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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#id2573716">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#id2574346"><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#id2574536"><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#id2574965"><span><strong class="command">include</strong></span> Statement Grammar</a></span></dt>
  62 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574982"><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#id2575005"><span><strong class="command">key</strong></span> Statement Grammar</a></span></dt>
  65 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575029"><span><strong class="command">key</strong></span> Statement Definition and Usage</a></span></dt>
  66 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575120"><span><strong class="command">logging</strong></span> Statement Grammar</a></span></dt>
  67 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575245"><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#id2577306"><span><strong class="command">lwres</strong></span> Statement Grammar</a></span></dt>
  70 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577448"><span><strong class="command">lwres</strong></span> Statement Definition and Usage</a></span></dt>
  71 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577512"><span><strong class="command">masters</strong></span> Statement Grammar</a></span></dt>
  72 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577556"><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#id2577571"><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#id2586754"><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#id2586908"><span><strong class="command">trusted-keys</strong></span> Statement Grammar</a></span></dt>
  84 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2586960"><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#id2587042"><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#id2588510"><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#id2591109">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#id2593203">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#id2593886">Inverse Mapping in IPv4</a></span></dt>
  98 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2594013">Other Zone File Directives</a></span></dt>
  99 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2594270"><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="id2573414"></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="id2573442"></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="id2573716"></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="id2573731"></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="id2573761"></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="id2574346"></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="id2574536"></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="id2574965"></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="id2574982"></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="id2575005"></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="id2575029"></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="id2575120"></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="id2575245"></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="id2575298"></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
1670                       those servers during resolution.
1671                     </p>
1672                   </td>
1673 </tr>
1674 <tr>
1675 <td>
1676                     <p><span><strong class="command">delegation-only</strong></span></p>
1677                   </td>
1678 <td>
1679                     <p>
1680                       Delegation only.  Logs queries that have
1681                       been forced to NXDOMAIN as the result of a
1682                       delegation-only zone or
1683                       a <span><strong class="command">delegation-only</strong></span> in a
1684                       hint or stub zone declaration.
1685                     </p>
1686                   </td>
1687 </tr>
1688 <tr>
1689 <td>
1690                     <p><span><strong class="command">edns-disabled</strong></span></p>
1691                   </td>
1692 <td>
1693                     <p>
1694                       Log queries that have been forced to use plain
1695                       DNS due to timeouts.  This is often due to
1696                       the remote servers not being RFC 1034 compliant
1697                       (not always returning FORMERR or similar to
1698                       EDNS queries and other extensions to the DNS
1699                       when they are not understood).  In other words, this is
1700                       targeted at servers that fail to respond to
1701                       DNS queries that they don't understand.
1702                     </p>
1703                     <p>
1704                       Note: the log message can also be due to
1705                       packet loss.  Before reporting servers for
1706                       non-RFC 1034 compliance they should be re-tested
1707                       to determine the nature of the non-compliance.
1708                       This testing should prevent or reduce the
1709                       number of false-positive reports.
1710                     </p>
1711                     <p>
1712                       Note: eventually <span><strong class="command">named</strong></span> will have to stop
1713                       treating such timeouts as due to RFC 1034 non
1714                       compliance and start treating it as plain
1715                       packet loss.  Falsely classifying packet
1716                       loss as due to RFC 1034 non compliance impacts
1717                       on DNSSEC validation which requires EDNS for
1718                       the DNSSEC records to be returned.
1719                     </p>
1720                   </td>
1721 </tr>
1722 </tbody>
1723 </table></div>
1724 </div>
1725 <div class="sect3" lang="en">
1726 <div class="titlepage"><div><div><h4 class="title">
1727 <a name="id2576793"></a>The <span><strong class="command">query-errors</strong></span> Category</h4></div></div></div>
1728 <p>
1729             The <span><strong class="command">query-errors</strong></span> category is
1730             specifically intended for debugging purposes: To identify
1731             why and how specific queries result in responses which
1732             indicate an error.
1733             Messages of this category are therefore only logged
1734             with <span><strong class="command">debug</strong></span> levels.
1735           </p>
1736 <p>
1737             At the debug levels of 1 or higher, each response with the
1738             rcode of SERVFAIL is logged as follows:
1739           </p>
1740 <p>
1741             <code class="computeroutput">client 127.0.0.1#61502: query failed (SERVFAIL) for www.example.com/IN/AAAA at query.c:3880</code>
1742           </p>
1743 <p>
1744             This means an error resulting in SERVFAIL was
1745             detected at line 3880 of source file
1746             <code class="filename">query.c</code>.
1747             Log messages of this level will particularly
1748             help identify the cause of SERVFAIL for an
1749             authoritative server.
1750           </p>
1751 <p>
1752             At the debug levels of 2 or higher, detailed context
1753             information of recursive resolutions that resulted in
1754             SERVFAIL is logged.
1755             The log message will look like as follows:
1756           </p>
1757 <p>
1758             <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>
1759           </p>
1760 <p>
1761             The first part before the colon shows that a recursive
1762             resolution for AAAA records of www.example.com completed
1763             in 30.000183 seconds and the final result that led to the
1764             SERVFAIL was determined at line 2970 of source file
1765             <code class="filename">resolver.c</code>.
1766           </p>
1767 <p>
1768             The following part shows the detected final result and the
1769             latest result of DNSSEC validation.
1770             The latter is always success when no validation attempt
1771             is made.
1772             In this example, this query resulted in SERVFAIL probably
1773             because all name servers are down or unreachable, leading
1774             to a timeout in 30 seconds.
1775             DNSSEC validation was probably not attempted.
1776           </p>
1777 <p>
1778             The last part enclosed in square brackets shows statistics
1779             information collected for this particular resolution
1780             attempt.
1781             The <code class="varname">domain</code> field shows the deepest zone
1782             that the resolver reached;
1783             it is the zone where the error was finally detected.
1784             The meaning of the other fields is summarized in the
1785             following table.
1786           </p>
1787 <div class="informaltable"><table border="1">
1788 <colgroup>
1789 <col>
1790 <col>
1791 </colgroup>
1792 <tbody>
1793 <tr>
1794 <td>
1795                     <p><code class="varname">referral</code></p>
1796                   </td>
1797 <td>
1798                     <p>
1799                       The number of referrals the resolver received
1800                       throughout the resolution process.
1801                       In the above example this is 2, which are most
1802                       likely com and example.com.
1803                     </p>
1804                   </td>
1805 </tr>
1806 <tr>
1807 <td>
1808                     <p><code class="varname">restart</code></p>
1809                   </td>
1810 <td>
1811                     <p>
1812                       The number of cycles that the resolver tried
1813                       remote servers at the <code class="varname">domain</code>
1814                       zone.
1815                       In each cycle the resolver sends one query
1816                       (possibly resending it, depending on the response)
1817                       to each known name server of
1818                       the <code class="varname">domain</code> zone.
1819                     </p>
1820                   </td>
1821 </tr>
1822 <tr>
1823 <td>
1824                     <p><code class="varname">qrysent</code></p>
1825                   </td>
1826 <td>
1827                     <p>
1828                       The number of queries the resolver sent at the
1829                       <code class="varname">domain</code> zone.
1830                     </p>
1831                   </td>
1832 </tr>
1833 <tr>
1834 <td>
1835                     <p><code class="varname">timeout</code></p>
1836                   </td>
1837 <td>
1838                     <p>
1839                       The number of timeouts since the resolver
1840                       received the last response.
1841                     </p>
1842                   </td>
1843 </tr>
1844 <tr>
1845 <td>
1846                     <p><code class="varname">lame</code></p>
1847                   </td>
1848 <td>
1849                     <p>
1850                       The number of lame servers the resolver detected
1851                       at the <code class="varname">domain</code> zone.
1852                       A server is detected to be lame either by an
1853                       invalid response or as a result of lookup in
1854                       BIND9's address database (ADB), where lame
1855                       servers are cached.
1856                     </p>
1857                   </td>
1858 </tr>
1859 <tr>
1860 <td>
1861                     <p><code class="varname">neterr</code></p>
1862                   </td>
1863 <td>
1864                     <p>
1865                       The number of erroneous results that the
1866                       resolver encountered in sending queries
1867                       at the <code class="varname">domain</code> zone.
1868                       One common case is the remote server is
1869                       unreachable and the resolver receives an ICMP
1870                       unreachable error message.
1871                     </p>
1872                   </td>
1873 </tr>
1874 <tr>
1875 <td>
1876                     <p><code class="varname">badresp</code></p>
1877                   </td>
1878 <td>
1879                     <p>
1880                       The number of unexpected responses (other than
1881                       <code class="varname">lame</code>) to queries sent by the
1882                       resolver at the <code class="varname">domain</code> zone.
1883                     </p>
1884                   </td>
1885 </tr>
1886 <tr>
1887 <td>
1888                     <p><code class="varname">adberr</code></p>
1889                   </td>
1890 <td>
1891                     <p>
1892                       Failures in finding remote server addresses
1893                       of the <code class="varname">domain</code> zone in the ADB.
1894                       One common case of this is that the remote
1895                       server's name does not have any address records.
1896                     </p>
1897                   </td>
1898 </tr>
1899 <tr>
1900 <td>
1901                     <p><code class="varname">findfail</code></p>
1902                   </td>
1903 <td>
1904                     <p>
1905                       Failures of resolving remote server addresses.
1906                       This is a total number of failures throughout
1907                       the resolution process.
1908                     </p>
1909                   </td>
1910 </tr>
1911 <tr>
1912 <td>
1913                     <p><code class="varname">valfail</code></p>
1914                   </td>
1915 <td>
1916                     <p>
1917                       Failures of DNSSEC validation.
1918                       Validation failures are counted throughout
1919                       the resolution process (not limited to
1920                       the <code class="varname">domain</code> zone), but should
1921                       only happen in <code class="varname">domain</code>.
1922                     </p>
1923                   </td>
1924 </tr>
1925 </tbody>
1926 </table></div>
1927 <p>
1928             At the debug levels of 3 or higher, the same messages
1929             as those at the debug 1 level are logged for other errors
1930             than SERVFAIL.
1931             Note that negative responses such as NXDOMAIN are not
1932             regarded as errors here.
1933           </p>
1934 <p>
1935             At the debug levels of 4 or higher, the same messages
1936             as those at the debug 2 level are logged for other errors
1937             than SERVFAIL.
1938             Unlike the above case of level 3, messages are logged for
1939             negative responses.
1940             This is because any unexpected results can be difficult to
1941             debug in the recursion case.
1942           </p>
1943 </div>
1944 </div>
1945 <div class="sect2" lang="en">
1946 <div class="titlepage"><div><div><h3 class="title">
1947 <a name="id2577306"></a><span><strong class="command">lwres</strong></span> Statement Grammar</h3></div></div></div>
1948 <p>
1949            This is the grammar of the <span><strong class="command">lwres</strong></span>
1950           statement in the <code class="filename">named.conf</code> file:
1951         </p>
1952 <pre class="programlisting"><span><strong class="command">lwres</strong></span> {
1953     [<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>]
1954     [<span class="optional"> view <em class="replaceable"><code>view_name</code></em>; </span>]
1955     [<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>]
1956     [<span class="optional"> ndots <em class="replaceable"><code>number</code></em>; </span>]
1957 };
1958 </pre>
1959 </div>
1960 <div class="sect2" lang="en">
1961 <div class="titlepage"><div><div><h3 class="title">
1962 <a name="id2577448"></a><span><strong class="command">lwres</strong></span> Statement Definition and Usage</h3></div></div></div>
1963 <p>
1964           The <span><strong class="command">lwres</strong></span> statement configures the
1965           name
1966           server to also act as a lightweight resolver server. (See
1967           <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
1968           <span><strong class="command">lwres</strong></span> statements configuring
1969           lightweight resolver servers with different properties.
1970         </p>
1971 <p>
1972           The <span><strong class="command">listen-on</strong></span> statement specifies a
1973           list of
1974           addresses (and ports) that this instance of a lightweight resolver
1975           daemon
1976           should accept requests on.  If no port is specified, port 921 is
1977           used.
1978           If this statement is omitted, requests will be accepted on
1979           127.0.0.1,
1980           port 921.
1981         </p>
1982 <p>
1983           The <span><strong class="command">view</strong></span> statement binds this
1984           instance of a
1985           lightweight resolver daemon to a view in the DNS namespace, so that
1986           the
1987           response will be constructed in the same manner as a normal DNS
1988           query
1989           matching this view.  If this statement is omitted, the default view
1990           is
1991           used, and if there is no default view, an error is triggered.
1992         </p>
1993 <p>
1994           The <span><strong class="command">search</strong></span> statement is equivalent to
1995           the
1996           <span><strong class="command">search</strong></span> statement in
1997           <code class="filename">/etc/resolv.conf</code>.  It provides a
1998           list of domains
1999           which are appended to relative names in queries.
2000         </p>
2001 <p>
2002           The <span><strong class="command">ndots</strong></span> statement is equivalent to
2003           the
2004           <span><strong class="command">ndots</strong></span> statement in
2005           <code class="filename">/etc/resolv.conf</code>.  It indicates the
2006           minimum
2007           number of dots in a relative domain name that should result in an
2008           exact match lookup before search path elements are appended.
2009         </p>
2010 </div>
2011 <div class="sect2" lang="en">
2012 <div class="titlepage"><div><div><h3 class="title">
2013 <a name="id2577512"></a><span><strong class="command">masters</strong></span> Statement Grammar</h3></div></div></div>
2014 <pre class="programlisting">
2015 <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>] };
2016 </pre>
2017 </div>
2018 <div class="sect2" lang="en">
2019 <div class="titlepage"><div><div><h3 class="title">
2020 <a name="id2577556"></a><span><strong class="command">masters</strong></span> Statement Definition and
2021           Usage</h3></div></div></div>
2022 <p><span><strong class="command">masters</strong></span>
2023           lists allow for a common set of masters to be easily used by
2024           multiple stub and slave zones.
2025         </p>
2026 </div>
2027 <div class="sect2" lang="en">
2028 <div class="titlepage"><div><div><h3 class="title">
2029 <a name="id2577571"></a><span><strong class="command">options</strong></span> Statement Grammar</h3></div></div></div>
2030 <p>
2031           This is the grammar of the <span><strong class="command">options</strong></span>
2032           statement in the <code class="filename">named.conf</code> file:
2033         </p>
2034 <pre class="programlisting"><span><strong class="command">options</strong></span> {
2035     [<span class="optional"> version <em class="replaceable"><code>version_string</code></em>; </span>]
2036     [<span class="optional"> hostname <em class="replaceable"><code>hostname_string</code></em>; </span>]
2037     [<span class="optional"> server-id <em class="replaceable"><code>server_id_string</code></em>; </span>]
2038     [<span class="optional"> directory <em class="replaceable"><code>path_name</code></em>; </span>]
2039     [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>]
2040     [<span class="optional"> named-xfer <em class="replaceable"><code>path_name</code></em>; </span>]
2041     [<span class="optional"> tkey-gssapi-credential <em class="replaceable"><code>principal</code></em>; </span>]
2042     [<span class="optional"> tkey-domain <em class="replaceable"><code>domainname</code></em>; </span>]
2043     [<span class="optional"> tkey-dhkey <em class="replaceable"><code>key_name</code></em> <em class="replaceable"><code>key_tag</code></em>; </span>]
2044     [<span class="optional"> cache-file <em class="replaceable"><code>path_name</code></em>; </span>]
2045     [<span class="optional"> dump-file <em class="replaceable"><code>path_name</code></em>; </span>]
2046     [<span class="optional"> memstatistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2047     [<span class="optional"> memstatistics-file <em class="replaceable"><code>path_name</code></em>; </span>]
2048     [<span class="optional"> pid-file <em class="replaceable"><code>path_name</code></em>; </span>]
2049     [<span class="optional"> recursing-file <em class="replaceable"><code>path_name</code></em>; </span>]
2050     [<span class="optional"> statistics-file <em class="replaceable"><code>path_name</code></em>; </span>]
2051     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2052     [<span class="optional"> auth-nxdomain <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2053     [<span class="optional"> deallocate-on-exit <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2054     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em>; </span>]
2055     [<span class="optional"> fake-iquery <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2056     [<span class="optional"> fetch-glue <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2057     [<span class="optional"> flush-zones-on-shutdown <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2058     [<span class="optional"> has-old-clients <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2059     [<span class="optional"> host-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2060     [<span class="optional"> host-statistics-max <em class="replaceable"><code>number</code></em>; </span>]
2061     [<span class="optional"> minimal-responses <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2062     [<span class="optional"> multiple-cnames <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2063     [<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>]
2064     [<span class="optional"> recursion <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2065     [<span class="optional"> rfc2308-type1 <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2066     [<span class="optional"> use-id-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2067     [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2068     [<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>]
2069     [<span class="optional"> dnssec-enable <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2070     [<span class="optional"> dnssec-validation <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2071     [<span class="optional"> dnssec-lookaside <em class="replaceable"><code>domain</code></em> trust-anchor <em class="replaceable"><code>domain</code></em>; </span>]
2072     [<span class="optional"> dnssec-must-be-secure <em class="replaceable"><code>domain yes_or_no</code></em>; </span>]
2073     [<span class="optional"> dnssec-accept-expired <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2074     [<span class="optional"> forward ( <em class="replaceable"><code>only</code></em> | <em class="replaceable"><code>first</code></em> ); </span>]
2075     [<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>]
2076     [<span class="optional"> dual-stack-servers [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] {
2077         ( <em class="replaceable"><code>domain_name</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] |
2078           <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ) ;
2079         ... }; </span>]
2080     [<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> )
2081         ( <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-mx ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2083     [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2084     [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2085     [<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>]
2086     [<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>]
2087     [<span class="optional"> check-sibling <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2088     [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2089     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2090     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2091     [<span class="optional"> allow-query-cache { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2092     [<span class="optional"> allow-query-cache-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2093     [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2094     [<span class="optional"> allow-recursion { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2095     [<span class="optional"> allow-recursion-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2096     [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2097     [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2098     [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2099     [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2100     [<span class="optional"> allow-v6-synthesis { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2101     [<span class="optional"> blackhole { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2102     [<span class="optional"> use-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2103     [<span class="optional"> avoid-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2104     [<span class="optional"> use-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2105     [<span class="optional"> avoid-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2106     [<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>]
2107     [<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>]
2108     [<span class="optional"> query-source ( ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> )
2109         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] |
2110         [<span class="optional"> address ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
2111         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>]
2112     [<span class="optional"> query-source-v6 ( ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> )
2113         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] |
2114         [<span class="optional"> address ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
2115         [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>]
2116     [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2117     [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>]
2118     [<span class="optional"> queryport-pool-interval <em class="replaceable"><code>number</code></em>; </span>]
2119     [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em>; </span>]
2120     [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em>; </span>]
2121     [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em>; </span>]
2122     [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em>; </span>]
2123     [<span class="optional"> tcp-clients <em class="replaceable"><code>number</code></em>; </span>]
2124     [<span class="optional"> reserved-sockets <em class="replaceable"><code>number</code></em>; </span>]
2125     [<span class="optional"> recursive-clients <em class="replaceable"><code>number</code></em>; </span>]
2126     [<span class="optional"> serial-query-rate <em class="replaceable"><code>number</code></em>; </span>]
2127     [<span class="optional"> serial-queries <em class="replaceable"><code>number</code></em>; </span>]
2128     [<span class="optional"> tcp-listen-queue <em class="replaceable"><code>number</code></em>; </span>]
2129     [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em>; </span>]
2130     [<span class="optional"> transfers-in  <em class="replaceable"><code>number</code></em>; </span>]
2131     [<span class="optional"> transfers-out <em class="replaceable"><code>number</code></em>; </span>]
2132     [<span class="optional"> transfers-per-ns <em class="replaceable"><code>number</code></em>; </span>]
2133     [<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>]
2134     [<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>]
2135     [<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>]
2136     [<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>]
2137     [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2138     [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
2139     [<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>]
2140     [<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>]
2141     [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2142     [<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>]
2143     [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em>; </span>]
2144     [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
2145     [<span class="optional"> coresize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2146     [<span class="optional"> datasize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2147     [<span class="optional"> files <em class="replaceable"><code>size_spec</code></em> ; </span>]
2148     [<span class="optional"> stacksize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2149     [<span class="optional"> cleaning-interval <em class="replaceable"><code>number</code></em>; </span>]
2150     [<span class="optional"> heartbeat-interval <em class="replaceable"><code>number</code></em>; </span>]
2151     [<span class="optional"> interface-interval <em class="replaceable"><code>number</code></em>; </span>]
2152     [<span class="optional"> statistics-interval <em class="replaceable"><code>number</code></em>; </span>]
2153     [<span class="optional"> topology { <em class="replaceable"><code>address_match_list</code></em> }</span>];
2154     [<span class="optional"> sortlist { <em class="replaceable"><code>address_match_list</code></em> }</span>];
2155     [<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>] };
2156     [<span class="optional"> lame-ttl <em class="replaceable"><code>number</code></em>; </span>]
2157     [<span class="optional"> max-ncache-ttl <em class="replaceable"><code>number</code></em>; </span>]
2158     [<span class="optional"> max-cache-ttl <em class="replaceable"><code>number</code></em>; </span>]
2159     [<span class="optional"> sig-validity-interval <em class="replaceable"><code>number</code></em> ; </span>]
2160     [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>]
2161     [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>]
2162     [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>]
2163     [<span class="optional"> min-roots <em class="replaceable"><code>number</code></em>; </span>]
2164     [<span class="optional"> use-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2165     [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2166     [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2167     [<span class="optional"> treat-cr-as-space <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2168     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
2169     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
2170     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
2171     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
2172     [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em>; </span>]
2173     [<span class="optional"> additional-from-auth <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2174     [<span class="optional"> additional-from-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2175     [<span class="optional"> random-device <em class="replaceable"><code>path_name</code></em> ; </span>]
2176     [<span class="optional"> max-cache-size <em class="replaceable"><code>size_spec</code></em> ; </span>]
2177     [<span class="optional"> match-mapped-addresses <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2178     [<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>]
2179     [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em>; </span>]
2180     [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em>; </span>]
2181     [<span class="optional"> root-delegation-only [<span class="optional"> exclude { <em class="replaceable"><code>namelist</code></em> } </span>] ; </span>]
2182     [<span class="optional"> querylog <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2183     [<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>]
2184     [<span class="optional"> acache-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2185     [<span class="optional"> acache-cleaning-interval <em class="replaceable"><code>number</code></em>; </span>]
2186     [<span class="optional"> max-acache-size <em class="replaceable"><code>size_spec</code></em> ; </span>]
2187     [<span class="optional"> clients-per-query <em class="replaceable"><code>number</code></em> ; </span>]
2188     [<span class="optional"> max-clients-per-query <em class="replaceable"><code>number</code></em> ; </span>]
2189     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
2190     [<span class="optional"> empty-server <em class="replaceable"><code>name</code></em> ; </span>]
2191     [<span class="optional"> empty-contact <em class="replaceable"><code>name</code></em> ; </span>]
2192     [<span class="optional"> empty-zones-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2193     [<span class="optional"> disable-empty-zone <em class="replaceable"><code>zone_name</code></em> ; </span>]
2194     [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2195     [<span class="optional"> zero-no-soa-ttl-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2196 };
2197 </pre>
2198 </div>
2199 <div class="sect2" lang="en">
2200 <div class="titlepage"><div><div><h3 class="title">
2201 <a name="options"></a><span><strong class="command">options</strong></span> Statement Definition and
2202           Usage</h3></div></div></div>
2203 <p>
2204           The <span><strong class="command">options</strong></span> statement sets up global
2205           options
2206           to be used by <acronym class="acronym">BIND</acronym>. This statement
2207           may appear only
2208           once in a configuration file. If there is no <span><strong class="command">options</strong></span>
2209           statement, an options block with each option set to its default will
2210           be used.
2211         </p>
2212 <div class="variablelist"><dl>
2213 <dt><span class="term"><span><strong class="command">directory</strong></span></span></dt>
2214 <dd><p>
2215                 The working directory of the server.
2216                 Any non-absolute pathnames in the configuration file will be
2217                 taken
2218                 as relative to this directory. The default location for most
2219                 server
2220                 output files (e.g. <code class="filename">named.run</code>)
2221                 is this directory.
2222                 If a directory is not specified, the working directory
2223                 defaults to `<code class="filename">.</code>', the directory from
2224                 which the server
2225                 was started. The directory specified should be an absolute
2226                 path.
2227               </p></dd>
2228 <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt>
2229 <dd><p>
2230                 When performing dynamic update of secure zones, the
2231                 directory where the public and private key files should be
2232                 found,
2233                 if different than the current working directory.  The
2234                 directory specified
2235                 must be an absolute path.
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><span class="term"><span><strong class="command">root-delegation-only</strong></span></span></dt>
2371 <dd>
2372 <p>
2373                 Turn on enforcement of delegation-only in TLDs (top level domains) and root zones
2374                 with an optional
2375                 exclude list.
