
1370                                         // this channel
1371 };
1372 </pre>
1373 <p>
1374             The <span><strong class="command">default_debug</strong></span> channel has the
1375             special
1376             property that it only produces output when the server's debug
1377             level is
1378             nonzero.  It normally writes to a file called <code class="filename">named.run</code>
1379             in the server's working directory.
1380           </p>
1381 <p>
1382             For security reasons, when the "<code class="option">-u</code>"
1383             command line option is used, the <code class="filename">named.run</code> file
1384             is created only after <span><strong class="command">named</strong></span> has
1385             changed to the
1386             new UID, and any debug output generated while <span><strong class="command">named</strong></span> is
1387             starting up and still running as root is discarded.  If you need
1388             to capture this output, you must run the server with the "<code class="option">-g</code>"
1389             option and redirect standard error to a file.
1390           </p>
1391 <p>
1392             Once a channel is defined, it cannot be redefined. Thus you
1393             cannot alter the built-in channels directly, but you can modify
1394             the default logging by pointing categories at channels you have
1395             defined.
1396           </p>
1397 </div>
1398 <div class="sect3" lang="en">
1399 <div class="titlepage"><div><div><h4 class="title">
1400 <a name="the_category_phrase"></a>The <span><strong class="command">category</strong></span> Phrase</h4></div></div></div>
1401 <p>
1402             There are many categories, so you can send the logs you want
1403             to see wherever you want, without seeing logs you don't want. If
1404             you don't specify a list of channels for a category, then log
1405             messages
1406             in that category will be sent to the <span><strong class="command">default</strong></span> category
1407             instead. If you don't specify a default category, the following
1408             "default default" is used:
1409           </p>
1410 <pre class="programlisting">category default { default_syslog; default_debug; };
1411 </pre>
1412 <p>
1413             As an example, let's say you want to log security events to
1414             a file, but you also want keep the default logging behavior. You'd
1415             specify the following:
1416           </p>
1417 <pre class="programlisting">channel my_security_channel {
1418     file "my_security_file";
1419     severity info;
1420 };
1421 category security {
1422     my_security_channel;
1423     default_syslog;
1424     default_debug;
1425 };</pre>
1426 <p>
1427             To discard all messages in a category, specify the <span><strong class="command">null</strong></span> channel:
1428           </p>
1429 <pre class="programlisting">category xfer-out { null; };
1430 category notify { null; };
1431 </pre>
1432 <p>
1433             Following are the available categories and brief descriptions
1434             of the types of log information they contain. More
1435             categories may be added in future <acronym class="acronym">BIND</acronym> releases.
1436           </p>
1437 <div class="informaltable"><table border="1">
1438 <colgroup>
1439 <col>
1440 <col>
1441 </colgroup>
1442 <tbody>
1443 <tr>
1444 <td>
1445                     <p><span><strong class="command">default</strong></span></p>
1446                   </td>
1447 <td>
1448                     <p>
1449                       The default category defines the logging
1450                       options for those categories where no specific
1451                       configuration has been
1452                       defined.
1453                     </p>
1454                   </td>
1455 </tr>
1456 <tr>
1457 <td>
1458                     <p><span><strong class="command">general</strong></span></p>
1459                   </td>
1460 <td>
1461                     <p>
1462                       The catch-all. Many things still aren't
1463                       classified into categories, and they all end up here.
1464                     </p>
1465                   </td>
1466 </tr>
1467 <tr>
1468 <td>
1469                     <p><span><strong class="command">database</strong></span></p>
1470                   </td>
1471 <td>
1472                     <p>
1473                       Messages relating to the databases used
1474                       internally by the name server to store zone and cache
1475                       data.
1476                     </p>
1477                   </td>
1478 </tr>
1479 <tr>
1480 <td>
1481                     <p><span><strong class="command">security</strong></span></p>
1482                   </td>
1483 <td>
1484                     <p>
1485                       Approval and denial of requests.
1486                     </p>
1487                   </td>
1488 </tr>
1489 <tr>
1490 <td>
1491                     <p><span><strong class="command">config</strong></span></p>
1492                   </td>
1493 <td>
1494                     <p>
1495                       Configuration file parsing and processing.
1496                     </p>
1497                   </td>
1498 </tr>
1499 <tr>
1500 <td>
1501                     <p><span><strong class="command">resolver</strong></span></p>
1502                   </td>
1503 <td>
1504                     <p>
1505                       DNS resolution, such as the recursive
1506                       lookups performed on behalf of clients by a caching name
1507                       server.
1508                     </p>
1509                   </td>
1510 </tr>
1511 <tr>
1512 <td>
1513                     <p><span><strong class="command">xfer-in</strong></span></p>
1514                   </td>
1515 <td>
1516                     <p>
1517                       Zone transfers the server is receiving.
1518                     </p>
1519                   </td>
1520 </tr>
1521 <tr>
1522 <td>
1523                     <p><span><strong class="command">xfer-out</strong></span></p>
1524                   </td>
1525 <td>
1526                     <p>
1527                       Zone transfers the server is sending.
1528                     </p>
1529                   </td>
1530 </tr>
1531 <tr>
1532 <td>
1533                     <p><span><strong class="command">notify</strong></span></p>
1534                   </td>
1535 <td>
1536                     <p>
1537                       The NOTIFY protocol.
1538                     </p>
1539                   </td>
1540 </tr>
1541 <tr>
1542 <td>
1543                     <p><span><strong class="command">client</strong></span></p>
1544                   </td>
1545 <td>
1546                     <p>
1547                       Processing of client requests.
1548                     </p>
1549                   </td>
1550 </tr>
1551 <tr>
1552 <td>
1553                     <p><span><strong class="command">unmatched</strong></span></p>
1554                   </td>
1555 <td>
1556                     <p>
1557                       Messages that <span><strong class="command">named</strong></span> was unable to determine the
1558                       class of or for which there was no matching <span><strong class="command">view</strong></span>.
1559                       A one line summary is also logged to the <span><strong class="command">client</strong></span> category.
1560                       This category is best sent to a file or stderr, by
1561                       default it is sent to
1562                       the <span><strong class="command">null</strong></span> channel.
1563                     </p>
1564                   </td>
1565 </tr>
1566 <tr>
1567 <td>
1568                     <p><span><strong class="command">network</strong></span></p>
1569                   </td>
1570 <td>
1571                     <p>
1572                       Network operations.
1573                     </p>
1574                   </td>
1575 </tr>
1576 <tr>
1577 <td>
1578                     <p><span><strong class="command">update</strong></span></p>
1579                   </td>
1580 <td>
1581                     <p>
1582                       Dynamic updates.
1583                     </p>
1584                   </td>
1585 </tr>
1586 <tr>
1587 <td>
1588                     <p><span><strong class="command">update-security</strong></span></p>
1589                   </td>
1590 <td>
1591                     <p>
1592                       Approval and denial of update requests.
1593                     </p>
1594                   </td>
1595 </tr>
1596 <tr>
1597 <td>
1598                     <p><span><strong class="command">queries</strong></span></p>
1599                   </td>
1600 <td>
1601                     <p>
1602                       Specify where queries should be logged to.
1603                     </p>
1604                     <p>
1605                       At startup, specifying the category <span><strong class="command">queries</strong></span> will also
1606                       enable query logging unless <span><strong class="command">querylog</strong></span> option has been
1607                       specified.
1608                     </p>
1609
1610                     <p>
1611                       The query log entry reports the client's IP
1612                       address and port number, and the query name,
1613                       class and type.  It also reports whether the
1614                       Recursion Desired flag was set (+ if set, -
1615                       if not set), if the query was signed (S),
1616                       EDNS was in use (E), if DO (DNSSEC Ok) was
1617                       set (D), or if CD (Checking Disabled) was set
1618                       (C).
1619                     </p>
1620
1621                     <p>
1622                       <code class="computeroutput">client 127.0.0.1#62536: query: www.example.com IN AAAA +SE</code>
1623                     </p>
1624                     <p>
1625                       <code class="computeroutput">client ::1#62537: query: www.example.net IN AAAA -SE</code>
1626                     </p>
1627                   </td>
1628 </tr>
1629 <tr>
1630 <td>
1631                     <p><span><strong class="command">query-errors</strong></span></p>
1632                   </td>
1633 <td>
1634                     <p>
1635                       Information about queries that resulted in some
1636                       failure.
1637                     </p>
1638                   </td>
1639 </tr>
1640 <tr>
1641 <td>
1642                     <p><span><strong class="command">dispatch</strong></span></p>
1643                   </td>
1644 <td>
1645                     <p>
1646                       Dispatching of incoming packets to the
1647                       server modules where they are to be processed.
1648                     </p>
1649                   </td>
1650 </tr>
1651 <tr>
1652 <td>
1653                     <p><span><strong class="command">dnssec</strong></span></p>
1654                   </td>
1655 <td>
1656                     <p>
1657                       DNSSEC and TSIG protocol processing.
1658                     </p>
1659                   </td>
1660 </tr>
1661 <tr>
1662 <td>
1663                     <p><span><strong class="command">lame-servers</strong></span></p>
1664                   </td>
1665 <td>
1666                     <p>
1667                       Lame servers.  These are misconfigurations
1668                       in remote servers, discovered by BIND 9 when trying to
1669                       query those servers during resolution.
1670                     </p>
1671                   </td>
1672 </tr>
1673 <tr>
1674 <td>
1675                     <p><span><strong class="command">delegation-only</strong></span></p>
1676                   </td>
1677 <td>
1678                     <p>
1679                       Delegation only.  Logs queries that have been
1680                       forced to NXDOMAIN as the result of a
1681                       delegation-only zone or a
1682                       <span><strong class="command">delegation-only</strong></span> in a hint
1683                       or stub zone declaration.
1684                     </p>
1685                   </td>
1686 </tr>
1687 <tr>
1688 <td>
1689                     <p><span><strong class="command">edns-disabled</strong></span></p>
1690                   </td>
1691 <td>
1692                     <p>
1693                       Log queries that have been forced to use plain
1694                       DNS due to timeouts.  This is often due to
1695                       the remote servers not being RFC 1034 compliant
1696                       (not always returning FORMERR or similar to
1697                       EDNS queries and other extensions to the DNS
1698                       when they are not understood).  In other words, this is
1699                       targeted at servers that fail to respond to
1700                       DNS queries that they don't understand.
1701                     </p>
1702                     <p>
1703                       Note: the log message can also be due to
1704                       packet loss.  Before reporting servers for
1705                       non-RFC 1034 compliance they should be re-tested
1706                       to determine the nature of the non-compliance.
1707                       This testing should prevent or reduce the
1708                       number of false-positive reports.
1709                     </p>
1710                     <p>
1711                       Note: eventually <span><strong class="command">named</strong></span> will have to stop
1712                       treating such timeouts as due to RFC 1034 non
1713                       compliance and start treating it as plain
1714                       packet loss.  Falsely classifying packet
1715                       loss as due to RFC 1034 non compliance impacts
1716                       on DNSSEC validation which requires EDNS for
1717                       the DNSSEC records to be returned.
1718                     </p>
1719                   </td>
1720 </tr>
1721 </tbody>
1722 </table></div>
1723 </div>
1724 <div class="sect3" lang="en">
1725 <div class="titlepage"><div><div><h4 class="title">
1726 <a name="id2576755"></a>The <span><strong class="command">query-errors</strong></span> Category</h4></div></div></div>
1727 <p>
1728             The <span><strong class="command">query-errors</strong></span> category is
1729             specifically intended for debugging purposes: To identify
1730             why and how specific queries result in responses which
1731             indicate an error.
1732             Messages of this category are therefore only logged
1733             with <span><strong class="command">debug</strong></span> levels.
1734           </p>
1735 <p>
1736             At the debug levels of 1 or higher, each response with the
1737             rcode of SERVFAIL is logged as follows:
1738           </p>
1739 <p>
1740             <code class="computeroutput">client 127.0.0.1#61502: query failed (SERVFAIL) for www.example.com/IN/AAAA at query.c:3880</code>
1741           </p>
1742 <p>
1743             This means an error resulting in SERVFAIL was
1744             detected at line 3880 of source file
1745             <code class="filename">query.c</code>.
1746             Log messages of this level will particularly
1747             help identify the cause of SERVFAIL for an
1748             authoritative server.
1749           </p>
1750 <p>
1751             At the debug levels of 2 or higher, detailed context
1752             information of recursive resolutions that resulted in
1753             SERVFAIL is logged.
1754             The log message will look like as follows:
1755           </p>
1756 <p>
1757             <code class="computeroutput">fetch completed at resolver.c:2970 for www.example.com/A in 30.000183: timed out/success [domain:example.com,referral:2,restart:7,qrysent:8,timeout:5,lame:0,neterr:0,badresp:1,adberr:0,findfail:0,valfail:0]</code>
1758           </p>
1759 <p>
1760             The first part before the colon shows that a recursive
1761             resolution for AAAA records of www.example.com completed
1762             in 30.000183 seconds and the final result that led to the
1763             SERVFAIL was determined at line 2970 of source file
1764             <code class="filename">resolver.c</code>.
1765           </p>
1766 <p>
1767             The following part shows the detected final result and the
1768             latest result of DNSSEC validation.
1769             The latter is always success when no validation attempt
1770             is made.
1771             In this example, this query resulted in SERVFAIL probably
1772             because all name servers are down or unreachable, leading
1773             to a timeout in 30 seconds.
1774             DNSSEC validation was probably not attempted.
1775           </p>
1776 <p>
1777             The last part enclosed in square brackets shows statistics
1778             information collected for this particular resolution
1779             attempt.
1780             The <code class="varname">domain</code> field shows the deepest zone
1781             that the resolver reached;
1782             it is the zone where the error was finally detected.
1783             The meaning of the other fields is summarized in the
1784             following table.
1785           </p>
1786 <div class="informaltable"><table border="1">
1787 <colgroup>
1788 <col>
1789 <col>
1790 </colgroup>
1791 <tbody>
1792 <tr>
1793 <td>
1794                     <p><code class="varname">referral</code></p>
1795                   </td>
1796 <td>
1797                     <p>
1798                       The number of referrals the resolver received
1799                       throughout the resolution process.
1800                       In the above example this is 2, which are most
1801                       likely com and example.com.
1802                     </p>
1803                   </td>
1804 </tr>
1805 <tr>
1806 <td>
1807                     <p><code class="varname">restart</code></p>
1808                   </td>
1809 <td>
1810                     <p>
1811                       The number of cycles that the resolver tried
1812                       remote servers at the <code class="varname">domain</code>
1813                       zone.
1814                       In each cycle the resolver sends one query
1815                       (possibly resending it, depending on the response)
1816                       to each known name server of
1817                       the <code class="varname">domain</code> zone.
1818                     </p>
1819                   </td>
1820 </tr>
1821 <tr>
1822 <td>
1823                     <p><code class="varname">qrysent</code></p>
1824                   </td>
1825 <td>
1826                     <p>
1827                       The number of queries the resolver sent at the
1828                       <code class="varname">domain</code> zone.
1829                     </p>
1830                   </td>
1831 </tr>
1832 <tr>
1833 <td>
1834                     <p><code class="varname">timeout</code></p>
1835                   </td>
1836 <td>
1837                     <p>
1838                       The number of timeouts since the resolver
1839                       received the last response.
1840                     </p>
1841                   </td>
1842 </tr>
1843 <tr>
1844 <td>
1845                     <p><code class="varname">lame</code></p>
1846                   </td>
1847 <td>
1848                     <p>
1849                       The number of lame servers the resolver detected
1850                       at the <code class="varname">domain</code> zone.
1851                       A server is detected to be lame either by an
1852                       invalid response or as a result of lookup in
1853                       BIND9's address database (ADB), where lame
1854                       servers are cached.
1855                     </p>
1856                   </td>
1857 </tr>
1858 <tr>
1859 <td>
1860                     <p><code class="varname">neterr</code></p>
1861                   </td>
1862 <td>
1863                     <p>
1864                       The number of erroneous results that the
1865                       resolver encountered in sending queries
1866                       at the <code class="varname">domain</code> zone.
1867                       One common case is the remote server is
1868                       unreachable and the resolver receives an ICMP
1869                       unreachable error message.
1870                     </p>
1871                   </td>
1872 </tr>
1873 <tr>
1874 <td>
1875                     <p><code class="varname">badresp</code></p>
1876                   </td>
1877 <td>
1878                     <p>
1879                       The number of unexpected responses (other than
1880                       <code class="varname">lame</code>) to queries sent by the
1881                       resolver at the <code class="varname">domain</code> zone.
1882                     </p>
1883                   </td>
1884 </tr>
1885 <tr>
1886 <td>
1887                     <p><code class="varname">adberr</code></p>
1888                   </td>
1889 <td>
1890                     <p>
1891                       Failures in finding remote server addresses
1892                       of the <code class="varname">domain</code> zone in the ADB.
1893                       One common case of this is that the remote
1894                       server's name does not have any address records.
1895                     </p>
1896                   </td>
1897 </tr>
1898 <tr>
1899 <td>
1900                     <p><code class="varname">findfail</code></p>
1901                   </td>
1902 <td>
1903                     <p>
1904                       Failures of resolving remote server addresses.
1905                       This is a total number of failures throughout
1906                       the resolution process.
1907                     </p>
1908                   </td>
1909 </tr>
1910 <tr>
1911 <td>
1912                     <p><code class="varname">valfail</code></p>
1913                   </td>
1914 <td>
1915                     <p>
1916                       Failures of DNSSEC validation.
1917                       Validation failures are counted throughout
1918                       the resolution process (not limited to
1919                       the <code class="varname">domain</code> zone), but should
1920                       only happen in <code class="varname">domain</code>.
1921                     </p>
1922                   </td>
1923 </tr>
1924 </tbody>
1925 </table></div>
1926 <p>
1927             At the debug levels of 3 or higher, the same messages
1928             as those at the debug 1 level are logged for other errors
1929             than SERVFAIL.
1930             Note that negative responses such as NXDOMAIN are not
1931             regarded as errors here.
1932           </p>
1933 <p>
1934             At the debug levels of 4 or higher, the same messages
1935             as those at the debug 2 level are logged for other errors
1936             than SERVFAIL.
1937             Unlike the above case of level 3, messages are logged for
1938             negative responses.
1939             This is because any unexpected results can be difficult to
1940             debug in the recursion case.
1941           </p>
1942 </div>
1943 </div>
1944 <div class="sect2" lang="en">
1945 <div class="titlepage"><div><div><h3 class="title">
1946 <a name="id2577268"></a><span><strong class="command">lwres</strong></span> Statement Grammar</h3></div></div></div>
1947 <p>
1948            This is the grammar of the <span><strong class="command">lwres</strong></span>
1949           statement in the <code class="filename">named.conf</code> file:
1950         </p>
1951 <pre class="programlisting"><span><strong class="command">lwres</strong></span> {
1952     [<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>] ; [<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>]
1953     [<span class="optional"> view <em class="replaceable"><code>view_name</code></em>; </span>]
1954     [<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>]
1955     [<span class="optional"> ndots <em class="replaceable"><code>number</code></em>; </span>]
1956 };
1957 </pre>
1958 </div>
1959 <div class="sect2" lang="en">
1960 <div class="titlepage"><div><div><h3 class="title">
1961 <a name="id2577341"></a><span><strong class="command">lwres</strong></span> Statement Definition and Usage</h3></div></div></div>
1962 <p>
1963           The <span><strong class="command">lwres</strong></span> statement configures the
1964           name
1965           server to also act as a lightweight resolver server. (See
1966           <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
1967           <span><strong class="command">lwres</strong></span> statements configuring
1968           lightweight resolver servers with different properties.
1969         </p>
1970 <p>
1971           The <span><strong class="command">listen-on</strong></span> statement specifies a
1972           list of
1973           addresses (and ports) that this instance of a lightweight resolver
1974           daemon
1975           should accept requests on.  If no port is specified, port 921 is
1976           used.
1977           If this statement is omitted, requests will be accepted on
1978           127.0.0.1,
1979           port 921.
1980         </p>
1981 <p>
1982           The <span><strong class="command">view</strong></span> statement binds this
1983           instance of a
1984           lightweight resolver daemon to a view in the DNS namespace, so that
1985           the
1986           response will be constructed in the same manner as a normal DNS
1987           query
1988           matching this view.  If this statement is omitted, the default view
1989           is
1990           used, and if there is no default view, an error is triggered.
1991         </p>
1992 <p>
1993           The <span><strong class="command">search</strong></span> statement is equivalent to
1994           the
1995           <span><strong class="command">search</strong></span> statement in
1996           <code class="filename">/etc/resolv.conf</code>.  It provides a
1997           list of domains
1998           which are appended to relative names in queries.
1999         </p>
2000 <p>
2001           The <span><strong class="command">ndots</strong></span> statement is equivalent to
2002           the
2003           <span><strong class="command">ndots</strong></span> statement in
2004           <code class="filename">/etc/resolv.conf</code>.  It indicates the
2005           minimum
2006           number of dots in a relative domain name that should result in an
2007           exact match lookup before search path elements are appended.
2008         </p>
2009 </div>
2010 <div class="sect2" lang="en">
2011 <div class="titlepage"><div><div><h3 class="title">
2012 <a name="id2577405"></a><span><strong class="command">masters</strong></span> Statement Grammar</h3></div></div></div>
2013 <pre class="programlisting">
2014 <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> | <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>] };
2015 </pre>
2016 </div>
2017 <div class="sect2" lang="en">
2018 <div class="titlepage"><div><div><h3 class="title">
2019 <a name="id2577449"></a><span><strong class="command">masters</strong></span> Statement Definition and
2020           Usage</h3></div></div></div>
2021 <p><span><strong class="command">masters</strong></span>
2022           lists allow for a common set of masters to be easily used by
2023           multiple stub and slave zones.
2024         </p>
2025 </div>
2026 <div class="sect2" lang="en">
2027 <div class="titlepage"><div><div><h3 class="title">
2028 <a name="id2577464"></a><span><strong class="command">options</strong></span> Statement Grammar</h3></div></div></div>
2029 <p>
2030           This is the grammar of the <span><strong class="command">options</strong></span>
2031           statement in the <code class="filename">named.conf</code> file:
2032         </p>
2033 <pre class="programlisting"><span><strong class="command">options</strong></span> {
2034     [<span class="optional"> version <em class="replaceable"><code>version_string</code></em>; </span>]
2035     [<span class="optional"> hostname <em class="replaceable"><code>hostname_string</code></em>; </span>]
2036     [<span class="optional"> server-id <em class="replaceable"><code>server_id_string</code></em>; </span>]
2037     [<span class="optional"> directory <em class="replaceable"><code>path_name</code></em>; </span>]
2038     [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>]
2039     [<span class="optional"> named-xfer <em class="replaceable"><code>path_name</code></em>; </span>]
2040     [<span class="optional"> tkey-gssapi-credential <em class="replaceable"><code>principal</code></em>; </span>]
2041     [<span class="optional"> tkey-domain <em class="replaceable"><code>domainname</code></em>; </span>]
2042     [<span class="optional"> tkey-dhkey <em class="replaceable"><code>key_name</code></em> <em class="replaceable"><code>key_tag</code></em>; </span>]
2043     [<span class="optional"> cache-file <em class="replaceable"><code>path_name</code></em>; </span>]
2044     [<span class="optional"> dump-file <em class="replaceable"><code>path_name</code></em>; </span>]
2045     [<span class="optional"> memstatistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2046     [<span class="optional"> memstatistics-file <em class="replaceable"><code>path_name</code></em>; </span>]
2047     [<span class="optional"> pid-file <em class="replaceable"><code>path_name</code></em>; </span>]
2048     [<span class="optional"> recursing-file <em class="replaceable"><code>path_name</code></em>; </span>]
2049     [<span class="optional"> statistics-file <em class="replaceable"><code>path_name</code></em>; </span>]
2050     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2051     [<span class="optional"> auth-nxdomain <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2052     [<span class="optional"> deallocate-on-exit <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2053     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em>; </span>]
2054     [<span class="optional"> fake-iquery <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2055     [<span class="optional"> fetch-glue <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2056     [<span class="optional"> flush-zones-on-shutdown <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2057     [<span class="optional"> has-old-clients <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2058     [<span class="optional"> host-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2059     [<span class="optional"> host-statistics-max <em class="replaceable"><code>number</code></em>; </span>]
2060     [<span class="optional"> minimal-responses <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2061     [<span class="optional"> multiple-cnames <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2062     [<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>]
2063     [<span class="optional"> recursion <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2064     [<span class="optional"> rfc2308-type1 <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2065     [<span class="optional"> use-id-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2066     [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2067     [<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>]
2068     [<span class="optional"> dnssec-enable <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2069     [<span class="optional"> dnssec-validation <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2070     [<span class="optional"> dnssec-lookaside <em class="replaceable"><code>domain</code></em> trust-anchor <em class="replaceable"><code>domain</code></em>; </span>]
2071     [<span class="optional"> dnssec-must-be-secure <em class="replaceable"><code>domain yes_or_no</code></em>; </span>]
2072     [<span class="optional"> dnssec-accept-expired <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2073     [<span class="optional"> forward ( <em class="replaceable"><code>only</code></em> | <em class="replaceable"><code>first</code></em> ); </span>]
2074     [<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>]
2075     [<span class="optional"> dual-stack-servers [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] {
2076         ( <em class="replaceable"><code>domain_name</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] |
2077           <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ) ;
2078         ... }; </span>]
2079     [<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> )
2080         ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2081     [<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>]
2082     [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2083     [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2084     [<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>]
2085     [<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>]
2086     [<span class="optional"> check-sibling <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2087     [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2088     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2089     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2090     [<span class="optional"> allow-query-cache { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2091     [<span class="optional"> allow-query-cache-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2092     [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2093     [<span class="optional"> allow-recursion { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2094     [<span class="optional"> allow-recursion-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2095     [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2096     [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2097     [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2098     [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2099     [<span class="optional"> allow-v6-synthesis { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2100     [<span class="optional"> blackhole { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2101     [<span class="optional"> use-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2102     [<span class="optional"> avoid-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2103     [<span class="optional"> use-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2104     [<span class="optional"> avoid-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2105     [<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>]
2106     [<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>]
2107     [<span class="optional"> query-source ( ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> )
2108         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] |
2109         [<span class="optional"> address ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
2110         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>]
2111     [<span class="optional"> query-source-v6 ( ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> )
2112         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] |
2113         [<span class="optional"> address ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
2114         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>]
2115     [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2116     [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>]
2117     [<span class="optional"> queryport-pool-updateinterval <em class="replaceable"><code>number</code></em>; </span>]
2118     [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em>; </span>]
2119     [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em>; </span>]
2120     [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em>; </span>]
2121     [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em>; </span>]
2122     [<span class="optional"> tcp-clients <em class="replaceable"><code>number</code></em>; </span>]
2123     [<span class="optional"> reserved-sockets <em class="replaceable"><code>number</code></em>; </span>]
2124     [<span class="optional"> recursive-clients <em class="replaceable"><code>number</code></em>; </span>]
2125     [<span class="optional"> serial-query-rate <em class="replaceable"><code>number</code></em>; </span>]
2126     [<span class="optional"> serial-queries <em class="replaceable"><code>number</code></em>; </span>]
2127     [<span class="optional"> tcp-listen-queue <em class="replaceable"><code>number</code></em>; </span>]
2128     [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em>; </span>]
2129     [<span class="optional"> transfers-in  <em class="replaceable"><code>number</code></em>; </span>]
2130     [<span class="optional"> transfers-out <em class="replaceable"><code>number</code></em>; </span>]
2131     [<span class="optional"> transfers-per-ns <em class="replaceable"><code>number</code></em>; </span>]
2132     [<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>]
2133     [<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>]
2134     [<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>]
2135     [<span class="optional"> alt-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>]
2136     [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2137     [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
2138     [<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>]
2139     [<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>]
2140     [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2141     [<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>] ; [<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>]
2142     [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em>; </span>]
2143     [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
2144     [<span class="optional"> coresize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2145     [<span class="optional"> datasize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2146     [<span class="optional"> files <em class="replaceable"><code>size_spec</code></em> ; </span>]
2147     [<span class="optional"> stacksize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2148     [<span class="optional"> cleaning-interval <em class="replaceable"><code>number</code></em>; </span>]
2149     [<span class="optional"> heartbeat-interval <em class="replaceable"><code>number</code></em>; </span>]
2150     [<span class="optional"> interface-interval <em class="replaceable"><code>number</code></em>; </span>]
2151     [<span class="optional"> statistics-interval <em class="replaceable"><code>number</code></em>; </span>]
2152     [<span class="optional"> topology { <em class="replaceable"><code>address_match_list</code></em> }</span>];
2153     [<span class="optional"> sortlist { <em class="replaceable"><code>address_match_list</code></em> }</span>];
2154     [<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>] };
2155     [<span class="optional"> lame-ttl <em class="replaceable"><code>number</code></em>; </span>]
2156     [<span class="optional"> max-ncache-ttl <em class="replaceable"><code>number</code></em>; </span>]
2157     [<span class="optional"> max-cache-ttl <em class="replaceable"><code>number</code></em>; </span>]
2158     [<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>]
2159     [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>]
2160     [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>]
2161     [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>]
2162     [<span class="optional"> min-roots <em class="replaceable"><code>number</code></em>; </span>]
2163     [<span class="optional"> use-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2164     [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2165     [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2166     [<span class="optional"> treat-cr-as-space <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2167     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
2168     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
2169     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
2170     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
2171     [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em>; </span>]
2172     [<span class="optional"> additional-from-auth <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2173     [<span class="optional"> additional-from-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2174     [<span class="optional"> random-device <em class="replaceable"><code>path_name</code></em> ; </span>]
2175     [<span class="optional"> max-cache-size <em class="replaceable"><code>size_spec</code></em> ; </span>]
2176     [<span class="optional"> match-mapped-addresses <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2177     [<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>]
2178     [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em>; </span>]
2179     [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em>; </span>]
2180     [<span class="optional"> root-delegation-only [<span class="optional"> exclude { <em class="replaceable"><code>namelist</code></em> } </span>] ; </span>]
2181     [<span class="optional"> querylog <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2182     [<span class="optional"> disable-algorithms <em class="replaceable"><code>domain</code></em> { <em class="replaceable"><code>algorithm</code></em>; [<span class="optional"> <em class="replaceable"><code>algorithm</code></em>; </span>] }; </span>]
2183     [<span class="optional"> acache-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2184     [<span class="optional"> acache-cleaning-interval <em class="replaceable"><code>number</code></em>; </span>]
2185     [<span class="optional"> max-acache-size <em class="replaceable"><code>size_spec</code></em> ; </span>]
2186     [<span class="optional"> clients-per-query <em class="replaceable"><code>number</code></em> ; </span>]
2187     [<span class="optional"> max-clients-per-query <em class="replaceable"><code>number</code></em> ; </span>]
2188     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
2189     [<span class="optional"> empty-server <em class="replaceable"><code>name</code></em> ; </span>]
2190     [<span class="optional"> empty-contact <em class="replaceable"><code>name</code></em> ; </span>]
2191     [<span class="optional"> empty-zones-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2192     [<span class="optional"> disable-empty-zone <em class="replaceable"><code>zone_name</code></em> ; </span>]
2193     [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2194     [<span class="optional"> zero-no-soa-ttl-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2195 };
2196 </pre>
2197 </div>
2198 <div class="sect2" lang="en">
2199 <div class="titlepage"><div><div><h3 class="title">
2200 <a name="options"></a><span><strong class="command">options</strong></span> Statement Definition and
2201           Usage</h3></div></div></div>
2202 <p>
2203           The <span><strong class="command">options</strong></span> statement sets up global
2204           options
2205           to be used by <acronym class="acronym">BIND</acronym>. This statement
2206           may appear only
2207           once in a configuration file. If there is no <span><strong class="command">options</strong></span>
2208           statement, an options block with each option set to its default will
2209           be used.
2210         </p>
2211 <div class="variablelist"><dl>
2212 <dt><span class="term"><span><strong class="command">directory</strong></span></span></dt>
2213 <dd><p>
2214                 The working directory of the server.
2215                 Any non-absolute pathnames in the configuration file will be
2216                 taken
2217                 as relative to this directory. The default location for most
2218                 server
2219                 output files (e.g. <code class="filename">named.run</code>)
2220                 is this directory.
2221                 If a directory is not specified, the working directory
2222                 defaults to `<code class="filename">.</code>', the directory from
2223                 which the server
2224                 was started. The directory specified should be an absolute
2225                 path.
2226               </p></dd>
2227 <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt>
2228 <dd><p>
2229                 When performing dynamic update of secure zones, the
2230                 directory where the public and private DNSSEC key files
2231                 should be found, if different than the current working
2232                 directory.  The directory specified must be an absolute
2233                 path.  (Note that this option has no effect on the paths
2234                 for files containing non-DNSSEC keys such as the
2235                 <code class="filename">rndc.key</code>.
2236               </p></dd>
2237 <dt><span class="term"><span><strong class="command">named-xfer</strong></span></span></dt>
2238 <dd><p>
2239                 <span class="emphasis"><em>This option is obsolete.</em></span> It
2240                 was used in <acronym class="acronym">BIND</acronym> 8 to specify
2241                 the pathname to the <span><strong class="command">named-xfer</strong></span>
2242                 program.  In <acronym class="acronym">BIND</acronym> 9, no separate
2243                 <span><strong class="command">named-xfer</strong></span> program is needed;
2244                 its functionality is built into the name server.
2245               </p></dd>
2246 <dt><span class="term"><span><strong class="command">tkey-gssapi-credential</strong></span></span></dt>
2247 <dd><p>
2248                 The security credential with which the server should
2249                 authenticate keys requested by the GSS-TSIG protocol.
2250                 Currently only Kerberos 5 authentication is available
2251                 and the credential is a Kerberos principal which
2252                 the server can acquire through the default system
2253                 key file, normally <code class="filename">/etc/krb5.keytab</code>.
2254                 Normally this principal is of the form
2255                 "<strong class="userinput"><code>DNS/</code></strong><code class="varname">server.domain</code>".
2256                 To use GSS-TSIG, <span><strong class="command">tkey-domain</strong></span>
2257                 must also be set.
2258               </p></dd>
2259 <dt><span class="term"><span><strong class="command">tkey-domain</strong></span></span></dt>
2260 <dd><p>
2261                 The domain appended to the names of all shared keys
2262                 generated with <span><strong class="command">TKEY</strong></span>.  When a
2263                 client requests a <span><strong class="command">TKEY</strong></span> exchange,
2264                 it may or may not specify the desired name for the
2265                 key. If present, the name of the shared key will
2266                 be <code class="varname">client specified part</code> +
2267                 <code class="varname">tkey-domain</code>.  Otherwise, the
2268                 name of the shared key will be <code class="varname">random hex
2269                 digits</code> + <code class="varname">tkey-domain</code>.
2270                 In most cases, the <span><strong class="command">domainname</strong></span>
2271                 should be the server's domain name, or an otherwise
2272                 non-existent subdomain like
2273                 "_tkey.<code class="varname">domainname</code>".  If you are
2274                 using GSS-TSIG, this variable must be defined.
2275               </p></dd>
2276 <dt><span class="term"><span><strong class="command">tkey-dhkey</strong></span></span></dt>
2277 <dd><p>
2278                 The Diffie-Hellman key used by the server
2279                 to generate shared keys with clients using the Diffie-Hellman
2280                 mode
2281                 of <span><strong class="command">TKEY</strong></span>. The server must be
2282                 able to load the
2283                 public and private keys from files in the working directory.
2284                 In
2285                 most cases, the keyname should be the server's host name.
2286               </p></dd>
2287 <dt><span class="term"><span><strong class="command">cache-file</strong></span></span></dt>
2288 <dd><p>
2289                 This is for testing only.  Do not use.
2290               </p></dd>
2291 <dt><span class="term"><span><strong class="command">dump-file</strong></span></span></dt>
2292 <dd><p>
2293                 The pathname of the file the server dumps
2294                 the database to when instructed to do so with
2295                 <span><strong class="command">rndc dumpdb</strong></span>.
2296                 If not specified, the default is <code class="filename">named_dump.db</code>.
2297               </p></dd>
2298 <dt><span class="term"><span><strong class="command">memstatistics-file</strong></span></span></dt>
2299 <dd><p>
2300                 The pathname of the file the server writes memory
2301                 usage statistics to on exit. If not specified,
2302                 the default is <code class="filename">named.memstats</code>.