2376               </p>
2377 <p>
2378                 Note some TLDs are not delegation only (e.g. "DE", "LV", "US"
2379                 and "MUSEUM").
2380               </p>
2381 <pre class="programlisting">
2382 options {
2383         root-delegation-only exclude { "de"; "lv"; "us"; "museum"; };
2384 };
2385 </pre>
2386 </dd>
2387 <dt><span class="term"><span><strong class="command">disable-algorithms</strong></span></span></dt>
2388 <dd><p>
2389                 Disable the specified DNSSEC algorithms at and below the
2390                 specified name.
2391                 Multiple <span><strong class="command">disable-algorithms</strong></span>
2392                 statements are allowed.
2393                 Only the most specific will be applied.
2394               </p></dd>
2395 <dt><span class="term"><span><strong class="command">dnssec-lookaside</strong></span></span></dt>
2396 <dd><p>
2397                 When set, <span><strong class="command">dnssec-lookaside</strong></span>
2398                 provides the
2399                 validator with an alternate method to validate DNSKEY records
2400                 at the
2401                 top of a zone.  When a DNSKEY is at or below a domain
2402                 specified by the
2403                 deepest <span><strong class="command">dnssec-lookaside</strong></span>, and
2404                 the normal DNSSEC validation
2405                 has left the key untrusted, the trust-anchor will be append to
2406                 the key
2407                 name and a DLV record will be looked up to see if it can
2408                 validate the
2409                 key.  If the DLV record validates a DNSKEY (similarly to the
2410                 way a DS
2411                 record does) the DNSKEY RRset is deemed to be trusted.
2412               </p></dd>
2413 <dt><span class="term"><span><strong class="command">dnssec-must-be-secure</strong></span></span></dt>
2414 <dd><p>
2415                 Specify hierarchies which must be or may not be secure (signed and
2416                 validated).
2417                 If <strong class="userinput"><code>yes</code></strong>, then <span><strong class="command">named</strong></span> will only accept
2418                 answers if they
2419                 are secure.
2420                 If <strong class="userinput"><code>no</code></strong>, then normal DNSSEC validation
2421                 applies
2422                 allowing for insecure answers to be accepted.
2423                 The specified domain must be under a <span><strong class="command">trusted-key</strong></span> or
2424                 <span><strong class="command">dnssec-lookaside</strong></span> must be
2425                 active.
2426               </p></dd>
2427 </dl></div>
2428 <div class="sect3" lang="en">
2429 <div class="titlepage"><div><div><h4 class="title">
2430 <a name="boolean_options"></a>Boolean Options</h4></div></div></div>
2431 <div class="variablelist"><dl>
2432 <dt><span class="term"><span><strong class="command">auth-nxdomain</strong></span></span></dt>
2433 <dd><p>
2434                   If <strong class="userinput"><code>yes</code></strong>, then the <span><strong class="command">AA</strong></span> bit
2435                   is always set on NXDOMAIN responses, even if the server is
2436                   not actually
2437                   authoritative. The default is <strong class="userinput"><code>no</code></strong>;
2438                   this is
2439                   a change from <acronym class="acronym">BIND</acronym> 8. If you
2440                   are using very old DNS software, you
2441                   may need to set it to <strong class="userinput"><code>yes</code></strong>.
2442                 </p></dd>
2443 <dt><span class="term"><span><strong class="command">deallocate-on-exit</strong></span></span></dt>
2444 <dd><p>
2445                   This option was used in <acronym class="acronym">BIND</acronym>
2446                   8 to enable checking
2447                   for memory leaks on exit. <acronym class="acronym">BIND</acronym> 9 ignores the option and always performs
2448                   the checks.
2449                 </p></dd>
2450 <dt><span class="term"><span><strong class="command">memstatistics</strong></span></span></dt>
2451 <dd><p>
2452                   Write memory statistics to the file specified by
2453                   <span><strong class="command">memstatistics-file</strong></span> at exit.
2454                   The default is <strong class="userinput"><code>no</code></strong> unless
2455                   '-m record' is specified on the command line in
2456                   which case it is <strong class="userinput"><code>yes</code></strong>.
2457                 </p></dd>
2458 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
2459 <dd>
2460 <p>
2461                   If <strong class="userinput"><code>yes</code></strong>, then the
2462                   server treats all zones as if they are doing zone transfers
2463                   across
2464                   a dial-on-demand dialup link, which can be brought up by
2465                   traffic
2466                   originating from this server. This has different effects
2467                   according
2468                   to zone type and concentrates the zone maintenance so that
2469                   it all
2470                   happens in a short interval, once every <span><strong class="command">heartbeat-interval</strong></span> and
2471                   hopefully during the one call. It also suppresses some of
2472                   the normal
2473                   zone maintenance traffic. The default is <strong class="userinput"><code>no</code></strong>.
2474                 </p>
2475 <p>
2476                   The <span><strong class="command">dialup</strong></span> option
2477                   may also be specified in the <span><strong class="command">view</strong></span> and
2478                   <span><strong class="command">zone</strong></span> statements,
2479                   in which case it overrides the global <span><strong class="command">dialup</strong></span>
2480                   option.
2481                 </p>
2482 <p>
2483                   If the zone is a master zone, then the server will send out a
2484                   NOTIFY
2485                   request to all the slaves (default). This should trigger the
2486                   zone serial
2487                   number check in the slave (providing it supports NOTIFY)
2488                   allowing the slave
2489                   to verify the zone while the connection is active.
2490                   The set of servers to which NOTIFY is sent can be controlled
2491                   by
2492                   <span><strong class="command">notify</strong></span> and <span><strong class="command">also-notify</strong></span>.
2493                 </p>
2494 <p>
2495                   If the
2496                   zone is a slave or stub zone, then the server will suppress
2497                   the regular
2498                   "zone up to date" (refresh) queries and only perform them
2499                   when the
2500                   <span><strong class="command">heartbeat-interval</strong></span> expires in
2501                   addition to sending
2502                   NOTIFY requests.
2503                 </p>
2504 <p>
2505                   Finer control can be achieved by using
2506                   <strong class="userinput"><code>notify</code></strong> which only sends NOTIFY
2507                   messages,
2508                   <strong class="userinput"><code>notify-passive</code></strong> which sends NOTIFY
2509                   messages and
2510                   suppresses the normal refresh queries, <strong class="userinput"><code>refresh</code></strong>
2511                   which suppresses normal refresh processing and sends refresh
2512                   queries
2513                   when the <span><strong class="command">heartbeat-interval</strong></span>
2514                   expires, and
2515                   <strong class="userinput"><code>passive</code></strong> which just disables normal
2516                   refresh
2517                   processing.
2518                 </p>
2519 <div class="informaltable"><table border="1">
2520 <colgroup>
2521 <col>
2522 <col>
2523 <col>
2524 <col>
2525 </colgroup>
2526 <tbody>
2527 <tr>
2528 <td>
2529                           <p>
2530                             dialup mode
2531                           </p>
2532                         </td>
2533 <td>
2534                           <p>
2535                             normal refresh
2536                           </p>
2537                         </td>
2538 <td>
2539                           <p>
2540                             heart-beat refresh
2541                           </p>
2542                         </td>
2543 <td>
2544                           <p>
2545                             heart-beat notify
2546                           </p>
2547                         </td>
2548 </tr>
2549 <tr>
2550 <td>
2551                           <p><span><strong class="command">no</strong></span> (default)</p>
2552                         </td>
2553 <td>
2554                           <p>
2555                             yes
2556                           </p>
2557                         </td>
2558 <td>
2559                           <p>
2560                             no
2561                           </p>
2562                         </td>
2563 <td>
2564                           <p>
2565                             no
2566                           </p>
2567                         </td>
2568 </tr>
2569 <tr>
2570 <td>
2571                           <p><span><strong class="command">yes</strong></span></p>
2572                         </td>
2573 <td>
2574                           <p>
2575                             no
2576                           </p>
2577                         </td>
2578 <td>
2579                           <p>
2580                             yes
2581                           </p>
2582                         </td>
2583 <td>
2584                           <p>
2585                             yes
2586                           </p>
2587                         </td>
2588 </tr>
2589 <tr>
2590 <td>
2591                           <p><span><strong class="command">notify</strong></span></p>
2592                         </td>
2593 <td>
2594                           <p>
2595                             yes
2596                           </p>
2597                         </td>
2598 <td>
2599                           <p>
2600                             no
2601                           </p>
2602                         </td>
2603 <td>
2604                           <p>
2605                             yes
2606                           </p>
2607                         </td>
2608 </tr>
2609 <tr>
2610 <td>
2611                           <p><span><strong class="command">refresh</strong></span></p>
2612                         </td>
2613 <td>
2614                           <p>
2615                             no
2616                           </p>
2617                         </td>
2618 <td>
2619                           <p>
2620                             yes
2621                           </p>
2622                         </td>
2623 <td>
2624                           <p>
2625                             no
2626                           </p>
2627                         </td>
2628 </tr>
2629 <tr>
2630 <td>
2631                           <p><span><strong class="command">passive</strong></span></p>
2632                         </td>
2633 <td>
2634                           <p>
2635                             no
2636                           </p>
2637                         </td>
2638 <td>
2639                           <p>
2640                             no
2641                           </p>
2642                         </td>
2643 <td>
2644                           <p>
2645                             no
2646                           </p>
2647                         </td>
2648 </tr>
2649 <tr>
2650 <td>
2651                           <p><span><strong class="command">notify-passive</strong></span></p>
2652                         </td>
2653 <td>
2654                           <p>
2655                             no
2656                           </p>
2657                         </td>
2658 <td>
2659                           <p>
2660                             no
2661                           </p>
2662                         </td>
2663 <td>
2664                           <p>
2665                             yes
2666                           </p>
2667                         </td>
2668 </tr>
2669 </tbody>
2670 </table></div>
2671 <p>
2672                   Note that normal NOTIFY processing is not affected by
2673                   <span><strong class="command">dialup</strong></span>.
2674                 </p>
2675 </dd>
2676 <dt><span class="term"><span><strong class="command">fake-iquery</strong></span></span></dt>
2677 <dd><p>
2678                   In <acronym class="acronym">BIND</acronym> 8, this option
2679                   enabled simulating the obsolete DNS query type
2680                   IQUERY. <acronym class="acronym">BIND</acronym> 9 never does
2681                   IQUERY simulation.
2682                 </p></dd>
2683 <dt><span class="term"><span><strong class="command">fetch-glue</strong></span></span></dt>
2684 <dd><p>
2685                   This option is obsolete.
2686                   In BIND 8, <strong class="userinput"><code>fetch-glue yes</code></strong>
2687                   caused the server to attempt to fetch glue resource records
2688                   it
2689                   didn't have when constructing the additional
2690                   data section of a response.  This is now considered a bad
2691                   idea
2692                   and BIND 9 never does it.
2693                 </p></dd>
2694 <dt><span class="term"><span><strong class="command">flush-zones-on-shutdown</strong></span></span></dt>
2695 <dd><p>
2696                   When the nameserver exits due receiving SIGTERM,
2697                   flush or do not flush any pending zone writes.  The default
2698                   is
2699                   <span><strong class="command">flush-zones-on-shutdown</strong></span> <strong class="userinput"><code>no</code></strong>.
2700                 </p></dd>
2701 <dt><span class="term"><span><strong class="command">has-old-clients</strong></span></span></dt>
2702 <dd><p>
2703                   This option was incorrectly implemented
2704                   in <acronym class="acronym">BIND</acronym> 8, and is ignored by <acronym class="acronym">BIND</acronym> 9.
2705                   To achieve the intended effect
2706                   of
2707                   <span><strong class="command">has-old-clients</strong></span> <strong class="userinput"><code>yes</code></strong>, specify
2708                   the two separate options <span><strong class="command">auth-nxdomain</strong></span> <strong class="userinput"><code>yes</code></strong>
2709                   and <span><strong class="command">rfc2308-type1</strong></span> <strong class="userinput"><code>no</code></strong> instead.
2710                 </p></dd>
2711 <dt><span class="term"><span><strong class="command">host-statistics</strong></span></span></dt>
2712 <dd><p>
2713                   In BIND 8, this enables keeping of
2714                   statistics for every host that the name server interacts
2715                   with.
2716                   Not implemented in BIND 9.
2717                 </p></dd>
2718 <dt><span class="term"><span><strong class="command">maintain-ixfr-base</strong></span></span></dt>
2719 <dd><p>
2720                   <span class="emphasis"><em>This option is obsolete</em></span>.
2721                   It was used in <acronym class="acronym">BIND</acronym> 8 to
2722                   determine whether a transaction log was
2723                   kept for Incremental Zone Transfer. <acronym class="acronym">BIND</acronym> 9 maintains a transaction
2724                   log whenever possible.  If you need to disable outgoing
2725                   incremental zone
2726                   transfers, use <span><strong class="command">provide-ixfr</strong></span> <strong class="userinput"><code>no</code></strong>.
2727                 </p></dd>
2728 <dt><span class="term"><span><strong class="command">minimal-responses</strong></span></span></dt>
2729 <dd><p>
2730                   If <strong class="userinput"><code>yes</code></strong>, then when generating
2731                   responses the server will only add records to the authority
2732                   and additional data sections when they are required (e.g.
2733                   delegations, negative responses).  This may improve the
2734                   performance of the server.
2735                   The default is <strong class="userinput"><code>no</code></strong>.
2736                 </p></dd>
2737 <dt><span class="term"><span><strong class="command">multiple-cnames</strong></span></span></dt>
2738 <dd><p>
2739                   This option was used in <acronym class="acronym">BIND</acronym> 8 to allow
2740                   a domain name to have multiple CNAME records in violation of
2741                   the DNS standards.  <acronym class="acronym">BIND</acronym> 9.2 onwards
2742                   always strictly enforces the CNAME rules both in master
2743                   files and dynamic updates.
2744                 </p></dd>
2745 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
2746 <dd>
2747 <p>
2748                   If <strong class="userinput"><code>yes</code></strong> (the default),
2749                   DNS NOTIFY messages are sent when a zone the server is
2750                   authoritative for
2751                   changes, see <a href="Bv9ARM.ch04.html#notify" title="Notify">the section called &#8220;Notify&#8221;</a>.  The messages are
2752                   sent to the
2753                   servers listed in the zone's NS records (except the master
2754                   server identified
2755                   in the SOA MNAME field), and to any servers listed in the
2756                   <span><strong class="command">also-notify</strong></span> option.
2757                 </p>
2758 <p>
2759                   If <strong class="userinput"><code>master-only</code></strong>, notifies are only
2760                   sent
2761                   for master zones.
2762                   If <strong class="userinput"><code>explicit</code></strong>, notifies are sent only
2763                   to
2764                   servers explicitly listed using <span><strong class="command">also-notify</strong></span>.
2765                   If <strong class="userinput"><code>no</code></strong>, no notifies are sent.
2766                 </p>
2767 <p>
2768                   The <span><strong class="command">notify</strong></span> option may also be
2769                   specified in the <span><strong class="command">zone</strong></span>
2770                   statement,
2771                   in which case it overrides the <span><strong class="command">options notify</strong></span> statement.
2772                   It would only be necessary to turn off this option if it
2773                   caused slaves
2774                   to crash.
2775                 </p>
2776 </dd>
2777 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
2778 <dd><p>
2779                   If <strong class="userinput"><code>yes</code></strong> do not check the nameservers
2780                   in the NS RRset against the SOA MNAME.  Normally a NOTIFY
2781                   message is not sent to the SOA MNAME (SOA ORIGIN) as it is
2782                   supposed to contain the name of the ultimate master.
2783                   Sometimes, however, a slave is listed as the SOA MNAME in
2784                   hidden master configurations and in that case you would
2785                   want the ultimate master to still send NOTIFY messages to
2786                   all the nameservers listed in the NS RRset.
2787                 </p></dd>
2788 <dt><span class="term"><span><strong class="command">recursion</strong></span></span></dt>
2789 <dd><p>
2790                   If <strong class="userinput"><code>yes</code></strong>, and a
2791                   DNS query requests recursion, then the server will attempt
2792                   to do
2793                   all the work required to answer the query. If recursion is
2794                   off
2795                   and the server does not already know the answer, it will
2796                   return a
2797                   referral response. The default is
2798                   <strong class="userinput"><code>yes</code></strong>.
2799                   Note that setting <span><strong class="command">recursion no</strong></span> does not prevent
2800                   clients from getting data from the server's cache; it only
2801                   prevents new data from being cached as an effect of client
2802                   queries.
2803                   Caching may still occur as an effect the server's internal
2804                   operation, such as NOTIFY address lookups.
2805                   See also <span><strong class="command">fetch-glue</strong></span> above.
2806                 </p></dd>
2807 <dt><span class="term"><span><strong class="command">rfc2308-type1</strong></span></span></dt>
2808 <dd>
2809 <p>
2810                   Setting this to <strong class="userinput"><code>yes</code></strong> will
2811                   cause the server to send NS records along with the SOA
2812                   record for negative
2813                   answers. The default is <strong class="userinput"><code>no</code></strong>.
2814                 </p>
2815 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
2816 <h3 class="title">Note</h3>
2817 <p>
2818                     Not yet implemented in <acronym class="acronym">BIND</acronym>
2819                     9.
2820                   </p>
2821 </div>
2822 </dd>
2823 <dt><span class="term"><span><strong class="command">use-id-pool</strong></span></span></dt>
2824 <dd><p>
2825                   <span class="emphasis"><em>This option is obsolete</em></span>.
2826                   <acronym class="acronym">BIND</acronym> 9 always allocates query
2827                   IDs from a pool.
2828                 </p></dd>
2829 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
2830 <dd><p>
2831                   If <strong class="userinput"><code>yes</code></strong>, the server will collect
2832                   statistical data on all zones (unless specifically turned
2833                   off
2834                   on a per-zone basis by specifying <span><strong class="command">zone-statistics no</strong></span>
2835                   in the <span><strong class="command">zone</strong></span> statement).
2836                   These statistics may be accessed
2837                   using <span><strong class="command">rndc stats</strong></span>, which will
2838                   dump them to the file listed
2839                   in the <span><strong class="command">statistics-file</strong></span>.  See
2840                   also <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called &#8220;The Statistics File&#8221;</a>.
2841                 </p></dd>
2842 <dt><span class="term"><span><strong class="command">use-ixfr</strong></span></span></dt>
2843 <dd><p>
2844                   <span class="emphasis"><em>This option is obsolete</em></span>.
2845                   If you need to disable IXFR to a particular server or
2846                   servers, see
2847                   the information on the <span><strong class="command">provide-ixfr</strong></span> option
2848                   in <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
2849             Usage">the section called &#8220;<span><strong class="command">server</strong></span> Statement Definition and
2850             Usage&#8221;</a>.
2851                   See also
2852                   <a href="Bv9ARM.ch04.html#incremental_zone_transfers" title="Incremental Zone Transfers (IXFR)">the section called &#8220;Incremental Zone Transfers (IXFR)&#8221;</a>.
2853                 </p></dd>
2854 <dt><span class="term"><span><strong class="command">provide-ixfr</strong></span></span></dt>
2855 <dd><p>
2856                   See the description of
2857                   <span><strong class="command">provide-ixfr</strong></span> in
2858                   <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
2859             Usage">the section called &#8220;<span><strong class="command">server</strong></span> Statement Definition and
2860             Usage&#8221;</a>.
2861                 </p></dd>
2862 <dt><span class="term"><span><strong class="command">request-ixfr</strong></span></span></dt>
2863 <dd><p>
2864                   See the description of
2865                   <span><strong class="command">request-ixfr</strong></span> in
2866                   <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
2867             Usage">the section called &#8220;<span><strong class="command">server</strong></span> Statement Definition and
2868             Usage&#8221;</a>.
2869                 </p></dd>
2870 <dt><span class="term"><span><strong class="command">treat-cr-as-space</strong></span></span></dt>
2871 <dd><p>
2872                   This option was used in <acronym class="acronym">BIND</acronym>
2873                   8 to make
2874                   the server treat carriage return ("<span><strong class="command">\r</strong></span>") characters the same way
2875                   as a space or tab character,
2876                   to facilitate loading of zone files on a UNIX system that
2877                   were generated
2878                   on an NT or DOS machine. In <acronym class="acronym">BIND</acronym> 9, both UNIX "<span><strong class="command">\n</strong></span>"
2879                   and NT/DOS "<span><strong class="command">\r\n</strong></span>" newlines
2880                   are always accepted,
2881                   and the option is ignored.
2882                 </p></dd>
2883 <dt>
2884 <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>
2885 </dt>
2886 <dd>
2887 <p>
2888                   These options control the behavior of an authoritative
2889                   server when
2890                   answering queries which have additional data, or when
2891                   following CNAME
2892                   and DNAME chains.
2893                 </p>
2894 <p>
2895                   When both of these options are set to <strong class="userinput"><code>yes</code></strong>
2896                   (the default) and a
2897                   query is being answered from authoritative data (a zone
2898                   configured into the server), the additional data section of
2899                   the
2900                   reply will be filled in using data from other authoritative
2901                   zones
2902                   and from the cache.  In some situations this is undesirable,
2903                   such
2904                   as when there is concern over the correctness of the cache,
2905                   or
2906                   in servers where slave zones may be added and modified by
2907                   untrusted third parties.  Also, avoiding
2908                   the search for this additional data will speed up server
2909                   operations
2910                   at the possible expense of additional queries to resolve
2911                   what would
2912                   otherwise be provided in the additional section.
2913                 </p>
2914 <p>
2915                   For example, if a query asks for an MX record for host <code class="literal">foo.example.com</code>,
2916                   and the record found is "<code class="literal">MX 10 mail.example.net</code>", normally the address
2917                   records (A and AAAA) for <code class="literal">mail.example.net</code> will be provided as well,
2918                   if known, even though they are not in the example.com zone.
2919                   Setting these options to <span><strong class="command">no</strong></span>
2920                   disables this behavior and makes
2921                   the server only search for additional data in the zone it
2922                   answers from.
2923                 </p>
2924 <p>
2925                   These options are intended for use in authoritative-only
2926                   servers, or in authoritative-only views.  Attempts to set
2927                   them to <span><strong class="command">no</strong></span> without also
2928                   specifying
2929                   <span><strong class="command">recursion no</strong></span> will cause the
2930                   server to
2931                   ignore the options and log a warning message.
2932                 </p>
2933 <p>
2934                   Specifying <span><strong class="command">additional-from-cache no</strong></span> actually
2935                   disables the use of the cache not only for additional data
2936                   lookups
2937                   but also when looking up the answer.  This is usually the
2938                   desired
2939                   behavior in an authoritative-only server where the
2940                   correctness of
2941                   the cached data is an issue.
2942                 </p>
2943 <p>
2944                   When a name server is non-recursively queried for a name
2945                   that is not
2946                   below the apex of any served zone, it normally answers with
2947                   an
2948                   "upwards referral" to the root servers or the servers of
2949                   some other
2950                   known parent of the query name.  Since the data in an
2951                   upwards referral
2952                   comes from the cache, the server will not be able to provide
2953                   upwards
2954                   referrals when <span><strong class="command">additional-from-cache no</strong></span>
2955                   has been specified.  Instead, it will respond to such
2956                   queries
2957                   with REFUSED.  This should not cause any problems since
2958                   upwards referrals are not required for the resolution
2959                   process.
2960                 </p>
2961 </dd>
2962 <dt><span class="term"><span><strong class="command">match-mapped-addresses</strong></span></span></dt>
2963 <dd><p>
2964                   If <strong class="userinput"><code>yes</code></strong>, then an
2965                   IPv4-mapped IPv6 address will match any address match
2966                   list entries that match the corresponding IPv4 address.
2967                   Enabling this option is sometimes useful on IPv6-enabled
2968                   Linux
2969                   systems, to work around a kernel quirk that causes IPv4
2970                   TCP connections such as zone transfers to be accepted
2971                   on an IPv6 socket using mapped addresses, causing
2972                   address match lists designed for IPv4 to fail to match.
2973                   The use of this option for any other purpose is discouraged.
2974                 </p></dd>
2975 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
2976 <dd>
2977 <p>
2978                   When <strong class="userinput"><code>yes</code></strong> and the server loads a new version of a master
2979                   zone from its zone file or receives a new version of a slave
2980                   file by a non-incremental zone transfer, it will compare
2981                   the new version to the previous one and calculate a set
2982                   of differences.  The differences are then logged in the
2983                   zone's journal file such that the changes can be transmitted
2984                   to downstream slaves as an incremental zone transfer.
2985                 </p>
2986 <p>
2987                   By allowing incremental zone transfers to be used for
2988                   non-dynamic zones, this option saves bandwidth at the
2989                   expense of increased CPU and memory consumption at the
2990                   master.
2991                   In particular, if the new version of a zone is completely
2992                   different from the previous one, the set of differences
2993                   will be of a size comparable to the combined size of the
2994                   old and new zone version, and the server will need to
2995                   temporarily allocate memory to hold this complete
2996                   difference set.
2997                 </p>
2998 <p><span><strong class="command">ixfr-from-differences</strong></span>
2999                   also accepts <span><strong class="command">master</strong></span> and
3000                   <span><strong class="command">slave</strong></span> at the view and options
3001                   levels which causes
3002                   <span><strong class="command">ixfr-from-differences</strong></span> to be enabled for
3003                   all <span><strong class="command">master</strong></span> or
3004                   <span><strong class="command">slave</strong></span> zones respectively.
3005                   It is off by default.
3006                 </p>
3007 </dd>
3008 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
3009 <dd><p>
3010                   This should be set when you have multiple masters for a zone
3011                   and the
3012                   addresses refer to different machines.  If <strong class="userinput"><code>yes</code></strong>, <span><strong class="command">named</strong></span> will
3013                   not log
3014                   when the serial number on the master is less than what <span><strong class="command">named</strong></span>
3015                   currently
3016                   has.  The default is <strong class="userinput"><code>no</code></strong>.
3017                 </p></dd>
3018 <dt><span class="term"><span><strong class="command">dnssec-enable</strong></span></span></dt>
3019 <dd><p>
3020                   Enable DNSSEC support in <span><strong class="command">named</strong></span>.  Unless set to <strong class="userinput"><code>yes</code></strong>,
3021                   <span><strong class="command">named</strong></span> behaves as if it does not support DNSSEC.
3022                   The default is <strong class="userinput"><code>yes</code></strong>.
3023                 </p></dd>
3024 <dt><span class="term"><span><strong class="command">dnssec-validation</strong></span></span></dt>
3025 <dd><p>
3026                   Enable DNSSEC validation in <span><strong class="command">named</strong></span>.
3027                   Note <span><strong class="command">dnssec-enable</strong></span> also needs to be
3028                   set to <strong class="userinput"><code>yes</code></strong> to be effective.
3029                   The default is <strong class="userinput"><code>yes</code></strong>.
3030                 </p></dd>
3031 <dt><span class="term"><span><strong class="command">dnssec-accept-expired</strong></span></span></dt>
3032 <dd><p>
3033                   Accept expired signatures when verifying DNSSEC signatures.
3034                   The default is <strong class="userinput"><code>no</code></strong>.
3035                   Setting this option to "yes" leaves <span><strong class="command">named</strong></span> vulnerable to replay attacks.
3036                 </p></dd>
3037 <dt><span class="term"><span><strong class="command">querylog</strong></span></span></dt>
3038 <dd><p>
3039                   Specify whether query logging should be started when <span><strong class="command">named</strong></span>
3040                   starts.
3041                   If <span><strong class="command">querylog</strong></span> is not specified,
3042                   then the query logging
3043                   is determined by the presence of the logging category <span><strong class="command">queries</strong></span>.
3044                 </p></dd>
3045 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
3046 <dd>
3047 <p>
3048                   This option is used to restrict the character set and syntax
3049                   of
3050                   certain domain names in master files and/or DNS responses
3051                   received
3052                   from the network.  The default varies according to usage
3053                   area.  For
3054                   <span><strong class="command">master</strong></span> zones the default is <span><strong class="command">fail</strong></span>.
3055                   For <span><strong class="command">slave</strong></span> zones the default
3056                   is <span><strong class="command">warn</strong></span>.
3057                   For answers received from the network (<span><strong class="command">response</strong></span>)
3058                   the default is <span><strong class="command">ignore</strong></span>.
3059                 </p>
3060 <p>
3061                   The rules for legal hostnames and mail domains are derived
3062                   from RFC 952 and RFC 821 as modified by RFC 1123.
3063                 </p>
3064 <p><span><strong class="command">check-names</strong></span>
3065                   applies to the owner names of A, AAAA and MX records.
3066                   It also applies to the domain names in the RDATA of NS, SOA,
3067                   MX, and SRV records.
3068                   It also applies to the RDATA of PTR records where the owner
3069                   name indicated that it is a reverse lookup of a hostname
3070                   (the owner name ends in IN-ADDR.ARPA, IP6.ARPA, or IP6.INT).
3071                 </p>
3072 </dd>
3073 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
3074 <dd><p>
3075                   Check whether the MX record appears to refer to a IP address.
3076                   The default is to <span><strong class="command">warn</strong></span>.  Other possible
3077                   values are <span><strong class="command">fail</strong></span> and
3078                   <span><strong class="command">ignore</strong></span>.
3079                 </p></dd>
3080 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
3081 <dd><p>
3082                   This option is used to check for non-terminal wildcards.
3083                   The use of non-terminal wildcards is almost always as a
3084                   result of a failure
3085                   to understand the wildcard matching algorithm (RFC 1034).
3086                   This option
3087                   affects master zones.  The default (<span><strong class="command">yes</strong></span>) is to check
3088                   for non-terminal wildcards and issue a warning.
3089                 </p></dd>
3090 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
3091 <dd><p>
3092                   Perform post load zone integrity checks on master
3093                   zones.  This checks that MX and SRV records refer
3094                   to address (A or AAAA) records and that glue
3095                   address records exist for delegated zones.  For
3096                   MX and SRV records only in-zone hostnames are
3097                   checked (for out-of-zone hostnames use
3098                   <span><strong class="command">named-checkzone</strong></span>).
3099                   For NS records only names below top of zone are
3100                   checked (for out-of-zone names and glue consistency
3101                   checks use <span><strong class="command">named-checkzone</strong></span>).
3102                   The default is <span><strong class="command">yes</strong></span>.
3103                 </p></dd>
3104 <dt><span class="term"><span><strong class="command">check-mx-cname</strong></span></span></dt>
3105 <dd><p>
3106                   If <span><strong class="command">check-integrity</strong></span> is set then
3107                   fail, warn or ignore MX records that refer
3108                   to CNAMES.  The default is to <span><strong class="command">warn</strong></span>.
3109                 </p></dd>
3110 <dt><span class="term"><span><strong class="command">check-srv-cname</strong></span></span></dt>
3111 <dd><p>
3112                   If <span><strong class="command">check-integrity</strong></span> is set then
3113                   fail, warn or ignore SRV records that refer
3114                   to CNAMES.  The default is to <span><strong class="command">warn</strong></span>.
3115                 </p></dd>
3116 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
3117 <dd><p>
3118                   When performing integrity checks, also check that
3119                   sibling glue exists.  The default is <span><strong class="command">yes</strong></span>.
3120                 </p></dd>
3121 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
3122 <dd><p>
3123                   When returning authoritative negative responses to
3124                   SOA queries set the TTL of the SOA record returned in
3125                   the authority section to zero.
3126                   The default is <span><strong class="command">yes</strong></span>.
3127                 </p></dd>
3128 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl-cache</strong></span></span></dt>
3129 <dd><p>
3130                   When caching a negative response to a SOA query
3131                   set the TTL to zero.
3132                   The default is <span><strong class="command">no</strong></span>.
3133                 </p></dd>
3134 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
3135 <dd><p>
3136                   When regenerating the RRSIGs following a UPDATE
3137                   request to a secure zone, check the KSK flag on
3138                   the DNSKEY RR to determine if this key should be
3139                   used to generate the RRSIG.  This flag is ignored
3140                   if there are not DNSKEY RRs both with and without
3141                   a KSK.
3142                   The default is <span><strong class="command">yes</strong></span>.
3143                 </p></dd>
3144 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
3145 <dd><p>
3146                   Try to refresh the zone using TCP if UDP queries fail.
3147                   For BIND 8 compatibility, the default is
3148                   <span><strong class="command">yes</strong></span>.
3149                 </p></dd>
3150 </dl></div>
3151 </div>
3152 <div class="sect3" lang="en">
3153 <div class="titlepage"><div><div><h4 class="title">
3154 <a name="id2581667"></a>Forwarding</h4></div></div></div>
3155 <p>
3156             The forwarding facility can be used to create a large site-wide
3157             cache on a few servers, reducing traffic over links to external
3158             name servers. It can also be used to allow queries by servers that
3159             do not have direct access to the Internet, but wish to look up
3160             exterior
3161             names anyway. Forwarding occurs only on those queries for which
3162             the server is not authoritative and does not have the answer in
3163             its cache.
3164           </p>
3165 <div class="variablelist"><dl>
3166 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
3167 <dd><p>
3168                   This option is only meaningful if the
3169                   forwarders list is not empty. A value of <code class="varname">first</code>,
3170                   the default, causes the server to query the forwarders
3171                   first &#8212; and
3172                   if that doesn't answer the question, the server will then
3173                   look for
3174                   the answer itself. If <code class="varname">only</code> is
3175                   specified, the
3176                   server will only query the forwarders.
3177                 </p></dd>
3178 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
3179 <dd><p>
3180                   Specifies the IP addresses to be used
3181                   for forwarding. The default is the empty list (no
3182                   forwarding).
3183                 </p></dd>
3184 </dl></div>
3185 <p>
3186             Forwarding can also be configured on a per-domain basis, allowing
3187             for the global forwarding options to be overridden in a variety
3188             of ways. You can set particular domains to use different
3189             forwarders,
3190             or have a different <span><strong class="command">forward only/first</strong></span> behavior,
3191             or not forward at all, see <a href="Bv9ARM.ch06.html#zone_statement_grammar" title="zone
3192             Statement Grammar">the section called &#8220;<span><strong class="command">zone</strong></span>
3193             Statement Grammar&#8221;</a>.
3194           </p>
3195 </div>
3196 <div class="sect3" lang="en">
3197 <div class="titlepage"><div><div><h4 class="title">
3198 <a name="id2581725"></a>Dual-stack Servers</h4></div></div></div>
3199 <p>
3200             Dual-stack servers are used as servers of last resort to work
3201             around
3202             problems in reachability due the lack of support for either IPv4
3203             or IPv6
3204             on the host machine.
3205           </p>
3206 <div class="variablelist"><dl>
3207 <dt><span class="term"><span><strong class="command">dual-stack-servers</strong></span></span></dt>
3208 <dd><p>
3209                   Specifies host names or addresses of machines with access to
3210                   both IPv4 and IPv6 transports. If a hostname is used, the
3211                   server must be able
3212                   to resolve the name using only the transport it has.  If the
3213                   machine is dual
3214                   stacked, then the <span><strong class="command">dual-stack-servers</strong></span> have no effect unless
3215                   access to a transport has been disabled on the command line
3216                   (e.g. <span><strong class="command">named -4</strong></span>).
3217                 </p></dd>
3218 </dl></div>
3219 </div>
3220 <div class="sect3" lang="en">
3221 <div class="titlepage"><div><div><h4 class="title">
3222 <a name="access_control"></a>Access Control</h4></div></div></div>
3223 <p>
3224             Access to the server can be restricted based on the IP address
3225             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
3226             details on how to specify IP address lists.
3227           </p>
3228 <div class="variablelist"><dl>
3229 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
3230 <dd><p>
3231                   Specifies which hosts are allowed to
3232                   notify this server, a slave, of zone changes in addition
3233                   to the zone masters.
3234                   <span><strong class="command">allow-notify</strong></span> may also be
3235                   specified in the
3236                   <span><strong class="command">zone</strong></span> statement, in which case
3237                   it overrides the
3238                   <span><strong class="command">options allow-notify</strong></span>
3239                   statement.  It is only meaningful
3240                   for a slave zone.  If not specified, the default is to
3241                   process notify messages
3242                   only from a zone's master.
3243                 </p></dd>
3244 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
3245 <dd>
3246 <p>
3247                   Specifies which hosts are allowed to ask ordinary
3248                   DNS questions. <span><strong class="command">allow-query</strong></span> may
3249                   also be specified in the <span><strong class="command">zone</strong></span>
3250                   statement, in which case it overrides the
3251                   <span><strong class="command">options allow-query</strong></span> statement.
3252                   If not specified, the default is to allow queries
3253                   from all hosts.
3254                 </p>
3255 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3256 <h3 class="title">Note</h3>
3257 <p>
3258                     <span><strong class="command">allow-query-cache</strong></span> is now
3259                     used to specify access to the cache.
3260                   </p>
3261 </div>
3262 </dd>
3263 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
3264 <dd>
3265 <p>
3266                   Specifies which local addresses can accept ordinary
3267                   DNS questions. This makes it possible, for instance,
3268                   to allow queries on internal-facing interfaces but
3269                   disallow them on external-facing ones, without
3270                   necessarily knowing the internal network's addresses.
3271                 </p>
3272 <p>
3273                   <span><strong class="command">allow-query-on</strong></span> may
3274                   also be specified in the <span><strong class="command">zone</strong></span>
3275                   statement, in which case it overrides the
3276                   <span><strong class="command">options allow-query-on</strong></span> statement.
3277                 </p>
3278 <p>
3279                   If not specified, the default is to allow queries
3280                   on all addresses.
3281                 </p>
3282 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3283 <h3 class="title">Note</h3>
3284 <p>
3285                     <span><strong class="command">allow-query-cache</strong></span> is
3286                     used to specify access to the cache.
3287                   </p>
3288 </div>
3289 </dd>
3290 <dt><span class="term"><span><strong class="command">allow-query-cache</strong></span></span></dt>
3291 <dd><p>
3292                   Specifies which hosts are allowed to get answers
3293                   from the cache.  If <span><strong class="command">allow-query-cache</strong></span>
3294                   is not set then <span><strong class="command">allow-recursion</strong></span>
3295                   is used if set, otherwise <span><strong class="command">allow-query</strong></span>
3296                   is used if set unless <span><strong class="command">recursion no;</strong></span> is
3297                   set in which case <span><strong class="command">none;</strong></span> is used,
3298                   otherwise the default (<span><strong class="command">localnets;</strong></span>
3299                   <span><strong class="command">localhost;</strong></span>) is used.
3300                 </p></dd>
3301 <dt><span class="term"><span><strong class="command">allow-query-cache-on</strong></span></span></dt>
3302 <dd><p>
3303                   Specifies which local addresses can give answers
3304                   from the cache.  If not specified, the default is
3305                   to allow cache queries on any address,
3306                   <span><strong class="command">localnets</strong></span> and
3307                   <span><strong class="command">localhost</strong></span>.
3308                 </p></dd>
3309 <dt><span class="term"><span><strong class="command">allow-recursion</strong></span></span></dt>
3310 <dd><p>
3311                   Specifies which hosts are allowed to make recursive
3312                   queries through this server. If
3313                   <span><strong class="command">allow-recursion</strong></span> is not set
3314                   then <span><strong class="command">allow-query-cache</strong></span> is
3315                   used if set, otherwise <span><strong class="command">allow-query</strong></span>
3316                   is used if set, otherwise the default
3317                   (<span><strong class="command">localnets;</strong></span>
3318                   <span><strong class="command">localhost;</strong></span>) is used.
3319                 </p></dd>
3320 <dt><span class="term"><span><strong class="command">allow-recursion-on</strong></span></span></dt>
3321 <dd><p>
3322                   Specifies which local addresses can accept recursive
3323                   queries.  If not specified, the default is to allow
3324                   recursive queries on all addresses.
3325                 </p></dd>
3326 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
3327 <dd><p>
3328                   Specifies which hosts are allowed to
3329                   submit Dynamic DNS updates for master zones. The default is
3330                   to deny
3331                   updates from all hosts.  Note that allowing updates based
3332                   on the requestor's IP address is insecure; see
3333                   <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called &#8220;Dynamic Update Security&#8221;</a> for details.
3334                 </p></dd>
3335 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
3336 <dd>
3337 <p>
3338                   Specifies which hosts are allowed to
3339                   submit Dynamic DNS updates to slave zones to be forwarded to
3340                   the
3341                   master.  The default is <strong class="userinput"><code>{ none; }</code></strong>,
3342                   which
3343                   means that no update forwarding will be performed.  To
3344                   enable
3345                   update forwarding, specify
3346                   <strong class="userinput"><code>allow-update-forwarding { any; };</code></strong>.
3347                   Specifying values other than <strong class="userinput"><code>{ none; }</code></strong> or
3348                   <strong class="userinput"><code>{ any; }</code></strong> is usually
3349                   counterproductive, since
3350                   the responsibility for update access control should rest
3351                   with the
3352                   master server, not the slaves.
3353                 </p>
3354 <p>
3355                   Note that enabling the update forwarding feature on a slave
3356                   server
3357                   may expose master servers relying on insecure IP address
3358                   based
3359                   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>
3360                   for more details.
3361                 </p>
3362 </dd>
3363 <dt><span class="term"><span><strong class="command">allow-v6-synthesis</strong></span></span></dt>
3364 <dd><p>
3365                   This option was introduced for the smooth transition from
3366                   AAAA
3367                   to A6 and from "nibble labels" to binary labels.
3368                   However, since both A6 and binary labels were then
3369                   deprecated,
3370                   this option was also deprecated.
3371                   It is now ignored with some warning messages.
3372                 </p></dd>
3373 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
3374 <dd><p>
3375                   Specifies which hosts are allowed to
3376                   receive zone transfers from the server. <span><strong class="command">allow-transfer</strong></span> may
3377                   also be specified in the <span><strong class="command">zone</strong></span>
3378                   statement, in which
3379                   case it overrides the <span><strong class="command">options allow-transfer</strong></span> statement.
3380                   If not specified, the default is to allow transfers to all
3381                   hosts.
3382                 </p></dd>
3383 <dt><span class="term"><span><strong class="command">blackhole</strong></span></span></dt>
3384 <dd><p>
3385                   Specifies a list of addresses that the
3386                   server will not accept queries from or use to resolve a
3387                   query. Queries
3388                   from these addresses will not be responded to. The default
3389                   is <strong class="userinput"><code>none</code></strong>.
3390                 </p></dd>
3391 </dl></div>
3392 </div>
3393 <div class="sect3" lang="en">
3394 <div class="titlepage"><div><div><h4 class="title">
3395 <a name="id2582231"></a>Interfaces</h4></div></div></div>
3396 <p>
3397             The interfaces and ports that the server will answer queries
3398             from may be specified using the <span><strong class="command">listen-on</strong></span> option. <span><strong class="command">listen-on</strong></span> takes
3399             an optional port and an <code class="varname">address_match_list</code>.
3400             The server will listen on all interfaces allowed by the address
3401             match list. If a port is not specified, port 53 will be used.
3402           </p>
3403 <p>
3404             Multiple <span><strong class="command">listen-on</strong></span> statements are
3405             allowed.
3406             For example,
3407           </p>
3408 <pre class="programlisting">listen-on { 5.6.7.8; };
3409 listen-on port 1234 { !1.2.3.4; 1.2/16; };
3410 </pre>
3411 <p>
3412             will enable the name server on port 53 for the IP address
3413             5.6.7.8, and on port 1234 of an address on the machine in net
3414             1.2 that is not 1.2.3.4.
3415           </p>
3416 <p>
3417             If no <span><strong class="command">listen-on</strong></span> is specified, the
3418             server will listen on port 53 on all IPv4 interfaces.
3419           </p>
3420 <p>
3421             The <span><strong class="command">listen-on-v6</strong></span> option is used to
3422             specify the interfaces and the ports on which the server will
3423             listen
3424             for incoming queries sent using IPv6.
3425           </p>
3426 <p>
3427             When </p>
3428 <pre class="programlisting">{ any; }</pre>
3429 <p> is
3430             specified
3431             as the <code class="varname">address_match_list</code> for the
3432             <span><strong class="command">listen-on-v6</strong></span> option,
3433             the server does not bind a separate socket to each IPv6 interface
3434             address as it does for IPv4 if the operating system has enough API
3435             support for IPv6 (specifically if it conforms to RFC 3493 and RFC
3436             3542).
3437             Instead, it listens on the IPv6 wildcard address.
3438             If the system only has incomplete API support for IPv6, however,
3439             the behavior is the same as that for IPv4.
3440           </p>
3441 <p>
3442             A list of particular IPv6 addresses can also be specified, in
3443             which case
3444             the server listens on a separate socket for each specified
3445             address,
3446             regardless of whether the desired API is supported by the system.
3447           </p>
3448 <p>
3449             Multiple <span><strong class="command">listen-on-v6</strong></span> options can
3450             be used.
3451             For example,
3452           </p>
3453 <pre class="programlisting">listen-on-v6 { any; };
3454 listen-on-v6 port 1234 { !2001:db8::/32; any; };
3455 </pre>
3456 <p>
3457             will enable the name server on port 53 for any IPv6 addresses
3458             (with a single wildcard socket),
3459             and on port 1234 of IPv6 addresses that is not in the prefix
3460             2001:db8::/32 (with separate sockets for each matched address.)
3461           </p>
3462 <p>
3463             To make the server not listen on any IPv6 address, use
3464           </p>
3465 <pre class="programlisting">listen-on-v6 { none; };
3466 </pre>
3467 <p>
3468             If no <span><strong class="command">listen-on-v6</strong></span> option is
3469             specified, the server will not listen on any IPv6 address
3470             unless <span><strong class="command">-6</strong></span> is specified when <span><strong class="command">named</strong></span> is
3471             invoked.  If <span><strong class="command">-6</strong></span> is specified then
3472             <span><strong class="command">named</strong></span> will listen on port 53 on all IPv6 interfaces by default.
3473           </p>
3474 </div>
3475 <div class="sect3" lang="en">
3476 <div class="titlepage"><div><div><h4 class="title">
3477 <a name="query_address"></a>Query Address</h4></div></div></div>
3478 <p>
3479             If the server doesn't know the answer to a question, it will
3480             query other name servers. <span><strong class="command">query-source</strong></span> specifies
3481             the address and port used for such queries. For queries sent over
3482             IPv6, there is a separate <span><strong class="command">query-source-v6</strong></span> option.
3483             If <span><strong class="command">address</strong></span> is <span><strong class="command">*</strong></span> (asterisk) or is omitted,
3484             a wildcard IP address (<span><strong class="command">INADDR_ANY</strong></span>)
3485             will be used.
3486           </p>
3487 <p>
3488             If <span><strong class="command">port</strong></span> is <span><strong class="command">*</strong></span> or is omitted,
3489             a random port number from a pre-configured
3490             range is picked up and will be used for each query.
3491             The port range(s) is that specified in
3492             the <span><strong class="command">use-v4-udp-ports</strong></span> (for IPv4)
3493             and <span><strong class="command">use-v6-udp-ports</strong></span> (for IPv6)
3494             options, excluding the ranges specified in
3495             the <span><strong class="command">avoid-v4-udp-ports</strong></span>
3496             and <span><strong class="command">avoid-v6-udp-ports</strong></span> options, respectively.
3497           </p>
3498 <p>
3499             The defaults of the <span><strong class="command">query-source</strong></span> and
3500             <span><strong class="command">query-source-v6</strong></span> options
3501             are:
3502           </p>
3503 <pre class="programlisting">query-source address * port *;
3504 query-source-v6 address * port *;
3505 </pre>
3506 <p>
3507             If <span><strong class="command">use-v4-udp-ports</strong></span> or
3508             <span><strong class="command">use-v6-udp-ports</strong></span> is unspecified,
3509             <span><strong class="command">named</strong></span> will check if the operating
3510             system provides a programming interface to retrieve the
3511             system's default range for ephemeral ports.
3512             If such an interface is available,
3513             <span><strong class="command">named</strong></span> will use the corresponding system
3514             default range; otherwise, it will use its own defaults:
3515          </p>
3516 <pre class="programlisting">use-v4-udp-ports { range 1024 65535; };
3517 use-v6-udp-ports { range 1024 65535; };
3518 </pre>
3519 <p>
3520             Note: make sure the ranges be sufficiently large for
3521             security.  A desirable size depends on various parameters,
3522             but we generally recommend it contain at least 16384 ports
3523             (14 bits of entropy).
3524             Note also that the system's default range when used may be
3525             too small for this purpose, and that the range may even be
3526             changed while <span><strong class="command">named</strong></span> is running; the new
3527             range will automatically be applied when <span><strong class="command">named</strong></span>
3528             is reloaded.
3529             It is encouraged to
3530             configure <span><strong class="command">use-v4-udp-ports</strong></span> and
3531             <span><strong class="command">use-v6-udp-ports</strong></span> explicitly so that the
3532             ranges are sufficiently large and are reasonably
3533             independent from the ranges used by other applications.
3534           </p>
3535 <p>
3536             Note: the operational configuration
3537             where <span><strong class="command">named</strong></span> runs may prohibit the use
3538             of some ports.  For example, UNIX systems will not allow
3539             <span><strong class="command">named</strong></span> running without a root privilege
3540             to use ports less than 1024.
3541             If such ports are included in the specified (or detected)
3542             set of query ports, the corresponding query attempts will
3543             fail, resulting in resolution failures or delay.
3544             It is therefore important to configure the set of ports
3545             that can be safely used in the expected operational environment.