2303               </p></dd>
2304 <dt><span class="term"><span><strong class="command">pid-file</strong></span></span></dt>
2305 <dd><p>
2306                 The pathname of the file the server writes its process ID
2307                 in. If not specified, the default is
2308                 <code class="filename">/var/run/named/named.pid</code>.
2309                 The PID file is used by programs that want to send signals to
2310                 the running
2311                 name server. Specifying <span><strong class="command">pid-file none</strong></span> disables the
2312                 use of a PID file &#8212; no file will be written and any
2313                 existing one will be removed.  Note that <span><strong class="command">none</strong></span>
2314                 is a keyword, not a filename, and therefore is not enclosed
2315                 in
2316                 double quotes.
2317               </p></dd>
2318 <dt><span class="term"><span><strong class="command">recursing-file</strong></span></span></dt>
2319 <dd><p>
2320                 The pathname of the file the server dumps
2321                 the queries that are currently recursing when instructed
2322                 to do so with <span><strong class="command">rndc recursing</strong></span>.
2323                 If not specified, the default is <code class="filename">named.recursing</code>.
2324               </p></dd>
2325 <dt><span class="term"><span><strong class="command">statistics-file</strong></span></span></dt>
2326 <dd><p>
2327                 The pathname of the file the server appends statistics
2328                 to when instructed to do so using <span><strong class="command">rndc stats</strong></span>.
2329                 If not specified, the default is <code class="filename">named.stats</code> in the
2330                 server's current directory.  The format of the file is
2331                 described
2332                 in <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called &#8220;The Statistics File&#8221;</a>.
2333               </p></dd>
2334 <dt><span class="term"><span><strong class="command">port</strong></span></span></dt>
2335 <dd><p>
2336                 The UDP/TCP port number the server uses for
2337                 receiving and sending DNS protocol traffic.
2338                 The default is 53.  This option is mainly intended for server
2339                 testing;
2340                 a server using a port other than 53 will not be able to
2341                 communicate with
2342                 the global DNS.
2343               </p></dd>
2344 <dt><span class="term"><span><strong class="command">random-device</strong></span></span></dt>
2345 <dd><p>
2346                 The source of entropy to be used by the server.  Entropy is
2347                 primarily needed
2348                 for DNSSEC operations, such as TKEY transactions and dynamic
2349                 update of signed
2350                 zones.  This options specifies the device (or file) from which
2351                 to read
2352                 entropy.  If this is a file, operations requiring entropy will
2353                 fail when the
2354                 file has been exhausted.  If not specified, the default value
2355                 is
2356                 <code class="filename">/dev/random</code>
2357                 (or equivalent) when present, and none otherwise.  The
2358                 <span><strong class="command">random-device</strong></span> option takes
2359                 effect during
2360                 the initial configuration load at server startup time and
2361                 is ignored on subsequent reloads.
2362               </p></dd>
2363 <dt><span class="term"><span><strong class="command">preferred-glue</strong></span></span></dt>
2364 <dd><p>
2365                 If specified, the listed type (A or AAAA) will be emitted
2366                 before other glue
2367                 in the additional section of a query response.
2368                 The default is not to prefer any type (NONE).
2369               </p></dd>
2370 <dt>
2371 <a name="root_delegation_only"></a><span class="term"><span><strong class="command">root-delegation-only</strong></span></span>
2372 </dt>
2373 <dd>
2374 <p>
2375                 Turn on enforcement of delegation-only in TLDs
2376                 (top level domains) and root zones with an optional
2377                 exclude list.
2378               </p>
2379 <p>
2380                 DS queries are expected to be made to and be answered by
2381                 delegation only zones.  Such queries and responses are
2382                 treated as a exception to delegation-only processing
2383                 and are not converted to NXDOMAIN responses provided
2384                 a CNAME is not discovered at the query name.
2385               </p>
2386 <p>
2387                 If a delegation only zone server also serves a child
2388                 zone it is not always possible to determine whether
2389                 a answer comes from the delegation only zone or the
2390                 child zone.  SOA NS and DNSKEY records are apex
2391                 only records and a matching response that contains
2392                 these records or DS is treated as coming from a
2393                 child zone.  RRSIG records are also examined to see
2394                 if they are signed by a child zone or not.  The
2395                 authority section is also examined to see if there
2396                 is evidence that the answer is from the child zone.
2397                 Answers that are determined to be from a child zone
2398                 are not converted to NXDOMAIN responses.  Despite
2399                 all these checks there is still a possibility of
2400                 false negatives when a child zone is being served.
2401               </p>
2402 <p>
2403                 Similarly false positives can arise from empty nodes
2404                 (no records at the name) in the delegation only zone
2405                 when the query type is not ANY.
2406               </p>
2407 <p>
2408                 Note some TLDs are not delegation only (e.g. "DE", "LV",
2409                 "US" and "MUSEUM").  This list is not exhaustive.
2410               </p>
2411 <pre class="programlisting">
2412 options {
2413         root-delegation-only exclude { "de"; "lv"; "us"; "museum"; };
2414 };
2415 </pre>
2416 </dd>
2417 <dt><span class="term"><span><strong class="command">disable-algorithms</strong></span></span></dt>
2418 <dd><p>
2419                 Disable the specified DNSSEC algorithms at and below the
2420                 specified name.
2421                 Multiple <span><strong class="command">disable-algorithms</strong></span>
2422                 statements are allowed.
2423                 Only the most specific will be applied.
2424               </p></dd>
2425 <dt><span class="term"><span><strong class="command">dnssec-lookaside</strong></span></span></dt>
2426 <dd><p>
2427                 When set, <span><strong class="command">dnssec-lookaside</strong></span>
2428                 provides the
2429                 validator with an alternate method to validate DNSKEY records
2430                 at the
2431                 top of a zone.  When a DNSKEY is at or below a domain
2432                 specified by the
2433                 deepest <span><strong class="command">dnssec-lookaside</strong></span>, and
2434                 the normal DNSSEC validation
2435                 has left the key untrusted, the trust-anchor will be append to
2436                 the key
2437                 name and a DLV record will be looked up to see if it can
2438                 validate the
2439                 key.  If the DLV record validates a DNSKEY (similarly to the
2440                 way a DS
2441                 record does) the DNSKEY RRset is deemed to be trusted.
2442               </p></dd>
2443 <dt><span class="term"><span><strong class="command">dnssec-must-be-secure</strong></span></span></dt>
2444 <dd><p>
2445                 Specify hierarchies which must be or may not be secure (signed and
2446                 validated).
2447                 If <strong class="userinput"><code>yes</code></strong>, then <span><strong class="command">named</strong></span> will only accept
2448                 answers if they
2449                 are secure.
2450                 If <strong class="userinput"><code>no</code></strong>, then normal DNSSEC validation
2451                 applies
2452                 allowing for insecure answers to be accepted.
2453                 The specified domain must be under a <span><strong class="command">trusted-key</strong></span> or
2454                 <span><strong class="command">dnssec-lookaside</strong></span> must be
2455                 active.
2456               </p></dd>
2457 </dl></div>
2458 <div class="sect3" lang="en">
2459 <div class="titlepage"><div><div><h4 class="title">
2460 <a name="boolean_options"></a>Boolean Options</h4></div></div></div>
2461 <div class="variablelist"><dl>
2462 <dt><span class="term"><span><strong class="command">auth-nxdomain</strong></span></span></dt>
2463 <dd><p>
2464                   If <strong class="userinput"><code>yes</code></strong>, then the <span><strong class="command">AA</strong></span> bit
2465                   is always set on NXDOMAIN responses, even if the server is
2466                   not actually
2467                   authoritative. The default is <strong class="userinput"><code>no</code></strong>;
2468                   this is
2469                   a change from <acronym class="acronym">BIND</acronym> 8. If you
2470                   are using very old DNS software, you
2471                   may need to set it to <strong class="userinput"><code>yes</code></strong>.
2472                 </p></dd>
2473 <dt><span class="term"><span><strong class="command">deallocate-on-exit</strong></span></span></dt>
2474 <dd><p>
2475                   This option was used in <acronym class="acronym">BIND</acronym>
2476                   8 to enable checking
2477                   for memory leaks on exit. <acronym class="acronym">BIND</acronym> 9 ignores the option and always performs
2478                   the checks.
2479                 </p></dd>
2480 <dt><span class="term"><span><strong class="command">memstatistics</strong></span></span></dt>
2481 <dd><p>
2482                   Write memory statistics to the file specified by
2483                   <span><strong class="command">memstatistics-file</strong></span> at exit.
2484                   The default is <strong class="userinput"><code>no</code></strong> unless
2485                   '-m record' is specified on the command line in
2486                   which case it is <strong class="userinput"><code>yes</code></strong>.
2487                 </p></dd>
2488 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
2489 <dd>
2490 <p>
2491                   If <strong class="userinput"><code>yes</code></strong>, then the
2492                   server treats all zones as if they are doing zone transfers
2493                   across
2494                   a dial-on-demand dialup link, which can be brought up by
2495                   traffic
2496                   originating from this server. This has different effects
2497                   according
2498                   to zone type and concentrates the zone maintenance so that
2499                   it all
2500                   happens in a short interval, once every <span><strong class="command">heartbeat-interval</strong></span> and
2501                   hopefully during the one call. It also suppresses some of
2502                   the normal
2503                   zone maintenance traffic. The default is <strong class="userinput"><code>no</code></strong>.
2504                 </p>
2505 <p>
2506                   The <span><strong class="command">dialup</strong></span> option
2507                   may also be specified in the <span><strong class="command">view</strong></span> and
2508                   <span><strong class="command">zone</strong></span> statements,
2509                   in which case it overrides the global <span><strong class="command">dialup</strong></span>
2510                   option.
2511                 </p>
2512 <p>
2513                   If the zone is a master zone, then the server will send out a
2514                   NOTIFY
2515                   request to all the slaves (default). This should trigger the
2516                   zone serial
2517                   number check in the slave (providing it supports NOTIFY)
2518                   allowing the slave
2519                   to verify the zone while the connection is active.
2520                   The set of servers to which NOTIFY is sent can be controlled
2521                   by
2522                   <span><strong class="command">notify</strong></span> and <span><strong class="command">also-notify</strong></span>.
2523                 </p>
2524 <p>
2525                   If the
2526                   zone is a slave or stub zone, then the server will suppress
2527                   the regular
2528                   "zone up to date" (refresh) queries and only perform them
2529                   when the
2530                   <span><strong class="command">heartbeat-interval</strong></span> expires in
2531                   addition to sending
2532                   NOTIFY requests.
2533                 </p>
2534 <p>
2535                   Finer control can be achieved by using
2536                   <strong class="userinput"><code>notify</code></strong> which only sends NOTIFY
2537                   messages,
2538                   <strong class="userinput"><code>notify-passive</code></strong> which sends NOTIFY
2539                   messages and
2540                   suppresses the normal refresh queries, <strong class="userinput"><code>refresh</code></strong>
2541                   which suppresses normal refresh processing and sends refresh
2542                   queries
2543                   when the <span><strong class="command">heartbeat-interval</strong></span>
2544                   expires, and
2545                   <strong class="userinput"><code>passive</code></strong> which just disables normal
2546                   refresh
2547                   processing.
2548                 </p>
2549 <div class="informaltable"><table border="1">
2550 <colgroup>
2551 <col>
2552 <col>
2553 <col>
2554 <col>
2555 </colgroup>
2556 <tbody>
2557 <tr>
2558 <td>
2559                           <p>
2560                             dialup mode
2561                           </p>
2562                         </td>
2563 <td>
2564                           <p>
2565                             normal refresh
2566                           </p>
2567                         </td>
2568 <td>
2569                           <p>
2570                             heart-beat refresh
2571                           </p>
2572                         </td>
2573 <td>
2574                           <p>
2575                             heart-beat notify
2576                           </p>
2577                         </td>
2578 </tr>
2579 <tr>
2580 <td>
2581                           <p><span><strong class="command">no</strong></span> (default)</p>
2582                         </td>
2583 <td>
2584                           <p>
2585                             yes
2586                           </p>
2587                         </td>
2588 <td>
2589                           <p>
2590                             no
2591                           </p>
2592                         </td>
2593 <td>
2594                           <p>
2595                             no
2596                           </p>
2597                         </td>
2598 </tr>
2599 <tr>
2600 <td>
2601                           <p><span><strong class="command">yes</strong></span></p>
2602                         </td>
2603 <td>
2604                           <p>
2605                             no
2606                           </p>
2607                         </td>
2608 <td>
2609                           <p>
2610                             yes
2611                           </p>
2612                         </td>
2613 <td>
2614                           <p>
2615                             yes
2616                           </p>
2617                         </td>
2618 </tr>
2619 <tr>
2620 <td>
2621                           <p><span><strong class="command">notify</strong></span></p>
2622                         </td>
2623 <td>
2624                           <p>
2625                             yes
2626                           </p>
2627                         </td>
2628 <td>
2629                           <p>
2630                             no
2631                           </p>
2632                         </td>
2633 <td>
2634                           <p>
2635                             yes
2636                           </p>
2637                         </td>
2638 </tr>
2639 <tr>
2640 <td>
2641                           <p><span><strong class="command">refresh</strong></span></p>
2642                         </td>
2643 <td>
2644                           <p>
2645                             no
2646                           </p>
2647                         </td>
2648 <td>
2649                           <p>
2650                             yes
2651                           </p>
2652                         </td>
2653 <td>
2654                           <p>
2655                             no
2656                           </p>
2657                         </td>
2658 </tr>
2659 <tr>
2660 <td>
2661                           <p><span><strong class="command">passive</strong></span></p>
2662                         </td>
2663 <td>
2664                           <p>
2665                             no
2666                           </p>
2667                         </td>
2668 <td>
2669                           <p>
2670                             no
2671                           </p>
2672                         </td>
2673 <td>
2674                           <p>
2675                             no
2676                           </p>
2677                         </td>
2678 </tr>
2679 <tr>
2680 <td>
2681                           <p><span><strong class="command">notify-passive</strong></span></p>
2682                         </td>
2683 <td>
2684                           <p>
2685                             no
2686                           </p>
2687                         </td>
2688 <td>
2689                           <p>
2690                             no
2691                           </p>
2692                         </td>
2693 <td>
2694                           <p>
2695                             yes
2696                           </p>
2697                         </td>
2698 </tr>
2699 </tbody>
2700 </table></div>
2701 <p>
2702                   Note that normal NOTIFY processing is not affected by
2703                   <span><strong class="command">dialup</strong></span>.
2704                 </p>
2705 </dd>
2706 <dt><span class="term"><span><strong class="command">fake-iquery</strong></span></span></dt>
2707 <dd><p>
2708                   In <acronym class="acronym">BIND</acronym> 8, this option
2709                   enabled simulating the obsolete DNS query type
2710                   IQUERY. <acronym class="acronym">BIND</acronym> 9 never does
2711                   IQUERY simulation.
2712                 </p></dd>
2713 <dt><span class="term"><span><strong class="command">fetch-glue</strong></span></span></dt>
2714 <dd><p>
2715                   This option is obsolete.
2716                   In BIND 8, <strong class="userinput"><code>fetch-glue yes</code></strong>
2717                   caused the server to attempt to fetch glue resource records
2718                   it
2719                   didn't have when constructing the additional
2720                   data section of a response.  This is now considered a bad
2721                   idea
2722                   and BIND 9 never does it.
2723                 </p></dd>
2724 <dt><span class="term"><span><strong class="command">flush-zones-on-shutdown</strong></span></span></dt>
2725 <dd><p>
2726                   When the nameserver exits due receiving SIGTERM,
2727                   flush or do not flush any pending zone writes.  The default
2728                   is
2729                   <span><strong class="command">flush-zones-on-shutdown</strong></span> <strong class="userinput"><code>no</code></strong>.
2730                 </p></dd>
2731 <dt><span class="term"><span><strong class="command">has-old-clients</strong></span></span></dt>
2732 <dd><p>
2733                   This option was incorrectly implemented
2734                   in <acronym class="acronym">BIND</acronym> 8, and is ignored by <acronym class="acronym">BIND</acronym> 9.
2735                   To achieve the intended effect
2736                   of
2737                   <span><strong class="command">has-old-clients</strong></span> <strong class="userinput"><code>yes</code></strong>, specify
2738                   the two separate options <span><strong class="command">auth-nxdomain</strong></span> <strong class="userinput"><code>yes</code></strong>
2739                   and <span><strong class="command">rfc2308-type1</strong></span> <strong class="userinput"><code>no</code></strong> instead.
2740                 </p></dd>
2741 <dt><span class="term"><span><strong class="command">host-statistics</strong></span></span></dt>
2742 <dd><p>
2743                   In BIND 8, this enables keeping of
2744                   statistics for every host that the name server interacts
2745                   with.
2746                   Not implemented in BIND 9.
2747                 </p></dd>
2748 <dt><span class="term"><span><strong class="command">maintain-ixfr-base</strong></span></span></dt>
2749 <dd><p>
2750                   <span class="emphasis"><em>This option is obsolete</em></span>.
2751                   It was used in <acronym class="acronym">BIND</acronym> 8 to
2752                   determine whether a transaction log was
2753                   kept for Incremental Zone Transfer. <acronym class="acronym">BIND</acronym> 9 maintains a transaction
2754                   log whenever possible.  If you need to disable outgoing
2755                   incremental zone
2756                   transfers, use <span><strong class="command">provide-ixfr</strong></span> <strong class="userinput"><code>no</code></strong>.
2757                 </p></dd>
2758 <dt><span class="term"><span><strong class="command">minimal-responses</strong></span></span></dt>
2759 <dd><p>
2760                   If <strong class="userinput"><code>yes</code></strong>, then when generating
2761                   responses the server will only add records to the authority
2762                   and additional data sections when they are required (e.g.
2763                   delegations, negative responses).  This may improve the
2764                   performance of the server.
2765                   The default is <strong class="userinput"><code>no</code></strong>.
2766                 </p></dd>
2767 <dt><span class="term"><span><strong class="command">multiple-cnames</strong></span></span></dt>
2768 <dd><p>
2769                   This option was used in <acronym class="acronym">BIND</acronym> 8 to allow
2770                   a domain name to have multiple CNAME records in violation of
2771                   the DNS standards.  <acronym class="acronym">BIND</acronym> 9.2 onwards
2772                   always strictly enforces the CNAME rules both in master
2773                   files and dynamic updates.
2774                 </p></dd>
2775 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
2776 <dd>
2777 <p>
2778                   If <strong class="userinput"><code>yes</code></strong> (the default),
2779                   DNS NOTIFY messages are sent when a zone the server is
2780                   authoritative for
2781                   changes, see <a href="Bv9ARM.ch04.html#notify" title="Notify">the section called &#8220;Notify&#8221;</a>.  The messages are
2782                   sent to the
2783                   servers listed in the zone's NS records (except the master
2784                   server identified
2785                   in the SOA MNAME field), and to any servers listed in the
2786                   <span><strong class="command">also-notify</strong></span> option.
2787                 </p>
2788 <p>
2789                   If <strong class="userinput"><code>master-only</code></strong>, notifies are only
2790                   sent
2791                   for master zones.
2792                   If <strong class="userinput"><code>explicit</code></strong>, notifies are sent only
2793                   to
2794                   servers explicitly listed using <span><strong class="command">also-notify</strong></span>.
2795                   If <strong class="userinput"><code>no</code></strong>, no notifies are sent.
2796                 </p>
2797 <p>
2798                   The <span><strong class="command">notify</strong></span> option may also be
2799                   specified in the <span><strong class="command">zone</strong></span>
2800                   statement,
2801                   in which case it overrides the <span><strong class="command">options notify</strong></span> statement.
2802                   It would only be necessary to turn off this option if it
2803                   caused slaves
2804                   to crash.
2805                 </p>
2806 </dd>
2807 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
2808 <dd><p>
2809                   If <strong class="userinput"><code>yes</code></strong> do not check the nameservers
2810                   in the NS RRset against the SOA MNAME.  Normally a NOTIFY
2811                   message is not sent to the SOA MNAME (SOA ORIGIN) as it is
2812                   supposed to contain the name of the ultimate master.
2813                   Sometimes, however, a slave is listed as the SOA MNAME in
2814                   hidden master configurations and in that case you would
2815                   want the ultimate master to still send NOTIFY messages to
2816                   all the nameservers listed in the NS RRset.
2817                 </p></dd>
2818 <dt><span class="term"><span><strong class="command">recursion</strong></span></span></dt>
2819 <dd><p>
2820                   If <strong class="userinput"><code>yes</code></strong>, and a
2821                   DNS query requests recursion, then the server will attempt
2822                   to do
2823                   all the work required to answer the query. If recursion is
2824                   off
2825                   and the server does not already know the answer, it will
2826                   return a
2827                   referral response. The default is
2828                   <strong class="userinput"><code>yes</code></strong>.
2829                   Note that setting <span><strong class="command">recursion no</strong></span> does not prevent
2830                   clients from getting data from the server's cache; it only
2831                   prevents new data from being cached as an effect of client
2832                   queries.
2833                   Caching may still occur as an effect the server's internal
2834                   operation, such as NOTIFY address lookups.
2835                   See also <span><strong class="command">fetch-glue</strong></span> above.
2836                 </p></dd>
2837 <dt><span class="term"><span><strong class="command">rfc2308-type1</strong></span></span></dt>
2838 <dd>
2839 <p>
2840                   Setting this to <strong class="userinput"><code>yes</code></strong> will
2841                   cause the server to send NS records along with the SOA
2842                   record for negative
2843                   answers. The default is <strong class="userinput"><code>no</code></strong>.
2844                 </p>
2845 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
2846 <h3 class="title">Note</h3>
2847 <p>
2848                     Not yet implemented in <acronym class="acronym">BIND</acronym>
2849                     9.
2850                   </p>
2851 </div>
2852 </dd>
2853 <dt><span class="term"><span><strong class="command">use-id-pool</strong></span></span></dt>
2854 <dd><p>
2855                   <span class="emphasis"><em>This option is obsolete</em></span>.
2856                   <acronym class="acronym">BIND</acronym> 9 always allocates query
2857                   IDs from a pool.
2858                 </p></dd>
2859 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
2860 <dd><p>
2861                   If <strong class="userinput"><code>yes</code></strong>, the server will collect
2862                   statistical data on all zones (unless specifically turned
2863                   off
2864                   on a per-zone basis by specifying <span><strong class="command">zone-statistics no</strong></span>
2865                   in the <span><strong class="command">zone</strong></span> statement).
2866                   These statistics may be accessed
2867                   using <span><strong class="command">rndc stats</strong></span>, which will
2868                   dump them to the file listed
2869                   in the <span><strong class="command">statistics-file</strong></span>.  See
2870                   also <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called &#8220;The Statistics File&#8221;</a>.
2871                 </p></dd>
2872 <dt><span class="term"><span><strong class="command">use-ixfr</strong></span></span></dt>
2873 <dd><p>
2874                   <span class="emphasis"><em>This option is obsolete</em></span>.
2875                   If you need to disable IXFR to a particular server or
2876                   servers, see
2877                   the information on the <span><strong class="command">provide-ixfr</strong></span> option
2878                   in <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
2879             Usage">the section called &#8220;<span><strong class="command">server</strong></span> Statement Definition and
2880             Usage&#8221;</a>.
2881                   See also
2882                   <a href="Bv9ARM.ch04.html#incremental_zone_transfers" title="Incremental Zone Transfers (IXFR)">the section called &#8220;Incremental Zone Transfers (IXFR)&#8221;</a>.
2883                 </p></dd>
2884 <dt><span class="term"><span><strong class="command">provide-ixfr</strong></span></span></dt>
2885 <dd><p>
2886                   See the description of
2887                   <span><strong class="command">provide-ixfr</strong></span> in
2888                   <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
2889             Usage">the section called &#8220;<span><strong class="command">server</strong></span> Statement Definition and
2890             Usage&#8221;</a>.
2891                 </p></dd>
2892 <dt><span class="term"><span><strong class="command">request-ixfr</strong></span></span></dt>
2893 <dd><p>
2894                   See the description of
2895                   <span><strong class="command">request-ixfr</strong></span> in
2896                   <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
2897             Usage">the section called &#8220;<span><strong class="command">server</strong></span> Statement Definition and
2898             Usage&#8221;</a>.
2899                 </p></dd>
2900 <dt><span class="term"><span><strong class="command">treat-cr-as-space</strong></span></span></dt>
2901 <dd><p>
2902                   This option was used in <acronym class="acronym">BIND</acronym>
2903                   8 to make
2904                   the server treat carriage return ("<span><strong class="command">\r</strong></span>") characters the same way
2905                   as a space or tab character,
2906                   to facilitate loading of zone files on a UNIX system that
2907                   were generated
2908                   on an NT or DOS machine. In <acronym class="acronym">BIND</acronym> 9, both UNIX "<span><strong class="command">\n</strong></span>"
2909                   and NT/DOS "<span><strong class="command">\r\n</strong></span>" newlines
2910                   are always accepted,
2911                   and the option is ignored.
2912                 </p></dd>
2913 <dt>
2914 <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>
2915 </dt>
2916 <dd>
2917 <p>
2918                   These options control the behavior of an authoritative
2919                   server when
2920                   answering queries which have additional data, or when
2921                   following CNAME
2922                   and DNAME chains.
2923                 </p>
2924 <p>
2925                   When both of these options are set to <strong class="userinput"><code>yes</code></strong>
2926                   (the default) and a
2927                   query is being answered from authoritative data (a zone
2928                   configured into the server), the additional data section of
2929                   the
2930                   reply will be filled in using data from other authoritative
2931                   zones
2932                   and from the cache.  In some situations this is undesirable,
2933                   such
2934                   as when there is concern over the correctness of the cache,
2935                   or
2936                   in servers where slave zones may be added and modified by
2937                   untrusted third parties.  Also, avoiding
2938                   the search for this additional data will speed up server
2939                   operations
2940                   at the possible expense of additional queries to resolve
2941                   what would
2942                   otherwise be provided in the additional section.
2943                 </p>
2944 <p>
2945                   For example, if a query asks for an MX record for host <code class="literal">foo.example.com</code>,
2946                   and the record found is "<code class="literal">MX 10 mail.example.net</code>", normally the address
2947                   records (A and AAAA) for <code class="literal">mail.example.net</code> will be provided as well,
2948                   if known, even though they are not in the example.com zone.
2949                   Setting these options to <span><strong class="command">no</strong></span>
2950                   disables this behavior and makes
2951                   the server only search for additional data in the zone it
2952                   answers from.
2953                 </p>
2954 <p>
2955                   These options are intended for use in authoritative-only
2956                   servers, or in authoritative-only views.  Attempts to set
2957                   them to <span><strong class="command">no</strong></span> without also
2958                   specifying
2959                   <span><strong class="command">recursion no</strong></span> will cause the
2960                   server to
2961                   ignore the options and log a warning message.
2962                 </p>
2963 <p>
2964                   Specifying <span><strong class="command">additional-from-cache no</strong></span> actually
2965                   disables the use of the cache not only for additional data
2966                   lookups
2967                   but also when looking up the answer.  This is usually the
2968                   desired
2969                   behavior in an authoritative-only server where the
2970                   correctness of
2971                   the cached data is an issue.
2972                 </p>
2973 <p>
2974                   When a name server is non-recursively queried for a name
2975                   that is not
2976                   below the apex of any served zone, it normally answers with
2977                   an
2978                   "upwards referral" to the root servers or the servers of
2979                   some other
2980                   known parent of the query name.  Since the data in an
2981                   upwards referral
2982                   comes from the cache, the server will not be able to provide
2983                   upwards
2984                   referrals when <span><strong class="command">additional-from-cache no</strong></span>
2985                   has been specified.  Instead, it will respond to such
2986                   queries
2987                   with REFUSED.  This should not cause any problems since
2988                   upwards referrals are not required for the resolution
2989                   process.
2990                 </p>
2991 </dd>
2992 <dt><span class="term"><span><strong class="command">match-mapped-addresses</strong></span></span></dt>
2993 <dd>
2994 <p>
2995                   If <strong class="userinput"><code>yes</code></strong>, then an
2996                   IPv4-mapped IPv6 address will match any address match
2997                   list entries that match the corresponding IPv4 address.
2998                 </p>
2999 <p>
3000                   This option was introduced to work around a kernel quirk
3001                   in some operating systems that causes IPv4 TCP
3002                   connections, such as zone transfers, to be accepted on an
3003                   IPv6 socket using mapped addresses.  This caused address
3004                   match lists designed for IPv4 to fail to match.  However,
3005                   <span><strong class="command">named</strong></span> now solves this problem
3006                   internally.  The use of this option is discouraged.
3007                 </p>
3008 </dd>
3009 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
3010 <dd>
3011 <p>
3012                   When <strong class="userinput"><code>yes</code></strong> and the server loads a new version of a master
3013                   zone from its zone file or receives a new version of a slave
3014                   file by a non-incremental zone transfer, it will compare
3015                   the new version to the previous one and calculate a set
3016                   of differences.  The differences are then logged in the
3017                   zone's journal file such that the changes can be transmitted
3018                   to downstream slaves as an incremental zone transfer.
3019                 </p>
3020 <p>
3021                   By allowing incremental zone transfers to be used for
3022                   non-dynamic zones, this option saves bandwidth at the
3023                   expense of increased CPU and memory consumption at the
3024                   master.
3025                   In particular, if the new version of a zone is completely
3026                   different from the previous one, the set of differences
3027                   will be of a size comparable to the combined size of the
3028                   old and new zone version, and the server will need to
3029                   temporarily allocate memory to hold this complete
3030                   difference set.
3031                 </p>
3032 <p><span><strong class="command">ixfr-from-differences</strong></span>
3033                   also accepts <span><strong class="command">master</strong></span> and
3034                   <span><strong class="command">slave</strong></span> at the view and options
3035                   levels which causes
3036                   <span><strong class="command">ixfr-from-differences</strong></span> to be enabled for
3037                   all <span><strong class="command">master</strong></span> or
3038                   <span><strong class="command">slave</strong></span> zones respectively.
3039                   It is off by default.
3040                 </p>
3041 </dd>
3042 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
3043 <dd><p>
3044                   This should be set when you have multiple masters for a zone
3045                   and the
3046                   addresses refer to different machines.  If <strong class="userinput"><code>yes</code></strong>, <span><strong class="command">named</strong></span> will
3047                   not log
3048                   when the serial number on the master is less than what <span><strong class="command">named</strong></span>
3049                   currently
3050                   has.  The default is <strong class="userinput"><code>no</code></strong>.
3051                 </p></dd>
3052 <dt><span class="term"><span><strong class="command">dnssec-enable</strong></span></span></dt>
3053 <dd><p>
3054                   Enable DNSSEC support in <span><strong class="command">named</strong></span>.  Unless set to <strong class="userinput"><code>yes</code></strong>,
3055                   <span><strong class="command">named</strong></span> behaves as if it does not support DNSSEC.
3056                   The default is <strong class="userinput"><code>yes</code></strong>.
3057                 </p></dd>
3058 <dt><span class="term"><span><strong class="command">dnssec-validation</strong></span></span></dt>
3059 <dd><p>
3060                   Enable DNSSEC validation in <span><strong class="command">named</strong></span>.
3061                   Note <span><strong class="command">dnssec-enable</strong></span> also needs to be
3062                   set to <strong class="userinput"><code>yes</code></strong> to be effective.
3063                   The default is <strong class="userinput"><code>yes</code></strong>.
3064                 </p></dd>
3065 <dt><span class="term"><span><strong class="command">dnssec-accept-expired</strong></span></span></dt>
3066 <dd><p>
3067                   Accept expired signatures when verifying DNSSEC signatures.
3068                   The default is <strong class="userinput"><code>no</code></strong>.
3069                   Setting this option to "yes" leaves <span><strong class="command">named</strong></span> vulnerable to replay attacks.
3070                 </p></dd>
3071 <dt><span class="term"><span><strong class="command">querylog</strong></span></span></dt>
3072 <dd><p>
3073                   Specify whether query logging should be started when <span><strong class="command">named</strong></span>
3074                   starts.
3075                   If <span><strong class="command">querylog</strong></span> is not specified,
3076                   then the query logging
3077                   is determined by the presence of the logging category <span><strong class="command">queries</strong></span>.
3078                 </p></dd>
3079 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
3080 <dd>
3081 <p>
3082                   This option is used to restrict the character set and syntax
3083                   of
3084                   certain domain names in master files and/or DNS responses
3085                   received
3086                   from the network.  The default varies according to usage
3087                   area.  For
3088                   <span><strong class="command">master</strong></span> zones the default is <span><strong class="command">fail</strong></span>.
3089                   For <span><strong class="command">slave</strong></span> zones the default
3090                   is <span><strong class="command">warn</strong></span>.
3091                   For answers received from the network (<span><strong class="command">response</strong></span>)
3092                   the default is <span><strong class="command">ignore</strong></span>.
3093                 </p>
3094 <p>
3095                   The rules for legal hostnames and mail domains are derived
3096                   from RFC 952 and RFC 821 as modified by RFC 1123.
3097                 </p>
3098 <p><span><strong class="command">check-names</strong></span>
3099                   applies to the owner names of A, AAAA and MX records.
3100                   It also applies to the domain names in the RDATA of NS, SOA,
3101                   MX, and SRV records.
3102                   It also applies to the RDATA of PTR records where the owner
3103                   name indicated that it is a reverse lookup of a hostname
3104                   (the owner name ends in IN-ADDR.ARPA, IP6.ARPA, or IP6.INT).
3105                 </p>
3106 </dd>
3107 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
3108 <dd><p>
3109                   Check whether the MX record appears to refer to a IP address.
3110                   The default is to <span><strong class="command">warn</strong></span>.  Other possible
3111                   values are <span><strong class="command">fail</strong></span> and
3112                   <span><strong class="command">ignore</strong></span>.
3113                 </p></dd>
3114 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
3115 <dd><p>
3116                   This option is used to check for non-terminal wildcards.
3117                   The use of non-terminal wildcards is almost always as a
3118                   result of a failure
3119                   to understand the wildcard matching algorithm (RFC 1034).
3120                   This option
3121                   affects master zones.  The default (<span><strong class="command">yes</strong></span>) is to check
3122                   for non-terminal wildcards and issue a warning.
3123                 </p></dd>
3124 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
3125 <dd><p>
3126                   Perform post load zone integrity checks on master
3127                   zones.  This checks that MX and SRV records refer
3128                   to address (A or AAAA) records and that glue
3129                   address records exist for delegated zones.  For
3130                   MX and SRV records only in-zone hostnames are
3131                   checked (for out-of-zone hostnames use
3132                   <span><strong class="command">named-checkzone</strong></span>).
3133                   For NS records only names below top of zone are
3134                   checked (for out-of-zone names and glue consistency
3135                   checks use <span><strong class="command">named-checkzone</strong></span>).
3136                   The default is <span><strong class="command">yes</strong></span>.
3137                 </p></dd>
3138 <dt><span class="term"><span><strong class="command">check-mx-cname</strong></span></span></dt>
3139 <dd><p>
3140                   If <span><strong class="command">check-integrity</strong></span> is set then
3141                   fail, warn or ignore MX records that refer
3142                   to CNAMES.  The default is to <span><strong class="command">warn</strong></span>.
3143                 </p></dd>
3144 <dt><span class="term"><span><strong class="command">check-srv-cname</strong></span></span></dt>
3145 <dd><p>
3146                   If <span><strong class="command">check-integrity</strong></span> is set then
3147                   fail, warn or ignore SRV records that refer
3148                   to CNAMES.  The default is to <span><strong class="command">warn</strong></span>.
3149                 </p></dd>
3150 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
3151 <dd><p>
3152                   When performing integrity checks, also check that
3153                   sibling glue exists.  The default is <span><strong class="command">yes</strong></span>.
3154                 </p></dd>
3155 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
3156 <dd><p>
3157                   When returning authoritative negative responses to
3158                   SOA queries set the TTL of the SOA record returned in
3159                   the authority section to zero.
3160                   The default is <span><strong class="command">yes</strong></span>.
3161                 </p></dd>
3162 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl-cache</strong></span></span></dt>
3163 <dd><p>
3164                   When caching a negative response to a SOA query
3165                   set the TTL to zero.