3546           </p>
3547 <p>
3548             The defaults of the <span><strong class="command">avoid-v4-udp-ports</strong></span> and
3549             <span><strong class="command">avoid-v6-udp-ports</strong></span> options
3550             are:
3551           </p>
3552 <pre class="programlisting">avoid-v4-udp-ports {};
3553 avoid-v6-udp-ports {};
3554 </pre>
3555 <p>
3556             Note: BIND 9.5.0 introduced
3557             the <span><strong class="command">use-queryport-pool</strong></span>
3558             option to support a pool of such random ports, but this
3559             option is now obsolete because reusing the same ports in
3560             the pool may not be sufficiently secure.
3561             For the same reason, it is generally strongly discouraged to
3562             specify a particular port for the
3563             <span><strong class="command">query-source</strong></span> or
3564             <span><strong class="command">query-source-v6</strong></span> options;
3565             it implicitly disables the use of randomized port numbers.
3566           </p>
3567 <div class="variablelist"><dl>
3568 <dt><span class="term"><span><strong class="command">use-queryport-pool</strong></span></span></dt>
3569 <dd><p>
3570                   This option is obsolete.
3571                 </p></dd>
3572 <dt><span class="term"><span><strong class="command">queryport-pool-ports</strong></span></span></dt>
3573 <dd><p>
3574                   This option is obsolete.
3575                 </p></dd>
3576 <dt><span class="term"><span><strong class="command">queryport-pool-updateinterval</strong></span></span></dt>
3577 <dd><p>
3578                   This option is obsolete.
3579                 </p></dd>
3580 </dl></div>
3581 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3582 <h3 class="title">Note</h3>
3583 <p>
3584               The address specified in the <span><strong class="command">query-source</strong></span> option
3585               is used for both UDP and TCP queries, but the port applies only
3586               to UDP queries.  TCP queries always use a random
3587               unprivileged port.
3588             </p>
3589 </div>
3590 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3591 <h3 class="title">Note</h3>
3592 <p>
3593               Solaris 2.5.1 and earlier does not support setting the source
3594               address for TCP sockets.
3595             </p>
3596 </div>
3597 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3598 <h3 class="title">Note</h3>
3599 <p>
3600               See also <span><strong class="command">transfer-source</strong></span> and
3601               <span><strong class="command">notify-source</strong></span>.
3602             </p>
3603 </div>
3604 </div>
3605 <div class="sect3" lang="en">
3606 <div class="titlepage"><div><div><h4 class="title">
3607 <a name="zone_transfers"></a>Zone Transfers</h4></div></div></div>
3608 <p>
3609             <acronym class="acronym">BIND</acronym> has mechanisms in place to
3610             facilitate zone transfers
3611             and set limits on the amount of load that transfers place on the
3612             system. The following options apply to zone transfers.
3613           </p>
3614 <div class="variablelist"><dl>
3615 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
3616 <dd><p>
3617                   Defines a global list of IP addresses of name servers
3618                   that are also sent NOTIFY messages whenever a fresh copy of
3619                   the
3620                   zone is loaded, in addition to the servers listed in the
3621                   zone's NS records.
3622                   This helps to ensure that copies of the zones will
3623                   quickly converge on stealth servers.
3624                   Optionally, a port may be specified with each
3625                   <span><strong class="command">also-notify</strong></span> address to send
3626                   the notify messages to a port other than the
3627                   default of 53.
3628                   If an <span><strong class="command">also-notify</strong></span> list
3629                   is given in a <span><strong class="command">zone</strong></span> statement,
3630                   it will override
3631                   the <span><strong class="command">options also-notify</strong></span>
3632                   statement. When a <span><strong class="command">zone notify</strong></span>
3633                   statement
3634                   is set to <span><strong class="command">no</strong></span>, the IP
3635                   addresses in the global <span><strong class="command">also-notify</strong></span> list will
3636                   not be sent NOTIFY messages for that zone. The default is
3637                   the empty
3638                   list (no global notification list).
3639                 </p></dd>
3640 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
3641 <dd><p>
3642                   Inbound zone transfers running longer than
3643                   this many minutes will be terminated. The default is 120
3644                   minutes
3645                   (2 hours).  The maximum value is 28 days (40320 minutes).
3646                 </p></dd>
3647 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
3648 <dd><p>
3649                   Inbound zone transfers making no progress
3650                   in this many minutes will be terminated. The default is 60
3651                   minutes
3652                   (1 hour).  The maximum value is 28 days (40320 minutes).
3653                 </p></dd>
3654 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
3655 <dd><p>
3656                   Outbound zone transfers running longer than
3657                   this many minutes will be terminated. The default is 120
3658                   minutes
3659                   (2 hours).  The maximum value is 28 days (40320 minutes).
3660                 </p></dd>
3661 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
3662 <dd><p>
3663                   Outbound zone transfers making no progress
3664                   in this many minutes will be terminated.  The default is 60
3665                   minutes (1
3666                   hour).  The maximum value is 28 days (40320 minutes).
3667                 </p></dd>
3668 <dt><span class="term"><span><strong class="command">serial-query-rate</strong></span></span></dt>
3669 <dd><p>
3670                   Slave servers will periodically query master servers
3671                   to find out if zone serial numbers have changed. Each such
3672                   query uses
3673                   a minute amount of the slave server's network bandwidth.  To
3674                   limit the
3675                   amount of bandwidth used, BIND 9 limits the rate at which
3676                   queries are
3677                   sent.  The value of the <span><strong class="command">serial-query-rate</strong></span> option,
3678                   an integer, is the maximum number of queries sent per
3679                   second.
3680                   The default is 20.
3681                 </p></dd>
3682 <dt><span class="term"><span><strong class="command">serial-queries</strong></span></span></dt>
3683 <dd><p>
3684                   In BIND 8, the <span><strong class="command">serial-queries</strong></span>
3685                   option
3686                   set the maximum number of concurrent serial number queries
3687                   allowed to be outstanding at any given time.
3688                   BIND 9 does not limit the number of outstanding
3689                   serial queries and ignores the <span><strong class="command">serial-queries</strong></span> option.
3690                   Instead, it limits the rate at which the queries are sent
3691                   as defined using the <span><strong class="command">serial-query-rate</strong></span> option.
3692                 </p></dd>
3693 <dt><span class="term"><span><strong class="command">transfer-format</strong></span></span></dt>
3694 <dd><p>
3695                   Zone transfers can be sent using two different formats,
3696                   <span><strong class="command">one-answer</strong></span> and
3697                   <span><strong class="command">many-answers</strong></span>.
3698                   The <span><strong class="command">transfer-format</strong></span> option is used
3699                   on the master server to determine which format it sends.
3700                   <span><strong class="command">one-answer</strong></span> uses one DNS message per
3701                   resource record transferred.
3702                   <span><strong class="command">many-answers</strong></span> packs as many resource
3703                   records as possible into a message.
3704                   <span><strong class="command">many-answers</strong></span> is more efficient, but is
3705                   only supported by relatively new slave servers,
3706                   such as <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
3707                   8.x and <acronym class="acronym">BIND</acronym> 4.9.5 onwards.
3708                   The <span><strong class="command">many-answers</strong></span> format is also supported by
3709                   recent Microsoft Windows nameservers.
3710                   The default is <span><strong class="command">many-answers</strong></span>.
3711                   <span><strong class="command">transfer-format</strong></span> may be overridden on a
3712                   per-server basis by using the <span><strong class="command">server</strong></span>
3713                   statement.
3714                 </p></dd>
3715 <dt><span class="term"><span><strong class="command">transfers-in</strong></span></span></dt>
3716 <dd><p>
3717                   The maximum number of inbound zone transfers
3718                   that can be running concurrently. The default value is <code class="literal">10</code>.
3719                   Increasing <span><strong class="command">transfers-in</strong></span> may
3720                   speed up the convergence
3721                   of slave zones, but it also may increase the load on the
3722                   local system.
3723                 </p></dd>
3724 <dt><span class="term"><span><strong class="command">transfers-out</strong></span></span></dt>
3725 <dd><p>
3726                   The maximum number of outbound zone transfers
3727                   that can be running concurrently. Zone transfer requests in
3728                   excess
3729                   of the limit will be refused. The default value is <code class="literal">10</code>.
3730                 </p></dd>
3731 <dt><span class="term"><span><strong class="command">transfers-per-ns</strong></span></span></dt>
3732 <dd><p>
3733                   The maximum number of inbound zone transfers
3734                   that can be concurrently transferring from a given remote
3735                   name server.
3736                   The default value is <code class="literal">2</code>.
3737                   Increasing <span><strong class="command">transfers-per-ns</strong></span>
3738                   may
3739                   speed up the convergence of slave zones, but it also may
3740                   increase
3741                   the load on the remote name server. <span><strong class="command">transfers-per-ns</strong></span> may
3742                   be overridden on a per-server basis by using the <span><strong class="command">transfers</strong></span> phrase
3743                   of the <span><strong class="command">server</strong></span> statement.
3744                 </p></dd>
3745 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
3746 <dd>
3747 <p><span><strong class="command">transfer-source</strong></span>
3748                   determines which local address will be bound to IPv4
3749                   TCP connections used to fetch zones transferred
3750                   inbound by the server.  It also determines the
3751                   source IPv4 address, and optionally the UDP port,
3752                   used for the refresh queries and forwarded dynamic
3753                   updates.  If not set, it defaults to a system
3754                   controlled value which will usually be the address
3755                   of the interface "closest to" the remote end. This
3756                   address must appear in the remote end's
3757                   <span><strong class="command">allow-transfer</strong></span> option for the
3758                   zone being transferred, if one is specified. This
3759                   statement sets the
3760                   <span><strong class="command">transfer-source</strong></span> for all zones,
3761                   but can be overridden on a per-view or per-zone
3762                   basis by including a
3763                   <span><strong class="command">transfer-source</strong></span> statement within
3764                   the <span><strong class="command">view</strong></span> or
3765                   <span><strong class="command">zone</strong></span> block in the configuration
3766                   file.
3767                 </p>
3768 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3769 <h3 class="title">Note</h3>
3770 <p>
3771                     Solaris 2.5.1 and earlier does not support setting the
3772                     source address for TCP sockets.
3773                   </p>
3774 </div>
3775 </dd>
3776 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
3777 <dd><p>
3778                   The same as <span><strong class="command">transfer-source</strong></span>,
3779                   except zone transfers are performed using IPv6.
3780                 </p></dd>
3781 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
3782 <dd>
3783 <p>
3784                   An alternate transfer source if the one listed in
3785                   <span><strong class="command">transfer-source</strong></span> fails and
3786                   <span><strong class="command">use-alt-transfer-source</strong></span> is
3787                   set.
3788                 </p>
3789 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3790 <h3 class="title">Note</h3>
3791                   If you do not wish the alternate transfer source
3792                   to be used, you should set
3793                   <span><strong class="command">use-alt-transfer-source</strong></span>
3794                   appropriately and you should not depend upon
3795                   getting an answer back to the first refresh
3796                   query.
3797                 </div>
3798 </dd>
3799 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
3800 <dd><p>
3801                   An alternate transfer source if the one listed in
3802                   <span><strong class="command">transfer-source-v6</strong></span> fails and
3803                   <span><strong class="command">use-alt-transfer-source</strong></span> is
3804                   set.
3805                 </p></dd>
3806 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
3807 <dd><p>
3808                   Use the alternate transfer sources or not.  If views are
3809                   specified this defaults to <span><strong class="command">no</strong></span>
3810                   otherwise it defaults to
3811                   <span><strong class="command">yes</strong></span> (for BIND 8
3812                   compatibility).
3813                 </p></dd>
3814 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
3815 <dd>
3816 <p><span><strong class="command">notify-source</strong></span>
3817                   determines which local source address, and
3818                   optionally UDP port, will be used to send NOTIFY
3819                   messages.  This address must appear in the slave
3820                   server's <span><strong class="command">masters</strong></span> zone clause or
3821                   in an <span><strong class="command">allow-notify</strong></span> clause.  This
3822                   statement sets the <span><strong class="command">notify-source</strong></span>
3823                   for all zones, but can be overridden on a per-zone or
3824                   per-view basis by including a
3825                   <span><strong class="command">notify-source</strong></span> statement within
3826                   the <span><strong class="command">zone</strong></span> or
3827                   <span><strong class="command">view</strong></span> block in the configuration
3828                   file.
3829                 </p>
3830 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3831 <h3 class="title">Note</h3>
3832 <p>
3833                     Solaris 2.5.1 and earlier does not support setting the
3834                     source address for TCP sockets.
3835                   </p>
3836 </div>
3837 </dd>
3838 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
3839 <dd><p>
3840                   Like <span><strong class="command">notify-source</strong></span>,
3841                   but applies to notify messages sent to IPv6 addresses.
3842                 </p></dd>
3843 </dl></div>
3844 </div>
3845 <div class="sect3" lang="en">
3846 <div class="titlepage"><div><div><h4 class="title">
3847 <a name="id2583571"></a>UDP Port Lists</h4></div></div></div>
3848 <p>
3849             <span><strong class="command">use-v4-udp-ports</strong></span>,
3850             <span><strong class="command">avoid-v4-udp-ports</strong></span>,
3851             <span><strong class="command">use-v6-udp-ports</strong></span>, and
3852             <span><strong class="command">avoid-v6-udp-ports</strong></span>
3853             specify a list of IPv4 and IPv6 UDP ports that will be
3854             used or not used as source ports for UDP messages.
3855             See <a href="Bv9ARM.ch06.html#query_address" title="Query Address">the section called &#8220;Query Address&#8221;</a> about how the
3856             available ports are determined.
3857             For example, with the following configuration
3858           </p>
3859 <pre class="programlisting">
3860 use-v6-udp-ports { range 32768 65535; };
3861 avoid-v6-udp-ports { 40000; range 50000 60000; };
3862 </pre>
3863 <p>
3864              UDP ports of IPv6 messages sent
3865              from <span><strong class="command">named</strong></span> will be in one
3866              of the following ranges: 32768 to 39999, 40001 to 49999,
3867              and 60001 to 65535.
3868            </p>
3869 <p>
3870              <span><strong class="command">avoid-v4-udp-ports</strong></span> and
3871              <span><strong class="command">avoid-v6-udp-ports</strong></span> can be used
3872              to prevent <span><strong class="command">named</strong></span> from choosing as its random source port a
3873              port that is blocked by your firewall or a port that is
3874              used by other applications;
3875              if a query went out with a source port blocked by a
3876              firewall, the
3877              answer would not get by the firewall and the name server would
3878              have to query again.
3879              Note: the desired range can also be represented only with
3880              <span><strong class="command">use-v4-udp-ports</strong></span> and
3881              <span><strong class="command">use-v6-udp-ports</strong></span>, and the
3882              <span><strong class="command">avoid-</strong></span> options are redundant in that
3883              sense; they are provided for backward compatibility and
3884              to possibly simplify the port specification.
3885            </p>
3886 </div>
3887 <div class="sect3" lang="en">
3888 <div class="titlepage"><div><div><h4 class="title">
3889 <a name="id2583699"></a>Operating System Resource Limits</h4></div></div></div>
3890 <p>
3891             The server's usage of many system resources can be limited.
3892             Scaled values are allowed when specifying resource limits.  For
3893             example, <span><strong class="command">1G</strong></span> can be used instead of
3894             <span><strong class="command">1073741824</strong></span> to specify a limit of
3895             one
3896             gigabyte. <span><strong class="command">unlimited</strong></span> requests
3897             unlimited use, or the
3898             maximum available amount. <span><strong class="command">default</strong></span>
3899             uses the limit
3900             that was in force when the server was started. See the description
3901             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>.
3902           </p>
3903 <p>
3904             The following options set operating system resource limits for
3905             the name server process.  Some operating systems don't support
3906             some or
3907             any of the limits. On such systems, a warning will be issued if
3908             the
3909             unsupported limit is used.
3910           </p>
3911 <div class="variablelist"><dl>
3912 <dt><span class="term"><span><strong class="command">coresize</strong></span></span></dt>
3913 <dd><p>
3914                   The maximum size of a core dump. The default
3915                   is <code class="literal">default</code>.
3916                 </p></dd>
3917 <dt><span class="term"><span><strong class="command">datasize</strong></span></span></dt>
3918 <dd><p>
3919                   The maximum amount of data memory the server
3920                   may use. The default is <code class="literal">default</code>.
3921                   This is a hard limit on server memory usage.
3922                   If the server attempts to allocate memory in excess of this
3923                   limit, the allocation will fail, which may in turn leave
3924                   the server unable to perform DNS service.  Therefore,
3925                   this option is rarely useful as a way of limiting the
3926                   amount of memory used by the server, but it can be used
3927                   to raise an operating system data size limit that is
3928                   too small by default.  If you wish to limit the amount
3929                   of memory used by the server, use the
3930                   <span><strong class="command">max-cache-size</strong></span> and
3931                   <span><strong class="command">recursive-clients</strong></span>
3932                   options instead.
3933                 </p></dd>
3934 <dt><span class="term"><span><strong class="command">files</strong></span></span></dt>
3935 <dd><p>
3936                   The maximum number of files the server
3937                   may have open concurrently. The default is <code class="literal">unlimited</code>.
3938                 </p></dd>
3939 <dt><span class="term"><span><strong class="command">stacksize</strong></span></span></dt>
3940 <dd><p>
3941                   The maximum amount of stack memory the server
3942                   may use. The default is <code class="literal">default</code>.
3943                 </p></dd>
3944 </dl></div>
3945 </div>
3946 <div class="sect3" lang="en">
3947 <div class="titlepage"><div><div><h4 class="title">
3948 <a name="server_resource_limits"></a>Server  Resource Limits</h4></div></div></div>
3949 <p>
3950             The following options set limits on the server's
3951             resource consumption that are enforced internally by the
3952             server rather than the operating system.
3953           </p>
3954 <div class="variablelist"><dl>
3955 <dt><span class="term"><span><strong class="command">max-ixfr-log-size</strong></span></span></dt>
3956 <dd><p>
3957                   This option is obsolete; it is accepted
3958                   and ignored for BIND 8 compatibility.  The option
3959                   <span><strong class="command">max-journal-size</strong></span> performs a
3960                   similar function in BIND 9.
3961                 </p></dd>
3962 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
3963 <dd><p>
3964                   Sets a maximum size for each journal file
3965                   (see <a href="Bv9ARM.ch04.html#journal" title="The journal file">the section called &#8220;The journal file&#8221;</a>).  When the journal file
3966                   approaches
3967                   the specified size, some of the oldest transactions in the
3968                   journal
3969                   will be automatically removed.  The default is
3970                   <code class="literal">unlimited</code>.
3971                   This may also be set on a per-zone basis.
3972                 </p></dd>
3973 <dt><span class="term"><span><strong class="command">host-statistics-max</strong></span></span></dt>
3974 <dd><p>
3975                   In BIND 8, specifies the maximum number of host statistics
3976                   entries to be kept.
3977                   Not implemented in BIND 9.
3978                 </p></dd>
3979 <dt><span class="term"><span><strong class="command">recursive-clients</strong></span></span></dt>
3980 <dd><p>
3981                   The maximum number of simultaneous recursive lookups
3982                   the server will perform on behalf of clients.  The default
3983                   is
3984                   <code class="literal">1000</code>.  Because each recursing
3985                   client uses a fair
3986                   bit of memory, on the order of 20 kilobytes, the value of
3987                   the
3988                   <span><strong class="command">recursive-clients</strong></span> option may
3989                   have to be decreased
3990                   on hosts with limited memory.
3991                 </p></dd>
3992 <dt><span class="term"><span><strong class="command">tcp-clients</strong></span></span></dt>
3993 <dd><p>
3994                   The maximum number of simultaneous client TCP
3995                   connections that the server will accept.
3996                   The default is <code class="literal">100</code>.
3997                 </p></dd>
3998 <dt><span class="term"><span><strong class="command">reserved-sockets</strong></span></span></dt>
3999 <dd>
4000 <p>
4001                   The number of file descriptors reserved for TCP, stdio,
4002                   etc.  This needs to be big enough to cover the number of
4003                   interfaces <span><strong class="command">named</strong></span> listens on, <span><strong class="command">tcp-clients</strong></span> as well as
4004                   to provide room for outgoing TCP queries and incoming zone
4005                   transfers.  The default is <code class="literal">512</code>.
4006                   The minimum value is <code class="literal">128</code> and the
4007                   maximum value is <code class="literal">128</code> less than
4008                   maxsockets (-S).  This option may be removed in the future.
4009                 </p>
4010 <p>
4011                   This option has little effect on Windows.
4012                 </p>
4013 </dd>
4014 <dt><span class="term"><span><strong class="command">max-cache-size</strong></span></span></dt>
4015 <dd><p>
4016                   The maximum amount of memory to use for the
4017                   server's cache, in bytes.
4018                   When the amount of data in the cache
4019                   reaches this limit, the server will cause records to expire
4020                   prematurely based on an LRU based strategy so that
4021                   the limit is not exceeded.
4022                   A value of 0 is special, meaning that
4023                   records are purged from the cache only when their
4024                   TTLs expire.
4025                   Another special keyword <strong class="userinput"><code>unlimited</code></strong>
4026                   means the maximum value of 32-bit unsigned integers
4027                   (0xffffffff), which may not have the same effect as
4028                   0 on machines that support more than 32 bits of
4029                   memory space.
4030                   Any positive values less than 2MB will be ignored reset
4031                   to 2MB.
4032                   In a server with multiple views, the limit applies
4033                   separately to the cache of each view.
4034                   The default is 0.
4035                 </p></dd>
4036 <dt><span class="term"><span><strong class="command">tcp-listen-queue</strong></span></span></dt>
4037 <dd><p>
4038                   The listen queue depth.  The default and minimum is 3.
4039                   If the kernel supports the accept filter "dataready" this
4040                   also controls how
4041                   many TCP connections that will be queued in kernel space
4042                   waiting for
4043                   some data before being passed to accept.  Values less than 3
4044                   will be
4045                   silently raised.
4046                 </p></dd>
4047 </dl></div>
4048 </div>
4049 <div class="sect3" lang="en">
4050 <div class="titlepage"><div><div><h4 class="title">
4051 <a name="id2583985"></a>Periodic Task Intervals</h4></div></div></div>
4052 <div class="variablelist"><dl>
4053 <dt><span class="term"><span><strong class="command">cleaning-interval</strong></span></span></dt>
4054 <dd><p>
4055                   This interval is effectively obsolete.  Previously,
4056                   the server would remove expired resource records
4057                   from the cache every <span><strong class="command">cleaning-interval</strong></span> minutes.
4058                   <acronym class="acronym">BIND</acronym> 9 now manages cache
4059                   memory in a more sophisticated manner and does not
4060                   rely on the periodic cleaning any more.
4061                   Specifying this option therefore has no effect on
4062                   the server's behavior.
4063                 </p></dd>
4064 <dt><span class="term"><span><strong class="command">heartbeat-interval</strong></span></span></dt>
4065 <dd><p>
4066                   The server will perform zone maintenance tasks
4067                   for all zones marked as <span><strong class="command">dialup</strong></span> whenever this
4068                   interval expires. The default is 60 minutes. Reasonable
4069                   values are up
4070                   to 1 day (1440 minutes).  The maximum value is 28 days
4071                   (40320 minutes).
4072                   If set to 0, no zone maintenance for these zones will occur.
4073                 </p></dd>
4074 <dt><span class="term"><span><strong class="command">interface-interval</strong></span></span></dt>
4075 <dd><p>
4076                   The server will scan the network interface list
4077                   every <span><strong class="command">interface-interval</strong></span>
4078                   minutes. The default
4079                   is 60 minutes. The maximum value is 28 days (40320 minutes).
4080                   If set to 0, interface scanning will only occur when
4081                   the configuration file is  loaded. After the scan, the
4082                   server will
4083                   begin listening for queries on any newly discovered
4084                   interfaces (provided they are allowed by the
4085                   <span><strong class="command">listen-on</strong></span> configuration), and
4086                   will
4087                   stop listening on interfaces that have gone away.
4088                 </p></dd>
4089 <dt><span class="term"><span><strong class="command">statistics-interval</strong></span></span></dt>
4090 <dd>
4091 <p>
4092                   Name server statistics will be logged
4093                   every <span><strong class="command">statistics-interval</strong></span>
4094                   minutes. The default is
4095                   60. The maximum value is 28 days (40320 minutes).
4096                   If set to 0, no statistics will be logged.
4097                   </p>
4098 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4099 <h3 class="title">Note</h3>
4100 <p>
4101                     Not yet implemented in
4102                     <acronym class="acronym">BIND</acronym> 9.
4103                   </p>
4104 </div>
4105 </dd>
4106 </dl></div>
4107 </div>
4108 <div class="sect3" lang="en">
4109 <div class="titlepage"><div><div><h4 class="title">
4110 <a name="topology"></a>Topology</h4></div></div></div>
4111 <p>
4112             All other things being equal, when the server chooses a name
4113             server
4114             to query from a list of name servers, it prefers the one that is
4115             topologically closest to itself. The <span><strong class="command">topology</strong></span> statement
4116             takes an <span><strong class="command">address_match_list</strong></span> and
4117             interprets it
4118             in a special way. Each top-level list element is assigned a
4119             distance.
4120             Non-negated elements get a distance based on their position in the
4121             list, where the closer the match is to the start of the list, the
4122             shorter the distance is between it and the server. A negated match
4123             will be assigned the maximum distance from the server. If there
4124             is no match, the address will get a distance which is further than
4125             any non-negated list element, and closer than any negated element.
4126             For example,
4127           </p>
4128 <pre class="programlisting">topology {
4129     10/8;
4130     !1.2.3/24;
4131     { 1.2/16; 3/8; };
4132 };</pre>
4133 <p>
4134             will prefer servers on network 10 the most, followed by hosts
4135             on network 1.2.0.0 (netmask 255.255.0.0) and network 3, with the
4136             exception of hosts on network 1.2.3 (netmask 255.255.255.0), which
4137             is preferred least of all.
4138           </p>
4139 <p>
4140             The default topology is
4141           </p>
4142 <pre class="programlisting">    topology { localhost; localnets; };
4143 </pre>
4144 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4145 <h3 class="title">Note</h3>
4146 <p>
4147               The <span><strong class="command">topology</strong></span> option
4148               is not implemented in <acronym class="acronym">BIND</acronym> 9.
4149             </p>
4150 </div>
4151 </div>
4152 <div class="sect3" lang="en">
4153 <div class="titlepage"><div><div><h4 class="title">
4154 <a name="the_sortlist_statement"></a>The <span><strong class="command">sortlist</strong></span> Statement</h4></div></div></div>
4155 <p>
4156             The response to a DNS query may consist of multiple resource
4157             records (RRs) forming a resource records set (RRset).
4158             The name server will normally return the
4159             RRs within the RRset in an indeterminate order
4160             (but see the <span><strong class="command">rrset-order</strong></span>
4161             statement in <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called &#8220;RRset Ordering&#8221;</a>).
4162             The client resolver code should rearrange the RRs as appropriate,
4163             that is, using any addresses on the local net in preference to
4164             other addresses.
4165             However, not all resolvers can do this or are correctly
4166             configured.
4167             When a client is using a local server, the sorting can be performed
4168             in the server, based on the client's address. This only requires
4169             configuring the name servers, not all the clients.
4170           </p>
4171 <p>
4172             The <span><strong class="command">sortlist</strong></span> statement (see below)
4173             takes
4174             an <span><strong class="command">address_match_list</strong></span> and
4175             interprets it even
4176             more specifically than the <span><strong class="command">topology</strong></span>
4177             statement
4178             does (<a href="Bv9ARM.ch06.html#topology" title="Topology">the section called &#8220;Topology&#8221;</a>).
4179             Each top level statement in the <span><strong class="command">sortlist</strong></span> must
4180             itself be an explicit <span><strong class="command">address_match_list</strong></span> with
4181             one or two elements. The first element (which may be an IP
4182             address,
4183             an IP prefix, an ACL name or a nested <span><strong class="command">address_match_list</strong></span>)
4184             of each top level list is checked against the source address of
4185             the query until a match is found.
4186           </p>
4187 <p>
4188             Once the source address of the query has been matched, if
4189             the top level statement contains only one element, the actual
4190             primitive
4191             element that matched the source address is used to select the
4192             address
4193             in the response to move to the beginning of the response. If the
4194             statement is a list of two elements, then the second element is
4195             treated the same as the <span><strong class="command">address_match_list</strong></span> in
4196             a <span><strong class="command">topology</strong></span> statement. Each top
4197             level element
4198             is assigned a distance and the address in the response with the
4199             minimum
4200             distance is moved to the beginning of the response.
4201           </p>
4202 <p>
4203             In the following example, any queries received from any of
4204             the addresses of the host itself will get responses preferring
4205             addresses
4206             on any of the locally connected networks. Next most preferred are
4207             addresses
4208             on the 192.168.1/24 network, and after that either the
4209             192.168.2/24
4210             or
4211             192.168.3/24 network with no preference shown between these two
4212             networks. Queries received from a host on the 192.168.1/24 network
4213             will prefer other addresses on that network to the 192.168.2/24
4214             and
4215             192.168.3/24 networks. Queries received from a host on the
4216             192.168.4/24
4217             or the 192.168.5/24 network will only prefer other addresses on
4218             their directly connected networks.
4219           </p>
4220 <pre class="programlisting">sortlist {
4221     { localhost;                                   // IF   the local host
4222         { localnets;                               // THEN first fit on the
4223             192.168.1/24;                          //   following nets
4224             { 192.168.2/24; 192.168.3/24; }; }; };
4225     { 192.168.1/24;                                // IF   on class C 192.168.1
4226         { 192.168.1/24;                            // THEN use .1, or .2 or .3
4227             { 192.168.2/24; 192.168.3/24; }; }; };
4228     { 192.168.2/24;                                // IF   on class C 192.168.2
4229         { 192.168.2/24;                            // THEN use .2, or .1 or .3
4230             { 192.168.1/24; 192.168.3/24; }; }; };
4231     { 192.168.3/24;                                // IF   on class C 192.168.3
4232         { 192.168.3/24;                            // THEN use .3, or .1 or .2
4233             { 192.168.1/24; 192.168.2/24; }; }; };
4234     { { 192.168.4/24; 192.168.5/24; };             // if .4 or .5, prefer that net
4235     };
4236 };</pre>
4237 <p>
4238             The following example will give reasonable behavior for the
4239             local host and hosts on directly connected networks. It is similar
4240             to the behavior of the address sort in <acronym class="acronym">BIND</acronym> 4.9.x. Responses sent
4241             to queries from the local host will favor any of the directly
4242             connected
4243             networks. Responses sent to queries from any other hosts on a
4244             directly
4245             connected network will prefer addresses on that same network.
4246             Responses
4247             to other queries will not be sorted.
4248           </p>
4249 <pre class="programlisting">sortlist {
4250            { localhost; localnets; };
4251            { localnets; };
4252 };
4253 </pre>
4254 </div>
4255 <div class="sect3" lang="en">
4256 <div class="titlepage"><div><div><h4 class="title">
4257 <a name="rrset_ordering"></a>RRset Ordering</h4></div></div></div>
4258 <p>
4259             When multiple records are returned in an answer it may be
4260             useful to configure the order of the records placed into the
4261             response.
4262             The <span><strong class="command">rrset-order</strong></span> statement permits
4263             configuration
4264             of the ordering of the records in a multiple record response.
4265             See also the <span><strong class="command">sortlist</strong></span> statement,
4266             <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>.
4267           </p>
4268 <p>
4269             An <span><strong class="command">order_spec</strong></span> is defined as
4270             follows:
4271           </p>
4272 <p>
4273             [<span class="optional">class <em class="replaceable"><code>class_name</code></em></span>]
4274             [<span class="optional">type <em class="replaceable"><code>type_name</code></em></span>]
4275             [<span class="optional">name <em class="replaceable"><code>"domain_name"</code></em></span>]
4276             order <em class="replaceable"><code>ordering</code></em>
4277           </p>
4278 <p>
4279             If no class is specified, the default is <span><strong class="command">ANY</strong></span>.
4280             If no type is specified, the default is <span><strong class="command">ANY</strong></span>.
4281             If no name is specified, the default is "<span><strong class="command">*</strong></span>" (asterisk).
4282           </p>
4283 <p>
4284             The legal values for <span><strong class="command">ordering</strong></span> are:
4285           </p>
4286 <div class="informaltable"><table border="1">
4287 <colgroup>
4288 <col>
4289 <col>
4290 </colgroup>
4291 <tbody>
4292 <tr>
4293 <td>
4294                     <p><span><strong class="command">fixed</strong></span></p>
4295                   </td>
4296 <td>
4297                     <p>
4298                       Records are returned in the order they
4299                       are defined in the zone file.
4300                     </p>
4301                   </td>
4302 </tr>
4303 <tr>
4304 <td>
4305                     <p><span><strong class="command">random</strong></span></p>
4306                   </td>
4307 <td>
4308                     <p>
4309                       Records are returned in some random order.
4310                     </p>
4311                   </td>
4312 </tr>
4313 <tr>
4314 <td>
4315                     <p><span><strong class="command">cyclic</strong></span></p>
4316                   </td>
4317 <td>
4318                     <p>
4319                       Records are returned in a cyclic round-robin order.
4320                     </p>
4321                     <p>
4322                       If <acronym class="acronym">BIND</acronym> is configured with the
4323                       "--enable-fixed-rrset" option at compile time, then
4324                       the initial ordering of the RRset will match the
4325                       one specified in the zone file.
4326                     </p>
4327                   </td>
4328 </tr>
4329 </tbody>
4330 </table></div>
4331 <p>
4332             For example:
4333           </p>
4334 <pre class="programlisting">rrset-order {
4335    class IN type A name "host.example.com" order random;
4336    order cyclic;
4337 };
4338 </pre>
4339 <p>
4340             will cause any responses for type A records in class IN that
4341             have "<code class="literal">host.example.com</code>" as a
4342             suffix, to always be returned
4343             in random order. All other records are returned in cyclic order.
4344           </p>
4345 <p>
4346             If multiple <span><strong class="command">rrset-order</strong></span> statements
4347             appear,
4348             they are not combined &#8212; the last one applies.
4349           </p>
4350 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4351 <h3 class="title">Note</h3>
4352 <p>
4353               In this release of <acronym class="acronym">BIND</acronym> 9, the
4354               <span><strong class="command">rrset-order</strong></span> statement does not support
4355               "fixed" ordering by default.  Fixed ordering can be enabled
4356               at compile time by specifying "--enable-fixed-rrset" on
4357               the "configure" command line.
4358             </p>
4359 </div>
4360 </div>
4361 <div class="sect3" lang="en">
4362 <div class="titlepage"><div><div><h4 class="title">
4363 <a name="tuning"></a>Tuning</h4></div></div></div>
4364 <div class="variablelist"><dl>
4365 <dt><span class="term"><span><strong class="command">lame-ttl</strong></span></span></dt>
4366 <dd><p>
4367                   Sets the number of seconds to cache a
4368                   lame server indication. 0 disables caching. (This is
4369                   <span class="bold"><strong>NOT</strong></span> recommended.)
4370                   The default is <code class="literal">600</code> (10 minutes) and the
4371                   maximum value is
4372                   <code class="literal">1800</code> (30 minutes).
4373                 </p></dd>
4374 <dt><span class="term"><span><strong class="command">max-ncache-ttl</strong></span></span></dt>
4375 <dd><p>
4376                   To reduce network traffic and increase performance,
4377                   the server stores negative answers. <span><strong class="command">max-ncache-ttl</strong></span> is
4378                   used to set a maximum retention time for these answers in
4379                   the server
4380                   in seconds. The default
4381                   <span><strong class="command">max-ncache-ttl</strong></span> is <code class="literal">10800</code> seconds (3 hours).
4382                   <span><strong class="command">max-ncache-ttl</strong></span> cannot exceed
4383                   7 days and will
4384                   be silently truncated to 7 days if set to a greater value.
4385                 </p></dd>
4386 <dt><span class="term"><span><strong class="command">max-cache-ttl</strong></span></span></dt>
4387 <dd><p>
4388                   Sets the maximum time for which the server will
4389                   cache ordinary (positive) answers. The default is
4390                   one week (7 days).
4391                   A value of zero may cause all queries to return
4392                   SERVFAIL, because of lost caches of intermediate
4393                   RRsets (such as NS and glue AAAA/A records) in the
4394                   resolution process.
4395                 </p></dd>
4396 <dt><span class="term"><span><strong class="command">min-roots</strong></span></span></dt>
4397 <dd>
4398 <p>
4399                   The minimum number of root servers that
4400                   is required for a request for the root servers to be
4401                   accepted. The default
4402                   is <strong class="userinput"><code>2</code></strong>.
4403                 </p>
4404 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4405 <h3 class="title">Note</h3>
4406 <p>
4407                     Not implemented in <acronym class="acronym">BIND</acronym> 9.
4408                   </p>
4409 </div>
4410 </dd>
4411 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
4412 <dd>
4413 <p>
4414                   Specifies the number of days into the future when
4415                   DNSSEC signatures automatically generated as a
4416                   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
4417                   is a optional second field which specifies how
4418                   long before expiry that the signatures will be
4419                   regenerated.  If not specified, the signatures will
4420                   be regenerated at 1/4 of base interval.  The second
4421                   field is specified in days if the base interval is
4422                   greater than 7 days otherwise it is specified in hours.
4423                   The default base interval is <code class="literal">30</code> days
4424                   giving a re-signing interval of 7 1/2 days.  The maximum
4425                   values are 10 years (3660 days).
4426                 </p>
4427 <p>
4428                   The signature inception time is unconditionally
4429                   set to one hour before the current time to allow
4430                   for a limited amount of clock skew.
4431                 </p>
4432 <p>
4433                   The <span><strong class="command">sig-validity-interval</strong></span>
4434                   should be, at least, several multiples of the SOA
4435                   expire interval to allow for reasonable interaction
4436                   between the various timer and expiry dates.
4437                 </p>
4438 </dd>
4439 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
4440 <dd><p>
4441                   Specify the maximum number of nodes to be
4442                   examined in each quantum when signing a zone with
4443                   a new DNSKEY. The default is
4444                   <code class="literal">100</code>.
4445                 </p></dd>
4446 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
4447 <dd><p>
4448                   Specify a threshold number of signatures that
4449                   will terminate processing a quantum when signing
4450                   a zone with a new DNSKEY.  The default is
4451                   <code class="literal">10</code>.
4452                 </p></dd>
4453 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
4454 <dd>
4455 <p>
4456                   Specify a private RDATA type to be used when generating
4457                   key signing records.  The default is
4458                   <code class="literal">65535</code>.
4459                 </p>
4460 <p>
4461                   It is expected that this parameter may be removed
4462                   in a future version once there is a standard type.
4463                 </p>
4464 </dd>
4465 <dt>
4466 <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>
4467 </dt>
4468 <dd>
4469 <p>
4470                   These options control the server's behavior on refreshing a
4471                   zone
4472                   (querying for SOA changes) or retrying failed transfers.
4473                   Usually the SOA values for the zone are used, but these
4474                   values
4475                   are set by the master, giving slave server administrators
4476                   little
4477                   control over their contents.
4478                 </p>
4479 <p>
4480                   These options allow the administrator to set a minimum and
4481                   maximum
4482                   refresh and retry time either per-zone, per-view, or
4483                   globally.
4484                   These options are valid for slave and stub zones,
4485                   and clamp the SOA refresh and retry times to the specified
4486                   values.
4487                 </p>
4488 </dd>
4489 <dt><span class="term"><span><strong class="command">edns-udp-size</strong></span></span></dt>
4490 <dd><p>
4491                   Sets the advertised EDNS UDP buffer size in bytes
4492                   to control the size of packets received.
4493                   Valid values are 512 to 4096 (values outside this range
4494                   will be silently adjusted).  The default value
4495                   is 4096.  The usual reason for setting
4496                   <span><strong class="command">edns-udp-size</strong></span> to a non-default
4497                   value is to get UDP answers to pass through broken
4498                   firewalls that block fragmented packets and/or
4499                   block UDP packets that are greater than 512 bytes.
4500                 </p></dd>
4501 <dt><span class="term"><span><strong class="command">max-udp-size</strong></span></span></dt>
4502 <dd><p>
4503                   Sets the maximum EDNS UDP message size <span><strong class="command">named</strong></span> will
4504                   send in bytes.  Valid values are 512 to 4096 (values outside
4505                   this range will be silently adjusted).  The default
4506                   value is 4096.  The usual reason for setting
4507                   <span><strong class="command">max-udp-size</strong></span> to a non-default value is to get UDP
4508                   answers to pass through broken firewalls that
4509                   block fragmented packets and/or block UDP packets
4510                   that are greater than 512 bytes.
4511                   This is independent of the advertised receive
4512                   buffer (<span><strong class="command">edns-udp-size</strong></span>).
4513                 </p></dd>
4514 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
4515 <dd><p>Specifies
4516                   the file format of zone files (see
4517                   <a href="Bv9ARM.ch06.html#zonefile_format" title="Additional File Formats">the section called &#8220;Additional File Formats&#8221;</a>).
4518                   The default value is <code class="constant">text</code>, which is the
4519                   standard textual representation.  Files in other formats
4520                   than <code class="constant">text</code> are typically expected
4521                   to be generated by the <span><strong class="command">named-compilezone</strong></span> tool.
4522                   Note that when a zone file in a different format than
4523                   <code class="constant">text</code> is loaded, <span><strong class="command">named</strong></span>
4524                   may omit some of the checks which would be performed for a
4525                   file in the <code class="constant">text</code> format.  In particular,
4526                   <span><strong class="command">check-names</strong></span> checks do not apply
4527                   for the <code class="constant">raw</code> format.  This means
4528                   a zone file in the <code class="constant">raw</code> format
4529                   must be generated with the same check level as that
4530                   specified in the <span><strong class="command">named</strong></span> configuration
4531                   file.  This statement sets the
4532                   <span><strong class="command">masterfile-format</strong></span> for all zones,
4533                   but can be overridden on a per-zone or per-view basis
4534                   by including a <span><strong class="command">masterfile-format</strong></span>
4535                   statement within the <span><strong class="command">zone</strong></span> or
4536                   <span><strong class="command">view</strong></span> block in the configuration
4537                   file.
4538                 </p></dd>
4539 <dt>
4540 <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>
4541 </dt>
4542 <dd>
4543 <p>These set the
4544                   initial value (minimum) and maximum number of recursive
4545                   simultaneous clients for any given query
4546                   (&lt;qname,qtype,qclass&gt;) that the server will accept
4547                   before dropping additional clients.  <span><strong class="command">named</strong></span> will attempt to
4548                   self tune this value and changes will be logged.  The
4549                   default values are 10 and 100.
4550                 </p>
4551 <p>
4552                   This value should reflect how many queries come in for
4553                   a given name in the time it takes to resolve that name.
4554                   If the number of queries exceed this value, <span><strong class="command">named</strong></span> will
4555                   assume that it is dealing with a non-responsive zone
4556                   and will drop additional queries.  If it gets a response
4557                   after dropping queries, it will raise the estimate.  The
4558                   estimate will then be lowered in 20 minutes if it has
4559                   remained unchanged.
4560                 </p>
4561 <p>
4562                   If <span><strong class="command">clients-per-query</strong></span> is set to zero,
4563                   then there is no limit on the number of clients per query
4564                   and no queries will be dropped.
4565                 </p>
4566 <p>
4567                   If <span><strong class="command">max-clients-per-query</strong></span> is set to zero,
4568                   then there is no upper bound other than imposed by
4569                   <span><strong class="command">recursive-clients</strong></span>.
4570                 </p>
4571 </dd>
4572 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
4573 <dd><p>
4574                   The delay, in seconds, between sending sets of notify
4575                   messages for a zone.  The default is zero.
4576                 </p></dd>
4577 </dl></div>
4578 </div>
4579 <div class="sect3" lang="en">
4580 <div class="titlepage"><div><div><h4 class="title">
4581 <a name="builtin"></a>Built-in server information zones</h4></div></div></div>
4582 <p>
4583             The server provides some helpful diagnostic information
4584             through a number of built-in zones under the
4585             pseudo-top-level-domain <code class="literal">bind</code> in the
4586             <span><strong class="command">CHAOS</strong></span> class.  These zones are part
4587             of a
4588             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
4589             class
4590             <span><strong class="command">CHAOS</strong></span> which is separate from the
4591             default view of
4592             class <span><strong class="command">IN</strong></span>; therefore, any global
4593             server options
4594             such as <span><strong class="command">allow-query</strong></span> do not apply
4595             the these zones.
4596             If you feel the need to disable these zones, use the options
4597             below, or hide the built-in <span><strong class="command">CHAOS</strong></span>
4598             view by
4599             defining an explicit view of class <span><strong class="command">CHAOS</strong></span>
4600             that matches all clients.
4601           </p>
4602 <div class="variablelist"><dl>
4603 <dt><span class="term"><span><strong class="command">version</strong></span></span></dt>
4604 <dd><p>
4605                   The version the server should report
4606                   via a query of the name <code class="literal">version.bind</code>
4607                   with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
4608                   The default is the real version number of this server.
4609                   Specifying <span><strong class="command">version none</strong></span>
4610                   disables processing of the queries.
4611                 </p></dd>
4612 <dt><span class="term"><span><strong class="command">hostname</strong></span></span></dt>
4613 <dd><p>
4614                   The hostname the server should report via a query of
4615                   the name <code class="filename">hostname.bind</code>
4616                   with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
4617                   This defaults to the hostname of the machine hosting the
4618                   name server as
4619                   found by the gethostname() function.  The primary purpose of such queries
4620                   is to
4621                   identify which of a group of anycast servers is actually
4622                   answering your queries.  Specifying <span><strong class="command">hostname none;</strong></span>
4623                   disables processing of the queries.
4624                 </p></dd>
4625 <dt><span class="term"><span><strong class="command">server-id</strong></span></span></dt>
4626 <dd><p>
4627                   The ID the server should report when receiving a Name
4628                   Server Identifier (NSID) query, or a query of the name
4629                   <code class="filename">ID.SERVER</code> with type
4630                   <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
4631                   The primary purpose of such queries is to
4632                   identify which of a group of anycast servers is actually
4633                   answering your queries.  Specifying <span><strong class="command">server-id none;</strong></span>
4634                   disables processing of the queries.
4635                   Specifying <span><strong class="command">server-id hostname;</strong></span> will cause <span><strong class="command">named</strong></span> to
4636                   use the hostname as found by the gethostname() function.
4637                   The default <span><strong class="command">server-id</strong></span> is <span><strong class="command">none</strong></span>.
4638                 </p></dd>
4639 </dl></div>
4640 </div>
4641 <div class="sect3" lang="en">
4642 <div class="titlepage"><div><div><h4 class="title">
4643 <a name="empty"></a>Built-in Empty Zones</h4></div></div></div>
4644 <p>
4645             Named has some built-in empty zones (SOA and NS records only).
4646             These are for zones that should normally be answered locally
4647             and which queries should not be sent to the Internet's root
4648             servers.  The official servers which cover these namespaces
4649             return NXDOMAIN responses to these queries.  In particular,
4650             these cover the reverse namespace for addresses from RFC 1918 and
4651             RFC 3330.  They also include the reverse namespace for IPv6 local
4652             address (locally assigned), IPv6 link local addresses, the IPv6
4653             loopback address and the IPv6 unknown address.
4654           </p>
4655 <p>
4656             Named will attempt to determine if a built-in zone already exists
4657             or is active (covered by a forward-only forwarding declaration)
4658             and will not create a empty zone in that case.
4659           </p>
4660 <p>
4661             The current list of empty zones is:
4662             </p>
4663 <div class="itemizedlist"><ul type="disc">
4664 <li>0.IN-ADDR.ARPA</li>
4665 <li>127.IN-ADDR.ARPA</li>
4666 <li>254.169.IN-ADDR.ARPA</li>
4667 <li>2.0.192.IN-ADDR.ARPA</li>
4668 <li>255.255.255.255.IN-ADDR.ARPA</li>
4669 <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>
4670 <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>
4671 <li>D.F.IP6.ARPA</li>
4672 <li>8.E.F.IP6.ARPA</li>
4673 <li>9.E.F.IP6.ARPA</li>
4674 <li>A.E.F.IP6.ARPA</li>
4675 <li>B.E.F.IP6.ARPA</li>
4676 </ul></div>
4677 <p>
4678           </p>
4679 <p>
4680             Empty zones are settable at the view level and only apply to
4681             views of class IN.  Disabled empty zones are only inherited
4682             from options if there are no disabled empty zones specified
4683             at the view level.  To override the options list of disabled
4684             zones, you can disable the root zone at the view level, for example:
4685 </p>
4686 <pre class="programlisting">
4687             disable-empty-zone ".";
4688 </pre>
4689 <p>
4690           </p>
4691 <p>
4692             If you are using the address ranges covered here, you should
4693             already have reverse zones covering the addresses you use.
4694             In practice this appears to not be the case with many queries
4695             being made to the infrastructure servers for names in these
4696             spaces.  So many in fact that sacrificial servers were needed
4697             to be deployed to channel the query load away from the
4698             infrastructure servers.
4699           </p>
4700 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4701 <h3 class="title">Note</h3>
4702             The real parent servers for these zones should disable all
4703             empty zone under the parent zone they serve.  For the real
4704             root servers, this is all built-in empty zones.  This will
4705             enable them to return referrals to deeper in the tree.