3166                   The default is <span><strong class="command">no</strong></span>.
3167                 </p></dd>
3168 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
3169 <dd><p>
3170                   When regenerating the RRSIGs following a UPDATE
3171                   request to a secure zone, check the KSK flag on
3172                   the DNSKEY RR to determine if this key should be
3173                   used to generate the RRSIG.  This flag is ignored
3174                   if there are not DNSKEY RRs both with and without
3175                   a KSK.
3176                   The default is <span><strong class="command">yes</strong></span>.
3177                 </p></dd>
3178 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
3179 <dd><p>
3180                   Try to refresh the zone using TCP if UDP queries fail.
3181                   For BIND 8 compatibility, the default is
3182                   <span><strong class="command">yes</strong></span>.
3183                 </p></dd>
3184 </dl></div>
3185 </div>
3186 <div class="sect3" lang="en">
3187 <div class="titlepage"><div><div><h4 class="title">
3188 <a name="id2581790"></a>Forwarding</h4></div></div></div>
3189 <p>
3190             The forwarding facility can be used to create a large site-wide
3191             cache on a few servers, reducing traffic over links to external
3192             name servers. It can also be used to allow queries by servers that
3193             do not have direct access to the Internet, but wish to look up
3194             exterior
3195             names anyway. Forwarding occurs only on those queries for which
3196             the server is not authoritative and does not have the answer in
3197             its cache.
3198           </p>
3199 <div class="variablelist"><dl>
3200 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
3201 <dd><p>
3202                   This option is only meaningful if the
3203                   forwarders list is not empty. A value of <code class="varname">first</code>,
3204                   the default, causes the server to query the forwarders
3205                   first &#8212; and
3206                   if that doesn't answer the question, the server will then
3207                   look for
3208                   the answer itself. If <code class="varname">only</code> is
3209                   specified, the
3210                   server will only query the forwarders.
3211                 </p></dd>
3212 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
3213 <dd><p>
3214                   Specifies the IP addresses to be used
3215                   for forwarding. The default is the empty list (no
3216                   forwarding).
3217                 </p></dd>
3218 </dl></div>
3219 <p>
3220             Forwarding can also be configured on a per-domain basis, allowing
3221             for the global forwarding options to be overridden in a variety
3222             of ways. You can set particular domains to use different
3223             forwarders,
3224             or have a different <span><strong class="command">forward only/first</strong></span> behavior,
3225             or not forward at all, see <a href="Bv9ARM.ch06.html#zone_statement_grammar" title="zone
3226             Statement Grammar">the section called &#8220;<span><strong class="command">zone</strong></span>
3227             Statement Grammar&#8221;</a>.
3228           </p>
3229 </div>
3230 <div class="sect3" lang="en">
3231 <div class="titlepage"><div><div><h4 class="title">
3232 <a name="id2581849"></a>Dual-stack Servers</h4></div></div></div>
3233 <p>
3234             Dual-stack servers are used as servers of last resort to work
3235             around
3236             problems in reachability due the lack of support for either IPv4
3237             or IPv6
3238             on the host machine.
3239           </p>
3240 <div class="variablelist"><dl>
3241 <dt><span class="term"><span><strong class="command">dual-stack-servers</strong></span></span></dt>
3242 <dd><p>
3243                   Specifies host names or addresses of machines with access to
3244                   both IPv4 and IPv6 transports. If a hostname is used, the
3245                   server must be able
3246                   to resolve the name using only the transport it has.  If the
3247                   machine is dual
3248                   stacked, then the <span><strong class="command">dual-stack-servers</strong></span> have no effect unless
3249                   access to a transport has been disabled on the command line
3250                   (e.g. <span><strong class="command">named -4</strong></span>).
3251                 </p></dd>
3252 </dl></div>
3253 </div>
3254 <div class="sect3" lang="en">
3255 <div class="titlepage"><div><div><h4 class="title">
3256 <a name="access_control"></a>Access Control</h4></div></div></div>
3257 <p>
3258             Access to the server can be restricted based on the IP address
3259             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
3260             details on how to specify IP address lists.
3261           </p>
3262 <div class="variablelist"><dl>
3263 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
3264 <dd><p>
3265                   Specifies which hosts are allowed to
3266                   notify this server, a slave, of zone changes in addition
3267                   to the zone masters.
3268                   <span><strong class="command">allow-notify</strong></span> may also be
3269                   specified in the
3270                   <span><strong class="command">zone</strong></span> statement, in which case
3271                   it overrides the
3272                   <span><strong class="command">options allow-notify</strong></span>
3273                   statement.  It is only meaningful
3274                   for a slave zone.  If not specified, the default is to
3275                   process notify messages
3276                   only from a zone's master.
3277                 </p></dd>
3278 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
3279 <dd>
3280 <p>
3281                   Specifies which hosts are allowed to ask ordinary
3282                   DNS questions. <span><strong class="command">allow-query</strong></span> may
3283                   also be specified in the <span><strong class="command">zone</strong></span>
3284                   statement, in which case it overrides the
3285                   <span><strong class="command">options allow-query</strong></span> statement.
3286                   If not specified, the default is to allow queries
3287                   from all hosts.
3288                 </p>
3289 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3290 <h3 class="title">Note</h3>
3291 <p>
3292                     <span><strong class="command">allow-query-cache</strong></span> is now
3293                     used to specify access to the cache.
3294                   </p>
3295 </div>
3296 </dd>
3297 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
3298 <dd>
3299 <p>
3300                   Specifies which local addresses can accept ordinary
3301                   DNS questions. This makes it possible, for instance,
3302                   to allow queries on internal-facing interfaces but
3303                   disallow them on external-facing ones, without
3304                   necessarily knowing the internal network's addresses.
3305                 </p>
3306 <p>
3307                   <span><strong class="command">allow-query-on</strong></span> may
3308                   also be specified in the <span><strong class="command">zone</strong></span>
3309                   statement, in which case it overrides the
3310                   <span><strong class="command">options allow-query-on</strong></span> statement.
3311                 </p>
3312 <p>
3313                   If not specified, the default is to allow queries
3314                   on all addresses.
3315                 </p>
3316 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3317 <h3 class="title">Note</h3>
3318 <p>
3319                     <span><strong class="command">allow-query-cache</strong></span> is
3320                     used to specify access to the cache.
3321                   </p>
3322 </div>
3323 </dd>
3324 <dt><span class="term"><span><strong class="command">allow-query-cache</strong></span></span></dt>
3325 <dd><p>
3326                   Specifies which hosts are allowed to get answers
3327                   from the cache.  If <span><strong class="command">allow-query-cache</strong></span>
3328                   is not set then <span><strong class="command">allow-recursion</strong></span>
3329                   is used if set, otherwise <span><strong class="command">allow-query</strong></span>
3330                   is used if set unless <span><strong class="command">recursion no;</strong></span> is
3331                   set in which case <span><strong class="command">none;</strong></span> is used,
3332                   otherwise the default (<span><strong class="command">localnets;</strong></span>
3333                   <span><strong class="command">localhost;</strong></span>) is used.
3334                 </p></dd>
3335 <dt><span class="term"><span><strong class="command">allow-query-cache-on</strong></span></span></dt>
3336 <dd><p>
3337                   Specifies which local addresses can give answers
3338                   from the cache.  If not specified, the default is
3339                   to allow cache queries on any address,
3340                   <span><strong class="command">localnets</strong></span> and
3341                   <span><strong class="command">localhost</strong></span>.
3342                 </p></dd>
3343 <dt><span class="term"><span><strong class="command">allow-recursion</strong></span></span></dt>
3344 <dd><p>
3345                   Specifies which hosts are allowed to make recursive
3346                   queries through this server. If
3347                   <span><strong class="command">allow-recursion</strong></span> is not set
3348                   then <span><strong class="command">allow-query-cache</strong></span> is
3349                   used if set, otherwise <span><strong class="command">allow-query</strong></span>
3350                   is used if set, otherwise the default
3351                   (<span><strong class="command">localnets;</strong></span>
3352                   <span><strong class="command">localhost;</strong></span>) is used.
3353                 </p></dd>
3354 <dt><span class="term"><span><strong class="command">allow-recursion-on</strong></span></span></dt>
3355 <dd><p>
3356                   Specifies which local addresses can accept recursive
3357                   queries.  If not specified, the default is to allow
3358                   recursive queries on all addresses.
3359                 </p></dd>
3360 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
3361 <dd><p>
3362                   Specifies which hosts are allowed to
3363                   submit Dynamic DNS updates for master zones. The default is
3364                   to deny
3365                   updates from all hosts.  Note that allowing updates based
3366                   on the requestor's IP address is insecure; see
3367                   <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called &#8220;Dynamic Update Security&#8221;</a> for details.
3368                 </p></dd>
3369 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
3370 <dd>
3371 <p>
3372                   Specifies which hosts are allowed to
3373                   submit Dynamic DNS updates to slave zones to be forwarded to
3374                   the
3375                   master.  The default is <strong class="userinput"><code>{ none; }</code></strong>,
3376                   which
3377                   means that no update forwarding will be performed.  To
3378                   enable
3379                   update forwarding, specify
3380                   <strong class="userinput"><code>allow-update-forwarding { any; };</code></strong>.
3381                   Specifying values other than <strong class="userinput"><code>{ none; }</code></strong> or
3382                   <strong class="userinput"><code>{ any; }</code></strong> is usually
3383                   counterproductive, since
3384                   the responsibility for update access control should rest
3385                   with the
3386                   master server, not the slaves.
3387                 </p>
3388 <p>
3389                   Note that enabling the update forwarding feature on a slave
3390                   server
3391                   may expose master servers relying on insecure IP address
3392                   based
3393                   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>
3394                   for more details.
3395                 </p>
3396 </dd>
3397 <dt><span class="term"><span><strong class="command">allow-v6-synthesis</strong></span></span></dt>
3398 <dd><p>
3399                   This option was introduced for the smooth transition from
3400                   AAAA
3401                   to A6 and from "nibble labels" to binary labels.
3402                   However, since both A6 and binary labels were then
3403                   deprecated,
3404                   this option was also deprecated.
3405                   It is now ignored with some warning messages.
3406                 </p></dd>
3407 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
3408 <dd><p>
3409                   Specifies which hosts are allowed to
3410                   receive zone transfers from the server. <span><strong class="command">allow-transfer</strong></span> may
3411                   also be specified in the <span><strong class="command">zone</strong></span>
3412                   statement, in which
3413                   case it overrides the <span><strong class="command">options allow-transfer</strong></span> statement.
3414                   If not specified, the default is to allow transfers to all
3415                   hosts.
3416                 </p></dd>
3417 <dt><span class="term"><span><strong class="command">blackhole</strong></span></span></dt>
3418 <dd><p>
3419                   Specifies a list of addresses that the
3420                   server will not accept queries from or use to resolve a
3421                   query. Queries
3422                   from these addresses will not be responded to. The default
3423                   is <strong class="userinput"><code>none</code></strong>.
3424                 </p></dd>
3425 </dl></div>
3426 </div>
3427 <div class="sect3" lang="en">
3428 <div class="titlepage"><div><div><h4 class="title">
3429 <a name="id2582355"></a>Interfaces</h4></div></div></div>
3430 <p>
3431             The interfaces and ports that the server will answer queries
3432             from may be specified using the <span><strong class="command">listen-on</strong></span> option. <span><strong class="command">listen-on</strong></span> takes
3433             an optional port and an <code class="varname">address_match_list</code>.
3434             The server will listen on all interfaces allowed by the address
3435             match list. If a port is not specified, port 53 will be used.
3436           </p>
3437 <p>
3438             Multiple <span><strong class="command">listen-on</strong></span> statements are
3439             allowed.
3440             For example,
3441           </p>
3442 <pre class="programlisting">listen-on { 5.6.7.8; };
3443 listen-on port 1234 { !1.2.3.4; 1.2/16; };
3444 </pre>
3445 <p>
3446             will enable the name server on port 53 for the IP address
3447             5.6.7.8, and on port 1234 of an address on the machine in net
3448             1.2 that is not 1.2.3.4.
3449           </p>
3450 <p>
3451             If no <span><strong class="command">listen-on</strong></span> is specified, the
3452             server will listen on port 53 on all IPv4 interfaces.
3453           </p>
3454 <p>
3455             The <span><strong class="command">listen-on-v6</strong></span> option is used to
3456             specify the interfaces and the ports on which the server will
3457             listen
3458             for incoming queries sent using IPv6.
3459           </p>
3460 <p>
3461             When </p>
3462 <pre class="programlisting">{ any; }</pre>
3463 <p> is
3464             specified
3465             as the <code class="varname">address_match_list</code> for the
3466             <span><strong class="command">listen-on-v6</strong></span> option,
3467             the server does not bind a separate socket to each IPv6 interface
3468             address as it does for IPv4 if the operating system has enough API
3469             support for IPv6 (specifically if it conforms to RFC 3493 and RFC
3470             3542).
3471             Instead, it listens on the IPv6 wildcard address.
3472             If the system only has incomplete API support for IPv6, however,
3473             the behavior is the same as that for IPv4.
3474           </p>
3475 <p>
3476             A list of particular IPv6 addresses can also be specified, in
3477             which case
3478             the server listens on a separate socket for each specified
3479             address,
3480             regardless of whether the desired API is supported by the system.
3481           </p>
3482 <p>
3483             Multiple <span><strong class="command">listen-on-v6</strong></span> options can
3484             be used.
3485             For example,
3486           </p>
3487 <pre class="programlisting">listen-on-v6 { any; };
3488 listen-on-v6 port 1234 { !2001:db8::/32; any; };
3489 </pre>
3490 <p>
3491             will enable the name server on port 53 for any IPv6 addresses
3492             (with a single wildcard socket),
3493             and on port 1234 of IPv6 addresses that is not in the prefix
3494             2001:db8::/32 (with separate sockets for each matched address.)
3495           </p>
3496 <p>
3497             To make the server not listen on any IPv6 address, use
3498           </p>
3499 <pre class="programlisting">listen-on-v6 { none; };
3500 </pre>
3501 <p>
3502             If no <span><strong class="command">listen-on-v6</strong></span> option is
3503             specified, the server will not listen on any IPv6 address
3504             unless <span><strong class="command">-6</strong></span> is specified when <span><strong class="command">named</strong></span> is
3505             invoked.  If <span><strong class="command">-6</strong></span> is specified then
3506             <span><strong class="command">named</strong></span> will listen on port 53 on all IPv6 interfaces by default.
3507           </p>
3508 </div>
3509 <div class="sect3" lang="en">
3510 <div class="titlepage"><div><div><h4 class="title">
3511 <a name="query_address"></a>Query Address</h4></div></div></div>
3512 <p>
3513             If the server doesn't know the answer to a question, it will
3514             query other name servers. <span><strong class="command">query-source</strong></span> specifies
3515             the address and port used for such queries. For queries sent over
3516             IPv6, there is a separate <span><strong class="command">query-source-v6</strong></span> option.
3517             If <span><strong class="command">address</strong></span> is <span><strong class="command">*</strong></span> (asterisk) or is omitted,
3518             a wildcard IP address (<span><strong class="command">INADDR_ANY</strong></span>)
3519             will be used.
3520           </p>
3521 <p>
3522             If <span><strong class="command">port</strong></span> is <span><strong class="command">*</strong></span> or is omitted,
3523             a random port number from a pre-configured
3524             range is picked up and will be used for each query.
3525             The port range(s) is that specified in
3526             the <span><strong class="command">use-v4-udp-ports</strong></span> (for IPv4)
3527             and <span><strong class="command">use-v6-udp-ports</strong></span> (for IPv6)
3528             options, excluding the ranges specified in
3529             the <span><strong class="command">avoid-v4-udp-ports</strong></span>
3530             and <span><strong class="command">avoid-v6-udp-ports</strong></span> options, respectively.
3531           </p>
3532 <p>
3533             The defaults of the <span><strong class="command">query-source</strong></span> and
3534             <span><strong class="command">query-source-v6</strong></span> options
3535             are:
3536           </p>
3537 <pre class="programlisting">query-source address * port *;
3538 query-source-v6 address * port *;
3539 </pre>
3540 <p>
3541             If <span><strong class="command">use-v4-udp-ports</strong></span> or
3542             <span><strong class="command">use-v6-udp-ports</strong></span> is unspecified,
3543             <span><strong class="command">named</strong></span> will check if the operating
3544             system provides a programming interface to retrieve the
3545             system's default range for ephemeral ports.
3546             If such an interface is available,
3547             <span><strong class="command">named</strong></span> will use the corresponding system
3548             default range; otherwise, it will use its own defaults:
3549          </p>
3550 <pre class="programlisting">use-v4-udp-ports { range 1024 65535; };
3551 use-v6-udp-ports { range 1024 65535; };
3552 </pre>
3553 <p>
3554             Note: make sure the ranges be sufficiently large for
3555             security.  A desirable size depends on various parameters,
3556             but we generally recommend it contain at least 16384 ports
3557             (14 bits of entropy).
3558             Note also that the system's default range when used may be
3559             too small for this purpose, and that the range may even be
3560             changed while <span><strong class="command">named</strong></span> is running; the new
3561             range will automatically be applied when <span><strong class="command">named</strong></span>
3562             is reloaded.
3563             It is encouraged to
3564             configure <span><strong class="command">use-v4-udp-ports</strong></span> and
3565             <span><strong class="command">use-v6-udp-ports</strong></span> explicitly so that the
3566             ranges are sufficiently large and are reasonably
3567             independent from the ranges used by other applications.
3568           </p>
3569 <p>
3570             Note: the operational configuration
3571             where <span><strong class="command">named</strong></span> runs may prohibit the use
3572             of some ports.  For example, UNIX systems will not allow
3573             <span><strong class="command">named</strong></span> running without a root privilege
3574             to use ports less than 1024.
3575             If such ports are included in the specified (or detected)
3576             set of query ports, the corresponding query attempts will
3577             fail, resulting in resolution failures or delay.
3578             It is therefore important to configure the set of ports
3579             that can be safely used in the expected operational environment.
3580           </p>
3581 <p>
3582             The defaults of the <span><strong class="command">avoid-v4-udp-ports</strong></span> and
3583             <span><strong class="command">avoid-v6-udp-ports</strong></span> options
3584             are:
3585           </p>
3586 <pre class="programlisting">avoid-v4-udp-ports {};
3587 avoid-v6-udp-ports {};
3588 </pre>
3589 <p>
3590             Note: BIND 9.5.0 introduced
3591             the <span><strong class="command">use-queryport-pool</strong></span>
3592             option to support a pool of such random ports, but this
3593             option is now obsolete because reusing the same ports in
3594             the pool may not be sufficiently secure.
3595             For the same reason, it is generally strongly discouraged to
3596             specify a particular port for the
3597             <span><strong class="command">query-source</strong></span> or
3598             <span><strong class="command">query-source-v6</strong></span> options;
3599             it implicitly disables the use of randomized port numbers.
3600           </p>
3601 <div class="variablelist"><dl>
3602 <dt><span class="term"><span><strong class="command">use-queryport-pool</strong></span></span></dt>
3603 <dd><p>
3604                   This option is obsolete.
3605                 </p></dd>
3606 <dt><span class="term"><span><strong class="command">queryport-pool-ports</strong></span></span></dt>
3607 <dd><p>
3608                   This option is obsolete.
3609                 </p></dd>
3610 <dt><span class="term"><span><strong class="command">queryport-pool-updateinterval</strong></span></span></dt>
3611 <dd><p>
3612                   This option is obsolete.
3613                 </p></dd>
3614 </dl></div>
3615 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3616 <h3 class="title">Note</h3>
3617 <p>
3618               The address specified in the <span><strong class="command">query-source</strong></span> option
3619               is used for both UDP and TCP queries, but the port applies only
3620               to UDP queries.  TCP queries always use a random
3621               unprivileged port.
3622             </p>
3623 </div>
3624 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3625 <h3 class="title">Note</h3>
3626 <p>
3627               Solaris 2.5.1 and earlier does not support setting the source
3628               address for TCP sockets.
3629             </p>
3630 </div>
3631 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3632 <h3 class="title">Note</h3>
3633 <p>
3634               See also <span><strong class="command">transfer-source</strong></span> and
3635               <span><strong class="command">notify-source</strong></span>.
3636             </p>
3637 </div>
3638 </div>
3639 <div class="sect3" lang="en">
3640 <div class="titlepage"><div><div><h4 class="title">
3641 <a name="zone_transfers"></a>Zone Transfers</h4></div></div></div>
3642 <p>
3643             <acronym class="acronym">BIND</acronym> has mechanisms in place to
3644             facilitate zone transfers
3645             and set limits on the amount of load that transfers place on the
3646             system. The following options apply to zone transfers.
3647           </p>
3648 <div class="variablelist"><dl>
3649 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
3650 <dd><p>
3651                   Defines a global list of IP addresses of name servers
3652                   that are also sent NOTIFY messages whenever a fresh copy of
3653                   the
3654                   zone is loaded, in addition to the servers listed in the
3655                   zone's NS records.
3656                   This helps to ensure that copies of the zones will
3657                   quickly converge on stealth servers.
3658                   Optionally, a port may be specified with each
3659                   <span><strong class="command">also-notify</strong></span> address to send
3660                   the notify messages to a port other than the
3661                   default of 53.
3662                   If an <span><strong class="command">also-notify</strong></span> list
3663                   is given in a <span><strong class="command">zone</strong></span> statement,
3664                   it will override
3665                   the <span><strong class="command">options also-notify</strong></span>
3666                   statement. When a <span><strong class="command">zone notify</strong></span>
3667                   statement
3668                   is set to <span><strong class="command">no</strong></span>, the IP
3669                   addresses in the global <span><strong class="command">also-notify</strong></span> list will
3670                   not be sent NOTIFY messages for that zone. The default is
3671                   the empty
3672                   list (no global notification list).
3673                 </p></dd>
3674 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
3675 <dd><p>
3676                   Inbound zone transfers running longer than
3677                   this many minutes will be terminated. The default is 120
3678                   minutes
3679                   (2 hours).  The maximum value is 28 days (40320 minutes).
3680                 </p></dd>
3681 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
3682 <dd><p>
3683                   Inbound zone transfers making no progress
3684                   in this many minutes will be terminated. The default is 60
3685                   minutes
3686                   (1 hour).  The maximum value is 28 days (40320 minutes).
3687                 </p></dd>
3688 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
3689 <dd><p>
3690                   Outbound zone transfers running longer than
3691                   this many minutes will be terminated. The default is 120
3692                   minutes
3693                   (2 hours).  The maximum value is 28 days (40320 minutes).
3694                 </p></dd>
3695 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
3696 <dd><p>
3697                   Outbound zone transfers making no progress
3698                   in this many minutes will be terminated.  The default is 60
3699                   minutes (1
3700                   hour).  The maximum value is 28 days (40320 minutes).
3701                 </p></dd>
3702 <dt><span class="term"><span><strong class="command">serial-query-rate</strong></span></span></dt>
3703 <dd>
3704 <p>
3705                   Slave servers will periodically query master
3706                   servers to find out if zone serial numbers have
3707                   changed. Each such query uses a minute amount of
3708                   the slave server's network bandwidth.  To limit
3709                   the amount of bandwidth used, BIND 9 limits the
3710                   rate at which queries are sent.  The value of the
3711                   <span><strong class="command">serial-query-rate</strong></span> option, an
3712                   integer, is the maximum number of queries sent
3713                   per second.  The default is 20.
3714                 </p>
3715 <p>
3716                   In addition to controlling the rate SOA refresh
3717                   queries are issued at
3718                   <span><strong class="command">serial-query-rate</strong></span> also controls
3719                   the rate at which NOTIFY messages are sent from
3720                   both master and slave zones.
3721                 </p>
3722 </dd>
3723 <dt><span class="term"><span><strong class="command">serial-queries</strong></span></span></dt>
3724 <dd><p>
3725                   In BIND 8, the <span><strong class="command">serial-queries</strong></span>
3726                   option
3727                   set the maximum number of concurrent serial number queries
3728                   allowed to be outstanding at any given time.
3729                   BIND 9 does not limit the number of outstanding
3730                   serial queries and ignores the <span><strong class="command">serial-queries</strong></span> option.
3731                   Instead, it limits the rate at which the queries are sent
3732                   as defined using the <span><strong class="command">serial-query-rate</strong></span> option.
3733                 </p></dd>
3734 <dt><span class="term"><span><strong class="command">transfer-format</strong></span></span></dt>
3735 <dd><p>
3736                   Zone transfers can be sent using two different formats,
3737                   <span><strong class="command">one-answer</strong></span> and
3738                   <span><strong class="command">many-answers</strong></span>.
3739                   The <span><strong class="command">transfer-format</strong></span> option is used
3740                   on the master server to determine which format it sends.
3741                   <span><strong class="command">one-answer</strong></span> uses one DNS message per
3742                   resource record transferred.
3743                   <span><strong class="command">many-answers</strong></span> packs as many resource
3744                   records as possible into a message.
3745                   <span><strong class="command">many-answers</strong></span> is more efficient, but is
3746                   only supported by relatively new slave servers,
3747                   such as <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
3748                   8.x and <acronym class="acronym">BIND</acronym> 4.9.5 onwards.
3749                   The <span><strong class="command">many-answers</strong></span> format is also supported by
3750                   recent Microsoft Windows nameservers.
3751                   The default is <span><strong class="command">many-answers</strong></span>.
3752                   <span><strong class="command">transfer-format</strong></span> may be overridden on a
3753                   per-server basis by using the <span><strong class="command">server</strong></span>
3754                   statement.
3755                 </p></dd>
3756 <dt><span class="term"><span><strong class="command">transfers-in</strong></span></span></dt>
3757 <dd><p>
3758                   The maximum number of inbound zone transfers
3759                   that can be running concurrently. The default value is <code class="literal">10</code>.
3760                   Increasing <span><strong class="command">transfers-in</strong></span> may
3761                   speed up the convergence
3762                   of slave zones, but it also may increase the load on the
3763                   local system.
3764                 </p></dd>
3765 <dt><span class="term"><span><strong class="command">transfers-out</strong></span></span></dt>
3766 <dd><p>
3767                   The maximum number of outbound zone transfers
3768                   that can be running concurrently. Zone transfer requests in
3769                   excess
3770                   of the limit will be refused. The default value is <code class="literal">10</code>.
3771                 </p></dd>
3772 <dt><span class="term"><span><strong class="command">transfers-per-ns</strong></span></span></dt>
3773 <dd><p>
3774                   The maximum number of inbound zone transfers
3775                   that can be concurrently transferring from a given remote
3776                   name server.
3777                   The default value is <code class="literal">2</code>.
3778                   Increasing <span><strong class="command">transfers-per-ns</strong></span>
3779                   may
3780                   speed up the convergence of slave zones, but it also may
3781                   increase
3782                   the load on the remote name server. <span><strong class="command">transfers-per-ns</strong></span> may
3783                   be overridden on a per-server basis by using the <span><strong class="command">transfers</strong></span> phrase
3784                   of the <span><strong class="command">server</strong></span> statement.
3785                 </p></dd>
3786 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
3787 <dd>
3788 <p><span><strong class="command">transfer-source</strong></span>
3789                   determines which local address will be bound to IPv4
3790                   TCP connections used to fetch zones transferred
3791                   inbound by the server.  It also determines the
3792                   source IPv4 address, and optionally the UDP port,
3793                   used for the refresh queries and forwarded dynamic
3794                   updates.  If not set, it defaults to a system
3795                   controlled value which will usually be the address
3796                   of the interface "closest to" the remote end. This
3797                   address must appear in the remote end's
3798                   <span><strong class="command">allow-transfer</strong></span> option for the
3799                   zone being transferred, if one is specified. This
3800                   statement sets the
3801                   <span><strong class="command">transfer-source</strong></span> for all zones,
3802                   but can be overridden on a per-view or per-zone
3803                   basis by including a
3804                   <span><strong class="command">transfer-source</strong></span> statement within
3805                   the <span><strong class="command">view</strong></span> or
3806                   <span><strong class="command">zone</strong></span> block in the configuration
3807                   file.
3808                 </p>
3809 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3810 <h3 class="title">Note</h3>
3811 <p>
3812                     Solaris 2.5.1 and earlier does not support setting the
3813                     source address for TCP sockets.
3814                   </p>
3815 </div>
3816 </dd>
3817 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
3818 <dd><p>
3819                   The same as <span><strong class="command">transfer-source</strong></span>,
3820                   except zone transfers are performed using IPv6.
3821                 </p></dd>
3822 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
3823 <dd>
3824 <p>
3825                   An alternate transfer source if the one listed in
3826                   <span><strong class="command">transfer-source</strong></span> fails and
3827                   <span><strong class="command">use-alt-transfer-source</strong></span> is
3828                   set.
3829                 </p>
3830 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3831 <h3 class="title">Note</h3>
3832                   If you do not wish the alternate transfer source
3833                   to be used, you should set
3834                   <span><strong class="command">use-alt-transfer-source</strong></span>
3835                   appropriately and you should not depend upon
3836                   getting an answer back to the first refresh
3837                   query.
3838                 </div>
3839 </dd>
3840 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
3841 <dd><p>
3842                   An alternate transfer source if the one listed in
3843                   <span><strong class="command">transfer-source-v6</strong></span> fails and
3844                   <span><strong class="command">use-alt-transfer-source</strong></span> is
3845                   set.
3846                 </p></dd>
3847 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
3848 <dd><p>
3849                   Use the alternate transfer sources or not.  If views are
3850                   specified this defaults to <span><strong class="command">no</strong></span>
3851                   otherwise it defaults to
3852                   <span><strong class="command">yes</strong></span> (for BIND 8
3853                   compatibility).
3854                 </p></dd>
3855 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
3856 <dd>
3857 <p><span><strong class="command">notify-source</strong></span>
3858                   determines which local source address, and
3859                   optionally UDP port, will be used to send NOTIFY
3860                   messages.  This address must appear in the slave
3861                   server's <span><strong class="command">masters</strong></span> zone clause or
3862                   in an <span><strong class="command">allow-notify</strong></span> clause.  This
3863                   statement sets the <span><strong class="command">notify-source</strong></span>
3864                   for all zones, but can be overridden on a per-zone or
3865                   per-view basis by including a
3866                   <span><strong class="command">notify-source</strong></span> statement within
3867                   the <span><strong class="command">zone</strong></span> or
3868                   <span><strong class="command">view</strong></span> block in the configuration
3869                   file.
3870                 </p>
3871 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3872 <h3 class="title">Note</h3>
3873 <p>
3874                     Solaris 2.5.1 and earlier does not support setting the
3875                     source address for TCP sockets.
3876                   </p>
3877 </div>
3878 </dd>
3879 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
3880 <dd><p>
3881                   Like <span><strong class="command">notify-source</strong></span>,
3882                   but applies to notify messages sent to IPv6 addresses.
3883                 </p></dd>
3884 </dl></div>
3885 </div>
3886 <div class="sect3" lang="en">
3887 <div class="titlepage"><div><div><h4 class="title">
3888 <a name="id2583701"></a>UDP Port Lists</h4></div></div></div>
3889 <p>
3890             <span><strong class="command">use-v4-udp-ports</strong></span>,
3891             <span><strong class="command">avoid-v4-udp-ports</strong></span>,
3892             <span><strong class="command">use-v6-udp-ports</strong></span>, and
3893             <span><strong class="command">avoid-v6-udp-ports</strong></span>
3894             specify a list of IPv4 and IPv6 UDP ports that will be
3895             used or not used as source ports for UDP messages.
3896             See <a href="Bv9ARM.ch06.html#query_address" title="Query Address">the section called &#8220;Query Address&#8221;</a> about how the
3897             available ports are determined.
3898             For example, with the following configuration
3899           </p>
3900 <pre class="programlisting">
3901 use-v6-udp-ports { range 32768 65535; };
3902 avoid-v6-udp-ports { 40000; range 50000 60000; };
3903 </pre>
3904 <p>
3905              UDP ports of IPv6 messages sent
3906              from <span><strong class="command">named</strong></span> will be in one
3907              of the following ranges: 32768 to 39999, 40001 to 49999,
3908              and 60001 to 65535.
3909            </p>
3910 <p>
3911              <span><strong class="command">avoid-v4-udp-ports</strong></span> and
3912              <span><strong class="command">avoid-v6-udp-ports</strong></span> can be used
3913              to prevent <span><strong class="command">named</strong></span> from choosing as its random source port a
3914              port that is blocked by your firewall or a port that is
3915              used by other applications;
3916              if a query went out with a source port blocked by a
3917              firewall, the
3918              answer would not get by the firewall and the name server would
3919              have to query again.
3920              Note: the desired range can also be represented only with
3921              <span><strong class="command">use-v4-udp-ports</strong></span> and
3922              <span><strong class="command">use-v6-udp-ports</strong></span>, and the
3923              <span><strong class="command">avoid-</strong></span> options are redundant in that
3924              sense; they are provided for backward compatibility and
3925              to possibly simplify the port specification.
3926            </p>
3927 </div>
3928 <div class="sect3" lang="en">
3929 <div class="titlepage"><div><div><h4 class="title">
3930 <a name="id2583761"></a>Operating System Resource Limits</h4></div></div></div>
3931 <p>
3932             The server's usage of many system resources can be limited.
3933             Scaled values are allowed when specifying resource limits.  For
3934             example, <span><strong class="command">1G</strong></span> can be used instead of
3935             <span><strong class="command">1073741824</strong></span> to specify a limit of
3936             one
3937             gigabyte. <span><strong class="command">unlimited</strong></span> requests
3938             unlimited use, or the
3939             maximum available amount. <span><strong class="command">default</strong></span>
3940             uses the limit
3941             that was in force when the server was started. See the description
3942             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>.
3943           </p>
3944 <p>
3945             The following options set operating system resource limits for
3946             the name server process.  Some operating systems don't support
3947             some or
3948             any of the limits. On such systems, a warning will be issued if
3949             the
3950             unsupported limit is used.
3951           </p>
3952 <div class="variablelist"><dl>
3953 <dt><span class="term"><span><strong class="command">coresize</strong></span></span></dt>
3954 <dd><p>
3955                   The maximum size of a core dump. The default
3956                   is <code class="literal">default</code>.
3957                 </p></dd>
3958 <dt><span class="term"><span><strong class="command">datasize</strong></span></span></dt>
3959 <dd><p>
3960                   The maximum amount of data memory the server
3961                   may use. The default is <code class="literal">default</code>.
3962                   This is a hard limit on server memory usage.
3963                   If the server attempts to allocate memory in excess of this
3964                   limit, the allocation will fail, which may in turn leave
3965                   the server unable to perform DNS service.  Therefore,
3966                   this option is rarely useful as a way of limiting the
3967                   amount of memory used by the server, but it can be used
3968                   to raise an operating system data size limit that is
3969                   too small by default.  If you wish to limit the amount
3970                   of memory used by the server, use the
3971                   <span><strong class="command">max-cache-size</strong></span> and
3972                   <span><strong class="command">recursive-clients</strong></span>
3973                   options instead.
3974                 </p></dd>
3975 <dt><span class="term"><span><strong class="command">files</strong></span></span></dt>
3976 <dd><p>
3977                   The maximum number of files the server
3978                   may have open concurrently. The default is <code class="literal">unlimited</code>.
3979                 </p></dd>
3980 <dt><span class="term"><span><strong class="command">stacksize</strong></span></span></dt>
3981 <dd><p>
3982                   The maximum amount of stack memory the server
3983                   may use. The default is <code class="literal">default</code>.
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="server_resource_limits"></a>Server  Resource Limits</h4></div></div></div>
3990 <p>
3991             The following options set limits on the server's
3992             resource consumption that are enforced internally by the
3993             server rather than the operating system.
3994           </p>
3995 <div class="variablelist"><dl>
3996 <dt><span class="term"><span><strong class="command">max-ixfr-log-size</strong></span></span></dt>
3997 <dd><p>
3998                   This option is obsolete; it is accepted
3999                   and ignored for BIND 8 compatibility.  The option
4000                   <span><strong class="command">max-journal-size</strong></span> performs a
4001                   similar function in BIND 9.
4002                 </p></dd>
4003 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
4004 <dd><p>
4005                   Sets a maximum size for each journal file
4006                   (see <a href="Bv9ARM.ch04.html#journal" title="The journal file">the section called &#8220;The journal file&#8221;</a>).  When the journal file
4007                   approaches
4008                   the specified size, some of the oldest transactions in the
4009                   journal
4010                   will be automatically removed.  The default is
4011                   <code class="literal">unlimited</code>.