4706           </div>
4707 <div class="variablelist"><dl>
4708 <dt><span class="term"><span><strong class="command">empty-server</strong></span></span></dt>
4709 <dd><p>
4710                   Specify what server name will appear in the returned
4711                   SOA record for empty zones.  If none is specified, then
4712                   the zone's name will be used.
4713                 </p></dd>
4714 <dt><span class="term"><span><strong class="command">empty-contact</strong></span></span></dt>
4715 <dd><p>
4716                   Specify what contact name will appear in the returned
4717                   SOA record for empty zones.  If none is specified, then
4718                   "." will be used.
4719                 </p></dd>
4720 <dt><span class="term"><span><strong class="command">empty-zones-enable</strong></span></span></dt>
4721 <dd><p>
4722                   Enable or disable all empty zones.  By default, they
4723                   are enabled.
4724                 </p></dd>
4725 <dt><span class="term"><span><strong class="command">disable-empty-zone</strong></span></span></dt>
4726 <dd><p>
4727                   Disable individual empty zones.  By default, none are
4728                   disabled.  This option can be specified multiple times.
4729                 </p></dd>
4730 </dl></div>
4731 </div>
4732 <div class="sect3" lang="en">
4733 <div class="titlepage"><div><div><h4 class="title">
4734 <a name="acache"></a>Additional Section Caching</h4></div></div></div>
4735 <p>
4736             The additional section cache, also called <span><strong class="command">acache</strong></span>,
4737             is an internal cache to improve the response performance of BIND 9.
4738             When additional section caching is enabled, BIND 9 will
4739             cache an internal short-cut to the additional section content for
4740             each answer RR.
4741             Note that <span><strong class="command">acache</strong></span> is an internal caching
4742             mechanism of BIND 9, and is not related to the DNS caching
4743             server function.
4744           </p>
4745 <p>
4746             Additional section caching does not change the
4747             response content (except the RRsets ordering of the additional
4748             section, see below), but can improve the response performance
4749             significantly.
4750             It is particularly effective when BIND 9 acts as an authoritative
4751             server for a zone that has many delegations with many glue RRs.
4752           </p>
4753 <p>
4754             In order to obtain the maximum performance improvement
4755             from additional section caching, setting
4756             <span><strong class="command">additional-from-cache</strong></span>
4757             to <span><strong class="command">no</strong></span> is recommended, since the current
4758             implementation of <span><strong class="command">acache</strong></span>
4759             does not short-cut of additional section information from the
4760             DNS cache data.
4761           </p>
4762 <p>
4763             One obvious disadvantage of <span><strong class="command">acache</strong></span> is
4764             that it requires much more
4765             memory for the internal cached data.
4766             Thus, if the response performance does not matter and memory
4767             consumption is much more critical, the
4768             <span><strong class="command">acache</strong></span> mechanism can be
4769             disabled by setting <span><strong class="command">acache-enable</strong></span> to
4770             <span><strong class="command">no</strong></span>.
4771             It is also possible to specify the upper limit of memory
4772             consumption
4773             for acache by using <span><strong class="command">max-acache-size</strong></span>.
4774           </p>
4775 <p>
4776             Additional section caching also has a minor effect on the
4777             RRset ordering in the additional section.
4778             Without <span><strong class="command">acache</strong></span>,
4779             <span><strong class="command">cyclic</strong></span> order is effective for the additional
4780             section as well as the answer and authority sections.
4781             However, additional section caching fixes the ordering when it
4782             first caches an RRset for the additional section, and the same
4783             ordering will be kept in succeeding responses, regardless of the
4784             setting of <span><strong class="command">rrset-order</strong></span>.
4785             The effect of this should be minor, however, since an
4786             RRset in the additional section
4787             typically only contains a small number of RRs (and in many cases
4788             it only contains a single RR), in which case the
4789             ordering does not matter much.
4790           </p>
4791 <p>
4792             The following is a summary of options related to
4793             <span><strong class="command">acache</strong></span>.
4794           </p>
4795 <div class="variablelist"><dl>
4796 <dt><span class="term"><span><strong class="command">acache-enable</strong></span></span></dt>
4797 <dd><p>
4798                   If <span><strong class="command">yes</strong></span>, additional section caching is
4799                   enabled.  The default value is <span><strong class="command">no</strong></span>.
4800                 </p></dd>
4801 <dt><span class="term"><span><strong class="command">acache-cleaning-interval</strong></span></span></dt>
4802 <dd><p>
4803                   The server will remove stale cache entries, based on an LRU
4804                   based
4805                   algorithm, every <span><strong class="command">acache-cleaning-interval</strong></span> minutes.
4806                   The default is 60 minutes.
4807                   If set to 0, no periodic cleaning will occur.
4808                 </p></dd>
4809 <dt><span class="term"><span><strong class="command">max-acache-size</strong></span></span></dt>
4810 <dd><p>
4811                   The maximum amount of memory in bytes to use for the server's acache.
4812                   When the amount of data in the acache reaches this limit,
4813                   the server
4814                   will clean more aggressively so that the limit is not
4815                   exceeded.
4816                   In a server with multiple views, the limit applies
4817                   separately to the
4818                   acache of each view.
4819                   The default is <code class="literal">16M</code>.
4820                 </p></dd>
4821 </dl></div>
4822 </div>
4823 </div>
4824 <div class="sect2" lang="en">
4825 <div class="titlepage"><div><div><h3 class="title">
4826 <a name="server_statement_grammar"></a><span><strong class="command">server</strong></span> Statement Grammar</h3></div></div></div>
4827 <pre class="programlisting"><span><strong class="command">server</strong></span> <em class="replaceable"><code>ip_addr[/prefixlen]</code></em> {
4828     [<span class="optional"> bogus <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4829     [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4830     [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4831     [<span class="optional"> edns <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4832     [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
4833     [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
4834     [<span class="optional"> transfers <em class="replaceable"><code>number</code></em> ; </span>]
4835     [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em> ; ]</span>]
4836     [<span class="optional"> keys <em class="replaceable"><code>{ string ; [<span class="optional"> string ; [<span class="optional">...</span>]</span>] }</code></em> ; </span>]
4837     [<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>]
4838     [<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>]
4839     [<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>]
4840     [<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>]
4841     [<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>]
4842     [<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>]
4843     [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
4844     [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>]
4845     [<span class="optional"> queryport-pool-interval <em class="replaceable"><code>number</code></em>; </span>]
4846 };
4847 </pre>
4848 </div>
4849 <div class="sect2" lang="en">
4850 <div class="titlepage"><div><div><h3 class="title">
4851 <a name="server_statement_definition_and_usage"></a><span><strong class="command">server</strong></span> Statement Definition and
4852             Usage</h3></div></div></div>
4853 <p>
4854             The <span><strong class="command">server</strong></span> statement defines
4855             characteristics
4856             to be associated with a remote name server.  If a prefix length is
4857             specified, then a range of servers is covered.  Only the most
4858             specific
4859             server clause applies regardless of the order in
4860             <code class="filename">named.conf</code>.
4861           </p>
4862 <p>
4863             The <span><strong class="command">server</strong></span> statement can occur at
4864             the top level of the
4865             configuration file or inside a <span><strong class="command">view</strong></span>
4866             statement.
4867             If a <span><strong class="command">view</strong></span> statement contains
4868             one or more <span><strong class="command">server</strong></span> statements, only
4869             those
4870             apply to the view and any top-level ones are ignored.
4871             If a view contains no <span><strong class="command">server</strong></span>
4872             statements,
4873             any top-level <span><strong class="command">server</strong></span> statements are
4874             used as
4875             defaults.
4876           </p>
4877 <p>
4878             If you discover that a remote server is giving out bad data,
4879             marking it as bogus will prevent further queries to it. The
4880             default
4881             value of <span><strong class="command">bogus</strong></span> is <span><strong class="command">no</strong></span>.
4882           </p>
4883 <p>
4884             The <span><strong class="command">provide-ixfr</strong></span> clause determines
4885             whether
4886             the local server, acting as master, will respond with an
4887             incremental
4888             zone transfer when the given remote server, a slave, requests it.
4889             If set to <span><strong class="command">yes</strong></span>, incremental transfer
4890             will be provided
4891             whenever possible. If set to <span><strong class="command">no</strong></span>,
4892             all transfers
4893             to the remote server will be non-incremental. If not set, the
4894             value
4895             of the <span><strong class="command">provide-ixfr</strong></span> option in the
4896             view or
4897             global options block is used as a default.
4898           </p>
4899 <p>
4900             The <span><strong class="command">request-ixfr</strong></span> clause determines
4901             whether
4902             the local server, acting as a slave, will request incremental zone
4903             transfers from the given remote server, a master. If not set, the
4904             value of the <span><strong class="command">request-ixfr</strong></span> option in
4905             the view or
4906             global options block is used as a default.
4907           </p>
4908 <p>
4909             IXFR requests to servers that do not support IXFR will
4910             automatically
4911             fall back to AXFR.  Therefore, there is no need to manually list
4912             which servers support IXFR and which ones do not; the global
4913             default
4914             of <span><strong class="command">yes</strong></span> should always work.
4915             The purpose of the <span><strong class="command">provide-ixfr</strong></span> and
4916             <span><strong class="command">request-ixfr</strong></span> clauses is
4917             to make it possible to disable the use of IXFR even when both
4918             master
4919             and slave claim to support it, for example if one of the servers
4920             is buggy and crashes or corrupts data when IXFR is used.
4921           </p>
4922 <p>
4923             The <span><strong class="command">edns</strong></span> clause determines whether
4924             the local server will attempt to use EDNS when communicating
4925             with the remote server.  The default is <span><strong class="command">yes</strong></span>.
4926           </p>
4927 <p>
4928             The <span><strong class="command">edns-udp-size</strong></span> option sets the EDNS UDP size
4929             that is advertised by <span><strong class="command">named</strong></span> when querying the remote server.
4930             Valid values are 512 to 4096 bytes (values outside this range will be
4931             silently adjusted).  This option is useful when you wish to
4932             advertises a different value to this server than the value you
4933             advertise globally, for example, when there is a firewall at the
4934             remote site that is blocking large replies.
4935           </p>
4936 <p>
4937             The <span><strong class="command">max-udp-size</strong></span> option sets the
4938             maximum EDNS UDP message size <span><strong class="command">named</strong></span> will send.  Valid
4939             values are 512 to 4096 bytes (values outside this range will
4940             be silently adjusted).  This option is useful when you
4941             know that there is a firewall that is blocking large
4942             replies from <span><strong class="command">named</strong></span>.
4943           </p>
4944 <p>
4945             The server supports two zone transfer methods. The first, <span><strong class="command">one-answer</strong></span>,
4946             uses one DNS message per resource record transferred. <span><strong class="command">many-answers</strong></span> packs
4947             as many resource records as possible into a message. <span><strong class="command">many-answers</strong></span> is
4948             more efficient, but is only known to be understood by <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
4949             8.x, and patched versions of <acronym class="acronym">BIND</acronym>
4950             4.9.5. You can specify which method
4951             to use for a server with the <span><strong class="command">transfer-format</strong></span> option.
4952             If <span><strong class="command">transfer-format</strong></span> is not
4953             specified, the <span><strong class="command">transfer-format</strong></span>
4954             specified
4955             by the <span><strong class="command">options</strong></span> statement will be
4956             used.
4957           </p>
4958 <p><span><strong class="command">transfers</strong></span>
4959             is used to limit the number of concurrent inbound zone
4960             transfers from the specified server. If no
4961             <span><strong class="command">transfers</strong></span> clause is specified, the
4962             limit is set according to the
4963             <span><strong class="command">transfers-per-ns</strong></span> option.
4964           </p>
4965 <p>
4966             The <span><strong class="command">keys</strong></span> clause identifies a
4967             <span><strong class="command">key_id</strong></span> defined by the <span><strong class="command">key</strong></span> statement,
4968             to be used for transaction security (TSIG, <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called &#8220;TSIG&#8221;</a>)
4969             when talking to the remote server.
4970             When a request is sent to the remote server, a request signature
4971             will be generated using the key specified here and appended to the
4972             message. A request originating from the remote server is not
4973             required
4974             to be signed by this key.
4975           </p>
4976 <p>
4977             Although the grammar of the <span><strong class="command">keys</strong></span>
4978             clause
4979             allows for multiple keys, only a single key per server is
4980             currently
4981             supported.
4982           </p>
4983 <p>
4984             The <span><strong class="command">transfer-source</strong></span> and
4985             <span><strong class="command">transfer-source-v6</strong></span> clauses specify
4986             the IPv4 and IPv6 source
4987             address to be used for zone transfer with the remote server,
4988             respectively.
4989             For an IPv4 remote server, only <span><strong class="command">transfer-source</strong></span> can
4990             be specified.
4991             Similarly, for an IPv6 remote server, only
4992             <span><strong class="command">transfer-source-v6</strong></span> can be
4993             specified.
4994             For more details, see the description of
4995             <span><strong class="command">transfer-source</strong></span> and
4996             <span><strong class="command">transfer-source-v6</strong></span> in
4997             <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
4998           </p>
4999 <p>
5000             The <span><strong class="command">notify-source</strong></span> and
5001             <span><strong class="command">notify-source-v6</strong></span> clauses specify the
5002             IPv4 and IPv6 source address to be used for notify
5003             messages sent to remote servers, respectively.  For an
5004             IPv4 remote server, only <span><strong class="command">notify-source</strong></span>
5005             can be specified.  Similarly, for an IPv6 remote server,
5006             only <span><strong class="command">notify-source-v6</strong></span> can be specified.
5007           </p>
5008 <p>
5009             The <span><strong class="command">query-source</strong></span> and
5010             <span><strong class="command">query-source-v6</strong></span> clauses specify the
5011             IPv4 and IPv6 source address to be used for queries
5012             sent to remote servers, respectively.  For an IPv4
5013             remote server, only <span><strong class="command">query-source</strong></span> can
5014             be specified.  Similarly, for an IPv6 remote server,
5015             only <span><strong class="command">query-source-v6</strong></span> can be specified.
5016           </p>
5017 </div>
5018 <div class="sect2" lang="en">
5019 <div class="titlepage"><div><div><h3 class="title">
5020 <a name="statschannels"></a><span><strong class="command">statistics-channels</strong></span> Statement Grammar</h3></div></div></div>
5021 <pre class="programlisting"><span><strong class="command">statistics-channels</strong></span> {
5022    [ inet ( ip_addr | * ) [ port ip_port ] [allow { <em class="replaceable"><code> address_match_list </code></em> } ]; ]
5023    [ inet ...; ]
5024 };
5025 </pre>
5026 </div>
5027 <div class="sect2" lang="en">
5028 <div class="titlepage"><div><div><h3 class="title">
5029 <a name="id2586754"></a><span><strong class="command">statistics-channels</strong></span> Statement Definition and
5030             Usage</h3></div></div></div>
5031 <p>
5032           The <span><strong class="command">statistics-channels</strong></span> statement
5033           declares communication channels to be used by system
5034           administrators to get access to statistics information of
5035           the name server.
5036         </p>
5037 <p>
5038           This statement intends to be flexible to support multiple
5039           communication protocols in the future, but currently only
5040           HTTP access is supported.
5041           It requires that BIND 9 be compiled with libxml2;
5042           the <span><strong class="command">statistics-channels</strong></span> statement is
5043           still accepted even if it is built without the library,
5044           but any HTTP access will fail with an error.
5045         </p>
5046 <p>
5047           An <span><strong class="command">inet</strong></span> control channel is a TCP socket
5048           listening at the specified <span><strong class="command">ip_port</strong></span> on the
5049           specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6
5050           address.  An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is
5051           interpreted as the IPv4 wildcard address; connections will be
5052           accepted on any of the system's IPv4 addresses.
5053           To listen on the IPv6 wildcard address,
5054           use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>.
5055         </p>
5056 <p>
5057           If no port is specified, port 80 is used for HTTP channels.
5058           The asterisk "<code class="literal">*</code>" cannot be used for
5059           <span><strong class="command">ip_port</strong></span>.
5060         </p>
5061 <p>
5062           The attempt of opening a statistics channel is
5063           restricted by the optional <span><strong class="command">allow</strong></span> clause.
5064           Connections to the statistics channel are permitted based on the
5065           <span><strong class="command">address_match_list</strong></span>.
5066           If no <span><strong class="command">allow</strong></span> clause is present,
5067           <span><strong class="command">named</strong></span> accepts connection
5068           attempts from any address; since the statistics may
5069           contain sensitive internal information, it is highly
5070           recommended to restrict the source of connection requests
5071           appropriately.
5072         </p>
5073 <p>
5074           If no <span><strong class="command">statistics-channels</strong></span> statement is present,
5075           <span><strong class="command">named</strong></span> will not open any communication channels.
5076         </p>
5077 </div>
5078 <div class="sect2" lang="en">
5079 <div class="titlepage"><div><div><h3 class="title">
5080 <a name="id2586908"></a><span><strong class="command">trusted-keys</strong></span> Statement Grammar</h3></div></div></div>
5081 <pre class="programlisting"><span><strong class="command">trusted-keys</strong></span> {
5082     <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> ;
5083     [<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>]
5084 };
5085 </pre>
5086 </div>
5087 <div class="sect2" lang="en">
5088 <div class="titlepage"><div><div><h3 class="title">
5089 <a name="id2586960"></a><span><strong class="command">trusted-keys</strong></span> Statement Definition
5090             and Usage</h3></div></div></div>
5091 <p>
5092             The <span><strong class="command">trusted-keys</strong></span> statement defines
5093             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
5094             public key for a non-authoritative zone is known, but
5095             cannot be securely obtained through DNS, either because
5096             it is the DNS root zone or because its parent zone is
5097             unsigned.  Once a key has been configured as a trusted
5098             key, it is treated as if it had been validated and
5099             proven secure. The resolver attempts DNSSEC validation
5100             on all DNS data in subdomains of a security root.
5101           </p>
5102 <p>
5103             All keys (and corresponding zones) listed in
5104             <span><strong class="command">trusted-keys</strong></span> are deemed to exist regardless
5105             of what parent zones say.  Similarly for all keys listed in
5106             <span><strong class="command">trusted-keys</strong></span> only those keys are
5107             used to validate the DNSKEY RRset.  The parent's DS RRset
5108             will not be used.
5109           </p>
5110 <p>
5111             The <span><strong class="command">trusted-keys</strong></span> statement can contain
5112             multiple key entries, each consisting of the key's
5113             domain name, flags, protocol, algorithm, and the Base-64
5114             representation of the key data.
5115             Spaces, tabs, newlines and carriage returns are ignored
5116             in the key data, so the configuration may be split up into
5117             multiple lines.
5118           </p>
5119 </div>
5120 <div class="sect2" lang="en">
5121 <div class="titlepage"><div><div><h3 class="title">
5122 <a name="view_statement_grammar"></a><span><strong class="command">view</strong></span> Statement Grammar</h3></div></div></div>
5123 <pre class="programlisting"><span><strong class="command">view</strong></span> <em class="replaceable"><code>view_name</code></em>
5124       [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5125       match-clients { <em class="replaceable"><code>address_match_list</code></em> };
5126       match-destinations { <em class="replaceable"><code>address_match_list</code></em> };
5127       match-recursive-only <em class="replaceable"><code>yes_or_no</code></em> ;
5128       [<span class="optional"> <em class="replaceable"><code>view_option</code></em>; ...</span>]
5129       [<span class="optional"> <em class="replaceable"><code>zone_statement</code></em>; ...</span>]
5130 };
5131 </pre>
5132 </div>
5133 <div class="sect2" lang="en">
5134 <div class="titlepage"><div><div><h3 class="title">
5135 <a name="id2587042"></a><span><strong class="command">view</strong></span> Statement Definition and Usage</h3></div></div></div>
5136 <p>
5137             The <span><strong class="command">view</strong></span> statement is a powerful
5138             feature
5139             of <acronym class="acronym">BIND</acronym> 9 that lets a name server
5140             answer a DNS query differently
5141             depending on who is asking. It is particularly useful for
5142             implementing
5143             split DNS setups without having to run multiple servers.
5144           </p>
5145 <p>
5146             Each <span><strong class="command">view</strong></span> statement defines a view
5147             of the
5148             DNS namespace that will be seen by a subset of clients.  A client
5149             matches
5150             a view if its source IP address matches the
5151             <code class="varname">address_match_list</code> of the view's
5152             <span><strong class="command">match-clients</strong></span> clause and its
5153             destination IP address matches
5154             the <code class="varname">address_match_list</code> of the
5155             view's
5156             <span><strong class="command">match-destinations</strong></span> clause.  If not
5157             specified, both
5158             <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
5159             default to matching all addresses.  In addition to checking IP
5160             addresses
5161             <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
5162             can also take <span><strong class="command">keys</strong></span> which provide an
5163             mechanism for the
5164             client to select the view.  A view can also be specified
5165             as <span><strong class="command">match-recursive-only</strong></span>, which
5166             means that only recursive
5167             requests from matching clients will match that view.
5168             The order of the <span><strong class="command">view</strong></span> statements is
5169             significant &#8212;
5170             a client request will be resolved in the context of the first
5171             <span><strong class="command">view</strong></span> that it matches.
5172           </p>
5173 <p>
5174             Zones defined within a <span><strong class="command">view</strong></span>
5175             statement will
5176             only be accessible to clients that match the <span><strong class="command">view</strong></span>.
5177             By defining a zone of the same name in multiple views, different
5178             zone data can be given to different clients, for example,
5179             "internal"
5180             and "external" clients in a split DNS setup.
5181           </p>
5182 <p>
5183             Many of the options given in the <span><strong class="command">options</strong></span> statement
5184             can also be used within a <span><strong class="command">view</strong></span>
5185             statement, and then
5186             apply only when resolving queries with that view.  When no
5187             view-specific
5188             value is given, the value in the <span><strong class="command">options</strong></span> statement
5189             is used as a default.  Also, zone options can have default values
5190             specified
5191             in the <span><strong class="command">view</strong></span> statement; these
5192             view-specific defaults
5193             take precedence over those in the <span><strong class="command">options</strong></span> statement.
5194           </p>
5195 <p>
5196             Views are class specific.  If no class is given, class IN
5197             is assumed.  Note that all non-IN views must contain a hint zone,
5198             since only the IN class has compiled-in default hints.
5199           </p>
5200 <p>
5201             If there are no <span><strong class="command">view</strong></span> statements in
5202             the config
5203             file, a default view that matches any client is automatically
5204             created
5205             in class IN. Any <span><strong class="command">zone</strong></span> statements
5206             specified on
5207             the top level of the configuration file are considered to be part
5208             of
5209             this default view, and the <span><strong class="command">options</strong></span>
5210             statement will
5211             apply to the default view. If any explicit <span><strong class="command">view</strong></span>
5212             statements are present, all <span><strong class="command">zone</strong></span>
5213             statements must
5214             occur inside <span><strong class="command">view</strong></span> statements.
5215           </p>
5216 <p>
5217             Here is an example of a typical split DNS setup implemented
5218             using <span><strong class="command">view</strong></span> statements:
5219           </p>
5220 <pre class="programlisting">view "internal" {
5221       // This should match our internal networks.
5222       match-clients { 10.0.0.0/8; };
5223
5224       // Provide recursive service to internal clients only.
5225       recursion yes;
5226
5227       // Provide a complete view of the example.com zone
5228       // including addresses of internal hosts.
5229       zone "example.com" {
5230             type master;
5231             file "example-internal.db";
5232       };
5233 };
5234
5235 view "external" {
5236       // Match all clients not matched by the previous view.
5237       match-clients { any; };
5238
5239       // Refuse recursive service to external clients.
5240       recursion no;
5241
5242       // Provide a restricted view of the example.com zone
5243       // containing only publicly accessible hosts.
5244       zone "example.com" {
5245            type master;
5246            file "example-external.db";
5247       };
5248 };
5249 </pre>
5250 </div>
5251 <div class="sect2" lang="en">
5252 <div class="titlepage"><div><div><h3 class="title">
5253 <a name="zone_statement_grammar"></a><span><strong class="command">zone</strong></span>
5254             Statement Grammar</h3></div></div></div>
5255 <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>] {
5256     type master;
5257     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5258     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5259     [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5260     [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5261     [<span class="optional"> update-policy { <em class="replaceable"><code>update_policy_rule</code></em> [<span class="optional">...</span>] }; </span>]
5262     [<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>]
5263     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5264     [<span class="optional"> check-mx (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5265     [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5266     [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5267     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
5268     [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
5269     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
5270     [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>]
5271     [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
5272     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5273     [<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>]
5274     [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>]
5275     [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5276     [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>]
5277     [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5278     [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
5279     [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
5280     [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
5281     [<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>]
5282     [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
5283     [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5284     [<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>]
5285     [<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>]
5286     [<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>]
5287     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5288     [<span class="optional"> sig-validity-interval <em class="replaceable"><code>number</code></em> ; </span>]
5289     [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>]
5290     [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>]
5291     [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>]
5292     [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
5293     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5294     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5295     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5296     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5297     [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>]
5298     [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5299 };
5300
5301 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5302     type slave;
5303     [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5304     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5305     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5306     [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5307     [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5308     [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5309     [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5310     [<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>]
5311     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5312     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
5313     [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
5314     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
5315     [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>]
5316     [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
5317     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5318     [<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>]
5319     [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>]
5320     [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5321     [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>]
5322     [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5323     [<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>]
5324     [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
5325     [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
5326     [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
5327     [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
5328     [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
5329     [<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>]
5330     [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
5331     [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5332     [<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>]
5333     [<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>]
5334     [<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>]
5335     [<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>]
5336     [<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>]
5337     [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5338     [<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>]
5339     [<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>]
5340     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5341     [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
5342     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5343     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5344     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5345     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5346     [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5347     [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5348 };
5349
5350 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5351     type hint;
5352     file <em class="replaceable"><code>string</code></em> ;
5353     [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5354     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; // Not Implemented. </span>]
5355 };
5356
5357 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5358     type stub;
5359     [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5360     [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5361     [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5362     [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
5363     [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5364     [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
5365     [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
5366     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5367     [<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>]
5368     [<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>]
5369     [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
5370     [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
5371     [<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>]
5372     [<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>]
5373     [<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>]
5374     [<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>]
5375     [<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>]
5376     [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5377     [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5378     [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
5379     [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5380     [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5381     [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5382     [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5383     [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5384 };
5385
5386 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5387     type forward;
5388     [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5389     [<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>]
5390     [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5391 };
5392
5393 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5394     type delegation-only;
5395 };
5396
5397 </pre>
5398 </div>
5399 <div class="sect2" lang="en">
5400 <div class="titlepage"><div><div><h3 class="title">
5401 <a name="id2588510"></a><span><strong class="command">zone</strong></span> Statement Definition and Usage</h3></div></div></div>
5402 <div class="sect3" lang="en">
5403 <div class="titlepage"><div><div><h4 class="title">
5404 <a name="id2588518"></a>Zone Types</h4></div></div></div>
5405 <div class="informaltable"><table border="1">
5406 <colgroup>
5407 <col>
5408 <col>
5409 </colgroup>
5410 <tbody>
5411 <tr>
5412 <td>
5413                       <p>
5414                         <code class="varname">master</code>
5415                       </p>
5416                     </td>
5417 <td>
5418                       <p>
5419                         The server has a master copy of the data
5420                         for the zone and will be able to provide authoritative
5421                         answers for
5422                         it.
5423                       </p>
5424                     </td>
5425 </tr>
5426 <tr>
5427 <td>
5428                       <p>
5429                         <code class="varname">slave</code>
5430                       </p>
5431                     </td>
5432 <td>
5433                       <p>
5434                         A slave zone is a replica of a master
5435                         zone. The <span><strong class="command">masters</strong></span> list
5436                         specifies one or more IP addresses
5437                         of master servers that the slave contacts to update
5438                         its copy of the zone.
5439                         Masters list elements can also be names of other
5440                         masters lists.
5441                         By default, transfers are made from port 53 on the
5442                         servers; this can
5443                         be changed for all servers by specifying a port number
5444                         before the
5445                         list of IP addresses, or on a per-server basis after
5446                         the IP address.
5447                         Authentication to the master can also be done with
5448                         per-server TSIG keys.
5449                         If a file is specified, then the
5450                         replica will be written to this file whenever the zone
5451                         is changed,
5452                         and reloaded from this file on a server restart. Use
5453                         of a file is
5454                         recommended, since it often speeds server startup and
5455                         eliminates
5456                         a needless waste of bandwidth. Note that for large
5457                         numbers (in the
5458                         tens or hundreds of thousands) of zones per server, it
5459                         is best to
5460                         use a two-level naming scheme for zone filenames. For
5461                         example,
5462                         a slave server for the zone <code class="literal">example.com</code> might place
5463                         the zone contents into a file called
5464                         <code class="filename">ex/example.com</code> where <code class="filename">ex/</code> is
5465                         just the first two letters of the zone name. (Most
5466                         operating systems
5467                         behave very slowly if you put 100000 files into
5468                         a single directory.)
5469                       </p>
5470                     </td>
5471 </tr>
5472 <tr>
5473 <td>
5474                       <p>
5475                         <code class="varname">stub</code>
5476                       </p>
5477                     </td>
5478 <td>
5479                       <p>
5480                         A stub zone is similar to a slave zone,
5481                         except that it replicates only the NS records of a
5482                         master zone instead
5483                         of the entire zone. Stub zones are not a standard part
5484                         of the DNS;
5485                         they are a feature specific to the <acronym class="acronym">BIND</acronym> implementation.
5486                       </p>
5487
5488                       <p>
5489                         Stub zones can be used to eliminate the need for glue
5490                         NS record
5491                         in a parent zone at the expense of maintaining a stub
5492                         zone entry and
5493                         a set of name server addresses in <code class="filename">named.conf</code>.
5494                         This usage is not recommended for new configurations,
5495                         and BIND 9
5496                         supports it only in a limited way.
5497                         In <acronym class="acronym">BIND</acronym> 4/8, zone
5498                         transfers of a parent zone
5499                         included the NS records from stub children of that
5500                         zone. This meant
5501                         that, in some cases, users could get away with
5502                         configuring child stubs
5503                         only in the master server for the parent zone. <acronym class="acronym">BIND</acronym>
5504                         9 never mixes together zone data from different zones
5505                         in this
5506                         way. Therefore, if a <acronym class="acronym">BIND</acronym> 9 master serving a parent
5507                         zone has child stub zones configured, all the slave
5508                         servers for the
5509                         parent zone also need to have the same child stub
5510                         zones
5511                         configured.
5512                       </p>
5513
5514                       <p>
5515                         Stub zones can also be used as a way of forcing the
5516                         resolution
5517                         of a given domain to use a particular set of
5518                         authoritative servers.
5519                         For example, the caching name servers on a private
5520                         network using
5521                         RFC1918 addressing may be configured with stub zones
5522                         for
5523                         <code class="literal">10.in-addr.arpa</code>
5524                         to use a set of internal name servers as the
5525                         authoritative
5526                         servers for that domain.
5527                       </p>
5528                     </td>
5529 </tr>
5530 <tr>
5531 <td>
5532                       <p>
5533                         <code class="varname">forward</code>
5534                       </p>
5535                     </td>
5536 <td>
5537                       <p>
5538                         A "forward zone" is a way to configure
5539                         forwarding on a per-domain basis.  A <span><strong class="command">zone</strong></span> statement
5540                         of type <span><strong class="command">forward</strong></span> can
5541                         contain a <span><strong class="command">forward</strong></span>
5542                         and/or <span><strong class="command">forwarders</strong></span>
5543                         statement,
5544                         which will apply to queries within the domain given by
5545                         the zone
5546                         name. If no <span><strong class="command">forwarders</strong></span>
5547                         statement is present or
5548                         an empty list for <span><strong class="command">forwarders</strong></span> is given, then no
5549                         forwarding will be done for the domain, canceling the
5550                         effects of
5551                         any forwarders in the <span><strong class="command">options</strong></span> statement. Thus
5552                         if you want to use this type of zone to change the
5553                         behavior of the
5554                         global <span><strong class="command">forward</strong></span> option
5555                         (that is, "forward first"
5556                         to, then "forward only", or vice versa, but want to
5557                         use the same
5558                         servers as set globally) you need to re-specify the
5559                         global forwarders.
5560                       </p>
5561                     </td>
5562 </tr>
5563 <tr>
5564 <td>
5565                       <p>
5566                         <code class="varname">hint</code>
5567                       </p>
5568                     </td>
5569 <td>
5570                       <p>
5571                         The initial set of root name servers is
5572                         specified using a "hint zone". When the server starts
5573                         up, it uses
5574                         the root hints to find a root name server and get the
5575                         most recent
5576                         list of root name servers. If no hint zone is
5577                         specified for class
5578                         IN, the server uses a compiled-in default set of root
5579                         servers hints.
5580                         Classes other than IN have no built-in defaults hints.
5581                       </p>
5582                     </td>
5583 </tr>
5584 <tr>
5585 <td>
5586                       <p>
5587                         <code class="varname">delegation-only</code>
5588                       </p>
5589                     </td>
5590 <td>
5591                       <p>
5592                         This is used to enforce the delegation-only
5593                         status of infrastructure zones (e.g. COM, NET, ORG).
5594                         Any answer that
5595                         is received without an explicit or implicit delegation
5596                         in the authority
5597                         section will be treated as NXDOMAIN.  This does not
5598                         apply to the zone
5599                         apex.  This should not be applied to leaf zones.
5600                       </p>
5601                       <p>
5602                         <code class="varname">delegation-only</code> has no
5603                         effect on answers received
5604                         from forwarders.
5605                       </p>
5606                     </td>
5607 </tr>
5608 </tbody>
5609 </table></div>
5610 </div>
5611 <div class="sect3" lang="en">
5612 <div class="titlepage"><div><div><h4 class="title">
5613 <a name="id2588937"></a>Class</h4></div></div></div>
5614 <p>
5615               The zone's name may optionally be followed by a class. If
5616               a class is not specified, class <code class="literal">IN</code> (for <code class="varname">Internet</code>),
5617               is assumed. This is correct for the vast majority of cases.
5618             </p>
5619 <p>
5620               The <code class="literal">hesiod</code> class is
5621               named for an information service from MIT's Project Athena. It
5622               is
5623               used to share information about various systems databases, such
5624               as users, groups, printers and so on. The keyword
5625               <code class="literal">HS</code> is
5626               a synonym for hesiod.
5627             </p>
5628 <p>
5629               Another MIT development is Chaosnet, a LAN protocol created
5630               in the mid-1970s. Zone data for it can be specified with the <code class="literal">CHAOS</code> class.
5631             </p>
5632 </div>
5633 <div class="sect3" lang="en">
5634 <div class="titlepage"><div><div><h4 class="title">
5635 <a name="id2588970"></a>Zone Options</h4></div></div></div>
5636 <div class="variablelist"><dl>
5637 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
5638 <dd><p>
5639                     See the description of
5640                     <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>.
5641                   </p></dd>
5642 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
5643 <dd><p>
5644                     See the description of
5645                     <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>.
5646                   </p></dd>
5647 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
5648 <dd><p>
5649                     See the description of
5650                     <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>.
5651                   </p></dd>
5652 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
5653 <dd><p>
5654                     See the description of <span><strong class="command">allow-transfer</strong></span>
5655                     in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
5656                   </p></dd>
5657 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
5658 <dd><p>
5659                     See the description of <span><strong class="command">allow-update</strong></span>
5660                     in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
5661                   </p></dd>
5662 <dt><span class="term"><span><strong class="command">update-policy</strong></span></span></dt>
5663 <dd><p>
5664                     Specifies a "Simple Secure Update" policy. See
5665                     <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called &#8220;Dynamic Update Policies&#8221;</a>.
5666                   </p></dd>
5667 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
5668 <dd><p>
5669                     See the description of <span><strong class="command">allow-update-forwarding</strong></span>
5670                     in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
5671                   </p></dd>
5672 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
5673 <dd><p>
5674                     Only meaningful if <span><strong class="command">notify</strong></span>
5675                     is
5676                     active for this zone. The set of machines that will
5677                     receive a
5678                     <code class="literal">DNS NOTIFY</code> message
5679                     for this zone is made up of all the listed name servers
5680                     (other than
5681                     the primary master) for the zone plus any IP addresses
5682                     specified
5683                     with <span><strong class="command">also-notify</strong></span>. A port
5684                     may be specified
5685                     with each <span><strong class="command">also-notify</strong></span>
5686                     address to send the notify
5687                     messages to a port other than the default of 53.
5688                     <span><strong class="command">also-notify</strong></span> is not
5689                     meaningful for stub zones.
5690                     The default is the empty list.
5691                   </p></dd>
5692 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
5693 <dd><p>
5694                     This option is used to restrict the character set and
5695                     syntax of
5696                     certain domain names in master files and/or DNS responses
5697                     received from the
5698                     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>
5699                     zones the default is <span><strong class="command">warn</strong></span>.
5700                   </p></dd>
5701 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
5702 <dd><p>
5703                     See the description of
5704                     <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>.
5705                   </p></dd>
5706 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
5707 <dd><p>
5708                     See the description of
5709                     <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>.
5710                   </p></dd>
5711 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
5712 <dd><p>
5713                     See the description of
5714                     <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>.
5715                   </p></dd>
5716 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
5717 <dd><p>
5718                     See the description of
5719                     <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>.
5720                   </p></dd>
5721 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
5722 <dd><p>
5723                     See the description of
5724                     <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>.
5725                   </p></dd>
5726 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
5727 <dd><p>
5728                     See the description of
5729                     <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>.
5730                   </p></dd>
5731 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
5732 <dd><p>
5733                     See the description of
5734                     <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>.
5735                   </p></dd>
5736 <dt><span class="term"><span><strong class="command">database</strong></span></span></dt>
5737 <dd>
5738 <p>
5739                     Specify the type of database to be used for storing the
5740                     zone data.  The string following the <span><strong class="command">database</strong></span> keyword
5741                     is interpreted as a list of whitespace-delimited words.
5742                     The first word
5743                     identifies the database type, and any subsequent words are
5744                     passed
5745                     as arguments to the database to be interpreted in a way
5746                     specific
5747                     to the database type.
5748                   </p>
5749 <p>
5750                     The default is <strong class="userinput"><code>"rbt"</code></strong>, BIND 9's
5751                     native in-memory
5752                     red-black-tree database.  This database does not take
5753                     arguments.
5754                   </p>
5755 <p>
5756                     Other values are possible if additional database drivers
5757                     have been linked into the server.  Some sample drivers are
5758                     included
5759                     with the distribution but none are linked in by default.
5760                   </p>
5761 </dd>
5762 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
5763 <dd><p>
5764                     See the description of
5765                     <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>.
5766                   </p></dd>
5767 <dt><span class="term"><span><strong class="command">delegation-only</strong></span></span></dt>
5768 <dd><p>
5769                     The flag only applies to hint and stub zones.  If set
5770                     to <strong class="userinput"><code>yes</code></strong>, then the zone will also be
5771                     treated as if it
5772                     is also a delegation-only type zone.
5773                   </p></dd>
5774 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
5775 <dd><p>
5776                     Only meaningful if the zone has a forwarders
5777                     list. The <span><strong class="command">only</strong></span> value causes
5778                     the lookup to fail
5779                     after trying the forwarders and getting no answer, while <span><strong class="command">first</strong></span> would
5780                     allow a normal lookup to be tried.
5781                   </p></dd>
5782 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
5783 <dd><p>
5784                     Used to override the list of global forwarders.
5785                     If it is not specified in a zone of type <span><strong class="command">forward</strong></span>,
5786                     no forwarding is done for the zone and the global options are
5787                     not used.
5788                   </p></dd>
5789 <dt><span class="term"><span><strong class="command">ixfr-base</strong></span></span></dt>
5790 <dd><p>
5791                     Was used in <acronym class="acronym">BIND</acronym> 8 to
5792                     specify the name
5793                     of the transaction log (journal) file for dynamic update
5794                     and IXFR.
5795                     <acronym class="acronym">BIND</acronym> 9 ignores the option
5796                     and constructs the name of the journal
5797                     file by appending "<code class="filename">.jnl</code>"
5798                     to the name of the
5799                     zone file.
5800                   </p></dd>
5801 <dt><span class="term"><span><strong class="command">ixfr-tmp-file</strong></span></span></dt>
5802 <dd><p>
5803                     Was an undocumented option in <acronym class="acronym">BIND</acronym> 8.
5804                     Ignored in <acronym class="acronym">BIND</acronym> 9.
5805                   </p></dd>
5806 <dt><span class="term"><span><strong class="command">journal</strong></span></span></dt>
5807 <dd><p>
5808                     Allow the default journal's filename to be overridden.
5809                     The default is the zone's filename with "<code class="filename">.jnl</code>" appended.
5810                     This is applicable to <span><strong class="command">master</strong></span> and <span><strong class="command">slave</strong></span> zones.
5811                   </p></dd>
5812 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
5813 <dd><p>
5814                     See the description of
5815                     <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>.
5816                   </p></dd>
5817 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
5818 <dd><p>
5819                     See the description of
5820                     <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>.
5821                   </p></dd>
5822 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
5823 <dd><p>
5824                     See the description of
5825                     <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>.
5826                   </p></dd>
5827 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
5828 <dd><p>
5829                     See the description of
5830                     <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>.
5831                   </p></dd>
5832 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
5833 <dd><p>
5834                     See the description of
5835                     <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>.
5836                   </p></dd>
5837 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
5838 <dd><p>
5839                     See the description of
5840                     <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>.
5841                   </p></dd>
5842 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
5843 <dd><p>
5844                     See the description of
5845                     <span><strong class="command">notify-delay</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
5846                   </p></dd>
5847 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
5848 <dd><p>
5849                     See the description of
5850                     <span><strong class="command">notify-to-soa</strong></span> in
5851                     <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
5852                   </p></dd>
5853 <dt><span class="term"><span><strong class="command">pubkey</strong></span></span></dt>
5854 <dd><p>
5855                     In <acronym class="acronym">BIND</acronym> 8, this option was
5856                     intended for specifying
5857                     a public zone key for verification of signatures in DNSSEC
5858                     signed
5859                     zones when they are loaded from disk. <acronym class="acronym">BIND</acronym> 9 does not verify signatures
5860                     on load and ignores the option.
5861                   </p></dd>
5862 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
5863 <dd><p>
5864                     If <strong class="userinput"><code>yes</code></strong>, the server will keep
5865                     statistical
5866                     information for this zone, which can be dumped to the
5867                     <span><strong class="command">statistics-file</strong></span> defined in
5868                     the server options.
5869                   </p></dd>
5870 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
5871 <dd><p>
5872                     See the description of
5873                     <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>.
5874                   </p></dd>
5875 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
5876 <dd><p>
5877                     See the description of
5878                     <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>.
5879                   </p></dd>
5880 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
5881 <dd><p>
5882                     See the description of
5883                     <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>.
5884                   </p></dd>
5885 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
5886 <dd><p>
5887                     See the description of
5888                     <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>.
5889                   </p></dd>
5890 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
5891 <dd><p>
5892                     See the description of
5893                     <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>.
5894                   </p></dd>
5895 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
5896 <dd><p>
5897                     See the description of
5898                     <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>.
5899                   </p></dd>
5900 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
5901 <dd><p>
5902                     See the description of
5903                     <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>.
5904                   </p></dd>
5905 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
5906 <dd><p>
5907                     See the description of
5908                     <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>.
5909                   </p></dd>
5910 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
5911 <dd><p>
5912                     See the description of
5913                     <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>.
5914                   </p></dd>
5915 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
5916 <dd><p>
5917                     See the description of
5918                     <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>.
5919                   </p></dd>
5920 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
5921 <dd><p>
5922                     See the description of
5923                     <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>.
5924                   </p></dd>
5925 <dt>
5926 <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>
5927 </dt>
5928 <dd><p>
5929                     See the description in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
5930                   </p></dd>
5931 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
5932 <dd><p>
5933                     See the description of
5934                     <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>.
5935                     (Note that the <span><strong class="command">ixfr-from-differences</strong></span>
5936                     <strong class="userinput"><code>master</code></strong> and
5937                     <strong class="userinput"><code>slave</code></strong> choices are not
5938                     available at the zone level.)
5939                   </p></dd>
5940 <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt>
5941 <dd><p>
5942                     See the description of
5943                     <span><strong class="command">key-directory</strong></span> in <a href="Bv9ARM.ch06.html#options" title="options Statement Definition and
5944           Usage">the section called &#8220;<span><strong class="command">options</strong></span> Statement Definition and
5945           Usage&#8221;</a>.
5946                   </p></dd>
5947 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
5948 <dd><p>
5949                     See the description of <span><strong class="command">multi-master</strong></span> in
5950                     <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
5951                   </p></dd>
5952 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
5953 <dd><p>
5954                     See the description of <span><strong class="command">masterfile-format</strong></span>
5955                     in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
5956                   </p></dd>
5957 </dl></div>
5958 </div>
5959 <div class="sect3" lang="en">
5960 <div class="titlepage"><div><div><h4 class="title">
5961 <a name="dynamic_update_policies"></a>Dynamic Update Policies</h4></div></div></div>
5962 <p><acronym class="acronym">BIND</acronym> 9 supports two alternative
5963               methods of granting clients the right to perform
5964               dynamic updates to a zone, configured by the
5965               <span><strong class="command">allow-update</strong></span> and
5966               <span><strong class="command">update-policy</strong></span> option, respectively.
5967             </p>
5968 <p>
5969               The <span><strong class="command">allow-update</strong></span> clause works the
5970               same way as in previous versions of <acronym class="acronym">BIND</acronym>.
5971               It grants given clients the permission to update any
5972               record of any name in the zone.
5973             </p>
5974 <p>
5975               The <span><strong class="command">update-policy</strong></span> clause is new
5976               in <acronym class="acronym">BIND</acronym> 9 and allows more fine-grained
5977               control over what updates are allowed.  A set of rules
5978               is specified, where each rule either grants or denies
5979               permissions for one or more names to be updated by
5980               one or more identities.  If the dynamic update request
5981               message is signed (that is, it includes either a TSIG
5982               or SIG(0) record), the identity of the signer can be
5983               determined.
5984             </p>
5985 <p>
5986               Rules are specified in the <span><strong class="command">update-policy</strong></span>
5987               zone option, and are only meaningful for master zones.
5988               When the <span><strong class="command">update-policy</strong></span> statement
5989               is present, it is a configuration error for the
5990               <span><strong class="command">allow-update</strong></span> statement to be
5991               present.  The <span><strong class="command">update-policy</strong></span> statement
5992               only examines the signer of a message; the source
5993               address is not relevant.
5994             </p>
5995 <p>
5996               This is how a rule definition looks:
5997             </p>
5998 <pre class="programlisting">
5999 ( <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>]
6000 </pre>
6001 <p>
6002               Each rule grants or denies privileges.  Once a message has
6003               successfully matched a rule, the operation is immediately
6004               granted
6005               or denied and no further rules are examined.  A rule is matched
6006               when the signer matches the identity field, the name matches the
6007               name field in accordance with the nametype field, and the type
6008               matches
6009               the types specified in the type field.
6010             </p>
6011 <p>
6012               No signer is required for <em class="replaceable"><code>tcp-self</code></em>
6013               or <em class="replaceable"><code>6to4-self</code></em> however the standard
6014               reverse mapping / prefix conversion must match the identity
6015               field.
6016             </p>
6017 <p>
6018               The identity field specifies a name or a wildcard
6019               name.  Normally, this is the name of the TSIG or
6020               SIG(0) key used to sign the update request.  When a
6021               TKEY exchange has been used to create a shared secret,
6022               the identity of the shared secret is the same as the
6023               identity of the key used to authenticate the TKEY
6024               exchange.  TKEY is also the negotiation method used
6025               by GSS-TSIG, which establishes an identity that is
6026               the Kerberos principal of the client, such as
6027               <strong class="userinput"><code>"user@host.domain"</code></strong>.  When the
6028               <em class="replaceable"><code>identity</code></em> field specifies
6029               a wildcard name, it is subject to DNS wildcard
6030               expansion, so the rule will apply to multiple identities.
6031               The <em class="replaceable"><code>identity</code></em> field must
6032               contain a fully-qualified domain name.
6033             </p>
6034 <p>
6035               The <em class="replaceable"><code>nametype</code></em> field has 12
6036               values:
6037               <code class="varname">name</code>, <code class="varname">subdomain</code>,
6038               <code class="varname">wildcard</code>, <code class="varname">self</code>,
6039               <code class="varname">selfsub</code>, <code class="varname">selfwild</code>,
6040               <code class="varname">krb5-self</code>, <code class="varname">ms-self</code>,
6041               <code class="varname">krb5-subdomain</code>,
6042               <code class="varname">ms-subdomain</code>,
6043               <code class="varname">tcp-self</code> and <code class="varname">6to4-self</code>.
6044             </p>
6045 <div class="informaltable"><table border="1">
6046 <colgroup>
6047 <col>
6048 <col>
6049 </colgroup>
6050 <tbody>
6051 <tr>
6052 <td>
6053                       <p>
6054                         <code class="varname">name</code>
6055                       </p>
6056                     </td>
6057 <td>
6058                       <p>
6059                         Exact-match semantics.  This rule matches
6060                         when the name being updated is identical
6061                         to the contents of the
6062                         <em class="replaceable"><code>name</code></em> field.
6063                       </p>
6064                     </td>
6065 </tr>
6066 <tr>
6067 <td>
6068                       <p>
6069                         <code class="varname">subdomain</code>
6070                       </p>
6071                     </td>
6072 <td>
6073                       <p>
6074                         This rule matches when the name being updated
6075                         is a subdomain of, or identical to, the
6076                         contents of the <em class="replaceable"><code>name</code></em>
6077                         field.