4012                   This may also be set on a per-zone basis.
4013                 </p></dd>
4014 <dt><span class="term"><span><strong class="command">host-statistics-max</strong></span></span></dt>
4015 <dd><p>
4016                   In BIND 8, specifies the maximum number of host statistics
4017                   entries to be kept.
4018                   Not implemented in BIND 9.
4019                 </p></dd>
4020 <dt><span class="term"><span><strong class="command">recursive-clients</strong></span></span></dt>
4021 <dd><p>
4022                   The maximum number of simultaneous recursive lookups
4023                   the server will perform on behalf of clients.  The default
4024                   is
4025                   <code class="literal">1000</code>.  Because each recursing
4026                   client uses a fair
4027                   bit of memory, on the order of 20 kilobytes, the value of
4028                   the
4029                   <span><strong class="command">recursive-clients</strong></span> option may
4030                   have to be decreased
4031                   on hosts with limited memory.
4032                 </p></dd>
4033 <dt><span class="term"><span><strong class="command">tcp-clients</strong></span></span></dt>
4034 <dd><p>
4035                   The maximum number of simultaneous client TCP
4036                   connections that the server will accept.
4037                   The default is <code class="literal">100</code>.
4038                 </p></dd>
4039 <dt><span class="term"><span><strong class="command">reserved-sockets</strong></span></span></dt>
4040 <dd>
4041 <p>
4042                   The number of file descriptors reserved for TCP, stdio,
4043                   etc.  This needs to be big enough to cover the number of
4044                   interfaces <span><strong class="command">named</strong></span> listens on, <span><strong class="command">tcp-clients</strong></span> as well as
4045                   to provide room for outgoing TCP queries and incoming zone
4046                   transfers.  The default is <code class="literal">512</code>.
4047                   The minimum value is <code class="literal">128</code> and the
4048                   maximum value is <code class="literal">128</code> less than
4049                   maxsockets (-S).  This option may be removed in the future.
4050                 </p>
4051 <p>
4052                   This option has little effect on Windows.
4053                 </p>
4054 </dd>
4055 <dt><span class="term"><span><strong class="command">max-cache-size</strong></span></span></dt>
4056 <dd><p>
4057                   The maximum amount of memory to use for the
4058                   server's cache, in bytes.
4059                   When the amount of data in the cache
4060                   reaches this limit, the server will cause records to expire
4061                   prematurely based on an LRU based strategy so that
4062                   the limit is not exceeded.
4063                   A value of 0 is special, meaning that
4064                   records are purged from the cache only when their
4065                   TTLs expire.
4066                   Another special keyword <strong class="userinput"><code>unlimited</code></strong>
4067                   means the maximum value of 32-bit unsigned integers
4068                   (0xffffffff), which may not have the same effect as
4069                   0 on machines that support more than 32 bits of
4070                   memory space.
4071                   Any positive values less than 2MB will be ignored reset
4072                   to 2MB.
4073                   In a server with multiple views, the limit applies
4074                   separately to the cache of each view.
4075                   The default is 0.
4076                 </p></dd>
4077 <dt><span class="term"><span><strong class="command">tcp-listen-queue</strong></span></span></dt>
4078 <dd><p>
4079                   The listen queue depth.  The default and minimum is 3.
4080                   If the kernel supports the accept filter "dataready" this
4081                   also controls how
4082                   many TCP connections that will be queued in kernel space
4083                   waiting for
4084                   some data before being passed to accept.  Values less than 3
4085                   will be
4086                   silently raised.
4087                 </p></dd>
4088 </dl></div>
4089 </div>
4090 <div class="sect3" lang="en">
4091 <div class="titlepage"><div><div><h4 class="title">
4092 <a name="id2584183"></a>Periodic Task Intervals</h4></div></div></div>
4093 <div class="variablelist"><dl>
4094 <dt><span class="term"><span><strong class="command">cleaning-interval</strong></span></span></dt>
4095 <dd><p>
4096                   This interval is effectively obsolete.  Previously,
4097                   the server would remove expired resource records
4098                   from the cache every <span><strong class="command">cleaning-interval</strong></span> minutes.
4099                   <acronym class="acronym">BIND</acronym> 9 now manages cache
4100                   memory in a more sophisticated manner and does not
4101                   rely on the periodic cleaning any more.
4102                   Specifying this option therefore has no effect on
4103                   the server's behavior.
4104                 </p></dd>
4105 <dt><span class="term"><span><strong class="command">heartbeat-interval</strong></span></span></dt>
4106 <dd><p>
4107                   The server will perform zone maintenance tasks
4108                   for all zones marked as <span><strong class="command">dialup</strong></span> whenever this
4109                   interval expires. The default is 60 minutes. Reasonable
4110                   values are up
4111                   to 1 day (1440 minutes).  The maximum value is 28 days
4112                   (40320 minutes).
4113                   If set to 0, no zone maintenance for these zones will occur.
4114                 </p></dd>
4115 <dt><span class="term"><span><strong class="command">interface-interval</strong></span></span></dt>
4116 <dd><p>
4117                   The server will scan the network interface list
4118                   every <span><strong class="command">interface-interval</strong></span>
4119                   minutes. The default
4120                   is 60 minutes. The maximum value is 28 days (40320 minutes).
4121                   If set to 0, interface scanning will only occur when
4122                   the configuration file is  loaded. After the scan, the
4123                   server will
4124                   begin listening for queries on any newly discovered
4125                   interfaces (provided they are allowed by the
4126                   <span><strong class="command">listen-on</strong></span> configuration), and
4127                   will
4128                   stop listening on interfaces that have gone away.
4129                 </p></dd>
4130 <dt><span class="term"><span><strong class="command">statistics-interval</strong></span></span></dt>
4131 <dd>
4132 <p>
4133                   Name server statistics will be logged
4134                   every <span><strong class="command">statistics-interval</strong></span>
4135                   minutes. The default is
4136                   60. The maximum value is 28 days (40320 minutes).
4137                   If set to 0, no statistics will be logged.
4138                   </p>
4139 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4140 <h3 class="title">Note</h3>
4141 <p>
4142                     Not yet implemented in
4143                     <acronym class="acronym">BIND</acronym> 9.
4144                   </p>
4145 </div>
4146 </dd>
4147 </dl></div>
4148 </div>
4149 <div class="sect3" lang="en">
4150 <div class="titlepage"><div><div><h4 class="title">
4151 <a name="topology"></a>Topology</h4></div></div></div>
4152 <p>
4153             All other things being equal, when the server chooses a name
4154             server
4155             to query from a list of name servers, it prefers the one that is
4156             topologically closest to itself. The <span><strong class="command">topology</strong></span> statement
4157             takes an <span><strong class="command">address_match_list</strong></span> and
4158             interprets it
4159             in a special way. Each top-level list element is assigned a
4160             distance.
4161             Non-negated elements get a distance based on their position in the
4162             list, where the closer the match is to the start of the list, the
4163             shorter the distance is between it and the server. A negated match
4164             will be assigned the maximum distance from the server. If there
4165             is no match, the address will get a distance which is further than
4166             any non-negated list element, and closer than any negated element.
4167             For example,
4168           </p>
4169 <pre class="programlisting">topology {
4170     10/8;
4171     !1.2.3/24;
4172     { 1.2/16; 3/8; };
4173 };</pre>
4174 <p>
4175             will prefer servers on network 10 the most, followed by hosts
4176             on network 1.2.0.0 (netmask 255.255.0.0) and network 3, with the
4177             exception of hosts on network 1.2.3 (netmask 255.255.255.0), which
4178             is preferred least of all.
4179           </p>
4180 <p>
4181             The default topology is
4182           </p>
4183 <pre class="programlisting">    topology { localhost; localnets; };
4184 </pre>
4185 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4186 <h3 class="title">Note</h3>
4187 <p>
4188               The <span><strong class="command">topology</strong></span> option
4189               is not implemented in <acronym class="acronym">BIND</acronym> 9.
4190             </p>
4191 </div>
4192 </div>
4193 <div class="sect3" lang="en">
4194 <div class="titlepage"><div><div><h4 class="title">
4195 <a name="the_sortlist_statement"></a>The <span><strong class="command">sortlist</strong></span> Statement</h4></div></div></div>
4196 <p>
4197             The response to a DNS query may consist of multiple resource
4198             records (RRs) forming a resource records set (RRset).
4199             The name server will normally return the
4200             RRs within the RRset in an indeterminate order
4201             (but see the <span><strong class="command">rrset-order</strong></span>
4202             statement in <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called &#8220;RRset Ordering&#8221;</a>).
4203             The client resolver code should rearrange the RRs as appropriate,
4204             that is, using any addresses on the local net in preference to
4205             other addresses.
4206             However, not all resolvers can do this or are correctly
4207             configured.
4208             When a client is using a local server, the sorting can be performed
4209             in the server, based on the client's address. This only requires
4210             configuring the name servers, not all the clients.
4211           </p>
4212 <p>
4213             The <span><strong class="command">sortlist</strong></span> statement (see below)
4214             takes
4215             an <span><strong class="command">address_match_list</strong></span> and
4216             interprets it even
4217             more specifically than the <span><strong class="command">topology</strong></span>
4218             statement
4219             does (<a href="Bv9ARM.ch06.html#topology" title="Topology">the section called &#8220;Topology&#8221;</a>).
4220             Each top level statement in the <span><strong class="command">sortlist</strong></span> must
4221             itself be an explicit <span><strong class="command">address_match_list</strong></span> with
4222             one or two elements. The first element (which may be an IP
4223             address,
4224             an IP prefix, an ACL name or a nested <span><strong class="command">address_match_list</strong></span>)
4225             of each top level list is checked against the source address of
4226             the query until a match is found.
4227           </p>
4228 <p>
4229             Once the source address of the query has been matched, if
4230             the top level statement contains only one element, the actual
4231             primitive
4232             element that matched the source address is used to select the
4233             address
4234             in the response to move to the beginning of the response. If the
4235             statement is a list of two elements, then the second element is
4236             treated the same as the <span><strong class="command">address_match_list</strong></span> in
4237             a <span><strong class="command">topology</strong></span> statement. Each top
4238             level element
4239             is assigned a distance and the address in the response with the
4240             minimum
4241             distance is moved to the beginning of the response.
4242           </p>
4243 <p>
4244             In the following example, any queries received from any of
4245             the addresses of the host itself will get responses preferring
4246             addresses
4247             on any of the locally connected networks. Next most preferred are
4248             addresses
4249             on the 192.168.1/24 network, and after that either the
4250             192.168.2/24
4251             or
4252             192.168.3/24 network with no preference shown between these two
4253             networks. Queries received from a host on the 192.168.1/24 network
4254             will prefer other addresses on that network to the 192.168.2/24
4255             and
4256             192.168.3/24 networks. Queries received from a host on the
4257             192.168.4/24
4258             or the 192.168.5/24 network will only prefer other addresses on
4259             their directly connected networks.
4260           </p>
4261 <pre class="programlisting">sortlist {
4262     { localhost;                                   // IF   the local host
4263         { localnets;                               // THEN first fit on the
4264             192.168.1/24;                          //   following nets
4265             { 192.168.2/24; 192.168.3/24; }; }; };
4266     { 192.168.1/24;                                // IF   on class C 192.168.1
4267         { 192.168.1/24;                            // THEN use .1, or .2 or .3
4268             { 192.168.2/24; 192.168.3/24; }; }; };
4269     { 192.168.2/24;                                // IF   on class C 192.168.2
4270         { 192.168.2/24;                            // THEN use .2, or .1 or .3
4271             { 192.168.1/24; 192.168.3/24; }; }; };
4272     { 192.168.3/24;                                // IF   on class C 192.168.3
4273         { 192.168.3/24;                            // THEN use .3, or .1 or .2
4274             { 192.168.1/24; 192.168.2/24; }; }; };
4275     { { 192.168.4/24; 192.168.5/24; };             // if .4 or .5, prefer that net
4276     };
4277 };</pre>
4278 <p>
4279             The following example will give reasonable behavior for the
4280             local host and hosts on directly connected networks. It is similar
4281             to the behavior of the address sort in <acronym class="acronym">BIND</acronym> 4.9.x. Responses sent
4282             to queries from the local host will favor any of the directly
4283             connected
4284             networks. Responses sent to queries from any other hosts on a
4285             directly
4286             connected network will prefer addresses on that same network.
4287             Responses
4288             to other queries will not be sorted.
4289           </p>
4290 <pre class="programlisting">sortlist {
4291            { localhost; localnets; };
4292            { localnets; };
4293 };
4294 </pre>
4295 </div>
4296 <div class="sect3" lang="en">
4297 <div class="titlepage"><div><div><h4 class="title">
4298 <a name="rrset_ordering"></a>RRset Ordering</h4></div></div></div>
4299 <p>
4300             When multiple records are returned in an answer it may be
4301             useful to configure the order of the records placed into the
4302             response.
4303             The <span><strong class="command">rrset-order</strong></span> statement permits
4304             configuration
4305             of the ordering of the records in a multiple record response.
4306             See also the <span><strong class="command">sortlist</strong></span> statement,
4307             <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>.
4308           </p>
4309 <p>
4310             An <span><strong class="command">order_spec</strong></span> is defined as
4311             follows:
4312           </p>
4313 <p>
4314             [<span class="optional">class <em class="replaceable"><code>class_name</code></em></span>]
4315             [<span class="optional">type <em class="replaceable"><code>type_name</code></em></span>]
4316             [<span class="optional">name <em class="replaceable"><code>"domain_name"</code></em></span>]
4317             order <em class="replaceable"><code>ordering</code></em>
4318           </p>
4319 <p>
4320             If no class is specified, the default is <span><strong class="command">ANY</strong></span>.
4321             If no type is specified, the default is <span><strong class="command">ANY</strong></span>.
4322             If no name is specified, the default is "<span><strong class="command">*</strong></span>" (asterisk).
4323           </p>
4324 <p>
4325             The legal values for <span><strong class="command">ordering</strong></span> are:
4326           </p>
4327 <div class="informaltable"><table border="1">
4328 <colgroup>
4329 <col>
4330 <col>
4331 </colgroup>
4332 <tbody>
4333 <tr>
4334 <td>
4335                     <p><span><strong class="command">fixed</strong></span></p>
4336                   </td>
4337 <td>
4338                     <p>
4339                       Records are returned in the order they
4340                       are defined in the zone file.
4341                     </p>
4342                   </td>
4343 </tr>
4344 <tr>
4345 <td>
4346                     <p><span><strong class="command">random</strong></span></p>
4347                   </td>
4348 <td>
4349                     <p>
4350                       Records are returned in some random order.
4351                     </p>
4352                   </td>
4353 </tr>
4354 <tr>
4355 <td>
4356                     <p><span><strong class="command">cyclic</strong></span></p>
4357                   </td>
4358 <td>
4359                     <p>
4360                       Records are returned in a cyclic round-robin order.
4361                     </p>
4362                     <p>
4363                       If <acronym class="acronym">BIND</acronym> is configured with the
4364                       "--enable-fixed-rrset" option at compile time, then
4365                       the initial ordering of the RRset will match the
4366                       one specified in the zone file.
4367                     </p>
4368                   </td>
4369 </tr>
4370 </tbody>
4371 </table></div>
4372 <p>
4373             For example:
4374           </p>
4375 <pre class="programlisting">rrset-order {
4376    class IN type A name "host.example.com" order random;
4377    order cyclic;
4378 };
4379 </pre>
4380 <p>
4381             will cause any responses for type A records in class IN that
4382             have "<code class="literal">host.example.com</code>" as a
4383             suffix, to always be returned
4384             in random order. All other records are returned in cyclic order.
4385           </p>
4386 <p>
4387             If multiple <span><strong class="command">rrset-order</strong></span> statements
4388             appear,
4389             they are not combined &#8212; the last one applies.
4390           </p>
4391 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4392 <h3 class="title">Note</h3>
4393 <p>
4394               In this release of <acronym class="acronym">BIND</acronym> 9, the
4395               <span><strong class="command">rrset-order</strong></span> statement does not support
4396               "fixed" ordering by default.  Fixed ordering can be enabled
4397               at compile time by specifying "--enable-fixed-rrset" on
4398               the "configure" command line.
4399             </p>
4400 </div>
4401 </div>
4402 <div class="sect3" lang="en">
4403 <div class="titlepage"><div><div><h4 class="title">
4404 <a name="tuning"></a>Tuning</h4></div></div></div>
4405 <div class="variablelist"><dl>
4406 <dt><span class="term"><span><strong class="command">lame-ttl</strong></span></span></dt>
4407 <dd>
4408 <p>
4409                   Sets the number of seconds to cache a
4410                   lame server indication. 0 disables caching. (This is
4411                   <span class="bold"><strong>NOT</strong></span> recommended.)
4412                   The default is <code class="literal">600</code> (10 minutes) and the
4413                   maximum value is
4414                   <code class="literal">1800</code> (30 minutes).
4415                 </p>
4416 <p>
4417                   Lame-ttl also controls the amount of time DNSSEC
4418                   validation failures are cached.  There is a minimum
4419                   of 30 seconds applied to bad cache entries if the
4420                   lame-ttl is set to less than 30 seconds.
4421                 </p>
4422 </dd>
4423 <dt><span class="term"><span><strong class="command">max-ncache-ttl</strong></span></span></dt>
4424 <dd><p>
4425                   To reduce network traffic and increase performance,
4426                   the server stores negative answers. <span><strong class="command">max-ncache-ttl</strong></span> is
4427                   used to set a maximum retention time for these answers in
4428                   the server
4429                   in seconds. The default
4430                   <span><strong class="command">max-ncache-ttl</strong></span> is <code class="literal">10800</code> seconds (3 hours).
4431                   <span><strong class="command">max-ncache-ttl</strong></span> cannot exceed
4432                   7 days and will
4433                   be silently truncated to 7 days if set to a greater value.
4434                 </p></dd>
4435 <dt><span class="term"><span><strong class="command">max-cache-ttl</strong></span></span></dt>
4436 <dd><p>
4437                   Sets the maximum time for which the server will
4438                   cache ordinary (positive) answers. The default is
4439                   one week (7 days).
4440                   A value of zero may cause all queries to return
4441                   SERVFAIL, because of lost caches of intermediate
4442                   RRsets (such as NS and glue AAAA/A records) in the
4443                   resolution process.
4444                 </p></dd>
4445 <dt><span class="term"><span><strong class="command">min-roots</strong></span></span></dt>
4446 <dd>
4447 <p>
4448                   The minimum number of root servers that
4449                   is required for a request for the root servers to be
4450                   accepted. The default
4451                   is <strong class="userinput"><code>2</code></strong>.
4452                 </p>
4453 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4454 <h3 class="title">Note</h3>
4455 <p>
4456                     Not implemented in <acronym class="acronym">BIND</acronym> 9.
4457                   </p>
4458 </div>
4459 </dd>
4460 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
4461 <dd>
4462 <p>
4463                   Specifies the number of days into the future when
4464                   DNSSEC signatures automatically generated as a
4465                   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
4466                   is a optional second field which specifies how
4467                   long before expiry that the signatures will be
4468                   regenerated.  If not specified, the signatures will
4469                   be regenerated at 1/4 of base interval.  The second
4470                   field is specified in days if the base interval is
4471                   greater than 7 days otherwise it is specified in hours.
4472                   The default base interval is <code class="literal">30</code> days
4473                   giving a re-signing interval of 7 1/2 days.  The maximum
4474                   values are 10 years (3660 days).
4475                 </p>
4476 <p>
4477                   The signature inception time is unconditionally
4478                   set to one hour before the current time to allow
4479                   for a limited amount of clock skew.
4480                 </p>
4481 <p>
4482                   The <span><strong class="command">sig-validity-interval</strong></span>
4483                   should be, at least, several multiples of the SOA
4484                   expire interval to allow for reasonable interaction
4485                   between the various timer and expiry dates.
4486                 </p>
4487 </dd>
4488 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
4489 <dd><p>
4490                   Specify the maximum number of nodes to be
4491                   examined in each quantum when signing a zone with
4492                   a new DNSKEY. The default is
4493                   <code class="literal">100</code>.
4494                 </p></dd>
4495 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
4496 <dd><p>
4497                   Specify a threshold number of signatures that
4498                   will terminate processing a quantum when signing
4499                   a zone with a new DNSKEY.  The default is
4500                   <code class="literal">10</code>.
4501                 </p></dd>
4502 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
4503 <dd>
4504 <p>
4505                   Specify a private RDATA type to be used when generating
4506                   key signing records.  The default is
4507                   <code class="literal">65535</code>.
4508                 </p>
4509 <p>
4510                   It is expected that this parameter may be removed
4511                   in a future version once there is a standard type.
4512                 </p>
4513 </dd>
4514 <dt>
4515 <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>
4516 </dt>
4517 <dd>
4518 <p>
4519                   These options control the server's behavior on refreshing a
4520                   zone
4521                   (querying for SOA changes) or retrying failed transfers.
4522                   Usually the SOA values for the zone are used, but these
4523                   values
4524                   are set by the master, giving slave server administrators
4525                   little
4526                   control over their contents.
4527                 </p>
4528 <p>
4529                   These options allow the administrator to set a minimum and
4530                   maximum
4531                   refresh and retry time either per-zone, per-view, or
4532                   globally.
4533                   These options are valid for slave and stub zones,
4534                   and clamp the SOA refresh and retry times to the specified
4535                   values.
4536                 </p>
4537 <p>
4538                   The following defaults apply.
4539                   <span><strong class="command">min-refresh-time</strong></span> 300 seconds,
4540                   <span><strong class="command">max-refresh-time</strong></span> 2419200 seconds
4541                   (4 weeks), <span><strong class="command">min-retry-time</strong></span> 500 seconds,
4542                   and <span><strong class="command">max-retry-time</strong></span> 1209600 seconds
4543                   (2 weeks).
4544                 </p>
4545 </dd>
4546 <dt><span class="term"><span><strong class="command">edns-udp-size</strong></span></span></dt>
4547 <dd><p>
4548                   Sets the advertised EDNS UDP buffer size in bytes
4549                   to control the size of packets received.
4550                   Valid values are 512 to 4096 (values outside this range
4551                   will be silently adjusted).  The default value
4552                   is 4096.  The usual reason for setting
4553                   <span><strong class="command">edns-udp-size</strong></span> to a non-default
4554                   value is to get UDP answers to pass through broken
4555                   firewalls that block fragmented packets and/or
4556                   block UDP packets that are greater than 512 bytes.
4557                 </p></dd>
4558 <dt><span class="term"><span><strong class="command">max-udp-size</strong></span></span></dt>
4559 <dd><p>
4560                   Sets the maximum EDNS UDP message size <span><strong class="command">named</strong></span> will
4561                   send in bytes.  Valid values are 512 to 4096 (values outside
4562                   this range will be silently adjusted).  The default
4563                   value is 4096.  The usual reason for setting
4564                   <span><strong class="command">max-udp-size</strong></span> to a non-default value is to get UDP
4565                   answers to pass through broken firewalls that
4566                   block fragmented packets and/or block UDP packets
4567                   that are greater than 512 bytes.
4568                   This is independent of the advertised receive
4569                   buffer (<span><strong class="command">edns-udp-size</strong></span>).
4570                 </p></dd>
4571 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
4572 <dd><p>Specifies
4573                   the file format of zone files (see
4574                   <a href="Bv9ARM.ch06.html#zonefile_format" title="Additional File Formats">the section called &#8220;Additional File Formats&#8221;</a>).
4575                   The default value is <code class="constant">text</code>, which is the
4576                   standard textual representation.  Files in other formats
4577                   than <code class="constant">text</code> are typically expected
4578                   to be generated by the <span><strong class="command">named-compilezone</strong></span> tool.
4579                   Note that when a zone file in a different format than
4580                   <code class="constant">text</code> is loaded, <span><strong class="command">named</strong></span>
4581                   may omit some of the checks which would be performed for a
4582                   file in the <code class="constant">text</code> format.  In particular,
4583                   <span><strong class="command">check-names</strong></span> checks do not apply
4584                   for the <code class="constant">raw</code> format.  This means
4585                   a zone file in the <code class="constant">raw</code> format
4586                   must be generated with the same check level as that
4587                   specified in the <span><strong class="command">named</strong></span> configuration
4588                   file.  This statement sets the
4589                   <span><strong class="command">masterfile-format</strong></span> for all zones,
4590                   but can be overridden on a per-zone or per-view basis
4591                   by including a <span><strong class="command">masterfile-format</strong></span>
4592                   statement within the <span><strong class="command">zone</strong></span> or
4593                   <span><strong class="command">view</strong></span> block in the configuration
4594                   file.
4595                 </p></dd>
4596 <dt>
4597 <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>
4598 </dt>
4599 <dd>
4600 <p>These set the
4601                   initial value (minimum) and maximum number of recursive
4602                   simultaneous clients for any given query
4603                   (&lt;qname,qtype,qclass&gt;) that the server will accept
4604                   before dropping additional clients.  <span><strong class="command">named</strong></span> will attempt to
4605                   self tune this value and changes will be logged.  The
4606                   default values are 10 and 100.
4607                 </p>
4608 <p>
4609                   This value should reflect how many queries come in for
4610                   a given name in the time it takes to resolve that name.
4611                   If the number of queries exceed this value, <span><strong class="command">named</strong></span> will
4612                   assume that it is dealing with a non-responsive zone
4613                   and will drop additional queries.  If it gets a response
4614                   after dropping queries, it will raise the estimate.  The
4615                   estimate will then be lowered in 20 minutes if it has
4616                   remained unchanged.
4617                 </p>
4618 <p>
4619                   If <span><strong class="command">clients-per-query</strong></span> is set to zero,
4620                   then there is no limit on the number of clients per query
4621                   and no queries will be dropped.
4622                 </p>
4623 <p>
4624                   If <span><strong class="command">max-clients-per-query</strong></span> is set to zero,
4625                   then there is no upper bound other than imposed by
4626                   <span><strong class="command">recursive-clients</strong></span>.
4627                 </p>
4628 </dd>
4629 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
4630 <dd>
4631 <p>
4632                   The delay, in seconds, between sending sets of notify
4633                   messages for a zone.  The default is five (5) seconds.
4634                 </p>
4635 <p>
4636                   The overall rate that NOTIFY messages are sent for all
4637                   zones is controlled by <span><strong class="command">serial-query-rate</strong></span>.
4638                 </p>
4639 </dd>
4640 </dl></div>
4641 </div>
4642 <div class="sect3" lang="en">
4643 <div class="titlepage"><div><div><h4 class="title">
4644 <a name="builtin"></a>Built-in server information zones</h4></div></div></div>
4645 <p>
4646             The server provides some helpful diagnostic information
4647             through a number of built-in zones under the
4648             pseudo-top-level-domain <code class="literal">bind</code> in the
4649             <span><strong class="command">CHAOS</strong></span> class.  These zones are part
4650             of a
4651             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
4652             class
4653             <span><strong class="command">CHAOS</strong></span> which is separate from the
4654             default view of
4655             class <span><strong class="command">IN</strong></span>; therefore, any global
4656             server options
4657             such as <span><strong class="command">allow-query</strong></span> do not apply
4658             the these zones.
4659             If you feel the need to disable these zones, use the options
4660             below, or hide the built-in <span><strong class="command">CHAOS</strong></span>
4661             view by
4662             defining an explicit view of class <span><strong class="command">CHAOS</strong></span>
4663             that matches all clients.
4664           </p>
4665 <div class="variablelist"><dl>
4666 <dt><span class="term"><span><strong class="command">version</strong></span></span></dt>
4667 <dd><p>
4668                   The version the server should report
4669                   via a query of the name <code class="literal">version.bind</code>
4670                   with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
4671                   The default is the real version number of this server.
4672                   Specifying <span><strong class="command">version none</strong></span>
4673                   disables processing of the queries.
4674                 </p></dd>
4675 <dt><span class="term"><span><strong class="command">hostname</strong></span></span></dt>
4676 <dd><p>
4677                   The hostname the server should report via a query of
4678                   the name <code class="filename">hostname.bind</code>
4679                   with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
4680                   This defaults to the hostname of the machine hosting the
4681                   name server as
4682                   found by the gethostname() function.  The primary purpose of such queries
4683                   is to
4684                   identify which of a group of anycast servers is actually
4685                   answering your queries.  Specifying <span><strong class="command">hostname none;</strong></span>
4686                   disables processing of the queries.
4687                 </p></dd>
4688 <dt><span class="term"><span><strong class="command">server-id</strong></span></span></dt>
4689 <dd><p>
4690                   The ID the server should report when receiving a Name
4691                   Server Identifier (NSID) query, or a query of the name
4692                   <code class="filename">ID.SERVER</code> with type
4693                   <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
4694                   The primary purpose of such queries is to
4695                   identify which of a group of anycast servers is actually
4696                   answering your queries.  Specifying <span><strong class="command">server-id none;</strong></span>
4697                   disables processing of the queries.
4698                   Specifying <span><strong class="command">server-id hostname;</strong></span> will cause <span><strong class="command">named</strong></span> to
4699                   use the hostname as found by the gethostname() function.
4700                   The default <span><strong class="command">server-id</strong></span> is <span><strong class="command">none</strong></span>.
4701                 </p></dd>
4702 </dl></div>
4703 </div>
4704 <div class="sect3" lang="en">
4705 <div class="titlepage"><div><div><h4 class="title">
4706 <a name="empty"></a>Built-in Empty Zones</h4></div></div></div>
4707 <p>
4708             Named has some built-in empty zones (SOA and NS records only).
4709             These are for zones that should normally be answered locally
4710             and which queries should not be sent to the Internet's root
4711             servers.  The official servers which cover these namespaces
4712             return NXDOMAIN responses to these queries.  In particular,
4713             these cover the reverse namespace for addresses from RFC 1918 and
4714             RFC 3330.  They also include the reverse namespace for IPv6 local
4715             address (locally assigned), IPv6 link local addresses, the IPv6
4716             loopback address and the IPv6 unknown address.
4717           </p>
4718 <p>
4719             Named will attempt to determine if a built-in zone already exists
4720             or is active (covered by a forward-only forwarding declaration)
4721             and will not create a empty zone in that case.
4722           </p>
4723 <p>
4724             The current list of empty zones is:
4725             </p>
4726 <div class="itemizedlist"><ul type="disc">
4727 <li>0.IN-ADDR.ARPA</li>
4728 <li>127.IN-ADDR.ARPA</li>
4729 <li>254.169.IN-ADDR.ARPA</li>
4730 <li>2.0.192.IN-ADDR.ARPA</li>
4731 <li>100.51.198.IN-ADDR.ARPA</li>
4732 <li>113.0.203.IN-ADDR.ARPA</li>
4733 <li>255.255.255.255.IN-ADDR.ARPA</li>
4734 <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>
4735 <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>
4736 <li>8.B.D.0.1.0.0.2.IP6.ARPA</li>
4737 <li>D.F.IP6.ARPA</li>
4738 <li>8.E.F.IP6.ARPA</li>
4739 <li>9.E.F.IP6.ARPA</li>
4740 <li>A.E.F.IP6.ARPA</li>
4741 <li>B.E.F.IP6.ARPA</li>
4742 </ul></div>
4743 <p>
4744           </p>
4745 <p>
4746             Empty zones are settable at the view level and only apply to
4747             views of class IN.  Disabled empty zones are only inherited
4748             from options if there are no disabled empty zones specified
4749             at the view level.  To override the options list of disabled
4750             zones, you can disable the root zone at the view level, for example:
4751 </p>
4752 <pre class="programlisting">
4753             disable-empty-zone ".";
4754 </pre>
4755 <p>
4756           </p>
4757 <p>
4758             If you are using the address ranges covered here, you should
4759             already have reverse zones covering the addresses you use.
4760             In practice this appears to not be the case with many queries
4761             being made to the infrastructure servers for names in these
4762             spaces.  So many in fact that sacrificial servers were needed
4763             to be deployed to channel the query load away from the
4764             infrastructure servers.
4765           </p>
4766 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4767 <h3 class="title">Note</h3>
4768             The real parent servers for these zones should disable all
4769             empty zone under the parent zone they serve.  For the real
4770             root servers, this is all built-in empty zones.  This will
4771             enable them to return referrals to deeper in the tree.
4772           </div>
4773 <div class="variablelist"><dl>
4774 <dt><span class="term"><span><strong class="command">empty-server</strong></span></span></dt>
4775 <dd><p>
4776                   Specify what server name will appear in the returned
4777                   SOA record for empty zones.  If none is specified, then
4778                   the zone's name will be used.
4779                 </p></dd>
4780 <dt><span class="term"><span><strong class="command">empty-contact</strong></span></span></dt>
4781 <dd><p>
4782                   Specify what contact name will appear in the returned
4783                   SOA record for empty zones.  If none is specified, then
4784                   "." will be used.
4785                 </p></dd>
4786 <dt><span class="term"><span><strong class="command">empty-zones-enable</strong></span></span></dt>
4787 <dd><p>
4788                   Enable or disable all empty zones.  By default, they
4789                   are enabled.
4790                 </p></dd>
4791 <dt><span class="term"><span><strong class="command">disable-empty-zone</strong></span></span></dt>
4792 <dd><p>
4793                   Disable individual empty zones.  By default, none are
4794                   disabled.  This option can be specified multiple times.
4795                 </p></dd>
4796 </dl></div>
4797 </div>
4798 <div class="sect3" lang="en">
4799 <div class="titlepage"><div><div><h4 class="title">
4800 <a name="acache"></a>Additional Section Caching</h4></div></div></div>
4801 <p>
4802             The additional section cache, also called <span><strong class="command">acache</strong></span>,
4803             is an internal cache to improve the response performance of BIND 9.
4804             When additional section caching is enabled, BIND 9 will
4805             cache an internal short-cut to the additional section content for
4806             each answer RR.
4807             Note that <span><strong class="command">acache</strong></span> is an internal caching
4808             mechanism of BIND 9, and is not related to the DNS caching
4809             server function.
4810           </p>
4811 <p>
4812             Additional section caching does not change the
4813             response content (except the RRsets ordering of the additional
4814             section, see below), but can improve the response performance
4815             significantly.
4816             It is particularly effective when BIND 9 acts as an authoritative
4817             server for a zone that has many delegations with many glue RRs.
4818           </p>
4819 <p>
4820             In order to obtain the maximum performance improvement
4821             from additional section caching, setting
4822             <span><strong class="command">additional-from-cache</strong></span>
4823             to <span><strong class="command">no</strong></span> is recommended, since the current
4824             implementation of <span><strong class="command">acache</strong></span>
4825             does not short-cut of additional section information from the
4826             DNS cache data.
4827           </p>
4828 <p>
4829             One obvious disadvantage of <span><strong class="command">acache</strong></span> is
4830             that it requires much more
4831             memory for the internal cached data.
4832             Thus, if the response performance does not matter and memory
4833             consumption is much more critical, the
4834             <span><strong class="command">acache</strong></span> mechanism can be
4835             disabled by setting <span><strong class="command">acache-enable</strong></span> to
4836             <span><strong class="command">no</strong></span>.
4837             It is also possible to specify the upper limit of memory
4838             consumption
4839             for acache by using <span><strong class="command">max-acache-size</strong></span>.
4840           </p>
4841 <p>
4842             Additional section caching also has a minor effect on the
4843             RRset ordering in the additional section.
4844             Without <span><strong class="command">acache</strong></span>,
4845             <span><strong class="command">cyclic</strong></span> order is effective for the additional
4846             section as well as the answer and authority sections.
4847             However, additional section caching fixes the ordering when it
4848             first caches an RRset for the additional section, and the same
4849             ordering will be kept in succeeding responses, regardless of the
4850             setting of <span><strong class="command">rrset-order</strong></span>.
4851             The effect of this should be minor, however, since an
4852             RRset in the additional section
4853             typically only contains a small number of RRs (and in many cases
4854             it only contains a single RR), in which case the
4855             ordering does not matter much.
4856           </p>
4857 <p>
4858             The following is a summary of options related to
4859             <span><strong class="command">acache</strong></span>.
4860           </p>
4861 <div class="variablelist"><dl>
4862 <dt><span class="term"><span><strong class="command">acache-enable</strong></span></span></dt>
4863 <dd><p>
4864                   If <span><strong class="command">yes</strong></span>, additional section caching is
4865                   enabled.  The default value is <span><strong class="command">no</strong></span>.
4866                 </p></dd>
4867 <dt><span class="term"><span><strong class="command">acache-cleaning-interval</strong></span></span></dt>
4868 <dd><p>
4869                   The server will remove stale cache entries, based on an LRU
4870                   based
4871                   algorithm, every <span><strong class="command">acache-cleaning-interval</strong></span> minutes.
4872                   The default is 60 minutes.
4873                   If set to 0, no periodic cleaning will occur.
4874                 </p></dd>
4875 <dt><span class="term"><span><strong class="command">max-acache-size</strong></span></span></dt>
4876 <dd><p>
4877                   The maximum amount of memory in bytes to use for the server's acache.
4878                   When the amount of data in the acache reaches this limit,
4879                   the server
4880                   will clean more aggressively so that the limit is not
4881                   exceeded.
4882                   In a server with multiple views, the limit applies
4883                   separately to the
4884                   acache of each view.
4885                   The default is <code class="literal">16M</code>.
4886                 </p></dd>
4887 </dl></div>
4888 </div>
4889 </div>
4890 <div class="sect2" lang="en">
4891 <div class="titlepage"><div><div><h3 class="title">
4892 <a name="server_statement_grammar"></a><span><strong class="command">server</strong></span> Statement Grammar</h3></div></div></div>
4893 <pre class="programlisting"><span><strong class="command">server</strong></span> <em class="replaceable"><code>ip_addr[/prefixlen]</code></em> {
4894     [<span class="optional"> bogus <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4895     [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4896     [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4897     [<span class="optional"> edns <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4898     [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
4899     [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
4900     [<span class="optional"> transfers <em class="replaceable"><code>number</code></em> ; </span>]
4901     [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em> ; ]</span>]
4902     [<span class="optional"> keys <em class="replaceable"><code>{ string ; [<span class="optional"> string ; [<span class="optional">...</span>]</span>] }</code></em> ; </span>]
4903     [<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>]
4904     [<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>]
4905     [<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>]
4906     [<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>]
4907     [<span class="optional"> query-source [<span class="optional"> address ( <em class="replaceable"><code>ip_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>]
4908     [<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>] [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>]
4909     [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
4910     [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>]
4911     [<span class="optional"> queryport-pool-updateinterval <em class="replaceable"><code>number</code></em>; </span>]
4912 };
4913 </pre>
4914 </div>
4915 <div class="sect2" lang="en">
4916 <div class="titlepage"><div><div><h3 class="title">
4917 <a name="server_statement_definition_and_usage"></a><span><strong class="command">server</strong></span> Statement Definition and
4918             Usage</h3></div></div></div>
4919 <p>
4920             The <span><strong class="command">server</strong></span> statement defines
4921             characteristics
4922             to be associated with a remote name server.  If a prefix length is
4923             specified, then a range of servers is covered.  Only the most
4924             specific
4925             server clause applies regardless of the order in
4926             <code class="filename">named.conf</code>.
4927           </p>
4928 <p>
4929             The <span><strong class="command">server</strong></span> statement can occur at
4930             the top level of the
4931             configuration file or inside a <span><strong class="command">view</strong></span>
4932             statement.
4933             If a <span><strong class="command">view</strong></span> statement contains
4934             one or more <span><strong class="command">server</strong></span> statements, only
4935             those
4936             apply to the view and any top-level ones are ignored.
4937             If a view contains no <span><strong class="command">server</strong></span>
4938             statements,
4939             any top-level <span><strong class="command">server</strong></span> statements are
4940             used as
4941             defaults.
4942           </p>
4943 <p>
4944             If you discover that a remote server is giving out bad data,
4945             marking it as bogus will prevent further queries to it. The
4946             default
4947             value of <span><strong class="command">bogus</strong></span> is <span><strong class="command">no</strong></span>.
4948           </p>
4949 <p>
4950             The <span><strong class="command">provide-ixfr</strong></span> clause determines
4951             whether
4952             the local server, acting as master, will respond with an
4953             incremental
4954             zone transfer when the given remote server, a slave, requests it.
4955             If set to <span><strong class="command">yes</strong></span>, incremental transfer
4956             will be provided
4957             whenever possible. If set to <span><strong class="command">no</strong></span>,
4958             all transfers
4959             to the remote server will be non-incremental. If not set, the
4960             value
4961             of the <span><strong class="command">provide-ixfr</strong></span> option in the
4962             view or
4963             global options block is used as a default.
4964           </p>
4965 <p>
4966             The <span><strong class="command">request-ixfr</strong></span> clause determines
4967             whether
4968             the local server, acting as a slave, will request incremental zone
4969             transfers from the given remote server, a master. If not set, the
4970             value of the <span><strong class="command">request-ixfr</strong></span> option in
4971             the view or
4972             global options block is used as a default.
4973           </p>
4974 <p>
4975             IXFR requests to servers that do not support IXFR will
4976             automatically
4977             fall back to AXFR.  Therefore, there is no need to manually list
4978             which servers support IXFR and which ones do not; the global
4979             default
4980             of <span><strong class="command">yes</strong></span> should always work.
4981             The purpose of the <span><strong class="command">provide-ixfr</strong></span> and
4982             <span><strong class="command">request-ixfr</strong></span> clauses is
4983             to make it possible to disable the use of IXFR even when both
4984             master
4985             and slave claim to support it, for example if one of the servers
4986             is buggy and crashes or corrupts data when IXFR is used.
4987           </p>
4988 <p>
4989             The <span><strong class="command">edns</strong></span> clause determines whether
4990             the local server will attempt to use EDNS when communicating
4991             with the remote server.  The default is <span><strong class="command">yes</strong></span>.
4992           </p>
4993 <p>
4994             The <span><strong class="command">edns-udp-size</strong></span> option sets the EDNS UDP size
4995             that is advertised by <span><strong class="command">named</strong></span> when querying the remote server.
4996             Valid values are 512 to 4096 bytes (values outside this range will be
4997             silently adjusted).  This option is useful when you wish to
4998             advertises a different value to this server than the value you
4999             advertise globally, for example, when there is a firewall at the
5000             remote site that is blocking large replies.
5001           </p>
5002 <p>
5003             The <span><strong class="command">max-udp-size</strong></span> option sets the
5004             maximum EDNS UDP message size <span><strong class="command">named</strong></span> will send.  Valid
5005             values are 512 to 4096 bytes (values outside this range will
5006             be silently adjusted).  This option is useful when you
5007             know that there is a firewall that is blocking large
5008             replies from <span><strong class="command">named</strong></span>.
5009           </p>
5010 <p>
5011             The server supports two zone transfer methods. The first, <span><strong class="command">one-answer</strong></span>,
5012             uses one DNS message per resource record transferred. <span><strong class="command">many-answers</strong></span> packs
5013             as many resource records as possible into a message. <span><strong class="command">many-answers</strong></span> is
5014             more efficient, but is only known to be understood by <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
5015             8.x, and patched versions of <acronym class="acronym">BIND</acronym>
5016             4.9.5. You can specify which method
5017             to use for a server with the <span><strong class="command">transfer-format</strong></span> option.
5018             If <span><strong class="command">transfer-format</strong></span> is not
5019             specified, the <span><strong class="command">transfer-format</strong></span>
5020             specified
5021             by the <span><strong class="command">options</strong></span> statement will be
5022             used.
5023           </p>
5024 <p><span><strong class="command">transfers</strong></span>
5025             is used to limit the number of concurrent inbound zone
5026             transfers from the specified server. If no
5027             <span><strong class="command">transfers</strong></span> clause is specified, the
5028             limit is set according to the
5029             <span><strong class="command">transfers-per-ns</strong></span> option.
5030           </p>
5031 <p>
5032             The <span><strong class="command">keys</strong></span> clause identifies a
5033             <span><strong class="command">key_id</strong></span> defined by the <span><strong class="command">key</strong></span> statement,
5034             to be used for transaction security (TSIG, <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called &#8220;TSIG&#8221;</a>)
5035             when talking to the remote server.
5036             When a request is sent to the remote server, a request signature
5037             will be generated using the key specified here and appended to the
5038             message. A request originating from the remote server is not
5039             required
5040             to be signed by this key.
5041           </p>
5042 <p>
5043             Although the grammar of the <span><strong class="command">keys</strong></span>
5044             clause
5045             allows for multiple keys, only a single key per server is
5046             currently
5047             supported.
5048           </p>
5049 <p>
5050             The <span><strong class="command">transfer-source</strong></span> and
5051             <span><strong class="command">transfer-source-v6</strong></span> clauses specify
5052             the IPv4 and IPv6 source
5053             address to be used for zone transfer with the remote server,
5054             respectively.
5055             For an IPv4 remote server, only <span><strong class="command">transfer-source</strong></span> can
5056             be specified.
5057             Similarly, for an IPv6 remote server, only
5058             <span><strong class="command">transfer-source-v6</strong></span> can be
5059             specified.
5060             For more details, see the description of
5061             <span><strong class="command">transfer-source</strong></span> and
5062             <span><strong class="command">transfer-source-v6</strong></span> in
5063             <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
5064           </p>
5065 <p>
5066             The <span><strong class="command">notify-source</strong></span> and
5067             <span><strong class="command">notify-source-v6</strong></span> clauses specify the
5068             IPv4 and IPv6 source address to be used for notify
5069             messages sent to remote servers, respectively.  For an
5070             IPv4 remote server, only <span><strong class="command">notify-source</strong></span>
5071             can be specified.  Similarly, for an IPv6 remote server,
5072             only <span><strong class="command">notify-source-v6</strong></span> can be specified.
5073           </p>
5074 <p>
5075             The <span><strong class="command">query-source</strong></span> and
5076             <span><strong class="command">query-source-v6</strong></span> clauses specify the
5077             IPv4 and IPv6 source address to be used for queries
5078             sent to remote servers, respectively.  For an IPv4
5079             remote server, only <span><strong class="command">query-source</strong></span> can
5080             be specified.  Similarly, for an IPv6 remote server,
5081             only <span><strong class="command">query-source-v6</strong></span> can be specified.
5082           </p>
5083 </div>
5084 <div class="sect2" lang="en">
5085 <div class="titlepage"><div><div><h3 class="title">
5086 <a name="statschannels"></a><span><strong class="command">statistics-channels</strong></span> Statement Grammar</h3></div></div></div>
5087 <pre class="programlisting"><span><strong class="command">statistics-channels</strong></span> {
5088    [ inet ( ip_addr | * ) [ port ip_port ] [allow { <em class="replaceable"><code> address_match_list </code></em> } ]; ]
5089    [ inet ...; ]
5090 };
5091 </pre>
5092 </div>
5093 <div class="sect2" lang="en">
5094 <div class="titlepage"><div><div><h3 class="title">
5095 <a name="id2586923"></a><span><strong class="command">statistics-channels</strong></span> Statement Definition and
5096             Usage</h3></div></div></div>
5097 <p>
5098           The <span><strong class="command">statistics-channels</strong></span> statement
5099           declares communication channels to be used by system
5100           administrators to get access to statistics information of
5101           the name server.
5102         </p>
5103 <p>
5104           This statement intends to be flexible to support multiple
5105           communication protocols in the future, but currently only
5106           HTTP access is supported.
5107           It requires that BIND 9 be compiled with libxml2;
5108           the <span><strong class="command">statistics-channels</strong></span> statement is
5109           still accepted even if it is built without the library,
5110           but any HTTP access will fail with an error.
5111         </p>
5112 <p>
5113           An <span><strong class="command">inet</strong></span> control channel is a TCP socket
5114           listening at the specified <span><strong class="command">ip_port</strong></span> on the
5115           specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6
5116           address.  An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is
5117           interpreted as the IPv4 wildcard address; connections will be
5118           accepted on any of the system's IPv4 addresses.
5119           To listen on the IPv6 wildcard address,
5120           use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>.
5121         </p>
5122 <p>
5123           If no port is specified, port 80 is used for HTTP channels.
5124           The asterisk "<code class="literal">*</code>" cannot be used for
5125           <span><strong class="command">ip_port</strong></span>.
5126         </p>
5127 <p>
5128           The attempt of opening a statistics channel is
5129           restricted by the optional <span><strong class="command">allow</strong></span> clause.
5130           Connections to the statistics channel are permitted based on the
5131           <span><strong class="command">address_match_list</strong></span>.
5132           If no <span><strong class="command">allow</strong></span> clause is present,
5133           <span><strong class="command">named</strong></span> accepts connection
5134           attempts from any address; since the statistics may
5135           contain sensitive internal information, it is highly
5136           recommended to restrict the source of connection requests
5137           appropriately.
5138         </p>
5139 <p>
5140           If no <span><strong class="command">statistics-channels</strong></span> statement is present,
5141           <span><strong class="command">named</strong></span> will not open any communication channels.
5142         </p>
5143 </div>
5144 <div class="sect2" lang="en">
5145 <div class="titlepage"><div><div><h3 class="title">
5146 <a name="id2587078"></a><span><strong class="command">trusted-keys</strong></span> Statement Grammar</h3></div></div></div>
5147 <pre class="programlisting"><span><strong class="command">trusted-keys</strong></span> {
5148     <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> ;
5149     [<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>]
5150 };
5151 </pre>
5152 </div>
5153 <div class="sect2" lang="en">
5154 <div class="titlepage"><div><div><h3 class="title">
5155 <a name="id2587129"></a><span><strong class="command">trusted-keys</strong></span> Statement Definition
5156             and Usage</h3></div></div></div>
5157 <p>
5158             The <span><strong class="command">trusted-keys</strong></span> statement defines
5159             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
5160             public key for a non-authoritative zone is known, but
5161             cannot be securely obtained through DNS, either because
5162             it is the DNS root zone or because its parent zone is
5163             unsigned.  Once a key has been configured as a trusted
5164             key, it is treated as if it had been validated and
5165             proven secure. The resolver attempts DNSSEC validation
5166             on all DNS data in subdomains of a security root.
5167           </p>
5168 <p>
5169             All keys (and corresponding zones) listed in
5170             <span><strong class="command">trusted-keys</strong></span> are deemed to exist regardless
5171             of what parent zones say.  Similarly for all keys listed in
5172             <span><strong class="command">trusted-keys</strong></span> only those keys are
5173             used to validate the DNSKEY RRset.  The parent's DS RRset
5174             will not be used.
5175           </p>
5176 <p>
5177             The <span><strong class="command">trusted-keys</strong></span> statement can contain
5178             multiple key entries, each consisting of the key's
5179             domain name, flags, protocol, algorithm, and the Base-64
5180             representation of the key data.
5181             Spaces, tabs, newlines and carriage returns are ignored
5182             in the key data, so the configuration may be split up into
5183             multiple lines.
5184           </p>
5185 </div>
5186 <div class="sect2" lang="en">
5187 <div class="titlepage"><div><div><h3 class="title">
5188 <a name="view_statement_grammar"></a><span><strong class="command">view</strong></span> Statement Grammar</h3></div></div></div>
5189 <pre class="programlisting"><span><strong class="command">view</strong></span> <em class="replaceable"><code>view_name</code></em>
5190       [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5191       match-clients { <em class="replaceable"><code>address_match_list</code></em> };
5192       match-destinations { <em class="replaceable"><code>address_match_list</code></em> };
5193       match-recursive-only <em class="replaceable"><code>yes_or_no</code></em> ;
5194       [<span class="optional"> <em class="replaceable"><code>view_option</code></em>; ...</span>]
5195       [<span class="optional"> <em class="replaceable"><code>zone_statement</code></em>; ...</span>]
5196 };
5197 </pre>
5198 </div>
5199 <div class="sect2" lang="en">
5200 <div class="titlepage"><div><div><h3 class="title">
5201 <a name="id2587211"></a><span><strong class="command">view</strong></span> Statement Definition and Usage</h3></div></div></div>
5202 <p>
5203             The <span><strong class="command">view</strong></span> statement is a powerful
5204             feature
5205             of <acronym class="acronym">BIND</acronym> 9 that lets a name server
5206             answer a DNS query differently
5207             depending on who is asking. It is particularly useful for
5208             implementing
5209             split DNS setups without having to run multiple servers.
5210           </p>
5211 <p>
5212             Each <span><strong class="command">view</strong></span> statement defines a view
5213             of the
5214             DNS namespace that will be seen by a subset of clients.  A client
5215             matches
5216             a view if its source IP address matches the
5217             <code class="varname">address_match_list</code> of the view's
5218             <span><strong class="command">match-clients</strong></span> clause and its
5219             destination IP address matches
5220             the <code class="varname">address_match_list</code> of the
5221             view's
5222             <span><strong class="command">match-destinations</strong></span> clause.  If not
5223             specified, both
5224             <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
5225             default to matching all addresses.  In addition to checking IP
5226             addresses
5227             <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
5228             can also take <span><strong class="command">keys</strong></span> which provide an
5229             mechanism for the
5230             client to select the view.  A view can also be specified
5231             as <span><strong class="command">match-recursive-only</strong></span>, which
5232             means that only recursive
5233             requests from matching clients will match that view.
5234             The order of the <span><strong class="command">view</strong></span> statements is
5235             significant &#8212;
5236             a client request will be resolved in the context of the first
5237             <span><strong class="command">view</strong></span> that it matches.
5238           </p>
5239 <p>
5240             Zones defined within a <span><strong class="command">view</strong></span>
5241             statement will
5242             only be accessible to clients that match the <span><strong class="command">view</strong></span>.
5243             By defining a zone of the same name in multiple views, different
5244             zone data can be given to different clients, for example,
5245             "internal"
5246             and "external" clients in a split DNS setup.
5247           </p>
5248 <p>
5249             Many of the options given in the <span><strong class="command">options</strong></span> statement
5250             can also be used within a <span><strong class="command">view</strong></span>
5251             statement, and then
5252             apply only when resolving queries with that view.  When no
5253             view-specific
5254             value is given, the value in the <span><strong class="command">options</strong></span> statement
5255             is used as a default.  Also, zone options can have default values
5256             specified
5257             in the <span><strong class="command">view</strong></span> statement; these
5258             view-specific defaults
5259             take precedence over those in the <span><strong class="command">options</strong></span> statement.
5260           </p>
5261 <p>
5262             Views are class specific.  If no class is given, class IN
5263             is assumed.  Note that all non-IN views must contain a hint zone,
5264             since only the IN class has compiled-in default hints.
5265           </p>
5266 <p>
5267             If there are no <span><strong class="command">view</strong></span> statements in
5268             the config
5269             file, a default view that matches any client is automatically
5270             created
5271             in class IN. Any <span><strong class="command">zone</strong></span> statements
5272             specified on
5273             the top level of the configuration file are considered to be part
5274             of
5275             this default view, and the <span><strong class="command">options</strong></span>
5276             statement will
5277             apply to the default view. If any explicit <span><strong class="command">view</strong></span>
5278             statements are present, all <span><strong class="command">zone</strong></span>
5279             statements must
5280             occur inside <span><strong class="command">view</strong></span> statements.
5281           </p>
5282 <p>
5283             Here is an example of a typical split DNS setup implemented
5284             using <span><strong class="command">view</strong></span> statements:
5285           </p>
5286 <pre class="programlisting">view "internal" {
5287       // This should match our internal networks.
5288       match-clients { 10.0.0.0/8; };
5289
5290       // Provide recursive service to internal clients only.
5291       recursion yes;
5292
5293       // Provide a complete view of the example.com zone
5294       // including addresses of internal hosts.
5295       zone "example.com" {
5296             type master;
5297             file "example-internal.db";
5298       };
5299 };
5300
5301 view "external" {
5302       // Match all clients not matched by the previous view.
5303       match-clients { any; };
5304
5305       // Refuse recursive service to external clients.
5306       recursion no;
5307
5308       // Provide a restricted view of the example.com zone
5309       // containing only publicly accessible hosts.
5310       zone "example.com" {
5311            type master;
5312            file "example-external.db";
5313       };
5314 };
5315 </pre>
5316 </div>
5317 <div class="sect2" lang="en">
5318 <div class="titlepage"><div><div><h3 class="title">
5319 <a name="zone_statement_grammar"></a><span><strong class="command">zone</strong></span>
5320             Statement Grammar</h3></div></div></div>
5321 <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>] {
5322     type master;
5323     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5324     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5325     [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5326     [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5327     [<span class="optional"> update-policy { <em class="replaceable"><code>update_policy_rule</code></em> [<span class="optional">...</span>] }; </span>]
5328     [<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>] ; [<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>]
5329     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5330     [<span class="optional"> check-mx (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5331     [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5332     [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5333     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
5334     [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
5335     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
5336     [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>]
5337     [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
5338     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5339     [<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>]
5340     [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>]
5341     [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5342     [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>]
5343     [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5344     [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
5345     [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
5346     [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
5347     [<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>]
5348     [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
5349     [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5350     [<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>]
5351     [<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>]
5352     [<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>]
5353     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5354     [<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>]
5355     [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>]
5356     [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>]
5357     [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>]
5358     [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
5359     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5360     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5361     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5362     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5363     [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>]
5364     [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5365 };
5366
5367 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5368     type slave;
5369     [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5370     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5371     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5372     [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5373     [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5374     [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5375     [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5376     [<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>] ; [<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>]
5377     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5378     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
5379     [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
5380     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
5381     [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>]
5382     [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
5383     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5384     [<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>]
5385     [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>]
5386     [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5387     [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>]
5388     [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5389     [<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> [<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>] }; </span>]
5390     [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
5391     [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
5392     [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
5393     [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
5394     [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
5395     [<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>]
5396     [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
5397     [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5398     [<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>]
5399     [<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>]
5400     [<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>]
5401     [<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>]
5402     [<span class="optional"> alt-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>]
5403     [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5404     [<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>]
5405     [<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>]
5406     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5407     [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
5408     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5409     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5410     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5411     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5412     [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5413     [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5414 };
5415
5416 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5417     type hint;
5418     file <em class="replaceable"><code>string</code></em> ;
5419     [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5420     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; // Not Implemented. </span>]
5421 };
5422
5423 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5424     type stub;
5425     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5426     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5427     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5428     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
5429     [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5430     [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
5431     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
5432     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5433     [<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>]
5434     [<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> [<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>] }; </span>]
5435     [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
5436     [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
5437     [<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>]
5438     [<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>]
5439     [<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>]
5440     [<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>]
5441     [<span class="optional"> alt-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>]
5442     [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5443     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5444     [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
5445     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5446     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5447     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5448     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5449     [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5450 };
5451
5452 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5453     type forward;
5454     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5455     [<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>]
5456     [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5457 };
5458
5459 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5460     type delegation-only;
5461 };
5462
5463 </pre>
5464 </div>
5465 <div class="sect2" lang="en">
5466 <div class="titlepage"><div><div><h3 class="title">
5467 <a name="id2588616"></a><span><strong class="command">zone</strong></span> Statement Definition and Usage</h3></div></div></div>
5468 <div class="sect3" lang="en">
5469 <div class="titlepage"><div><div><h4 class="title">
5470 <a name="id2588624"></a>Zone Types</h4></div></div></div>
5471 <div class="informaltable"><table border="1">
5472 <colgroup>
5473 <col>
5474 <col>
5475 </colgroup>
5476 <tbody>
5477 <tr>
5478 <td>
5479                       <p>
5480                         <code class="varname">master</code>
5481                       </p>
5482                     </td>
5483 <td>
5484                       <p>
5485                         The server has a master copy of the data
5486                         for the zone and will be able to provide authoritative
5487                         answers for
5488                         it.
5489                       </p>
5490                     </td>
5491 </tr>
5492 <tr>
5493 <td>
5494                       <p>
5495                         <code class="varname">slave</code>
5496                       </p>
5497                     </td>
5498 <td>
5499                       <p>
5500                         A slave zone is a replica of a master
5501                         zone. The <span><strong class="command">masters</strong></span> list
5502                         specifies one or more IP addresses
5503                         of master servers that the slave contacts to update
5504                         its copy of the zone.
5505                         Masters list elements can also be names of other
5506                         masters lists.
5507                         By default, transfers are made from port 53 on the
5508                         servers; this can
5509                         be changed for all servers by specifying a port number
5510                         before the
5511                         list of IP addresses, or on a per-server basis after
5512                         the IP address.
5513                         Authentication to the master can also be done with
5514                         per-server TSIG keys.
5515                         If a file is specified, then the
5516                         replica will be written to this file whenever the zone
5517                         is changed,
5518                         and reloaded from this file on a server restart. Use
5519                         of a file is
5520                         recommended, since it often speeds server startup and
5521                         eliminates
5522                         a needless waste of bandwidth. Note that for large
5523                         numbers (in the
5524                         tens or hundreds of thousands) of zones per server, it
5525                         is best to
5526                         use a two-level naming scheme for zone filenames. For
5527                         example,
5528                         a slave server for the zone <code class="literal">example.com</code> might place
5529                         the zone contents into a file called
5530                         <code class="filename">ex/example.com</code> where <code class="filename">ex/</code> is
5531                         just the first two letters of the zone name. (Most
5532                         operating systems
5533                         behave very slowly if you put 100000 files into
5534                         a single directory.)
5535                       </p>
5536                     </td>
5537 </tr>
5538 <tr>
5539 <td>
5540                       <p>
5541                         <code class="varname">stub</code>
5542                       </p>
5543                     </td>
5544 <td>
5545                       <p>
5546                         A stub zone is similar to a slave zone,
5547                         except that it replicates only the NS records of a
5548                         master zone instead
5549                         of the entire zone. Stub zones are not a standard part
5550                         of the DNS;
5551                         they are a feature specific to the <acronym class="acronym">BIND</acronym> implementation.
5552                       </p>
5553
5554                       <p>
5555                         Stub zones can be used to eliminate the need for glue
5556                         NS record
5557                         in a parent zone at the expense of maintaining a stub
5558                         zone entry and
5559                         a set of name server addresses in <code class="filename">named.conf</code>.
5560                         This usage is not recommended for new configurations,
5561                         and BIND 9
5562                         supports it only in a limited way.
5563                         In <acronym class="acronym">BIND</acronym> 4/8, zone
5564                         transfers of a parent zone
5565                         included the NS records from stub children of that
5566                         zone. This meant
5567                         that, in some cases, users could get away with
5568                         configuring child stubs
5569                         only in the master server for the parent zone. <acronym class="acronym">BIND</acronym>
5570                         9 never mixes together zone data from different zones
5571                         in this
5572                         way. Therefore, if a <acronym class="acronym">BIND</acronym> 9 master serving a parent
5573                         zone has child stub zones configured, all the slave
5574                         servers for the
5575                         parent zone also need to have the same child stub
5576                         zones
5577                         configured.
5578                       </p>
5579
5580                       <p>
5581                         Stub zones can also be used as a way of forcing the
5582                         resolution
5583                         of a given domain to use a particular set of
5584                         authoritative servers.
5585                         For example, the caching name servers on a private
5586                         network using
5587                         RFC1918 addressing may be configured with stub zones
5588                         for
5589                         <code class="literal">10.in-addr.arpa</code>
5590                         to use a set of internal name servers as the
5591                         authoritative
5592                         servers for that domain.
5593                       </p>
5594                     </td>
5595 </tr>
5596 <tr>
5597 <td>
5598                       <p>
5599                         <code class="varname">forward</code>
5600                       </p>
5601                     </td>
5602 <td>
5603                       <p>
5604                         A "forward zone" is a way to configure
5605                         forwarding on a per-domain basis.  A <span><strong class="command">zone</strong></span> statement
5606                         of type <span><strong class="command">forward</strong></span> can
5607                         contain a <span><strong class="command">forward</strong></span>
5608                         and/or <span><strong class="command">forwarders</strong></span>
5609                         statement,
5610                         which will apply to queries within the domain given by
5611                         the zone
5612                         name. If no <span><strong class="command">forwarders</strong></span>
5613                         statement is present or
5614                         an empty list for <span><strong class="command">forwarders</strong></span> is given, then no
5615                         forwarding will be done for the domain, canceling the
5616                         effects of
5617                         any forwarders in the <span><strong class="command">options</strong></span> statement. Thus
5618                         if you want to use this type of zone to change the
5619                         behavior of the
5620                         global <span><strong class="command">forward</strong></span> option
5621                         (that is, "forward first"
5622                         to, then "forward only", or vice versa, but want to
5623                         use the same
5624                         servers as set globally) you need to re-specify the
5625                         global forwarders.
5626                       </p>
5627                     </td>
5628 </tr>
5629 <tr>
5630 <td>
5631                       <p>
5632                         <code class="varname">hint</code>
5633                       </p>
5634                     </td>
5635 <td>
5636                       <p>
5637                         The initial set of root name servers is
5638                         specified using a "hint zone". When the server starts
5639                         up, it uses
5640                         the root hints to find a root name server and get the
5641                         most recent
5642                         list of root name servers. If no hint zone is
5643                         specified for class
5644                         IN, the server uses a compiled-in default set of root
5645                         servers hints.
5646                         Classes other than IN have no built-in defaults hints.
5647                       </p>
5648                     </td>
5649 </tr>
5650 <tr>
5651 <td>
5652                       <p>
5653                         <code class="varname">delegation-only</code>
5654                       </p>
5655                     </td>
5656 <td>
5657                       <p>
5658                         This is used to enforce the delegation-only
5659                         status of infrastructure zones (e.g. COM,
5660                         NET, ORG).  Any answer that is received
5661                         without an explicit or implicit delegation
5662                         in the authority section will be treated
5663                         as NXDOMAIN.  This does not apply to the
5664                         zone apex.  This should not be applied to
5665                         leaf zones.
5666                       </p>
5667                       <p>
5668                         <code class="varname">delegation-only</code> has no
5669                         effect on answers received from forwarders.
5670                       </p>
5671                       <p>
5672                         See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>.
5673                       </p>
5674                     </td>
5675 </tr>
5676 </tbody>
5677 </table></div>
5678 </div>
5679 <div class="sect3" lang="en">
5680 <div class="titlepage"><div><div><h4 class="title">
5681 <a name="id2589051"></a>Class</h4></div></div></div>
5682 <p>
5683               The zone's name may optionally be followed by a class. If
5684               a class is not specified, class <code class="literal">IN</code> (for <code class="varname">Internet</code>),
5685               is assumed. This is correct for the vast majority of cases.
5686             </p>
5687 <p>
5688               The <code class="literal">hesiod</code> class is
5689               named for an information service from MIT's Project Athena. It
5690               is
5691               used to share information about various systems databases, such
5692               as users, groups, printers and so on. The keyword
5693               <code class="literal">HS</code> is
5694               a synonym for hesiod.
5695             </p>
5696 <p>
5697               Another MIT development is Chaosnet, a LAN protocol created
5698               in the mid-1970s. Zone data for it can be specified with the <code class="literal">CHAOS</code> class.
5699             </p>
5700 </div>
5701 <div class="sect3" lang="en">
5702 <div class="titlepage"><div><div><h4 class="title">
5703 <a name="id2589221"></a>Zone Options</h4></div></div></div>
5704 <div class="variablelist"><dl>
5705 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
5706 <dd><p>
5707                     See the description of
5708                     <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>.
5709                   </p></dd>
5710 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
5711 <dd><p>
5712                     See the description of
5713                     <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>.
5714                   </p></dd>
5715 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
5716 <dd><p>
5717                     See the description of
5718                     <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>.
5719                   </p></dd>
5720 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
5721 <dd><p>
5722                     See the description of <span><strong class="command">allow-transfer</strong></span>
5723                     in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
5724                   </p></dd>
5725 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
5726 <dd><p>
5727                     See the description of <span><strong class="command">allow-update</strong></span>
5728                     in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
5729                   </p></dd>
5730 <dt><span class="term"><span><strong class="command">update-policy</strong></span></span></dt>
5731 <dd><p>
5732                     Specifies a "Simple Secure Update" policy. See
5733                     <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called &#8220;Dynamic Update Policies&#8221;</a>.
5734                   </p></dd>
5735 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
5736 <dd><p>
5737                     See the description of <span><strong class="command">allow-update-forwarding</strong></span>
5738                     in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
5739                   </p></dd>
5740 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
5741 <dd><p>
5742                     Only meaningful if <span><strong class="command">notify</strong></span>
5743                     is
5744                     active for this zone. The set of machines that will
5745                     receive a
5746                     <code class="literal">DNS NOTIFY</code> message
5747                     for this zone is made up of all the listed name servers
5748                     (other than
5749                     the primary master) for the zone plus any IP addresses
5750                     specified
5751                     with <span><strong class="command">also-notify</strong></span>. A port
5752                     may be specified
5753                     with each <span><strong class="command">also-notify</strong></span>
5754                     address to send the notify
5755                     messages to a port other than the default of 53.
5756                     <span><strong class="command">also-notify</strong></span> is not
5757                     meaningful for stub zones.
5758                     The default is the empty list.
5759                   </p></dd>
5760 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
5761 <dd><p>
5762                     This option is used to restrict the character set and
5763                     syntax of
5764                     certain domain names in master files and/or DNS responses
5765                     received from the
5766                     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>
5767                     zones the default is <span><strong class="command">warn</strong></span>.
5768                   </p></dd>
5769 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
5770 <dd><p>
5771                     See the description of
5772                     <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>.
5773                   </p></dd>
5774 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
5775 <dd><p>
5776                     See the description of
5777                     <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>.
5778                   </p></dd>
5779 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
5780 <dd><p>
5781                     See the description of
5782                     <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>.
5783                   </p></dd>
5784 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
5785 <dd><p>
5786                     See the description of
5787                     <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>.
5788                   </p></dd>
5789 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
5790 <dd><p>
5791                     See the description of
5792                     <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>.
5793                   </p></dd>
5794 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
5795 <dd><p>
5796                     See the description of
5797                     <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>.
5798                   </p></dd>
5799 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
5800 <dd><p>
5801                     See the description of
5802                     <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>.
5803                   </p></dd>
5804 <dt><span class="term"><span><strong class="command">database</strong></span></span></dt>
5805 <dd>
5806 <p>
5807                     Specify the type of database to be used for storing the
5808                     zone data.  The string following the <span><strong class="command">database</strong></span> keyword
5809                     is interpreted as a list of whitespace-delimited words.
5810                     The first word
5811                     identifies the database type, and any subsequent words are
5812                     passed
5813                     as arguments to the database to be interpreted in a way
5814                     specific
5815                     to the database type.
5816                   </p>
5817 <p>
5818                     The default is <strong class="userinput"><code>"rbt"</code></strong>, BIND 9's
5819                     native in-memory
5820                     red-black-tree database.  This database does not take
5821                     arguments.
5822                   </p>
5823 <p>
5824                     Other values are possible if additional database drivers
5825                     have been linked into the server.  Some sample drivers are
5826                     included
5827                     with the distribution but none are linked in by default.
5828                   </p>
5829 </dd>
5830 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
5831 <dd><p>
5832                     See the description of
5833                     <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>.
5834                   </p></dd>
5835 <dt><span class="term"><span><strong class="command">delegation-only</strong></span></span></dt>
5836 <dd>
5837 <p>
5838                     The flag only applies to hint and stub zones.  If set
5839                     to <strong class="userinput"><code>yes</code></strong>, then the zone will also be
5840                     treated as if it is also a delegation-only type zone.
5841                   </p>
5842 <p>
5843                     See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>.
5844                   </p>
5845 </dd>
5846 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
5847 <dd><p>
5848                     Only meaningful if the zone has a forwarders
5849                     list. The <span><strong class="command">only</strong></span> value causes
5850                     the lookup to fail
5851                     after trying the forwarders and getting no answer, while <span><strong class="command">first</strong></span> would
5852                     allow a normal lookup to be tried.
5853                   </p></dd>
5854 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
5855 <dd><p>
5856                     Used to override the list of global forwarders.
5857                     If it is not specified in a zone of type <span><strong class="command">forward</strong></span>,
5858                     no forwarding is done for the zone and the global options are
5859                     not used.
5860                   </p></dd>
5861 <dt><span class="term"><span><strong class="command">ixfr-base</strong></span></span></dt>
5862 <dd><p>
5863                     Was used in <acronym class="acronym">BIND</acronym> 8 to
5864                     specify the name
5865                     of the transaction log (journal) file for dynamic update
5866                     and IXFR.
5867                     <acronym class="acronym">BIND</acronym> 9 ignores the option
5868                     and constructs the name of the journal
5869                     file by appending "<code class="filename">.jnl</code>"
5870                     to the name of the
5871                     zone file.
5872                   </p></dd>
5873 <dt><span class="term"><span><strong class="command">ixfr-tmp-file</strong></span></span></dt>
5874 <dd><p>
5875                     Was an undocumented option in <acronym class="acronym">BIND</acronym> 8.
5876                     Ignored in <acronym class="acronym">BIND</acronym> 9.
5877                   </p></dd>
5878 <dt><span class="term"><span><strong class="command">journal</strong></span></span></dt>
5879 <dd><p>
5880                     Allow the default journal's filename to be overridden.
5881                     The default is the zone's filename with "<code class="filename">.jnl</code>" appended.
5882                     This is applicable to <span><strong class="command">master</strong></span> and <span><strong class="command">slave</strong></span> zones.
5883                   </p></dd>
5884 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
5885 <dd><p>
5886                     See the description of
5887                     <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>.
5888                   </p></dd>
5889 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
5890 <dd><p>
5891                     See the description of
5892                     <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>.
5893                   </p></dd>
5894 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
5895 <dd><p>
5896                     See the description of
5897                     <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>.
5898                   </p></dd>
5899 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
5900 <dd><p>
5901                     See the description of
5902                     <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>.
5903                   </p></dd>
5904 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
5905 <dd><p>
5906                     See the description of
5907                     <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>.
5908                   </p></dd>
5909 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
5910 <dd><p>
5911                     See the description of
5912                     <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>.
5913                   </p></dd>
5914 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
5915 <dd><p>
5916                     See the description of
5917                     <span><strong class="command">notify-delay</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
5918                   </p></dd>
5919 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
5920 <dd><p>
5921                     See the description of
5922                     <span><strong class="command">notify-to-soa</strong></span> in
5923                     <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
5924                   </p></dd>
5925 <dt><span class="term"><span><strong class="command">pubkey</strong></span></span></dt>
5926 <dd><p>
5927                     In <acronym class="acronym">BIND</acronym> 8, this option was
5928                     intended for specifying
5929                     a public zone key for verification of signatures in DNSSEC
5930                     signed
5931                     zones when they are loaded from disk. <acronym class="acronym">BIND</acronym> 9 does not verify signatures
5932                     on load and ignores the option.
5933                   </p></dd>
5934 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
5935 <dd><p>
5936                     If <strong class="userinput"><code>yes</code></strong>, the server will keep
5937                     statistical
5938                     information for this zone, which can be dumped to the
5939                     <span><strong class="command">statistics-file</strong></span> defined in
5940                     the server options.
5941                   </p></dd>
5942 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
5943 <dd><p>
5944                     See the description of
5945                     <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>.
5946                   </p></dd>
5947 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
5948 <dd><p>
5949                     See the description of
5950                     <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>.
5951                   </p></dd>
5952 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
5953 <dd><p>
5954                     See the description of
5955                     <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>.
5956                   </p></dd>
5957 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
5958 <dd><p>
5959                     See the description of
5960                     <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>.
5961                   </p></dd>
5962 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
5963 <dd><p>
5964                     See the description of
5965                     <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>.
5966                   </p></dd>
5967 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
5968 <dd><p>
5969                     See the description of
5970                     <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>.
5971                   </p></dd>
5972 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
5973 <dd><p>
5974                     See the description of
5975                     <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>.
5976                   </p></dd>
5977 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
5978 <dd><p>
5979                     See the description of
5980                     <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>.
5981                   </p></dd>
5982 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
5983 <dd><p>
5984                     See the description of
5985                     <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>.
5986                   </p></dd>
5987 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
5988 <dd><p>
5989                     See the description of
5990                     <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>.
5991                   </p></dd>
5992 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
5993 <dd><p>
5994                     See the description of
5995                     <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>.
5996                   </p></dd>
5997 <dt>
5998 <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>
5999 </dt>
6000 <dd><p>
6001                     See the description in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
6002                   </p></dd>
6003 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
6004 <dd><p>
6005                     See the description of
6006                     <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>.
6007                     (Note that the <span><strong class="command">ixfr-from-differences</strong></span>
6008                     <strong class="userinput"><code>master</code></strong> and
6009                     <strong class="userinput"><code>slave</code></strong> choices are not
6010                     available at the zone level.)
6011                   </p></dd>
6012 <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt>
6013 <dd><p>
6014                     See the description of
6015                     <span><strong class="command">key-directory</strong></span> in <a href="Bv9ARM.ch06.html#options" title="options Statement Definition and
6016           Usage">the section called &#8220;<span><strong class="command">options</strong></span> Statement Definition and
6017           Usage&#8221;</a>.
6018                   </p></dd>
6019 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
6020 <dd><p>
6021                     See the description of <span><strong class="command">multi-master</strong></span> in
6022                     <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
6023                   </p></dd>
6024 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
6025 <dd><p>
6026                     See the description of <span><strong class="command">masterfile-format</strong></span>
6027                     in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
6028                   </p></dd>
6029 </dl></div>
6030 </div>
6031 <div class="sect3" lang="en">
6032 <div class="titlepage"><div><div><h4 class="title">
6033 <a name="dynamic_update_policies"></a>Dynamic Update Policies</h4></div></div></div>
6034 <p><acronym class="acronym">BIND</acronym> 9 supports two alternative
6035               methods of granting clients the right to perform
6036               dynamic updates to a zone, configured by the
6037               <span><strong class="command">allow-update</strong></span> and
6038               <span><strong class="command">update-policy</strong></span> option, respectively.
6039             </p>
6040 <p>
6041               The <span><strong class="command">allow-update</strong></span> clause works the
6042               same way as in previous versions of <acronym class="acronym">BIND</acronym>.
6043               It grants given clients the permission to update any
6044               record of any name in the zone.
6045             </p>
6046 <p>
6047               The <span><strong class="command">update-policy</strong></span> clause is new
6048               in <acronym class="acronym">BIND</acronym> 9 and allows more fine-grained
6049               control over what updates are allowed.  A set of rules
6050               is specified, where each rule either grants or denies
6051               permissions for one or more names to be updated by
6052               one or more identities.  If the dynamic update request
6053               message is signed (that is, it includes either a TSIG
6054               or SIG(0) record), the identity of the signer can be
6055               determined.
6056             </p>
6057 <p>
6058               Rules are specified in the <span><strong class="command">update-policy</strong></span>
6059               zone option, and are only meaningful for master zones.
6060               When the <span><strong class="command">update-policy</strong></span> statement
6061               is present, it is a configuration error for the
6062               <span><strong class="command">allow-update</strong></span> statement to be
6063               present.  The <span><strong class="command">update-policy</strong></span> statement
6064               only examines the signer of a message; the source
6065               address is not relevant.
6066             </p>
6067 <p>
6068               This is how a rule definition looks:
6069             </p>
6070 <pre class="programlisting">
6071 ( <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> <em class="replaceable"><code>name</code></em> [<span class="optional"> <em class="replaceable"><code>types</code></em> </span>]
6072 </pre>
6073 <p>
6074               Each rule grants or denies privileges.  Once a message has
6075               successfully matched a rule, the operation is immediately
6076               granted
6077               or denied and no further rules are examined.  A rule is matched
6078               when the signer matches the identity field, the name matches the
6079               name field in accordance with the nametype field, and the type
6080               matches
6081               the types specified in the type field.
6082             </p>
6083 <p>
6084               No signer is required for <em class="replaceable"><code>tcp-self</code></em>
6085               or <em class="replaceable"><code>6to4-self</code></em> however the standard
6086               reverse mapping / prefix conversion must match the identity
6087               field.
6088             </p>
6089 <p>
6090               The identity field specifies a name or a wildcard
6091               name.  Normally, this is the name of the TSIG or
6092               SIG(0) key used to sign the update request.  When a
6093               TKEY exchange has been used to create a shared secret,
6094               the identity of the shared secret is the same as the
6095               identity of the key used to authenticate the TKEY
6096               exchange.  TKEY is also the negotiation method used
6097               by GSS-TSIG, which establishes an identity that is
6098               the Kerberos principal of the client, such as
6099               <strong class="userinput"><code>"user@host.domain"</code></strong>.  When the
6100               <em class="replaceable"><code>identity</code></em> field specifies
6101               a wildcard name, it is subject to DNS wildcard
6102               expansion, so the rule will apply to multiple identities.
6103               The <em class="replaceable"><code>identity</code></em> field must
6104               contain a fully-qualified domain name.
6105             </p>
6106 <p>
6107               For nametypes <code class="varname">krb5-self</code>,
6108               <code class="varname">ms-self</code>, <code class="varname">krb5-subdomain</code>,
6109               and <code class="varname">ms-subdomain</code> the
6110               <em class="replaceable"><code>identity</code></em> field specifies
6111               the Windows or Kerberos realm of the machine belongs to.
6112             </p>
6113 <p>
6114               The <em class="replaceable"><code>nametype</code></em> field has 12
6115               values:
6116               <code class="varname">name</code>, <code class="varname">subdomain</code>,
6117               <code class="varname">wildcard</code>, <code class="varname">self</code>,
6118               <code class="varname">selfsub</code>, <code class="varname">selfwild</code>,
6119               <code class="varname">krb5-self</code>, <code class="varname">ms-self</code>,
6120               <code class="varname">krb5-subdomain</code>,
6121               <code class="varname">ms-subdomain</code>,
6122               <code class="varname">tcp-self</code> and <code class="varname">6to4-self</code>.
6123             </p>
6124 <div class="informaltable"><table border="1">
6125 <colgroup>
6126 <col>
6127 <col>
6128 </colgroup>
6129 <tbody>
6130 <tr>
6131 <td>
6132                       <p>
6133                         <code class="varname">name</code>
6134                       </p>
6135                     </td>
6136 <td>
6137                       <p>
6138                         Exact-match semantics.  This rule matches
6139                         when the name being updated is identical
6140                         to the contents of the
6141                         <em class="replaceable"><code>name</code></em> field.
6142                       </p>
6143                     </td>
6144 </tr>
6145 <tr>
6146 <td>
6147                       <p>
6148                         <code class="varname">subdomain</code>
6149                       </p>
6150                     </td>
6151 <td>
6152                       <p>
6153                         This rule matches when the name being updated
6154                         is a subdomain of, or identical to, the
6155                         contents of the <em class="replaceable"><code>name</code></em>
6156                         field.
6157                       </p>
6158                     </td>
6159 </tr>
6160 <tr>
6161 <td>
6162                       <p>
6163                         <code class="varname">wildcard</code>
6164                       </p>
6165                     </td>
6166 <td>
6167                       <p>
6168                         The <em class="replaceable"><code>name</code></em> field
6169                         is subject to DNS wildcard expansion, and
6170                         this rule matches when the name being updated
6171                         name is a valid expansion of the wildcard.
6172                       </p>
6173                     </td>
6174 </tr>
6175 <tr>
6176 <td>
6177                       <p>
6178                         <code class="varname">self</code>
6179                       </p>
6180                     </td>
6181 <td>
6182                       <p>
6183                         This rule matches when the name being updated
6184                         matches the contents of the
6185                         <em class="replaceable"><code>identity</code></em> field.
6186                         The <em class="replaceable"><code>name</code></em> field
6187                         is ignored, but should be the same as the
6188                         <em class="replaceable"><code>identity</code></em> field.
6189                         The <code class="varname">self</code> nametype is
6190                         most useful when allowing using one key per
6191                         name to update, where the key has the same
6192                         name as the name to be updated.  The
6193                         <em class="replaceable"><code>identity</code></em> would
6194                         be specified as <code class="constant">*</code> (an asterisk) in
6195                         this case.
6196                       </p>
6197                     </td>
6198 </tr>
6199 <tr>
6200 <td>
6201                       <p>
6202                         <code class="varname">selfsub</code>
6203                       </p>
6204                     </td>
6205 <td>
6206                       <p>
6207                         This rule is similar to <code class="varname">self</code>
6208                         except that subdomains of <code class="varname">self</code>
6209                         can also be updated.
6210                       </p>
6211                     </td>
6212 </tr>
6213 <tr>
6214 <td>
6215                       <p>
6216                         <code class="varname">selfwild</code>
6217                       </p>
6218                     </td>
6219 <td>
6220                       <p>
6221                         This rule is similar to <code class="varname">self</code>
6222                         except that only subdomains of
6223                         <code class="varname">self</code> can be updated.
6224                       </p>
6225                     </td>
6226 </tr>
6227 <tr>
6228 <td>
6229                       <p>
6230                         <code class="varname">ms-self</code>
6231                       </p>
6232                     </td>
6233 <td>
6234                       <p>
6235                         This rule takes a Windows machine principal
6236                         (machine$@REALM) for machine in REALM and
6237                         and converts it machine.realm allowing the machine
6238                         to update machine.realm.  The REALM to be matched
6239                         is specified in the <font color="red">&lt;replacable&gt;identity&lt;/replacable&gt;</font>
6240                         field.
6241                       </p>
6242                     </td>
6243 </tr>
6244 <tr>
6245 <td>
6246                       <p>
6247                         <code class="varname">ms-subdomain</code>
6248                       </p>
6249                     </td>
6250 <td>
6251                       <p>
6252                         This rule takes a Windows machine principal
6253                         (machine$@REALM) for machine in REALM and
6254                         converts it to machine.realm allowing the machine
6255                         to update subdomains of machine.realm.  The REALM
6256                         to be matched is specified in the
6257                         <font color="red">&lt;replacable&gt;identity&lt;/replacable&gt;</font> field.
6258                       </p>
6259                     </td>
6260 </tr>
6261 <tr>
6262 <td>
6263                       <p>
6264                         <code class="varname">krb5-self</code>
6265                       </p>
6266                     </td>
6267 <td>
6268                       <p>
6269                         This rule takes a Kerberos machine principal
6270                         (host/machine@REALM) for machine in REALM and
6271                         and converts it machine.realm allowing the machine
6272                         to update machine.realm.  The REALM to be matched
6273                         is specified in the <font color="red">&lt;replacable&gt;identity&lt;/replacable&gt;</font>
6274                         field.
6275                       </p>
6276                     </td>
6277 </tr>
6278 <tr>
6279 <td>
6280                       <p>
6281                         <code class="varname">krb5-subdomain</code>
6282                       </p>
6283                     </td>
6284 <td>
6285                       <p>
6286                         This rule takes a Kerberos machine principal
6287                         (host/machine@REALM) for machine in REALM and
6288                         converts it to machine.realm allowing the machine
6289                         to update subdomains of machine.realm.  The REALM
6290                         to be matched is specified in the
6291                         <font color="red">&lt;replacable&gt;identity&lt;/replacable&gt;</font> field.
6292                       </p>
6293                     </td>
6294 </tr>
6295 <tr>
6296 <td>
6297                       <p>
6298                         <code class="varname">tcp-self</code>
6299                       </p>
6300                     </td>
6301 <td>
6302                       <p>
6303                         Allow updates that have been sent via TCP and
6304                         for which the standard mapping from the initiating
6305                         IP address into the IN-ADDR.ARPA and IP6.ARPA
6306                         namespaces match the name to be updated.
6307                       </p>
6308                       <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
6309 <h3 class="title">Note</h3>
6310                         It is theoretically possible to spoof these TCP
6311                         sessions.
6312                       </div>
6313                     </td>
6314 </tr>
6315 <tr>
6316 <td>
6317                       <p>
6318                         <code class="varname">6to4-self</code>
6319                       </p>
6320                     </td>
6321 <td>
6322                       <p>
6323                         Allow the 6to4 prefix to be update by any TCP
6324                         conection from the 6to4 network or from the
6325                         corresponding IPv4 address.  This is intended
6326                         to allow NS or DNAME RRsets to be added to the
6327                         reverse tree.
6328                       </p>
6329                       <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
6330 <h3 class="title">Note</h3>
6331                         It is theoretically possible to spoof these TCP
6332                         sessions.
6333                       </div>
6334                     </td>
6335 </tr>
6336 </tbody>
6337 </table></div>
6338 <p>
6339               In all cases, the <em class="replaceable"><code>name</code></em>
6340               field must
6341               specify a fully-qualified domain name.
6342             </p>
6343 <p>
6344               If no types are explicitly specified, this rule matches
6345               all types except RRSIG, NS, SOA, NSEC and NSEC3. Types
6346               may be specified by name, including "ANY" (ANY matches
6347               all types except NSEC and NSEC3, which can never be
6348               updated).  Note that when an attempt is made to delete
6349               all records associated with a name, the rules are
6350               checked for each existing record type.
6351             </p>
6352 </div>
6353 </div>
6354 </div>
6355 <div class="sect1" lang="en">
6356 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
6357 <a name="id2591300"></a>Zone File</h2></div></div></div>
6358 <div class="sect2" lang="en">
6359 <div class="titlepage"><div><div><h3 class="title">
6360 <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>
6361 <p>
6362             This section, largely borrowed from RFC 1034, describes the
6363             concept of a Resource Record (RR) and explains when each is used.
6364             Since the publication of RFC 1034, several new RRs have been
6365             identified
6366             and implemented in the DNS. These are also included.
6367           </p>
6368 <div class="sect3" lang="en">
6369 <div class="titlepage"><div><div><h4 class="title">
6370 <a name="id2591318"></a>Resource Records</h4></div></div></div>
6371 <p>
6372               A domain name identifies a node.  Each node has a set of
6373               resource information, which may be empty.  The set of resource
6374               information associated with a particular name is composed of
6375               separate RRs. The order of RRs in a set is not significant and
6376               need not be preserved by name servers, resolvers, or other
6377               parts of the DNS. However, sorting of multiple RRs is
6378               permitted for optimization purposes, for example, to specify
6379               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>.
6380             </p>
6381 <p>
6382               The components of a Resource Record are:
6383             </p>
6384 <div class="informaltable"><table border="1">
6385 <colgroup>
6386 <col>
6387 <col>
6388 </colgroup>
6389 <tbody>
6390 <tr>
6391 <td>
6392                       <p>
6393                         owner name
6394                       </p>
6395                     </td>
6396 <td>
6397                       <p>
6398                         The domain name where the RR is found.
6399                       </p>
6400                     </td>
6401 </tr>
6402 <tr>
6403 <td>
6404                       <p>
6405                         type
6406                       </p>
6407                     </td>
6408 <td>
6409                       <p>
6410                         An encoded 16-bit value that specifies
6411                         the type of the resource record.
6412                       </p>
6413                     </td>
6414 </tr>
6415 <tr>
6416 <td>
6417                       <p>
6418                         TTL
6419                       </p>
6420                     </td>
6421 <td>
6422                       <p>
6423                         The time-to-live of the RR. This field
6424                         is a 32-bit integer in units of seconds, and is
6425                         primarily used by
6426                         resolvers when they cache RRs. The TTL describes how
6427                         long a RR can
6428                         be cached before it should be discarded.
6429                       </p>
6430                     </td>
6431 </tr>
6432 <tr>
6433 <td>
6434                       <p>
6435                         class
6436                       </p>
6437                     </td>
6438 <td>
6439                       <p>
6440                         An encoded 16-bit value that identifies
6441                         a protocol family or instance of a protocol.
6442                       </p>
6443                     </td>
6444 </tr>
6445 <tr>
6446 <td>
6447                       <p>
6448                         RDATA
6449                       </p>
6450                     </td>
6451 <td>
6452                       <p>
6453                         The resource data.  The format of the
6454                         data is type (and sometimes class) specific.
6455                       </p>
6456                     </td>
6457 </tr>
6458 </tbody>
6459 </table></div>
6460 <p>
6461               The following are <span class="emphasis"><em>types</em></span> of valid RRs:
6462             </p>
6463 <div class="informaltable"><table border="1">
6464 <colgroup>
6465 <col>
6466 <col>
6467 </colgroup>
6468 <tbody>
6469 <tr>
6470 <td>
6471                       <p>
6472                         A
6473                       </p>
6474                     </td>
6475 <td>
6476                       <p>
6477                         A host address.  In the IN class, this is a
6478                         32-bit IP address.  Described in RFC 1035.
6479                       </p>
6480                     </td>
6481 </tr>
6482 <tr>
6483 <td>
6484                       <p>
6485                         AAAA
6486                       </p>
6487                     </td>
6488 <td>
6489                       <p>
6490                         IPv6 address.  Described in RFC 1886.
6491                       </p>
6492                     </td>
6493 </tr>
6494 <tr>
6495 <td>
6496                       <p>
6497                         A6
6498                       </p>
6499                     </td>
6500 <td>
6501                       <p>
6502                         IPv6 address.  This can be a partial
6503                         address (a suffix) and an indirection to the name
6504                         where the rest of the
6505                         address (the prefix) can be found.  Experimental.
6506                         Described in RFC 2874.
6507                       </p>
6508                     </td>
6509 </tr>
6510 <tr>
6511 <td>
6512                       <p>
6513                         AFSDB
6514                       </p>
6515                     </td>
6516 <td>
6517                       <p>
6518                         Location of AFS database servers.
6519                         Experimental.  Described in RFC 1183.
6520                       </p>
6521                     </td>
6522 </tr>
6523 <tr>
6524 <td>
6525                       <p>
6526                         APL
6527                       </p>
6528                     </td>
6529 <td>
6530                       <p>
6531                         Address prefix list.  Experimental.
6532                         Described in RFC 3123.
6533                       </p>
6534                     </td>
6535 </tr>
6536 <tr>
6537 <td>
6538                       <p>
6539                         CERT
6540                       </p>
6541                     </td>
6542 <td>
6543                       <p>
6544                         Holds a digital certificate.
6545                         Described in RFC 2538.
6546                       </p>
6547                     </td>
6548 </tr>
6549 <tr>
6550 <td>
6551                       <p>
6552                         CNAME
6553                       </p>
6554                     </td>
6555 <td>
6556                       <p>
6557                         Identifies the canonical name of an alias.
6558                         Described in RFC 1035.
6559                       </p>
6560                     </td>
6561 </tr>
6562 <tr>
6563 <td>
6564                       <p>
6565                         DHCID
6566                       </p>
6567                     </td>
6568 <td>
6569                       <p>
6570                         Is used for identifying which DHCP client is
6571                         associated with this name.  Described in RFC 4701.
6572                       </p>
6573                     </td>
6574 </tr>
6575 <tr>
6576 <td>
6577                       <p>
6578                         DNAME
6579                       </p>
6580                     </td>
6581 <td>
6582                       <p>
6583                         Replaces the domain name specified with
6584                         another name to be looked up, effectively aliasing an
6585                         entire
6586                         subtree of the domain name space rather than a single
6587                         record
6588                         as in the case of the CNAME RR.
6589                         Described in RFC 2672.
6590                       </p>
6591                     </td>
6592 </tr>
6593 <tr>
6594 <td>
6595                       <p>
6596                         DNSKEY
6597                       </p>
6598                     </td>
6599 <td>
6600                       <p>
6601                         Stores a public key associated with a signed
6602                         DNS zone.  Described in RFC 4034.
6603                       </p>
6604                     </td>
6605 </tr>
6606 <tr>
6607 <td>
6608                       <p>
6609                         DS
6610                       </p>
6611                     </td>
6612 <td>
6613                       <p>
6614                         Stores the hash of a public key associated with a
6615                         signed DNS zone.  Described in RFC 4034.
6616                       </p>
6617                     </td>
6618 </tr>
6619 <tr>
6620 <td>
6621                       <p>
6622                         GPOS
6623                       </p>
6624                     </td>
6625 <td>
6626                       <p>
6627                         Specifies the global position.  Superseded by LOC.
6628                       </p>
6629                     </td>
6630 </tr>
6631 <tr>
6632 <td>
6633                       <p>
6634                         HINFO
6635                       </p>
6636                     </td>
6637 <td>
6638                       <p>
6639                         Identifies the CPU and OS used by a host.
6640                         Described in RFC 1035.
6641                       </p>
6642                     </td>
6643 </tr>
6644 <tr>
6645 <td>
6646                       <p>
6647                         IPSECKEY
6648                       </p>
6649                     </td>
6650 <td>
6651                       <p>
6652                         Provides a method for storing IPsec keying material in
6653                         DNS.  Described in RFC 4025.
6654                       </p>
6655                     </td>
6656 </tr>
6657 <tr>
6658 <td>
6659                       <p>
6660                         ISDN
6661                       </p>
6662                     </td>
6663 <td>
6664                       <p>
6665                         Representation of ISDN addresses.
6666                         Experimental.  Described in RFC 1183.
6667                       </p>
6668                     </td>
6669 </tr>
6670 <tr>
6671 <td>
6672                       <p>
6673                         KEY
6674                       </p>
6675                     </td>
6676 <td>
6677                       <p>
6678                         Stores a public key associated with a
6679                         DNS name.  Used in original DNSSEC; replaced
6680                         by DNSKEY in DNSSECbis, but still used with
6681                         SIG(0).  Described in RFCs 2535 and 2931.
6682                       </p>
6683                     </td>
6684 </tr>
6685 <tr>
6686 <td>
6687                       <p>
6688                         KX
6689                       </p>
6690                     </td>
6691 <td>
6692                       <p>
6693                         Identifies a key exchanger for this
6694                         DNS name.  Described in RFC 2230.
6695                       </p>
6696                     </td>
6697 </tr>
6698 <tr>
6699 <td>
6700                       <p>
6701                         LOC
6702                       </p>
6703                     </td>
6704 <td>
6705                       <p>
6706                         For storing GPS info.  Described in RFC 1876.
6707                         Experimental.
6708                       </p>
6709                     </td>
6710 </tr>
6711 <tr>
6712 <td>
6713                       <p>
6714                         MX
6715                       </p>
6716                     </td>
6717 <td>
6718                       <p>
6719                         Identifies a mail exchange for the domain with
6720                         a 16-bit preference value (lower is better)
6721                         followed by the host name of the mail exchange.
6722                         Described in RFC 974, RFC 1035.
6723                       </p>
6724                     </td>
6725 </tr>
6726 <tr>
6727 <td>
6728                       <p>
6729                         NAPTR
6730                       </p>
6731                     </td>
6732 <td>
6733                       <p>
6734                         Name authority pointer.  Described in RFC 2915.
6735                       </p>
6736                     </td>
6737 </tr>
6738 <tr>
6739 <td>
6740                       <p>
6741                         NSAP
6742                       </p>
6743                     </td>
6744 <td>
6745                       <p>
6746                         A network service access point.
6747                         Described in RFC 1706.
6748                       </p>
6749                     </td>
6750 </tr>
6751 <tr>
6752 <td>
6753                       <p>
6754                         NS
6755                       </p>
6756                     </td>
6757 <td>
6758                       <p>
6759                         The authoritative name server for the
6760                         domain.  Described in RFC 1035.
6761                       </p>
6762                     </td>
6763 </tr>
6764 <tr>
6765 <td>
6766                       <p>
6767                         NSEC
6768                       </p>
6769                     </td>
6770 <td>
6771                       <p>
6772                         Used in DNSSECbis to securely indicate that
6773                         RRs with an owner name in a certain name interval do
6774                         not exist in
6775                         a zone and indicate what RR types are present for an
6776                         existing name.
6777                         Described in RFC 4034.
6778                       </p>
6779                     </td>
6780 </tr>
6781 <tr>
6782 <td>
6783                       <p>
6784                         NSEC3
6785                       </p>
6786                     </td>
6787 <td>
6788                       <p>
6789                         Used in DNSSECbis to securely indicate that
6790                         RRs with an owner name in a certain name
6791                         interval do not exist in a zone and indicate
6792                         what RR types are present for an existing
6793                         name.  NSEC3 differs from NSEC in that it
6794                         prevents zone enumeration but is more
6795                         computationally expensive on both the server
6796                         and the client than NSEC.  Described in RFC
6797                         5155.
6798                       </p>
6799                     </td>
6800 </tr>
6801 <tr>
6802 <td>
6803                       <p>
6804                         NSEC3PARAM
6805                       </p>
6806                     </td>
6807 <td>
6808                       <p>
6809                         Used in DNSSECbis to tell the authoritative
6810                         server which NSEC3 chains are available to use.
6811                         Described in RFC 5155.
6812                       </p>
6813                     </td>
6814 </tr>
6815 <tr>
6816 <td>
6817                       <p>
6818                         NXT
6819                       </p>
6820                     </td>
6821 <td>
6822                       <p>
6823                         Used in DNSSEC to securely indicate that
6824                         RRs with an owner name in a certain name interval do
6825                         not exist in
6826                         a zone and indicate what RR types are present for an
6827                         existing name.
6828                         Used in original DNSSEC; replaced by NSEC in
6829                         DNSSECbis.
6830                         Described in RFC 2535.
6831                       </p>
6832                     </td>
6833 </tr>
6834 <tr>
6835 <td>
6836                       <p>
6837                         PTR
6838                       </p>
6839                     </td>
6840 <td>
6841                       <p>
6842                         A pointer to another part of the domain
6843                         name space.  Described in RFC 1035.
6844                       </p>
6845                     </td>
6846 </tr>
6847 <tr>
6848 <td>
6849                       <p>
6850                         PX
6851                       </p>
6852                     </td>
6853 <td>
6854                       <p>
6855                         Provides mappings between RFC 822 and X.400
6856                         addresses.  Described in RFC 2163.
6857                       </p>
6858                     </td>
6859 </tr>
6860 <tr>
6861 <td>
6862                       <p>
6863                         RP
6864                       </p>
6865                     </td>
6866 <td>
6867                       <p>
6868                         Information on persons responsible
6869                         for the domain.  Experimental.  Described in RFC 1183.
6870                       </p>
6871                     </td>
6872 </tr>
6873 <tr>
6874 <td>
6875                       <p>
6876                         RRSIG
6877                       </p>
6878                     </td>
6879 <td>
6880                       <p>
6881                         Contains DNSSECbis signature data.  Described
6882                         in RFC 4034.
6883                       </p>
6884                     </td>
6885 </tr>
6886 <tr>
6887 <td>
6888                       <p>
6889                         RT
6890                       </p>
6891                     </td>
6892 <td>
6893                       <p>
6894                         Route-through binding for hosts that
6895                         do not have their own direct wide area network
6896                         addresses.
6897                         Experimental.  Described in RFC 1183.
6898                       </p>
6899                     </td>
6900 </tr>
6901 <tr>
6902 <td>
6903                       <p>
6904                         SIG
6905                       </p>
6906                     </td>
6907 <td>
6908                       <p>
6909                         Contains DNSSEC signature data.  Used in
6910                         original DNSSEC; replaced by RRSIG in
6911                         DNSSECbis, but still used for SIG(0).
6912                         Described in RFCs 2535 and 2931.
6913                       </p>
6914                     </td>
6915 </tr>
6916 <tr>
6917 <td>
6918                       <p>
6919                         SOA
6920                       </p>
6921                     </td>
6922 <td>
6923                       <p>
6924                         Identifies the start of a zone of authority.
6925                         Described in RFC 1035.
6926                       </p>
6927                     </td>
6928 </tr>
6929 <tr>
6930 <td>
6931                       <p>
6932                         SPF
6933                       </p>
6934                     </td>
6935 <td>
6936                       <p>
6937                         Contains the Sender Policy Framework information
6938                         for a given email domain.  Described in RFC 4408.
6939                       </p>
6940                     </td>
6941 </tr>
6942 <tr>
6943 <td>
6944                       <p>
6945                         SRV
6946                       </p>
6947                     </td>
6948 <td>
6949                       <p>
6950                         Information about well known network
6951                         services (replaces WKS).  Described in RFC 2782.
6952                       </p>
6953                     </td>
6954 </tr>
6955 <tr>
6956 <td>
6957                       <p>
6958                         SSHFP
6959                       </p>
6960                     </td>
6961 <td>
6962                       <p>
6963                         Provides a way to securely publish a secure shell key's
6964                         fingerprint.  Described in RFC 4255.
6965                       </p>
6966                     </td>
6967 </tr>
6968 <tr>
6969 <td>
6970                       <p>
6971                         TXT
6972                       </p>
6973                     </td>
6974 <td>
6975                       <p>
6976                         Text records.  Described in RFC 1035.
6977                       </p>
6978                     </td>
6979 </tr>
6980 <tr>
6981 <td>
6982                       <p>
6983                         WKS
6984                       </p>
6985                     </td>
6986 <td>
6987                       <p>
6988                         Information about which well known
6989                         network services, such as SMTP, that a domain
6990                         supports. Historical.
6991                       </p>
6992                     </td>
6993 </tr>
6994 <tr>
6995 <td>
6996                       <p>
6997                         X25
6998                       </p>
6999                     </td>
7000 <td>
7001                       <p>
7002                         Representation of X.25 network addresses.
7003                         Experimental.  Described in RFC 1183.
7004                       </p>
7005                     </td>
7006 </tr>
7007 </tbody>
7008 </table></div>
7009 <p>
7010               The following <span class="emphasis"><em>classes</em></span> of resource records
7011               are currently valid in the DNS:
7012             </p>
7013 <div class="informaltable"><table border="1">
7014 <colgroup>
7015 <col>
7016 <col>
7017 </colgroup>
7018 <tbody>
7019 <tr>
7020 <td>
7021                       <p>
7022                         IN
7023                       </p>
7024                     </td>
7025 <td>
7026                       <p>
7027                         The Internet.
7028                       </p>
7029                     </td>
7030 </tr>
7031 <tr>
7032 <td>
7033                       <p>
7034                         CH
7035                       </p>
7036                     </td>
7037 <td>
7038                       <p>
7039                         Chaosnet, a LAN protocol created at MIT in the
7040                         mid-1970s.
7041                         Rarely used for its historical purpose, but reused for
7042                         BIND's
7043                         built-in server information zones, e.g.,
7044                         <code class="literal">version.bind</code>.
7045                       </p>
7046                     </td>
7047 </tr>
7048 <tr>
7049 <td>
7050                       <p>
7051                         HS
7052                       </p>
7053                     </td>
7054 <td>
7055                       <p>
7056                         Hesiod, an information service
7057                         developed by MIT's Project Athena. It is used to share
7058                         information
7059                         about various systems databases, such as users,
7060                         groups, printers
7061                         and so on.
7062                       </p>
7063                     </td>
7064 </tr>
7065 </tbody>
7066 </table></div>
7067 <p>
7068               The owner name is often implicit, rather than forming an
7069               integral
7070               part of the RR.  For example, many name servers internally form
7071               tree
7072               or hash structures for the name space, and chain RRs off nodes.
7073               The remaining RR parts are the fixed header (type, class, TTL)
7074               which is consistent for all RRs, and a variable part (RDATA)
7075               that
7076               fits the needs of the resource being described.
7077             </p>
7078 <p>
7079               The meaning of the TTL field is a time limit on how long an
7080               RR can be kept in a cache.  This limit does not apply to
7081               authoritative
7082               data in zones; it is also timed out, but by the refreshing
7083               policies
7084               for the zone.  The TTL is assigned by the administrator for the
7085               zone where the data originates.  While short TTLs can be used to
7086               minimize caching, and a zero TTL prohibits caching, the
7087               realities
7088               of Internet performance suggest that these times should be on
7089               the
7090               order of days for the typical host.  If a change can be
7091               anticipated,
7092               the TTL can be reduced prior to the change to minimize
7093               inconsistency
7094               during the change, and then increased back to its former value
7095               following
7096               the change.
7097             </p>
7098 <p>
7099               The data in the RDATA section of RRs is carried as a combination
7100               of binary strings and domain names.  The domain names are
7101               frequently
7102               used as "pointers" to other data in the DNS.
7103             </p>
7104 </div>
7105 <div class="sect3" lang="en">
7106 <div class="titlepage"><div><div><h4 class="title">
7107 <a name="id2593010"></a>Textual expression of RRs</h4></div></div></div>
7108 <p>
7109               RRs are represented in binary form in the packets of the DNS
7110               protocol, and are usually represented in highly encoded form
7111               when
7112               stored in a name server or resolver.  In the examples provided
7113               in
7114               RFC 1034, a style similar to that used in master files was
7115               employed
7116               in order to show the contents of RRs.  In this format, most RRs
7117               are shown on a single line, although continuation lines are
7118               possible
7119               using parentheses.
7120             </p>
7121 <p>
7122               The start of the line gives the owner of the RR.  If a line
7123               begins with a blank, then the owner is assumed to be the same as
7124               that of the previous RR.  Blank lines are often included for
7125               readability.
7126             </p>
7127 <p>
7128               Following the owner, we list the TTL, type, and class of the
7129               RR.  Class and type use the mnemonics defined above, and TTL is
7130               an integer before the type field.  In order to avoid ambiguity
7131               in
7132               parsing, type and class mnemonics are disjoint, TTLs are
7133               integers,
7134               and the type mnemonic is always last. The IN class and TTL
7135               values
7136               are often omitted from examples in the interests of clarity.
7137             </p>
7138 <p>
7139               The resource data or RDATA section of the RR are given using
7140               knowledge of the typical representation for the data.
7141             </p>
7142 <p>
7143               For example, we might show the RRs carried in a message as:
7144             </p>
7145 <div class="informaltable"><table border="1">
7146 <colgroup>
7147 <col>
7148 <col>
7149 <col>
7150 </colgroup>
7151 <tbody>
7152 <tr>
7153 <td>
7154                       <p>
7155                         <code class="literal">ISI.EDU.</code>
7156                       </p>
7157                     </td>
7158 <td>
7159                       <p>
7160                         <code class="literal">MX</code>
7161                       </p>
7162                     </td>
7163 <td>
7164                       <p>
7165                         <code class="literal">10 VENERA.ISI.EDU.</code>
7166                       </p>
7167                     </td>
7168 </tr>
7169 <tr>
7170 <td>
7171                       <p></p>
7172                     </td>
7173 <td>
7174                       <p>
7175                         <code class="literal">MX</code>
7176                       </p>
7177                     </td>
7178 <td>
7179                       <p>
7180                         <code class="literal">10 VAXA.ISI.EDU</code>
7181                       </p>
7182                     </td>
7183 </tr>
7184 <tr>
7185 <td>
7186                       <p>
7187                         <code class="literal">VENERA.ISI.EDU</code>
7188                       </p>
7189                     </td>
7190 <td>
7191                       <p>
7192                         <code class="literal">A</code>
7193                       </p>
7194                     </td>
7195 <td>
7196                       <p>
7197                         <code class="literal">128.9.0.32</code>
7198                       </p>
7199                     </td>
7200 </tr>
7201 <tr>
7202 <td>
7203                       <p></p>
7204                     </td>
7205 <td>
7206                       <p>
7207                         <code class="literal">A</code>
7208                       </p>
7209                     </td>
7210 <td>
7211                       <p>
7212                         <code class="literal">10.1.0.52</code>
7213                       </p>
7214                     </td>
7215 </tr>
7216 <tr>
7217 <td>
7218                       <p>
7219                         <code class="literal">VAXA.ISI.EDU</code>
7220                       </p>
7221                     </td>
7222 <td>
7223                       <p>
7224                         <code class="literal">A</code>
7225                       </p>
7226                     </td>
7227 <td>
7228                       <p>
7229                         <code class="literal">10.2.0.27</code>
7230                       </p>
7231                     </td>
7232 </tr>
7233 <tr>
7234 <td>
7235                       <p></p>
7236                     </td>
7237 <td>
7238                       <p>
7239                         <code class="literal">A</code>
7240                       </p>
7241                     </td>
7242 <td>
7243                       <p>
7244                         <code class="literal">128.9.0.33</code>
7245                       </p>
7246                     </td>
7247 </tr>
7248 </tbody>
7249 </table></div>
7250 <p>
7251               The MX RRs have an RDATA section which consists of a 16-bit
7252               number followed by a domain name.  The address RRs use a
7253               standard
7254               IP address format to contain a 32-bit internet address.
7255             </p>
7256 <p>
7257               The above example shows six RRs, with two RRs at each of three
7258               domain names.
7259             </p>
7260 <p>
7261               Similarly we might see:
7262             </p>
7263 <div class="informaltable"><table border="1">
7264 <colgroup>
7265 <col>
7266 <col>
7267 <col>
7268 </colgroup>
7269 <tbody>
7270 <tr>
7271 <td>
7272                       <p>
7273                         <code class="literal">XX.LCS.MIT.EDU.</code>
7274                       </p>
7275                     </td>
7276 <td>
7277                       <p>
7278                         <code class="literal">IN A</code>
7279                       </p>
7280                     </td>
7281 <td>
7282                       <p>
7283                         <code class="literal">10.0.0.44</code>
7284                       </p>
7285                     </td>
7286 </tr>
7287 <tr>
7288 <td> </td>
7289 <td>
7290                       <p>
7291                         <code class="literal">CH A</code>
7292                       </p>
7293                     </td>
7294 <td>
7295                       <p>
7296                         <code class="literal">MIT.EDU. 2420</code>
7297                       </p>
7298                     </td>
7299 </tr>
7300 </tbody>
7301 </table></div>
7302 <p>
7303               This example shows two addresses for
7304               <code class="literal">XX.LCS.MIT.EDU</code>, each of a different class.
7305             </p>
7306 </div>
7307 </div>
7308 <div class="sect2" lang="en">
7309 <div class="titlepage"><div><div><h3 class="title">
7310 <a name="id2593530"></a>Discussion of MX Records</h3></div></div></div>
7311 <p>
7312             As described above, domain servers store information as a
7313             series of resource records, each of which contains a particular
7314             piece of information about a given domain name (which is usually,
7315             but not always, a host). The simplest way to think of a RR is as
7316             a typed pair of data, a domain name matched with a relevant datum,
7317             and stored with some additional type information to help systems
7318             determine when the RR is relevant.
7319           </p>
7320 <p>
7321             MX records are used to control delivery of email. The data
7322             specified in the record is a priority and a domain name. The
7323             priority
7324             controls the order in which email delivery is attempted, with the
7325             lowest number first. If two priorities are the same, a server is
7326             chosen randomly. If no servers at a given priority are responding,
7327             the mail transport agent will fall back to the next largest
7328             priority.
7329             Priority numbers do not have any absolute meaning &#8212; they are
7330             relevant
7331             only respective to other MX records for that domain name. The
7332             domain
7333             name given is the machine to which the mail will be delivered.
7334             It <span class="emphasis"><em>must</em></span> have an associated address record
7335             (A or AAAA) &#8212; CNAME is not sufficient.
7336           </p>
7337 <p>
7338             For a given domain, if there is both a CNAME record and an
7339             MX record, the MX record is in error, and will be ignored.
7340             Instead,
7341             the mail will be delivered to the server specified in the MX
7342             record
7343             pointed to by the CNAME.
7344             For example:
7345           </p>
7346 <div class="informaltable"><table border="1">
7347 <colgroup>
7348 <col>
7349 <col>
7350 <col>
7351 <col>
7352 <col>
7353 </colgroup>
7354 <tbody>
7355 <tr>
7356 <td>
7357                     <p>
7358                       <code class="literal">example.com.</code>
7359                     </p>
7360                   </td>
7361 <td>
7362                     <p>
7363                       <code class="literal">IN</code>
7364                     </p>
7365                   </td>
7366 <td>
7367                     <p>
7368                       <code class="literal">MX</code>
7369                     </p>
7370                   </td>
7371 <td>
7372                     <p>
7373                       <code class="literal">10</code>
7374                     </p>
7375                   </td>
7376 <td>
7377                     <p>
7378                       <code class="literal">mail.example.com.</code>
7379                     </p>
7380                   </td>
7381 </tr>
7382 <tr>
7383 <td>
7384                     <p></p>
7385                   </td>
7386 <td>
7387                     <p>
7388                       <code class="literal">IN</code>
7389                     </p>
7390                   </td>
7391 <td>
7392                     <p>
7393                       <code class="literal">MX</code>
7394                     </p>
7395                   </td>
7396 <td>
7397                     <p>
7398                       <code class="literal">10</code>
7399                     </p>
7400                   </td>
7401 <td>
7402                     <p>
7403                       <code class="literal">mail2.example.com.</code>
7404                     </p>
7405                   </td>
7406 </tr>
7407 <tr>
7408 <td>
7409                     <p></p>
7410                   </td>
7411 <td>
7412                     <p>
7413                       <code class="literal">IN</code>
7414                     </p>
7415                   </td>
7416 <td>
7417                     <p>
7418                       <code class="literal">MX</code>
7419                     </p>
7420                   </td>
7421 <td>
7422                     <p>
7423                       <code class="literal">20</code>
7424                     </p>
7425                   </td>
7426 <td>
7427                     <p>
7428                       <code class="literal">mail.backup.org.</code>
7429                     </p>
7430                   </td>
7431 </tr>
7432 <tr>
7433 <td>
7434                     <p>
7435                       <code class="literal">mail.example.com.</code>
7436                     </p>
7437                   </td>
7438 <td>
7439                     <p>
7440                       <code class="literal">IN</code>
7441                     </p>
7442                   </td>
7443 <td>
7444                     <p>
7445                       <code class="literal">A</code>
7446                     </p>
7447                   </td>
7448 <td>
7449                     <p>
7450                       <code class="literal">10.0.0.1</code>
7451                     </p>
7452                   </td>
7453 <td>
7454                     <p></p>
7455                   </td>
7456 </tr>
7457 <tr>
7458 <td>
7459                     <p>
7460                       <code class="literal">mail2.example.com.</code>
7461                     </p>
7462                   </td>
7463 <td>
7464                     <p>
7465                       <code class="literal">IN</code>
7466                     </p>
7467                   </td>
7468 <td>
7469                     <p>
7470                       <code class="literal">A</code>
7471                     </p>
7472                   </td>
7473 <td>
7474                     <p>
7475                       <code class="literal">10.0.0.2</code>
7476                     </p>
7477                   </td>
7478 <td>
7479                     <p></p>
7480                   </td>
7481 </tr>
7482 </tbody>
7483 </table></div>
7484 <p>
7485             Mail delivery will be attempted to <code class="literal">mail.example.com</code> and
7486             <code class="literal">mail2.example.com</code> (in
7487             any order), and if neither of those succeed, delivery to <code class="literal">mail.backup.org</code> will
7488             be attempted.
7489           </p>
7490 </div>
7491 <div class="sect2" lang="en">
7492 <div class="titlepage"><div><div><h3 class="title">
7493 <a name="Setting_TTLs"></a>Setting TTLs</h3></div></div></div>
7494 <p>
7495             The time-to-live of the RR field is a 32-bit integer represented
7496             in units of seconds, and is primarily used by resolvers when they
7497             cache RRs. The TTL describes how long a RR can be cached before it
7498             should be discarded. The following three types of TTL are
7499             currently
7500             used in a zone file.
7501           </p>
7502 <div class="informaltable"><table border="1">
7503 <colgroup>
7504 <col>
7505 <col>
7506 </colgroup>
7507 <tbody>
7508 <tr>
7509 <td>
7510                     <p>
7511                       SOA
7512                     </p>
7513                   </td>
7514 <td>
7515                     <p>
7516                       The last field in the SOA is the negative
7517                       caching TTL. This controls how long other servers will
7518                       cache no-such-domain
7519                       (NXDOMAIN) responses from you.
7520                     </p>
7521                     <p>
7522                       The maximum time for
7523                       negative caching is 3 hours (3h).
7524                     </p>
7525                   </td>
7526 </tr>
7527 <tr>
7528 <td>
7529                     <p>
7530                       $TTL
7531                     </p>
7532                   </td>
7533 <td>
7534                     <p>
7535                       The $TTL directive at the top of the
7536                       zone file (before the SOA) gives a default TTL for every
7537                       RR without
7538                       a specific TTL set.
7539                     </p>
7540                   </td>
7541 </tr>
7542 <tr>
7543 <td>
7544                     <p>
7545                       RR TTLs
7546                     </p>
7547                   </td>
7548 <td>
7549                     <p>
7550                       Each RR can have a TTL as the second
7551                       field in the RR, which will control how long other
7552                       servers can cache
7553                       the it.
7554                     </p>
7555                   </td>
7556 </tr>
7557 </tbody>
7558 </table></div>
7559 <p>
7560             All of these TTLs default to units of seconds, though units
7561             can be explicitly specified, for example, <code class="literal">1h30m</code>.
7562           </p>
7563 </div>
7564 <div class="sect2" lang="en">
7565 <div class="titlepage"><div><div><h3 class="title">
7566 <a name="id2594214"></a>Inverse Mapping in IPv4</h3></div></div></div>
7567 <p>
7568             Reverse name resolution (that is, translation from IP address
7569             to name) is achieved by means of the <span class="emphasis"><em>in-addr.arpa</em></span> domain
7570             and PTR records. Entries in the in-addr.arpa domain are made in
7571             least-to-most significant order, read left to right. This is the
7572             opposite order to the way IP addresses are usually written. Thus,
7573             a machine with an IP address of 10.1.2.3 would have a
7574             corresponding
7575             in-addr.arpa name of
7576             3.2.1.10.in-addr.arpa. This name should have a PTR resource record
7577             whose data field is the name of the machine or, optionally,
7578             multiple
7579             PTR records if the machine has more than one name. For example,
7580             in the [<span class="optional">example.com</span>] domain:
7581           </p>
7582 <div class="informaltable"><table border="1">
7583 <colgroup>
7584 <col>
7585 <col>
7586 </colgroup>
7587 <tbody>
7588 <tr>
7589 <td>
7590                     <p>
7591                       <code class="literal">$ORIGIN</code>
7592                     </p>
7593                   </td>
7594 <td>
7595                     <p>
7596                       <code class="literal">2.1.10.in-addr.arpa</code>
7597                     </p>
7598                   </td>
7599 </tr>
7600 <tr>
7601 <td>
7602                     <p>
7603                       <code class="literal">3</code>
7604                     </p>
7605                   </td>
7606 <td>
7607                     <p>
7608                       <code class="literal">IN PTR foo.example.com.</code>
7609                     </p>
7610                   </td>
7611 </tr>
7612 </tbody>
7613 </table></div>
7614 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7615 <h3 class="title">Note</h3>
7616 <p>
7617               The <span><strong class="command">$ORIGIN</strong></span> lines in the examples
7618               are for providing context to the examples only &#8212; they do not
7619               necessarily
7620               appear in the actual usage. They are only used here to indicate
7621               that the example is relative to the listed origin.
7622             </p>
7623 </div>
7624 </div>
7625 <div class="sect2" lang="en">
7626 <div class="titlepage"><div><div><h3 class="title">
7627 <a name="id2594341"></a>Other Zone File Directives</h3></div></div></div>
7628 <p>
7629             The Master File Format was initially defined in RFC 1035 and
7630             has subsequently been extended. While the Master File Format
7631             itself
7632             is class independent all records in a Master File must be of the
7633             same
7634             class.
7635           </p>
7636 <p>
7637             Master File Directives include <span><strong class="command">$ORIGIN</strong></span>, <span><strong class="command">$INCLUDE</strong></span>,
7638             and <span><strong class="command">$TTL.</strong></span>
7639           </p>
7640 <div class="sect3" lang="en">
7641 <div class="titlepage"><div><div><h4 class="title">
7642 <a name="id2594363"></a>The <span><strong class="command">@</strong></span> (at-sign)</h4></div></div></div>
7643 <p>
7644               When used in the label (or name) field, the asperand or
7645               at-sign (@) symbol represents the current origin.
7646               At the start of the zone file, it is the
7647               &lt;<code class="varname">zone_name</code>&gt; (followed by
7648               trailing dot).
7649             </p>
7650 </div>
7651 <div class="sect3" lang="en">
7652 <div class="titlepage"><div><div><h4 class="title">
7653 <a name="id2594379"></a>The <span><strong class="command">$ORIGIN</strong></span> Directive</h4></div></div></div>
7654 <p>
7655               Syntax: <span><strong class="command">$ORIGIN</strong></span>
7656               <em class="replaceable"><code>domain-name</code></em>
7657               [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
7658             </p>
7659 <p><span><strong class="command">$ORIGIN</strong></span>
7660               sets the domain name that will be appended to any
7661               unqualified records. When a zone is first read in there
7662               is an implicit <span><strong class="command">$ORIGIN</strong></span>
7663               &lt;<code class="varname">zone_name</code>&gt;<span><strong class="command">.</strong></span>
7664               (followed by trailing dot).
7665               The current <span><strong class="command">$ORIGIN</strong></span> is appended to
7666               the domain specified in the <span><strong class="command">$ORIGIN</strong></span>
7667               argument if it is not absolute.
7668             </p>
7669 <pre class="programlisting">
7670 $ORIGIN example.com.
7671 WWW     CNAME   MAIN-SERVER
7672 </pre>
7673 <p>
7674               is equivalent to
7675             </p>
7676 <pre class="programlisting">
7677 WWW.EXAMPLE.COM. CNAME MAIN-SERVER.EXAMPLE.COM.
7678 </pre>
7679 </div>
7680 <div class="sect3" lang="en">
7681 <div class="titlepage"><div><div><h4 class="title">
7682 <a name="id2594508"></a>The <span><strong class="command">$INCLUDE</strong></span> Directive</h4></div></div></div>
7683 <p>
7684               Syntax: <span><strong class="command">$INCLUDE</strong></span>
7685               <em class="replaceable"><code>filename</code></em>
7686               [<span class="optional">
7687 <em class="replaceable"><code>origin</code></em> </span>]
7688               [<span class="optional"> <em class="replaceable"><code>comment</code></em> </span>]
7689             </p>
7690 <p>
7691               Read and process the file <code class="filename">filename</code> as
7692               if it were included into the file at this point.  If <span><strong class="command">origin</strong></span> is
7693               specified the file is processed with <span><strong class="command">$ORIGIN</strong></span> set
7694               to that value, otherwise the current <span><strong class="command">$ORIGIN</strong></span> is
7695               used.
7696             </p>
7697 <p>
7698               The origin and the current domain name
7699               revert to the values they had prior to the <span><strong class="command">$INCLUDE</strong></span> once
7700               the file has been read.
7701             </p>
7702 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7703 <h3 class="title">Note</h3>
7704 <p>
7705                 RFC 1035 specifies that the current origin should be restored
7706                 after
7707                 an <span><strong class="command">$INCLUDE</strong></span>, but it is silent
7708                 on whether the current
7709                 domain name should also be restored.  BIND 9 restores both of
7710                 them.
7711                 This could be construed as a deviation from RFC 1035, a
7712                 feature, or both.
7713               </p>
7714 </div>
7715 </div>
7716 <div class="sect3" lang="en">
7717 <div class="titlepage"><div><div><h4 class="title">
7718 <a name="id2594646"></a>The <span><strong class="command">$TTL</strong></span> Directive</h4></div></div></div>
7719 <p>
7720               Syntax: <span><strong class="command">$TTL</strong></span>
7721               <em class="replaceable"><code>default-ttl</code></em>
7722               [<span class="optional">
7723 <em class="replaceable"><code>comment</code></em> </span>]
7724             </p>
7725 <p>
7726               Set the default Time To Live (TTL) for subsequent records
7727               with undefined TTLs. Valid TTLs are of the range 0-2147483647
7728               seconds.
7729             </p>
7730 <p><span><strong class="command">$TTL</strong></span>
7731                is defined in RFC 2308.
7732             </p>
7733 </div>
7734 </div>
7735 <div class="sect2" lang="en">
7736 <div class="titlepage"><div><div><h3 class="title">
7737 <a name="id2594682"></a><acronym class="acronym">BIND</acronym> Master File Extension: the  <span><strong class="command">$GENERATE</strong></span> Directive</h3></div></div></div>
7738 <p>
7739             Syntax: <span><strong class="command">$GENERATE</strong></span>
7740             <em class="replaceable"><code>range</code></em>
7741             <em class="replaceable"><code>lhs</code></em>
7742             [<span class="optional"><em class="replaceable"><code>ttl</code></em></span>]
7743             [<span class="optional"><em class="replaceable"><code>class</code></em></span>]
7744             <em class="replaceable"><code>type</code></em>
7745             <em class="replaceable"><code>rhs</code></em>
7746             [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
7747           </p>
7748 <p><span><strong class="command">$GENERATE</strong></span>
7749             is used to create a series of resource records that only
7750             differ from each other by an
7751             iterator. <span><strong class="command">$GENERATE</strong></span> can be used to
7752             easily generate the sets of records required to support
7753             sub /24 reverse delegations described in RFC 2317:
7754             Classless IN-ADDR.ARPA delegation.
7755           </p>
7756 <pre class="programlisting">$ORIGIN 0.0.192.IN-ADDR.ARPA.
7757 $GENERATE 1-2 0 NS SERVER$.EXAMPLE.
7758 $GENERATE 1-127 $ CNAME $.0</pre>
7759 <p>
7760             is equivalent to
7761           </p>
7762 <pre class="programlisting">0.0.0.192.IN-ADDR.ARPA. NS SERVER1.EXAMPLE.
7763 0.0.0.192.IN-ADDR.ARPA. NS SERVER2.EXAMPLE.
7764 1.0.0.192.IN-ADDR.ARPA. CNAME 1.0.0.0.192.IN-ADDR.ARPA.
7765 2.0.0.192.IN-ADDR.ARPA. CNAME 2.0.0.0.192.IN-ADDR.ARPA.
7766 ...
7767 127.0.0.192.IN-ADDR.ARPA. CNAME 127.0.0.0.192.IN-ADDR.ARPA.
7768 </pre>
7769 <div class="informaltable"><table border="1">
7770 <colgroup>
7771 <col>
7772 <col>
7773 </colgroup>
7774 <tbody>
7775 <tr>
7776 <td>
7777                     <p><span><strong class="command">range</strong></span></p>
7778                   </td>
7779 <td>
7780                     <p>
7781                       This can be one of two forms: start-stop
7782                       or start-stop/step. If the first form is used, then step
7783                       is set to
7784                       1. All of start, stop and step must be positive.
7785                     </p>
7786                   </td>
7787 </tr>
7788 <tr>
7789 <td>
7790                     <p><span><strong class="command">lhs</strong></span></p>
7791                   </td>
7792 <td>
7793                     <p>This
7794                       describes the owner name of the resource records
7795                       to be created.  Any single <span><strong class="command">$</strong></span>
7796                       (dollar sign)
7797                       symbols within the <span><strong class="command">lhs</strong></span> string
7798                       are replaced by the iterator value.
7799
7800                       To get a $ in the output, you need to escape the
7801                       <span><strong class="command">$</strong></span> using a backslash
7802                       <span><strong class="command">\</strong></span>,
7803                       e.g. <span><strong class="command">\$</strong></span>. The
7804                       <span><strong class="command">$</strong></span> may optionally be followed
7805                       by modifiers which change the offset from the
7806                       iterator, field width and base.
7807
7808                       Modifiers are introduced by a
7809                       <span><strong class="command">{</strong></span> (left brace) immediately following the
7810                       <span><strong class="command">$</strong></span> as
7811                       <span><strong class="command">${offset[,width[,base]]}</strong></span>.
7812                       For example, <span><strong class="command">${-20,3,d}</strong></span>
7813                       subtracts 20 from the current value, prints the
7814                       result as a decimal in a zero-padded field of
7815                       width 3.
7816
7817                       Available output forms are decimal
7818                       (<span><strong class="command">d</strong></span>), octal
7819                       (<span><strong class="command">o</strong></span>) and hexadecimal
7820                       (<span><strong class="command">x</strong></span> or <span><strong class="command">X</strong></span>
7821                       for uppercase).  The default modifier is
7822                       <span><strong class="command">${0,0,d}</strong></span>.  If the
7823                       <span><strong class="command">lhs</strong></span> is not absolute, the
7824                       current <span><strong class="command">$ORIGIN</strong></span> is appended
7825                       to the name.
7826                     </p>
7827                     <p>
7828                       For compatibility with earlier versions, <span><strong class="command">$$</strong></span> is still
7829                       recognized as indicating a literal $ in the output.
7830                     </p>
7831                   </td>
7832 </tr>
7833 <tr>
7834 <td>
7835                     <p><span><strong class="command">ttl</strong></span></p>
7836                   </td>
7837 <td>
7838                     <p>
7839                       Specifies the time-to-live of the generated records. If
7840                       not specified this will be inherited using the
7841                       normal TTL inheritance rules.
7842                     </p>
7843                     <p><span><strong class="command">class</strong></span>
7844                       and <span><strong class="command">ttl</strong></span> can be
7845                       entered in either order.
7846                     </p>
7847                   </td>
7848 </tr>
7849 <tr>
7850 <td>
7851                     <p><span><strong class="command">class</strong></span></p>
7852                   </td>
7853 <td>
7854                     <p>
7855                       Specifies the class of the generated records.
7856                       This must match the zone class if it is
7857                       specified.
7858                     </p>
7859                     <p><span><strong class="command">class</strong></span>
7860                       and <span><strong class="command">ttl</strong></span> can be
7861                       entered in either order.
7862                     </p>
7863                   </td>
7864 </tr>
7865 <tr>
7866 <td>
7867                     <p><span><strong class="command">type</strong></span></p>
7868                   </td>
7869 <td>
7870                     <p>
7871                       At present the only supported types are
7872                       PTR, CNAME, DNAME, A, AAAA and NS.
7873                     </p>
7874                   </td>
7875 </tr>
7876 <tr>
7877 <td>
7878                     <p><span><strong class="command">rhs</strong></span></p>
7879                   </td>
7880 <td>
7881                     <p>
7882                       <span><strong class="command">rhs</strong></span> is a domain name. It is processed
7883                       similarly to lhs.
7884                     </p>
7885                   </td>
7886 </tr>
7887 </tbody>
7888 </table></div>
7889 <p>
7890             The <span><strong class="command">$GENERATE</strong></span> directive is a <acronym class="acronym">BIND</acronym> extension
7891             and not part of the standard zone file format.
7892           </p>
7893 <p>
7894             BIND 8 does not support the optional TTL and CLASS fields.
7895           </p>
7896 </div>
7897 <div class="sect2" lang="en">
7898 <div class="titlepage"><div><div><h3 class="title">
7899 <a name="zonefile_format"></a>Additional File Formats</h3></div></div></div>
7900 <p>
7901             In addition to the standard textual format, BIND 9
7902             supports the ability to read or dump to zone files in
7903             other formats.  The <code class="constant">raw</code> format is
7904             currently available as an additional format.  It is a
7905             binary format representing BIND 9's internal data
7906             structure directly, thereby remarkably improving the
7907             loading time.
7908           </p>
7909 <p>
7910             For a primary server, a zone file in the
7911             <code class="constant">raw</code> format is expected to be
7912             generated from a textual zone file by the
7913             <span><strong class="command">named-compilezone</strong></span> command.  For a
7914             secondary server or for a dynamic zone, it is automatically
7915             generated (if this format is specified by the
7916             <span><strong class="command">masterfile-format</strong></span> option) when
7917             <span><strong class="command">named</strong></span> dumps the zone contents after
7918             zone transfer or when applying prior updates.
7919           </p>
7920 <p>
7921             If a zone file in a binary format needs manual modification,
7922             it first must be converted to a textual form by the
7923             <span><strong class="command">named-compilezone</strong></span> command.  All
7924             necessary modification should go to the text file, which
7925             should then be converted to the binary form by the
7926             <span><strong class="command">named-compilezone</strong></span> command again.
7927           </p>
7928 <p>
7929              Although the <code class="constant">raw</code> format uses the
7930              network byte order and avoids architecture-dependent
7931              data alignment so that it is as much portable as
7932              possible, it is primarily expected to be used inside
7933              the same single system.  In order to export a zone
7934              file in the <code class="constant">raw</code> format or make a
7935              portable backup of the file, it is recommended to
7936              convert the file to the standard textual representation.
7937           </p>
7938 </div>
7939 </div>
7940 <div class="sect1" lang="en">
7941 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
7942 <a name="statistics"></a>BIND9 Statistics</h2></div></div></div>
7943 <p>
7944           <acronym class="acronym">BIND</acronym> 9 maintains lots of statistics
7945           information and provides several interfaces for users to
7946           get access to the statistics.
7947           The available statistics include all statistics counters
7948           that were available in <acronym class="acronym">BIND</acronym> 8 and
7949           are meaningful in <acronym class="acronym">BIND</acronym> 9,
7950           and other information that is considered useful.
7951         </p>
7952 <p>
7953           The statistics information is categorized into the following
7954           sections.
7955         </p>
7956 <div class="informaltable"><table border="1">
7957 <colgroup>
7958 <col>
7959 <col>
7960 </colgroup>
7961 <tbody>
7962 <tr>
7963 <td>
7964                   <p>Incoming Requests</p>
7965                 </td>
7966 <td>
7967                   <p>
7968                     The number of incoming DNS requests for each OPCODE.
7969                   </p>
7970                 </td>
7971 </tr>
7972 <tr>
7973 <td>
7974                   <p>Incoming Queries</p>
7975                 </td>
7976 <td>
7977                   <p>
7978                     The number of incoming queries for each RR type.
7979                   </p>
7980                 </td>
7981 </tr>
7982 <tr>
7983 <td>
7984                   <p>Outgoing Queries</p>
7985                 </td>
7986 <td>
7987                   <p>
7988                     The number of outgoing queries for each RR
7989                     type sent from the internal resolver.
7990                     Maintained per view.
7991                   </p>
7992                 </td>
7993 </tr>
7994 <tr>
7995 <td>
7996                   <p>Name Server Statistics</p>
7997                 </td>
7998 <td>
7999                   <p>
8000                     Statistics counters about incoming request processing.
8001                   </p>
8002                 </td>
8003 </tr>
8004 <tr>
8005 <td>
8006                   <p>Zone Maintenance Statistics</p>
8007                 </td>
8008 <td>
8009                   <p>
8010                     Statistics counters regarding zone maintenance
8011                     operations such as zone transfers.
8012                   </p>
8013                 </td>
8014 </tr>
8015 <tr>
8016 <td>
8017                   <p>Resolver Statistics</p>
8018                 </td>
8019 <td>
8020                   <p>
8021                     Statistics counters about name resolution
8022                     performed in the internal resolver.
8023                     Maintained per view.
8024                   </p>
8025                 </td>
8026 </tr>
8027 <tr>
8028 <td>
8029                   <p>Cache DB RRsets</p>
8030                 </td>
8031 <td>
8032                   <p>
8033                     The number of RRsets per RR type (positive
8034                     or negative) and nonexistent names stored in the
8035                     cache database.
8036                     Maintained per view.
8037                   </p>
8038                 </td>
8039 </tr>
8040 <tr>
8041 <td>
8042                   <p>Socket I/O Statistics</p>
8043                 </td>
8044 <td>
8045                   <p>
8046                     Statistics counters about network related events.
8047                   </p>
8048                 </td>
8049 </tr>
8050 </tbody>
8051 </table></div>
8052 <p>
8053           A subset of Name Server Statistics is collected and shown
8054           per zone for which the server has the authority when
8055           <span><strong class="command">zone-statistics</strong></span> is set to
8056           <strong class="userinput"><code>yes</code></strong>.
8057           These statistics counters are shown with their zone and view
8058           names.
8059           In some cases the view names are omitted for the default view.
8060         </p>
8061 <p>
8062           There are currently two user interfaces to get access to the
8063           statistics.
8064           One is in the plain text format dumped to the file specified
8065           by the <span><strong class="command">statistics-file</strong></span> configuration option.
8066           The other is remotely accessible via a statistics channel
8067           when the <span><strong class="command">statistics-channels</strong></span> statement
8068           is specified in the configuration file
8069           (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>.)
8070         </p>
8071 <div class="sect3" lang="en">
8072 <div class="titlepage"><div><div><h4 class="title">
8073 <a name="statsfile"></a>The Statistics File</h4></div></div></div>
8074 <p>
8075             The text format statistics dump begins with a line, like:
8076           </p>
8077 <p>
8078             <span><strong class="command">+++ Statistics Dump +++ (973798949)</strong></span>
8079           </p>
8080 <p>
8081             The number in parentheses is a standard
8082             Unix-style timestamp, measured as seconds since January 1, 1970.
8083
8084             Following
8085             that line is a set of statistics information, which is categorized
8086             as described above.
8087             Each section begins with a line, like:
8088           </p>
8089 <p>
8090             <span><strong class="command">++ Name Server Statistics ++</strong></span>
8091           </p>
8092 <p>
8093             Each section consists of lines, each containing the statistics
8094             counter value followed by its textual description.
8095             See below for available counters.
8096             For brevity, counters that have a value of 0 are not shown
8097             in the statistics file.
8098           </p>
8099 <p>
8100             The statistics dump ends with the line where the
8101             number is identical to the number in the beginning line; for example:
8102           </p>
8103 <p>
8104             <span><strong class="command">--- Statistics Dump --- (973798949)</strong></span>
8105           </p>
8106 </div>
8107 <div class="sect2" lang="en">
8108 <div class="titlepage"><div><div><h3 class="title">
8109 <a name="statistics_counters"></a>Statistics Counters</h3></div></div></div>
8110 <p>
8111             The following tables summarize statistics counters that
8112             <acronym class="acronym">BIND</acronym> 9 provides.
8113             For each row of the tables, the leftmost column is the
8114             abbreviated symbol name of that counter.
8115             These symbols are shown in the statistics information
8116             accessed via an HTTP statistics channel.
8117             The rightmost column gives the description of the counter,
8118             which is also shown in the statistics file
8119             (but, in this document, possibly with slight modification
8120             for better readability).
8121             Additional notes may also be provided in this column.
8122             When a middle column exists between these two columns,
8123             it gives the corresponding counter name of the
8124             <acronym class="acronym">BIND</acronym> 8 statistics, if applicable.
8125           </p>
8126 <div class="sect3" lang="en">
8127 <div class="titlepage"><div><div><h4 class="title">
8128 <a name="id2595610"></a>Name Server Statistics Counters</h4></div></div></div>
8129 <div class="informaltable"><table border="1">
8130 <colgroup>
8131 <col>
8132 <col>
8133 <col>
8134 </colgroup>
8135 <tbody>
8136 <tr>
8137 <td>
8138                       <p>
8139                         <span class="emphasis"><em>Symbol</em></span>
8140                       </p>
8141                     </td>
8142 <td>
8143                       <p>
8144                         <span class="emphasis"><em>BIND8 Symbol</em></span>
8145                       </p>
8146                     </td>
8147 <td>
8148                       <p>
8149                         <span class="emphasis"><em>Description</em></span>
8150                       </p>
8151                     </td>
8152 </tr>
8153 <tr>
8154 <td>
8155                       <p><span><strong class="command">Requestv4</strong></span></p>
8156                     </td>
8157 <td>
8158                       <p><span><strong class="command">RQ</strong></span></p>
8159                     </td>
8160 <td>
8161                       <p>
8162                         IPv4 requests received.
8163                         Note: this also counts non query requests.
8164                       </p>
8165                     </td>
8166 </tr>
8167 <tr>
8168 <td>
8169                       <p><span><strong class="command">Requestv6</strong></span></p>
8170                     </td>
8171 <td>
8172                       <p><span><strong class="command">RQ</strong></span></p>
8173                     </td>
8174 <td>
8175                       <p>
8176                         IPv6 requests received.
8177                         Note: this also counts non query requests.
8178                       </p>
8179                     </td>
8180 </tr>
8181 <tr>
8182 <td>
8183                       <p><span><strong class="command">ReqEdns0</strong></span></p>
8184                     </td>
8185 <td>
8186                       <p><span><strong class="command"></strong></span></p>
8187                     </td>
8188 <td>
8189                       <p>
8190                         Requests with EDNS(0) received.
8191                       </p>
8192                     </td>
8193 </tr>
8194 <tr>
8195 <td>
8196                       <p><span><strong class="command">ReqBadEDNSVer</strong></span></p>
8197                     </td>
8198 <td>
8199                       <p><span><strong class="command"></strong></span></p>
8200                     </td>
8201 <td>
8202                       <p>
8203                         Requests with unsupported EDNS version received.
8204                       </p>
8205                     </td>
8206 </tr>
8207 <tr>
8208 <td>
8209                       <p><span><strong class="command">ReqTSIG</strong></span></p>
8210                     </td>
8211 <td>
8212                       <p><span><strong class="command"></strong></span></p>
8213                     </td>
8214 <td>
8215                       <p>
8216                         Requests with TSIG received.
8217                       </p>
8218                     </td>
8219 </tr>
8220 <tr>
8221 <td>
8222                       <p><span><strong class="command">ReqSIG0</strong></span></p>
8223                     </td>
8224 <td>
8225                       <p><span><strong class="command"></strong></span></p>
8226                     </td>
8227 <td>
8228                       <p>
8229                         Requests with SIG(0) received.
8230                       </p>
8231                     </td>
8232 </tr>
8233 <tr>
8234 <td>
8235                       <p><span><strong class="command">ReqBadSIG</strong></span></p>
8236                     </td>
8237 <td>
8238                       <p><span><strong class="command"></strong></span></p>
8239                     </td>
8240 <td>
8241                       <p>
8242                         Requests with invalid (TSIG or SIG(0)) signature.
8243                       </p>
8244                     </td>
8245 </tr>
8246 <tr>
8247 <td>
8248                       <p><span><strong class="command">ReqTCP</strong></span></p>
8249                     </td>
8250 <td>
8251                       <p><span><strong class="command">RTCP</strong></span></p>
8252                     </td>
8253 <td>
8254                       <p>
8255                         TCP requests received.
8256                       </p>
8257                     </td>
8258 </tr>
8259 <tr>
8260 <td>
8261                       <p><span><strong class="command">AuthQryRej</strong></span></p>
8262                     </td>
8263 <td>
8264                       <p><span><strong class="command">RUQ</strong></span></p>
8265                     </td>
8266 <td>
8267                       <p>
8268                         Authoritative (non recursive) queries rejected.
8269                       </p>
8270                     </td>
8271 </tr>
8272 <tr>
8273 <td>
8274                       <p><span><strong class="command">RecQryRej</strong></span></p>
8275                     </td>
8276 <td>
8277                       <p><span><strong class="command">RURQ</strong></span></p>
8278                     </td>
8279 <td>
8280                       <p>
8281                         Recursive queries rejected.
8282                       </p>
8283                     </td>
8284 </tr>
8285 <tr>
8286 <td>
8287                       <p><span><strong class="command">XfrRej</strong></span></p>
8288                     </td>
8289 <td>
8290                       <p><span><strong class="command">RUXFR</strong></span></p>
8291                     </td>
8292 <td>
8293                       <p>
8294                         Zone transfer requests rejected.
8295                       </p>
8296                     </td>
8297 </tr>
8298 <tr>
8299 <td>
8300                       <p><span><strong class="command">UpdateRej</strong></span></p>
8301                     </td>
8302 <td>
8303                       <p><span><strong class="command">RUUpd</strong></span></p>
8304                     </td>
8305 <td>
8306                       <p>
8307                         Dynamic update requests rejected.
8308                       </p>
8309                     </td>
8310 </tr>
8311 <tr>
8312 <td>
8313                       <p><span><strong class="command">Response</strong></span></p>
8314                     </td>
8315 <td>
8316                       <p><span><strong class="command">SAns</strong></span></p>
8317                     </td>
8318 <td>
8319                       <p>
8320                         Responses sent.
8321                       </p>
8322                     </td>
8323 </tr>
8324 <tr>
8325 <td>
8326                       <p><span><strong class="command">RespTruncated</strong></span></p>
8327                     </td>
8328 <td>
8329                       <p><span><strong class="command"></strong></span></p>
8330                     </td>
8331 <td>
8332                       <p>
8333                         Truncated responses sent.
8334                       </p>
8335                     </td>
8336 </tr>
8337 <tr>
8338 <td>
8339                       <p><span><strong class="command">RespEDNS0</strong></span></p>
8340                     </td>
8341 <td>
8342                       <p><span><strong class="command"></strong></span></p>
8343                     </td>
8344 <td>
8345                       <p>
8346                         Responses with EDNS(0) sent.
8347                       </p>
8348                     </td>
8349 </tr>
8350 <tr>
8351 <td>
8352                       <p><span><strong class="command">RespTSIG</strong></span></p>
8353                     </td>
8354 <td>
8355                       <p><span><strong class="command"></strong></span></p>
8356                     </td>
8357 <td>
8358                       <p>
8359                         Responses with TSIG sent.
8360                       </p>
8361                     </td>
8362 </tr>
8363 <tr>
8364 <td>
8365                       <p><span><strong class="command">RespSIG0</strong></span></p>
8366                     </td>
8367 <td>
8368                       <p><span><strong class="command"></strong></span></p>
8369                     </td>
8370 <td>
8371                       <p>
8372                         Responses with SIG(0) sent.
8373                       </p>
8374                     </td>
8375 </tr>
8376 <tr>
8377 <td>
8378                       <p><span><strong class="command">QrySuccess</strong></span></p>
8379                     </td>
8380 <td>
8381                       <p><span><strong class="command"></strong></span></p>
8382                     </td>
8383 <td>
8384                       <p>
8385                         Queries resulted in a successful answer.
8386                         This means the query which returns a NOERROR response
8387                         with at least one answer RR.
8388                         This corresponds to the
8389                         <span><strong class="command">success</strong></span> counter
8390                         of previous versions of
8391                         <acronym class="acronym">BIND</acronym> 9.
8392                       </p>
8393                     </td>
8394 </tr>
8395 <tr>
8396 <td>
8397                       <p><span><strong class="command">QryAuthAns</strong></span></p>
8398                     </td>
8399 <td>
8400                       <p><span><strong class="command"></strong></span></p>
8401                     </td>
8402 <td>
8403                       <p>
8404                         Queries resulted in authoritative answer.
8405                       </p>
8406                     </td>
8407 </tr>
8408 <tr>
8409 <td>
8410                       <p><span><strong class="command">QryNoauthAns</strong></span></p>
8411                     </td>
8412 <td>
8413                       <p><span><strong class="command">SNaAns</strong></span></p>
8414                     </td>
8415 <td>
8416                       <p>
8417                         Queries resulted in non authoritative answer.
8418                       </p>
8419                     </td>
8420 </tr>
8421 <tr>
8422 <td>
8423                       <p><span><strong class="command">QryReferral</strong></span></p>
8424                     </td>
8425 <td>
8426                       <p><span><strong class="command"></strong></span></p>
8427                     </td>
8428 <td>
8429                       <p>
8430                         Queries resulted in referral answer.
8431                         This corresponds to the
8432                         <span><strong class="command">referral</strong></span> counter
8433                         of previous versions of
8434                         <acronym class="acronym">BIND</acronym> 9.
8435                       </p>
8436                     </td>
8437 </tr>
8438 <tr>
8439 <td>
8440                       <p><span><strong class="command">QryNxrrset</strong></span></p>
8441                     </td>
8442 <td>
8443                       <p><span><strong class="command"></strong></span></p>
8444                     </td>
8445 <td>
8446                       <p>
8447                         Queries resulted in NOERROR responses with no data.
8448                         This corresponds to the
8449                         <span><strong class="command">nxrrset</strong></span> counter
8450                         of previous versions of
8451                         <acronym class="acronym">BIND</acronym> 9.
8452                       </p>
8453                     </td>
8454 </tr>
8455 <tr>
8456 <td>
8457                       <p><span><strong class="command">QrySERVFAIL</strong></span></p>
8458                     </td>
8459 <td>
8460                       <p><span><strong class="command">SFail</strong></span></p>
8461                     </td>
8462 <td>
8463                       <p>
8464                         Queries resulted in SERVFAIL.
8465                       </p>
8466                     </td>
8467 </tr>
8468 <tr>
8469 <td>
8470                       <p><span><strong class="command">QryFORMERR</strong></span></p>
8471                     </td>
8472 <td>
8473                       <p><span><strong class="command">SFErr</strong></span></p>
8474                     </td>
8475 <td>
8476                       <p>
8477                         Queries resulted in FORMERR.
8478                       </p>
8479                     </td>
8480 </tr>
8481 <tr>
8482 <td>
8483                       <p><span><strong class="command">QryNXDOMAIN</strong></span></p>
8484                     </td>
8485 <td>
8486                       <p><span><strong class="command">SNXD</strong></span></p>
8487                     </td>
8488 <td>
8489                       <p>
8490                         Queries resulted in NXDOMAIN.
8491                         This corresponds to the
8492                         <span><strong class="command">nxdomain</strong></span> counter
8493                         of previous versions of
8494                         <acronym class="acronym">BIND</acronym> 9.
8495                       </p>
8496                     </td>
8497 </tr>
8498 <tr>
8499 <td>
8500                       <p><span><strong class="command">QryRecursion</strong></span></p>
8501                     </td>
8502 <td>
8503                       <p><span><strong class="command">RFwdQ</strong></span></p>
8504                     </td>
8505 <td>
8506                       <p>
8507                         Queries which caused the server
8508                         to perform recursion in order to find the final answer.
8509                         This corresponds to the
8510                         <span><strong class="command">recursion</strong></span> counter
8511                         of previous versions of
8512                         <acronym class="acronym">BIND</acronym> 9.
8513                       </p>
8514                     </td>
8515 </tr>
8516 <tr>
8517 <td>
8518                       <p><span><strong class="command">QryDuplicate</strong></span></p>
8519                     </td>
8520 <td>
8521                       <p><span><strong class="command">RDupQ</strong></span></p>
8522                     </td>
8523 <td>
8524                       <p>
8525                         Queries which the server attempted to
8526                         recurse but discovered an existing query with the same
8527                         IP address, port, query ID, name, type and class
8528                         already being processed.
8529                         This corresponds to the
8530                         <span><strong class="command">duplicate</strong></span> counter
8531                         of previous versions of
8532                         <acronym class="acronym">BIND</acronym> 9.
8533                       </p>
8534                     </td>
8535 </tr>
8536 <tr>
8537 <td>
8538                       <p><span><strong class="command">QryDropped</strong></span></p>
8539                     </td>
8540 <td>
8541                       <p><span><strong class="command"></strong></span></p>
8542                     </td>
8543 <td>
8544                       <p>
8545                         Recursive queries for which the server
8546                         discovered an excessive number of existing
8547                         recursive queries for the same name, type and
8548                         class and were subsequently dropped.
8549                         This is the number of dropped queries due to
8550                         the reason explained with the
8551                         <span><strong class="command">clients-per-query</strong></span>
8552                         and
8553                         <span><strong class="command">max-clients-per-query</strong></span>
8554                         options
8555                         (see the description about
8556                         <a href="Bv9ARM.ch06.html#clients-per-query"><span><strong class="command">clients-per-query</strong></span></a>.)
8557                         This corresponds to the
8558                         <span><strong class="command">dropped</strong></span> counter
8559                         of previous versions of
8560                         <acronym class="acronym">BIND</acronym> 9.
8561                       </p>
8562                     </td>
8563 </tr>
8564 <tr>
8565 <td>
8566                       <p><span><strong class="command">QryFailure</strong></span></p>
8567                     </td>
8568 <td>
8569                       <p><span><strong class="command"></strong></span></p>
8570                     </td>
8571 <td>
8572                       <p>
8573                         Other query failures.
8574                         This corresponds to the
8575                         <span><strong class="command">failure</strong></span> counter
8576                         of previous versions of
8577                         <acronym class="acronym">BIND</acronym> 9.
8578                         Note: this counter is provided mainly for
8579                         backward compatibility with the previous versions.
8580                         Normally a more fine-grained counters such as
8581                         <span><strong class="command">AuthQryRej</strong></span> and
8582                         <span><strong class="command">RecQryRej</strong></span>
8583                         that would also fall into this counter are provided,
8584                         and so this counter would not be of much
8585                         interest in practice.
8586                       </p>
8587                     </td>
8588 </tr>
8589 <tr>
8590 <td>
8591                       <p><span><strong class="command">XfrReqDone</strong></span></p>
8592                     </td>
8593 <td>
8594                       <p><span><strong class="command"></strong></span></p>
8595                     </td>
8596 <td>
8597                       <p>
8598                         Requested zone transfers completed.
8599                       </p>
8600                     </td>
8601 </tr>
8602 <tr>
8603 <td>
8604                       <p><span><strong class="command">UpdateReqFwd</strong></span></p>
8605                     </td>
8606 <td>
8607                       <p><span><strong class="command"></strong></span></p>
8608                     </td>
8609 <td>
8610                       <p>
8611                         Update requests forwarded.
8612                       </p>
8613                     </td>
8614 </tr>
8615 <tr>
8616 <td>
8617                       <p><span><strong class="command">UpdateRespFwd</strong></span></p>
8618                     </td>
8619 <td>
8620                       <p><span><strong class="command"></strong></span></p>
8621                     </td>
8622 <td>
8623                       <p>
8624                         Update responses forwarded.
8625                       </p>
8626                     </td>
8627 </tr>
8628 <tr>
8629 <td>
8630                       <p><span><strong class="command">UpdateFwdFail</strong></span></p>
8631                     </td>
8632 <td>
8633                       <p><span><strong class="command"></strong></span></p>
8634                     </td>
8635 <td>
8636                       <p>
8637                         Dynamic update forward failed.
8638                       </p>
8639                     </td>
8640 </tr>
8641 <tr>
8642 <td>
8643                       <p><span><strong class="command">UpdateDone</strong></span></p>
8644                     </td>
8645 <td>
8646                       <p><span><strong class="command"></strong></span></p>
8647                     </td>
8648 <td>
8649                       <p>
8650                         Dynamic updates completed.
8651                       </p>
8652                     </td>
8653 </tr>
8654 <tr>
8655 <td>
8656                       <p><span><strong class="command">UpdateFail</strong></span></p>
8657                     </td>
8658 <td>
8659                       <p><span><strong class="command"></strong></span></p>
8660                     </td>
8661 <td>
8662                       <p>
8663                         Dynamic updates failed.
8664                       </p>
8665                     </td>
8666 </tr>
8667 <tr>
8668 <td>
8669                       <p><span><strong class="command">UpdateBadPrereq</strong></span></p>
8670                     </td>
8671 <td>
8672                       <p><span><strong class="command"></strong></span></p>
8673                     </td>
8674 <td>
8675                       <p>
8676                         Dynamic updates rejected due to prerequisite failure.
8677                       </p>
8678                     </td>
8679 </tr>
8680 </tbody>
8681 </table></div>
8682 </div>
8683 <div class="sect3" lang="en">
8684 <div class="titlepage"><div><div><h4 class="title">
8685 <a name="id2597083"></a>Zone Maintenance Statistics Counters</h4></div></div></div>
8686 <div class="informaltable"><table border="1">
8687 <colgroup>
8688 <col>
8689 <col>
8690 </colgroup>
8691 <tbody>
8692 <tr>
8693 <td>
8694                       <p>
8695                         <span class="emphasis"><em>Symbol</em></span>
8696                       </p>
8697                     </td>
8698 <td>
8699                       <p>
8700                         <span class="emphasis"><em>Description</em></span>
8701                       </p>
8702                     </td>
8703 </tr>
8704 <tr>
8705 <td>
8706                       <p><span><strong class="command">NotifyOutv4</strong></span></p>
8707                     </td>
8708 <td>
8709                       <p>
8710                         IPv4 notifies sent.
8711                       </p>
8712                     </td>
8713 </tr>
8714 <tr>
8715 <td>
8716                       <p><span><strong class="command">NotifyOutv6</strong></span></p>
8717                     </td>
8718 <td>
8719                       <p>
8720                         IPv6 notifies sent.
8721                       </p>
8722                     </td>
8723 </tr>
8724 <tr>
8725 <td>
8726                       <p><span><strong class="command">NotifyInv4</strong></span></p>
8727                     </td>
8728 <td>
8729                       <p>
8730                         IPv4 notifies received.
8731                       </p>
8732                     </td>
8733 </tr>
8734 <tr>
8735 <td>
8736                       <p><span><strong class="command">NotifyInv6</strong></span></p>
8737                     </td>
8738 <td>
8739                       <p>
8740                         IPv6 notifies received.
8741                       </p>
8742                     </td>
8743 </tr>
8744 <tr>
8745 <td>
8746                       <p><span><strong class="command">NotifyRej</strong></span></p>
8747                     </td>
8748 <td>
8749                       <p>
8750                         Incoming notifies rejected.
8751                       </p>
8752                     </td>
8753 </tr>
8754 <tr>
8755 <td>
8756                       <p><span><strong class="command">SOAOutv4</strong></span></p>
8757                     </td>
8758 <td>
8759                       <p>
8760                         IPv4 SOA queries sent.
8761                       </p>
8762                     </td>
8763 </tr>
8764 <tr>
8765 <td>
8766                       <p><span><strong class="command">SOAOutv6</strong></span></p>
8767                     </td>
8768 <td>
8769                       <p>
8770                         IPv6 SOA queries sent.
8771                       </p>
8772                     </td>
8773 </tr>
8774 <tr>
8775 <td>
8776                       <p><span><strong class="command">AXFRReqv4</strong></span></p>
8777                     </td>
8778 <td>
8779                       <p>
8780                         IPv4 AXFR requested.
8781                       </p>
8782                     </td>
8783 </tr>
8784 <tr>
8785 <td>
8786                       <p><span><strong class="command">AXFRReqv6</strong></span></p>
8787                     </td>
8788 <td>
8789                       <p>
8790                         IPv6 AXFR requested.
8791                       </p>
8792                     </td>
8793 </tr>
8794 <tr>
8795 <td>
8796                       <p><span><strong class="command">IXFRReqv4</strong></span></p>
8797                     </td>
8798 <td>
8799                       <p>
8800                         IPv4 IXFR requested.
8801                       </p>
8802                     </td>
8803 </tr>
8804 <tr>
8805 <td>
8806                       <p><span><strong class="command">IXFRReqv6</strong></span></p>
8807                     </td>
8808 <td>
8809                       <p>
8810                         IPv6 IXFR requested.
8811                       </p>
8812                     </td>
8813 </tr>
8814 <tr>
8815 <td>
8816                       <p><span><strong class="command">XfrSuccess</strong></span></p>
8817                     </td>
8818 <td>
8819                       <p>
8820                         Zone transfer requests succeeded.
8821                       </p>
8822                     </td>
8823 </tr>
8824 <tr>
8825 <td>
8826                       <p><span><strong class="command">XfrFail</strong></span></p>
8827                     </td>
8828 <td>
8829                       <p>
8830                         Zone transfer requests failed.
8831                       </p>
8832                     </td>
8833 </tr>
8834 </tbody>
8835 </table></div>
8836 </div>
8837 <div class="sect3" lang="en">
8838 <div class="titlepage"><div><div><h4 class="title">
8839 <a name="id2597466"></a>Resolver Statistics Counters</h4></div></div></div>
8840 <div class="informaltable"><table border="1">
8841 <colgroup>
8842 <col>
8843 <col>
8844 <col>
8845 </colgroup>
8846 <tbody>
8847 <tr>
8848 <td>
8849                       <p>
8850                         <span class="emphasis"><em>Symbol</em></span>
8851                       </p>
8852                     </td>
8853 <td>
8854                       <p>
8855                         <span class="emphasis"><em>BIND8 Symbol</em></span>
8856                       </p>
8857                     </td>
8858 <td>
8859                       <p>
8860                         <span class="emphasis"><em>Description</em></span>
8861                       </p>
8862                     </td>
8863 </tr>
8864 <tr>
8865 <td>
8866                       <p><span><strong class="command">Queryv4</strong></span></p>
8867                     </td>
8868 <td>
8869                       <p><span><strong class="command">SFwdQ</strong></span></p>
8870                     </td>
8871 <td>
8872                       <p>
8873                         IPv4 queries sent.
8874                       </p>
8875                     </td>
8876 </tr>
8877 <tr>
8878 <td>
8879                       <p><span><strong class="command">Queryv6</strong></span></p>
8880                     </td>
8881 <td>
8882                       <p><span><strong class="command">SFwdQ</strong></span></p>
8883                     </td>
8884 <td>
8885                       <p>
8886                         IPv6 queries sent.
8887                       </p>
8888                     </td>
8889 </tr>
8890 <tr>
8891 <td>
8892                       <p><span><strong class="command">Responsev4</strong></span></p>
8893                     </td>
8894 <td>
8895                       <p><span><strong class="command">RR</strong></span></p>
8896                     </td>
8897 <td>
8898                       <p>
8899                         IPv4 responses received.
8900                       </p>
8901                     </td>
8902 </tr>
8903 <tr>
8904 <td>
8905                       <p><span><strong class="command">Responsev6</strong></span></p>
8906                     </td>
8907 <td>
8908                       <p><span><strong class="command">RR</strong></span></p>
8909                     </td>
8910 <td>
8911                       <p>
8912                         IPv6 responses received.
8913                       </p>
8914                     </td>
8915 </tr>
8916 <tr>
8917 <td>
8918                       <p><span><strong class="command">NXDOMAIN</strong></span></p>
8919                     </td>
8920 <td>
8921                       <p><span><strong class="command">RNXD</strong></span></p>
8922                     </td>
8923 <td>
8924                       <p>
8925                         NXDOMAIN received.
8926                       </p>
8927                     </td>
8928 </tr>
8929 <tr>
8930 <td>
8931                       <p><span><strong class="command">SERVFAIL</strong></span></p>
8932                     </td>
8933 <td>
8934                       <p><span><strong class="command">RFail</strong></span></p>
8935                     </td>
8936 <td>
8937                       <p>
8938                         SERVFAIL received.
8939                       </p>
8940                     </td>
8941 </tr>
8942 <tr>
8943 <td>
8944                       <p><span><strong class="command">FORMERR</strong></span></p>
8945                     </td>
8946 <td>
8947                       <p><span><strong class="command">RFErr</strong></span></p>
8948                     </td>
8949 <td>
8950                       <p>
8951                         FORMERR received.
8952                       </p>
8953                     </td>
8954 </tr>
8955 <tr>
8956 <td>
8957                       <p><span><strong class="command">OtherError</strong></span></p>
8958                     </td>
8959 <td>
8960                       <p><span><strong class="command">RErr</strong></span></p>
8961                     </td>
8962 <td>
8963                       <p>
8964                         Other errors received.
8965                       </p>
8966                     </td>
8967 </tr>
8968 <tr>
8969 <td>
8970                       <p><span><strong class="command">EDNS0Fail</strong></span></p>
8971                                                  </td>
8972 <td>
8973                       <p><span><strong class="command"></strong></span></p>
8974                     </td>
8975 <td>
8976                       <p>
8977                         EDNS(0) query failures.
8978                       </p>
8979                     </td>
8980 </tr>
8981 <tr>
8982 <td>
8983                       <p><span><strong class="command">Mismatch</strong></span></p>
8984                     </td>
8985 <td>
8986                       <p><span><strong class="command">RDupR</strong></span></p>
8987                     </td>
8988 <td>
8989                       <p>
8990                         Mismatch responses received.
8991                       </p>
8992                     </td>
8993 </tr>
8994 <tr>
8995 <td>
8996                       <p><span><strong class="command">Truncated</strong></span></p>
8997                     </td>
8998 <td>
8999                       <p><span><strong class="command"></strong></span></p>
9000                     </td>
9001 <td>
9002                       <p>
9003                         Truncated responses received.
9004                       </p>
9005                     </td>
9006 </tr>
9007 <tr>
9008 <td>
9009                       <p><span><strong class="command">Lame</strong></span></p>
9010                     </td>
9011 <td>
9012                       <p><span><strong class="command">RLame</strong></span></p>
9013                     </td>
9014 <td>
9015                       <p>
9016                         Lame delegations received.
9017                       </p>
9018                     </td>
9019 </tr>
9020 <tr>
9021 <td>
9022                       <p><span><strong class="command">Retry</strong></span></p>
9023                     </td>
9024 <td>
9025                       <p><span><strong class="command">SDupQ</strong></span></p>
9026                     </td>
9027 <td>
9028                       <p>
9029                         Query retries performed.
9030                       </p>
9031                     </td>
9032 </tr>
9033 <tr>
9034 <td>
9035                       <p><span><strong class="command">QueryAbort</strong></span></p>
9036                     </td>
9037 <td>
9038                       <p><span><strong class="command"></strong></span></p>
9039                     </td>
9040 <td>
9041                       <p>
9042                         Queries aborted due to quota control.
9043                       </p>
9044                     </td>
9045 </tr>
9046 <tr>
9047 <td>
9048                       <p><span><strong class="command">QuerySockFail</strong></span></p>
9049                     </td>
9050 <td>
9051                       <p><span><strong class="command"></strong></span></p>
9052                     </td>
9053 <td>
9054                       <p>
9055                         Failures in opening query sockets.
9056                         One common reason for such failures is a
9057                         failure of opening a new socket due to a
9058                         limitation on file descriptors.
9059                       </p>
9060                     </td>
9061 </tr>
9062 <tr>
9063 <td>
9064                       <p><span><strong class="command">QueryTimeout</strong></span></p>
9065                     </td>
9066 <td>
9067                       <p><span><strong class="command"></strong></span></p>
9068                     </td>
9069 <td>
9070                       <p>
9071                         Query timeouts.
9072                       </p>
9073                     </td>
9074 </tr>
9075 <tr>
9076 <td>
9077                       <p><span><strong class="command">GlueFetchv4</strong></span></p>
9078                     </td>
9079 <td>
9080                       <p><span><strong class="command">SSysQ</strong></span></p>
9081                     </td>
9082 <td>
9083                       <p>
9084                         IPv4 NS address fetches invoked.
9085                       </p>
9086                     </td>
9087 </tr>
9088 <tr>
9089 <td>
9090                       <p><span><strong class="command">GlueFetchv6</strong></span></p>
9091                     </td>
9092 <td>
9093                       <p><span><strong class="command">SSysQ</strong></span></p>
9094                     </td>
9095 <td>
9096                       <p>
9097                         IPv6 NS address fetches invoked.
9098                       </p>
9099                     </td>
9100 </tr>
9101 <tr>
9102 <td>
9103                       <p><span><strong class="command">GlueFetchv4Fail</strong></span></p>
9104                     </td>
9105 <td>
9106                       <p><span><strong class="command"></strong></span></p>
9107                     </td>
9108 <td>
9109                       <p>
9110                         IPv4 NS address fetch failed.
9111                       </p>
9112                     </td>
9113 </tr>
9114 <tr>
9115 <td>
9116                       <p><span><strong class="command">GlueFetchv6Fail</strong></span></p>
9117                     </td>
9118 <td>
9119                       <p><span><strong class="command"></strong></span></p>
9120                     </td>
9121 <td>
9122                       <p>
9123                         IPv6 NS address fetch failed.
9124                       </p>
9125                     </td>
9126 </tr>
9127 <tr>
9128 <td>
9129                       <p><span><strong class="command">ValAttempt</strong></span></p>
9130                     </td>
9131 <td>
9132                       <p><span><strong class="command"></strong></span></p>
9133                     </td>
9134 <td>
9135                       <p>
9136                         DNSSEC validation attempted.
9137                       </p>
9138                     </td>
9139 </tr>
9140 <tr>
9141 <td>
9142                       <p><span><strong class="command">ValOk</strong></span></p>
9143                     </td>
9144 <td>
9145                       <p><span><strong class="command"></strong></span></p>
9146                     </td>
9147 <td>
9148                       <p>
9149                         DNSSEC validation succeeded.
9150                       </p>
9151                     </td>
9152 </tr>
9153 <tr>
9154 <td>
9155                       <p><span><strong class="command">ValNegOk</strong></span></p>
9156                     </td>
9157 <td>
9158                       <p><span><strong class="command"></strong></span></p>
9159                     </td>
9160 <td>
9161                       <p>
9162                         DNSSEC validation on negative information succeeded.
9163                       </p>
9164                     </td>
9165 </tr>
9166 <tr>
9167 <td>
9168                       <p><span><strong class="command">ValFail</strong></span></p>
9169                     </td>
9170 <td>
9171                       <p><span><strong class="command"></strong></span></p>
9172                     </td>
9173 <td>
9174                       <p>
9175                         DNSSEC validation failed.
9176                       </p>
9177                     </td>
9178 </tr>
9179 <tr>
9180 <td>
9181                       <p><span><strong class="command">QryRTTnn</strong></span></p>
9182                     </td>
9183 <td>
9184                       <p><span><strong class="command"></strong></span></p>
9185                     </td>
9186 <td>
9187                       <p>
9188                         Frequency table on round trip times (RTTs) of
9189                         queries.
9190                         Each <span><strong class="command">nn</strong></span> specifies the corresponding
9191                         frequency.
9192                         In the sequence of
9193                         <span><strong class="command">nn_1</strong></span>,
9194                         <span><strong class="command">nn_2</strong></span>,
9195                         ...,
9196                         <span><strong class="command">nn_m</strong></span>,
9197                         the value of <span><strong class="command">nn_i</strong></span> is the
9198                         number of queries whose RTTs are between
9199                         <span><strong class="command">nn_(i-1)</strong></span> (inclusive) and
9200                         <span><strong class="command">nn_i</strong></span> (exclusive) milliseconds.
9201                         For the sake of convenience we define
9202                         <span><strong class="command">nn_0</strong></span> to be 0.
9203                         The last entry should be represented as
9204                         <span><strong class="command">nn_m+</strong></span>, which means the
9205                         number of queries whose RTTs are equal to or over
9206                         <span><strong class="command">nn_m</strong></span> milliseconds.
9207                       </p>
9208                     </td>
9209 </tr>
9210 </tbody>
9211 </table></div>
9212 </div>
9213 <div class="sect3" lang="en">
9214 <div class="titlepage"><div><div><h4 class="title">
9215 <a name="id2598553"></a>Socket I/O Statistics Counters</h4></div></div></div>
9216 <p>
9217               Socket I/O statistics counters are defined per socket
9218               types, which are
9219               <span><strong class="command">UDP4</strong></span> (UDP/IPv4),
9220               <span><strong class="command">UDP6</strong></span> (UDP/IPv6),
9221               <span><strong class="command">TCP4</strong></span> (TCP/IPv4),
9222               <span><strong class="command">TCP6</strong></span> (TCP/IPv6),
9223               <span><strong class="command">Unix</strong></span> (Unix Domain), and
9224               <span><strong class="command">FDwatch</strong></span> (sockets opened outside the
9225               socket module).
9226               In the following table <span><strong class="command">&lt;TYPE&gt;</strong></span>
9227               represents a socket type.
9228               Not all counters are available for all socket types;
9229               exceptions are noted in the description field.
9230             </p>
9231 <div class="informaltable"><table border="1">
9232 <colgroup>
9233 <col>
9234 <col>
9235 </colgroup>
9236 <tbody>
9237 <tr>
9238 <td>
9239                       <p>
9240                         <span class="emphasis"><em>Symbol</em></span>
9241                       </p>
9242                     </td>
9243 <td>
9244                       <p>
9245                         <span class="emphasis"><em>Description</em></span>
9246                       </p>
9247                     </td>
9248 </tr>
9249 <tr>
9250 <td>
9251                       <p><span><strong class="command">&lt;TYPE&gt;Open</strong></span></p>
9252                     </td>
9253 <td>
9254                       <p>
9255                         Sockets opened successfully.
9256                         This counter is not applicable to the
9257                         <span><strong class="command">FDwatch</strong></span> type.
9258                       </p>
9259                     </td>
9260 </tr>
9261 <tr>
9262 <td>
9263                       <p><span><strong class="command">&lt;TYPE&gt;OpenFail</strong></span></p>
9264                     </td>
9265 <td>
9266                       <p>
9267                         Failures of opening sockets.
9268                         This counter is not applicable to the
9269                         <span><strong class="command">FDwatch</strong></span> type.
9270                       </p>
9271                     </td>
9272 </tr>
9273 <tr>
9274 <td>
9275                       <p><span><strong class="command">&lt;TYPE&gt;Close</strong></span></p>
9276                     </td>
9277 <td>
9278                       <p>
9279                         Sockets closed.
9280                       </p>
9281                     </td>
9282 </tr>
9283 <tr>
9284 <td>
9285                       <p><span><strong class="command">&lt;TYPE&gt;BindFail</strong></span></p>
9286                     </td>
9287 <td>
9288                       <p>
9289                         Failures of binding sockets.
9290                       </p>
9291                     </td>
9292 </tr>
9293 <tr>
9294 <td>
9295                       <p><span><strong class="command">&lt;TYPE&gt;ConnFail</strong></span></p>
9296                     </td>
9297 <td>
9298                       <p>
9299                         Failures of connecting sockets.
9300                       </p>
9301                     </td>
9302 </tr>
9303 <tr>
9304 <td>
9305                       <p><span><strong class="command">&lt;TYPE&gt;Conn</strong></span></p>
9306                     </td>
9307 <td>
9308                       <p>
9309                         Connections established successfully.
9310                       </p>
9311                     </td>
9312 </tr>
9313 <tr>
9314 <td>
9315                       <p><span><strong class="command">&lt;TYPE&gt;AcceptFail</strong></span></p>
9316                     </td>
9317 <td>
9318                       <p>
9319                         Failures of accepting incoming connection requests.
9320                         This counter is not applicable to the
9321                         <span><strong class="command">UDP</strong></span> and
9322                         <span><strong class="command">FDwatch</strong></span> types.
9323                       </p>
9324                     </td>
9325 </tr>
9326 <tr>
9327 <td>
9328                       <p><span><strong class="command">&lt;TYPE&gt;Accept</strong></span></p>
9329                     </td>
9330 <td>
9331                       <p>
9332                         Incoming connections successfully accepted.
9333                         This counter is not applicable to the
9334                         <span><strong class="command">UDP</strong></span> and
9335                         <span><strong class="command">FDwatch</strong></span> types.
9336                       </p>
9337                     </td>
9338 </tr>
9339 <tr>
9340 <td>
9341                       <p><span><strong class="command">&lt;TYPE&gt;SendErr</strong></span></p>
9342                     </td>
9343 <td>
9344                       <p>
9345                         Errors in socket send operations.
9346                         This counter corresponds
9347                         to <span><strong class="command">SErr</strong></span> counter of
9348                         <span><strong class="command">BIND</strong></span> 8.
9349                       </p>
9350                     </td>
9351 </tr>
9352 <tr>
9353 <td>
9354                       <p><span><strong class="command">&lt;TYPE&gt;RecvErr</strong></span></p>
9355                     </td>
9356 <td>
9357                       <p>
9358                         Errors in socket receive operations.
9359                         This includes errors of send operations on a
9360                         connected UDP socket notified by an ICMP error
9361                         message.
9362                       </p>
9363                     </td>
9364 </tr>
9365 </tbody>
9366 </table></div>
9367 </div>
9368 <div class="sect3" lang="en">
9369 <div class="titlepage"><div><div><h4 class="title">
9370 <a name="id2598995"></a>Compatibility with <span class="emphasis"><em>BIND</em></span> 8 Counters</h4></div></div></div>
9371 <p>
9372               Most statistics counters that were available
9373               in <span><strong class="command">BIND</strong></span> 8 are also supported in
9374               <span><strong class="command">BIND</strong></span> 9 as shown in the above tables.
9375               Here are notes about other counters that do not appear
9376               in these tables.
9377             </p>
9378 <div class="variablelist"><dl>
9379 <dt><span class="term"><span><strong class="command">RFwdR,SFwdR</strong></span></span></dt>
9380 <dd><p>
9381                     These counters are not supported
9382                     because <span><strong class="command">BIND</strong></span> 9 does not adopt
9383                     the notion of <span class="emphasis"><em>forwarding</em></span>
9384                     as <span><strong class="command">BIND</strong></span> 8 did.
9385                   </p></dd>
9386 <dt><span class="term"><span><strong class="command">RAXFR</strong></span></span></dt>
9387 <dd><p>
9388                     This counter is accessible in the Incoming Queries section.
9389                   </p></dd>
9390 <dt><span class="term"><span><strong class="command">RIQ</strong></span></span></dt>
9391 <dd><p>
9392                     This counter is accessible in the Incoming Requests section.
9393                   </p></dd>
9394 <dt><span class="term"><span><strong class="command">ROpts</strong></span></span></dt>
9395 <dd><p>
9396                     This counter is not supported
9397                     because <span><strong class="command">BIND</strong></span> 9 does not care
9398                     about IP options in the first place.
9399                   </p></dd>
9400 </dl></div>
9401 </div>
9402 </div>
9403 </div>
9404 </div>
9405 <div class="navfooter">
9406 <hr>
9407 <table width="100%" summary="Navigation footer">
9408 <tr>
9409 <td width="40%" align="left">
9410 <a accesskey="p" href="Bv9ARM.ch05.html">Prev</a> </td>
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9413 </td>
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9415 <tr>
9416 <td width="40%" align="left" valign="top">Chapter 5. The <acronym class="acronym">BIND</acronym> 9 Lightweight Resolver </td>
9417 <td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td>
9418 <td width="40%" align="right" valign="top"> Chapter 7. <acronym class="acronym">BIND</acronym> 9 Security Considerations</td>
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