6078                       </p>
6079                     </td>
6080 </tr>
6081 <tr>
6082 <td>
6083                       <p>
6084                         <code class="varname">wildcard</code>
6085                       </p>
6086                     </td>
6087 <td>
6088                       <p>
6089                         The <em class="replaceable"><code>name</code></em> field
6090                         is subject to DNS wildcard expansion, and
6091                         this rule matches when the name being updated
6092                         name is a valid expansion of the wildcard.
6093                       </p>
6094                     </td>
6095 </tr>
6096 <tr>
6097 <td>
6098                       <p>
6099                         <code class="varname">self</code>
6100                       </p>
6101                     </td>
6102 <td>
6103                       <p>
6104                         This rule matches when the name being updated
6105                         matches the contents of the
6106                         <em class="replaceable"><code>identity</code></em> field.
6107                         The <em class="replaceable"><code>name</code></em> field
6108                         is ignored, but should be the same as the
6109                         <em class="replaceable"><code>identity</code></em> field.
6110                         The <code class="varname">self</code> nametype is
6111                         most useful when allowing using one key per
6112                         name to update, where the key has the same
6113                         name as the name to be updated.  The
6114                         <em class="replaceable"><code>identity</code></em> would
6115                         be specified as <code class="constant">*</code> (an asterisk) in
6116                         this case.
6117                       </p>
6118                     </td>
6119 </tr>
6120 <tr>
6121 <td>
6122                       <p>
6123                         <code class="varname">selfsub</code>
6124                       </p>
6125                     </td>
6126 <td>
6127                       <p>
6128                         This rule is similar to <code class="varname">self</code>
6129                         except that subdomains of <code class="varname">self</code>
6130                         can also be updated.
6131                       </p>
6132                     </td>
6133 </tr>
6134 <tr>
6135 <td>
6136                       <p>
6137                         <code class="varname">selfwild</code>
6138                       </p>
6139                     </td>
6140 <td>
6141                       <p>
6142                         This rule is similar to <code class="varname">self</code>
6143                         except that only subdomains of
6144                         <code class="varname">self</code> can be updated.
6145                       </p>
6146                     </td>
6147 </tr>
6148 <tr>
6149 <td>
6150                       <p>
6151                         <code class="varname">tcp-self</code>
6152                       </p>
6153                     </td>
6154 <td>
6155                       <p>
6156                         Allow updates that have been sent via TCP and
6157                         for which the standard mapping from the initiating
6158                         IP address into the IN-ADDR.ARPA and IP6.ARPA
6159                         namespaces match the name to be updated.
6160                       </p>
6161                       <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
6162 <h3 class="title">Note</h3>
6163                         It is theoretically possible to spoof these TCP
6164                         sessions.
6165                       </div>
6166                     </td>
6167 </tr>
6168 <tr>
6169 <td>
6170                       <p>
6171                         <code class="varname">6to4-self</code>
6172                       </p>
6173                     </td>
6174 <td>
6175                       <p>
6176                         Allow the 6to4 prefix to be update by any TCP
6177                         conection from the 6to4 network or from the
6178                         corresponding IPv4 address.  This is intended
6179                         to allow NS or DNAME RRsets to be added to the
6180                         reverse tree.
6181                       </p>
6182                       <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
6183 <h3 class="title">Note</h3>
6184                         It is theoretically possible to spoof these TCP
6185                         sessions.
6186                       </div>
6187                     </td>
6188 </tr>
6189 </tbody>
6190 </table></div>
6191 <p>
6192               In all cases, the <em class="replaceable"><code>name</code></em>
6193               field must
6194               specify a fully-qualified domain name.
6195             </p>
6196 <p>
6197               If no types are explicitly specified, this rule matches
6198               all types except RRSIG, NS, SOA, NSEC and NSEC3. Types
6199               may be specified by name, including "ANY" (ANY matches
6200               all types except NSEC and NSEC3, which can never be
6201               updated).  Note that when an attempt is made to delete
6202               all records associated with a name, the rules are
6203               checked for each existing record type.
6204             </p>
6205 </div>
6206 </div>
6207 </div>
6208 <div class="sect1" lang="en">
6209 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
6210 <a name="id2591109"></a>Zone File</h2></div></div></div>
6211 <div class="sect2" lang="en">
6212 <div class="titlepage"><div><div><h3 class="title">
6213 <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>
6214 <p>
6215             This section, largely borrowed from RFC 1034, describes the
6216             concept of a Resource Record (RR) and explains when each is used.
6217             Since the publication of RFC 1034, several new RRs have been
6218             identified
6219             and implemented in the DNS. These are also included.
6220           </p>
6221 <div class="sect3" lang="en">
6222 <div class="titlepage"><div><div><h4 class="title">
6223 <a name="id2591127"></a>Resource Records</h4></div></div></div>
6224 <p>
6225               A domain name identifies a node.  Each node has a set of
6226               resource information, which may be empty.  The set of resource
6227               information associated with a particular name is composed of
6228               separate RRs. The order of RRs in a set is not significant and
6229               need not be preserved by name servers, resolvers, or other
6230               parts of the DNS. However, sorting of multiple RRs is
6231               permitted for optimization purposes, for example, to specify
6232               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>.
6233             </p>
6234 <p>
6235               The components of a Resource Record are:
6236             </p>
6237 <div class="informaltable"><table border="1">
6238 <colgroup>
6239 <col>
6240 <col>
6241 </colgroup>
6242 <tbody>
6243 <tr>
6244 <td>
6245                       <p>
6246                         owner name
6247                       </p>
6248                     </td>
6249 <td>
6250                       <p>
6251                         The domain name where the RR is found.
6252                       </p>
6253                     </td>
6254 </tr>
6255 <tr>
6256 <td>
6257                       <p>
6258                         type
6259                       </p>
6260                     </td>
6261 <td>
6262                       <p>
6263                         An encoded 16-bit value that specifies
6264                         the type of the resource record.
6265                       </p>
6266                     </td>
6267 </tr>
6268 <tr>
6269 <td>
6270                       <p>
6271                         TTL
6272                       </p>
6273                     </td>
6274 <td>
6275                       <p>
6276                         The time-to-live of the RR. This field
6277                         is a 32-bit integer in units of seconds, and is
6278                         primarily used by
6279                         resolvers when they cache RRs. The TTL describes how
6280                         long a RR can
6281                         be cached before it should be discarded.
6282                       </p>
6283                     </td>
6284 </tr>
6285 <tr>
6286 <td>
6287                       <p>
6288                         class
6289                       </p>
6290                     </td>
6291 <td>
6292                       <p>
6293                         An encoded 16-bit value that identifies
6294                         a protocol family or instance of a protocol.
6295                       </p>
6296                     </td>
6297 </tr>
6298 <tr>
6299 <td>
6300                       <p>
6301                         RDATA
6302                       </p>
6303                     </td>
6304 <td>
6305                       <p>
6306                         The resource data.  The format of the
6307                         data is type (and sometimes class) specific.
6308                       </p>
6309                     </td>
6310 </tr>
6311 </tbody>
6312 </table></div>
6313 <p>
6314               The following are <span class="emphasis"><em>types</em></span> of valid RRs:
6315             </p>
6316 <div class="informaltable"><table border="1">
6317 <colgroup>
6318 <col>
6319 <col>
6320 </colgroup>
6321 <tbody>
6322 <tr>
6323 <td>
6324                       <p>
6325                         A
6326                       </p>
6327                     </td>
6328 <td>
6329                       <p>
6330                         A host address.  In the IN class, this is a
6331                         32-bit IP address.  Described in RFC 1035.
6332                       </p>
6333                     </td>
6334 </tr>
6335 <tr>
6336 <td>
6337                       <p>
6338                         AAAA
6339                       </p>
6340                     </td>
6341 <td>
6342                       <p>
6343                         IPv6 address.  Described in RFC 1886.
6344                       </p>
6345                     </td>
6346 </tr>
6347 <tr>
6348 <td>
6349                       <p>
6350                         A6
6351                       </p>
6352                     </td>
6353 <td>
6354                       <p>
6355                         IPv6 address.  This can be a partial
6356                         address (a suffix) and an indirection to the name
6357                         where the rest of the
6358                         address (the prefix) can be found.  Experimental.
6359                         Described in RFC 2874.
6360                       </p>
6361                     </td>
6362 </tr>
6363 <tr>
6364 <td>
6365                       <p>
6366                         AFSDB
6367                       </p>
6368                     </td>
6369 <td>
6370                       <p>
6371                         Location of AFS database servers.
6372                         Experimental.  Described in RFC 1183.
6373                       </p>
6374                     </td>
6375 </tr>
6376 <tr>
6377 <td>
6378                       <p>
6379                         APL
6380                       </p>
6381                     </td>
6382 <td>
6383                       <p>
6384                         Address prefix list.  Experimental.
6385                         Described in RFC 3123.
6386                       </p>
6387                     </td>
6388 </tr>
6389 <tr>
6390 <td>
6391                       <p>
6392                         CERT
6393                       </p>
6394                     </td>
6395 <td>
6396                       <p>
6397                         Holds a digital certificate.
6398                         Described in RFC 2538.
6399                       </p>
6400                     </td>
6401 </tr>
6402 <tr>
6403 <td>
6404                       <p>
6405                         CNAME
6406                       </p>
6407                     </td>
6408 <td>
6409                       <p>
6410                         Identifies the canonical name of an alias.
6411                         Described in RFC 1035.
6412                       </p>
6413                     </td>
6414 </tr>
6415 <tr>
6416 <td>
6417                       <p>
6418                         DHCID
6419                       </p>
6420                     </td>
6421 <td>
6422                       <p>
6423                         Is used for identifying which DHCP client is
6424                         associated with this name.  Described in RFC 4701.
6425                       </p>
6426                     </td>
6427 </tr>
6428 <tr>
6429 <td>
6430                       <p>
6431                         DNAME
6432                       </p>
6433                     </td>
6434 <td>
6435                       <p>
6436                         Replaces the domain name specified with
6437                         another name to be looked up, effectively aliasing an
6438                         entire
6439                         subtree of the domain name space rather than a single
6440                         record
6441                         as in the case of the CNAME RR.
6442                         Described in RFC 2672.
6443                       </p>
6444                     </td>
6445 </tr>
6446 <tr>
6447 <td>
6448                       <p>
6449                         DNSKEY
6450                       </p>
6451                     </td>
6452 <td>
6453                       <p>
6454                         Stores a public key associated with a signed
6455                         DNS zone.  Described in RFC 4034.
6456                       </p>
6457                     </td>
6458 </tr>
6459 <tr>
6460 <td>
6461                       <p>
6462                         DS
6463                       </p>
6464                     </td>
6465 <td>
6466                       <p>
6467                         Stores the hash of a public key associated with a
6468                         signed DNS zone.  Described in RFC 4034.
6469                       </p>
6470                     </td>
6471 </tr>
6472 <tr>
6473 <td>
6474                       <p>
6475                         GPOS
6476                       </p>
6477                     </td>
6478 <td>
6479                       <p>
6480                         Specifies the global position.  Superseded by LOC.
6481                       </p>
6482                     </td>
6483 </tr>
6484 <tr>
6485 <td>
6486                       <p>
6487                         HINFO
6488                       </p>
6489                     </td>
6490 <td>
6491                       <p>
6492                         Identifies the CPU and OS used by a host.
6493                         Described in RFC 1035.
6494                       </p>
6495                     </td>
6496 </tr>
6497 <tr>
6498 <td>
6499                       <p>
6500                         IPSECKEY
6501                       </p>
6502                     </td>
6503 <td>
6504                       <p>
6505                         Provides a method for storing IPsec keying material in
6506                         DNS.  Described in RFC 4025.
6507                       </p>
6508                     </td>
6509 </tr>
6510 <tr>
6511 <td>
6512                       <p>
6513                         ISDN
6514                       </p>
6515                     </td>
6516 <td>
6517                       <p>
6518                         Representation of ISDN addresses.
6519                         Experimental.  Described in RFC 1183.
6520                       </p>
6521                     </td>
6522 </tr>
6523 <tr>
6524 <td>
6525                       <p>
6526                         KEY
6527                       </p>
6528                     </td>
6529 <td>
6530                       <p>
6531                         Stores a public key associated with a
6532                         DNS name.  Used in original DNSSEC; replaced
6533                         by DNSKEY in DNSSECbis, but still used with
6534                         SIG(0).  Described in RFCs 2535 and 2931.
6535                       </p>
6536                     </td>
6537 </tr>
6538 <tr>
6539 <td>
6540                       <p>
6541                         KX
6542                       </p>
6543                     </td>
6544 <td>
6545                       <p>
6546                         Identifies a key exchanger for this
6547                         DNS name.  Described in RFC 2230.
6548                       </p>
6549                     </td>
6550 </tr>
6551 <tr>
6552 <td>
6553                       <p>
6554                         LOC
6555                       </p>
6556                     </td>
6557 <td>
6558                       <p>
6559                         For storing GPS info.  Described in RFC 1876.
6560                         Experimental.
6561                       </p>
6562                     </td>
6563 </tr>
6564 <tr>
6565 <td>
6566                       <p>
6567                         MX
6568                       </p>
6569                     </td>
6570 <td>
6571                       <p>
6572                         Identifies a mail exchange for the domain with
6573                         a 16-bit preference value (lower is better)
6574                         followed by the host name of the mail exchange.
6575                         Described in RFC 974, RFC 1035.
6576                       </p>
6577                     </td>
6578 </tr>
6579 <tr>
6580 <td>
6581                       <p>
6582                         NAPTR
6583                       </p>
6584                     </td>
6585 <td>
6586                       <p>
6587                         Name authority pointer.  Described in RFC 2915.
6588                       </p>
6589                     </td>
6590 </tr>
6591 <tr>
6592 <td>
6593                       <p>
6594                         NSAP
6595                       </p>
6596                     </td>
6597 <td>
6598                       <p>
6599                         A network service access point.
6600                         Described in RFC 1706.
6601                       </p>
6602                     </td>
6603 </tr>
6604 <tr>
6605 <td>
6606                       <p>
6607                         NS
6608                       </p>
6609                     </td>
6610 <td>
6611                       <p>
6612                         The authoritative name server for the
6613                         domain.  Described in RFC 1035.
6614                       </p>
6615                     </td>
6616 </tr>
6617 <tr>
6618 <td>
6619                       <p>
6620                         NSEC
6621                       </p>
6622                     </td>
6623 <td>
6624                       <p>
6625                         Used in DNSSECbis to securely indicate that
6626                         RRs with an owner name in a certain name interval do
6627                         not exist in
6628                         a zone and indicate what RR types are present for an
6629                         existing name.
6630                         Described in RFC 4034.
6631                       </p>
6632                     </td>
6633 </tr>
6634 <tr>
6635 <td>
6636                       <p>
6637                         NSEC3
6638                       </p>
6639                     </td>
6640 <td>
6641                       <p>
6642                         Used in DNSSECbis to securely indicate that
6643                         RRs with an owner name in a certain name
6644                         interval do not exist in a zone and indicate
6645                         what RR types are present for an existing
6646                         name.  NSEC3 differs from NSEC in that it
6647                         prevents zone enumeration but is more
6648                         computationally expensive on both the server
6649                         and the client than NSEC.  Described in RFC
6650                         5155.
6651                       </p>
6652                     </td>
6653 </tr>
6654 <tr>
6655 <td>
6656                       <p>
6657                         NSEC3PARAM
6658                       </p>
6659                     </td>
6660 <td>
6661                       <p>
6662                         Used in DNSSECbis to tell the authoritative
6663                         server which NSEC3 chains are available to use.
6664                         Described in RFC 5155.
6665                       </p>
6666                     </td>
6667 </tr>
6668 <tr>
6669 <td>
6670                       <p>
6671                         NXT
6672                       </p>
6673                     </td>
6674 <td>
6675                       <p>
6676                         Used in DNSSEC to securely indicate that
6677                         RRs with an owner name in a certain name interval do
6678                         not exist in
6679                         a zone and indicate what RR types are present for an
6680                         existing name.
6681                         Used in original DNSSEC; replaced by NSEC in
6682                         DNSSECbis.
6683                         Described in RFC 2535.
6684                       </p>
6685                     </td>
6686 </tr>
6687 <tr>
6688 <td>
6689                       <p>
6690                         PTR
6691                       </p>
6692                     </td>
6693 <td>
6694                       <p>
6695                         A pointer to another part of the domain
6696                         name space.  Described in RFC 1035.
6697                       </p>
6698                     </td>
6699 </tr>
6700 <tr>
6701 <td>
6702                       <p>
6703                         PX
6704                       </p>
6705                     </td>
6706 <td>
6707                       <p>
6708                         Provides mappings between RFC 822 and X.400
6709                         addresses.  Described in RFC 2163.
6710                       </p>
6711                     </td>
6712 </tr>
6713 <tr>
6714 <td>
6715                       <p>
6716                         RP
6717                       </p>
6718                     </td>
6719 <td>
6720                       <p>
6721                         Information on persons responsible
6722                         for the domain.  Experimental.  Described in RFC 1183.
6723                       </p>
6724                     </td>
6725 </tr>
6726 <tr>
6727 <td>
6728                       <p>
6729                         RRSIG
6730                       </p>
6731                     </td>
6732 <td>
6733                       <p>
6734                         Contains DNSSECbis signature data.  Described
6735                         in RFC 4034.
6736                       </p>
6737                     </td>
6738 </tr>
6739 <tr>
6740 <td>
6741                       <p>
6742                         RT
6743                       </p>
6744                     </td>
6745 <td>
6746                       <p>
6747                         Route-through binding for hosts that
6748                         do not have their own direct wide area network
6749                         addresses.
6750                         Experimental.  Described in RFC 1183.
6751                       </p>
6752                     </td>
6753 </tr>
6754 <tr>
6755 <td>
6756                       <p>
6757                         SIG
6758                       </p>
6759                     </td>
6760 <td>
6761                       <p>
6762                         Contains DNSSEC signature data.  Used in
6763                         original DNSSEC; replaced by RRSIG in
6764                         DNSSECbis, but still used for SIG(0).
6765                         Described in RFCs 2535 and 2931.
6766                       </p>
6767                     </td>
6768 </tr>
6769 <tr>
6770 <td>
6771                       <p>
6772                         SOA
6773                       </p>
6774                     </td>
6775 <td>
6776                       <p>
6777                         Identifies the start of a zone of authority.
6778                         Described in RFC 1035.
6779                       </p>
6780                     </td>
6781 </tr>
6782 <tr>
6783 <td>
6784                       <p>
6785                         SPF
6786                       </p>
6787                     </td>
6788 <td>
6789                       <p>
6790                         Contains the Sender Policy Framework information
6791                         for a given email domain.  Described in RFC 4408.
6792                       </p>
6793                     </td>
6794 </tr>
6795 <tr>
6796 <td>
6797                       <p>
6798                         SRV
6799                       </p>
6800                     </td>
6801 <td>
6802                       <p>
6803                         Information about well known network
6804                         services (replaces WKS).  Described in RFC 2782.
6805                       </p>
6806                     </td>
6807 </tr>
6808 <tr>
6809 <td>
6810                       <p>
6811                         SSHFP
6812                       </p>
6813                     </td>
6814 <td>
6815                       <p>
6816                         Provides a way to securely publish a secure shell key's
6817                         fingerprint.  Described in RFC 4255.
6818                       </p>
6819                     </td>
6820 </tr>
6821 <tr>
6822 <td>
6823                       <p>
6824                         TXT
6825                       </p>
6826                     </td>
6827 <td>
6828                       <p>
6829                         Text records.  Described in RFC 1035.
6830                       </p>
6831                     </td>
6832 </tr>
6833 <tr>
6834 <td>
6835                       <p>
6836                         WKS
6837                       </p>
6838                     </td>
6839 <td>
6840                       <p>
6841                         Information about which well known
6842                         network services, such as SMTP, that a domain
6843                         supports. Historical.
6844                       </p>
6845                     </td>
6846 </tr>
6847 <tr>
6848 <td>
6849                       <p>
6850                         X25
6851                       </p>
6852                     </td>
6853 <td>
6854                       <p>
6855                         Representation of X.25 network addresses.
6856                         Experimental.  Described in RFC 1183.
6857                       </p>
6858                     </td>
6859 </tr>
6860 </tbody>
6861 </table></div>
6862 <p>
6863               The following <span class="emphasis"><em>classes</em></span> of resource records
6864               are currently valid in the DNS:
6865             </p>
6866 <div class="informaltable"><table border="1">
6867 <colgroup>
6868 <col>
6869 <col>
6870 </colgroup>
6871 <tbody>
6872 <tr>
6873 <td>
6874                       <p>
6875                         IN
6876                       </p>
6877                     </td>
6878 <td>
6879                       <p>
6880                         The Internet.
6881                       </p>
6882                     </td>
6883 </tr>
6884 <tr>
6885 <td>
6886                       <p>
6887                         CH
6888                       </p>
6889                     </td>
6890 <td>
6891                       <p>
6892                         Chaosnet, a LAN protocol created at MIT in the
6893                         mid-1970s.
6894                         Rarely used for its historical purpose, but reused for
6895                         BIND's
6896                         built-in server information zones, e.g.,
6897                         <code class="literal">version.bind</code>.
6898                       </p>
6899                     </td>
6900 </tr>
6901 <tr>
6902 <td>
6903                       <p>
6904                         HS
6905                       </p>
6906                     </td>
6907 <td>
6908                       <p>
6909                         Hesiod, an information service
6910                         developed by MIT's Project Athena. It is used to share
6911                         information
6912                         about various systems databases, such as users,
6913                         groups, printers
6914                         and so on.
6915                       </p>
6916                     </td>
6917 </tr>
6918 </tbody>
6919 </table></div>
6920 <p>
6921               The owner name is often implicit, rather than forming an
6922               integral
6923               part of the RR.  For example, many name servers internally form
6924               tree
6925               or hash structures for the name space, and chain RRs off nodes.
6926               The remaining RR parts are the fixed header (type, class, TTL)
6927               which is consistent for all RRs, and a variable part (RDATA)
6928               that
6929               fits the needs of the resource being described.
6930             </p>
6931 <p>
6932               The meaning of the TTL field is a time limit on how long an
6933               RR can be kept in a cache.  This limit does not apply to
6934               authoritative
6935               data in zones; it is also timed out, but by the refreshing
6936               policies
6937               for the zone.  The TTL is assigned by the administrator for the
6938               zone where the data originates.  While short TTLs can be used to
6939               minimize caching, and a zero TTL prohibits caching, the
6940               realities
6941               of Internet performance suggest that these times should be on
6942               the
6943               order of days for the typical host.  If a change can be
6944               anticipated,
6945               the TTL can be reduced prior to the change to minimize
6946               inconsistency
6947               during the change, and then increased back to its former value
6948               following
6949               the change.
6950             </p>
6951 <p>
6952               The data in the RDATA section of RRs is carried as a combination
6953               of binary strings and domain names.  The domain names are
6954               frequently
6955               used as "pointers" to other data in the DNS.
6956             </p>
6957 </div>
6958 <div class="sect3" lang="en">
6959 <div class="titlepage"><div><div><h4 class="title">
6960 <a name="id2592682"></a>Textual expression of RRs</h4></div></div></div>
6961 <p>
6962               RRs are represented in binary form in the packets of the DNS
6963               protocol, and are usually represented in highly encoded form
6964               when
6965               stored in a name server or resolver.  In the examples provided
6966               in
6967               RFC 1034, a style similar to that used in master files was
6968               employed
6969               in order to show the contents of RRs.  In this format, most RRs
6970               are shown on a single line, although continuation lines are
6971               possible
6972               using parentheses.
6973             </p>
6974 <p>
6975               The start of the line gives the owner of the RR.  If a line
6976               begins with a blank, then the owner is assumed to be the same as
6977               that of the previous RR.  Blank lines are often included for
6978               readability.
6979             </p>
6980 <p>
6981               Following the owner, we list the TTL, type, and class of the
6982               RR.  Class and type use the mnemonics defined above, and TTL is
6983               an integer before the type field.  In order to avoid ambiguity
6984               in
6985               parsing, type and class mnemonics are disjoint, TTLs are
6986               integers,
6987               and the type mnemonic is always last. The IN class and TTL
6988               values
6989               are often omitted from examples in the interests of clarity.
6990             </p>
6991 <p>
6992               The resource data or RDATA section of the RR are given using
6993               knowledge of the typical representation for the data.
6994             </p>
6995 <p>
6996               For example, we might show the RRs carried in a message as:
6997             </p>
6998 <div class="informaltable"><table border="1">
6999 <colgroup>
7000 <col>
7001 <col>
7002 <col>
7003 </colgroup>
7004 <tbody>
7005 <tr>
7006 <td>
7007                       <p>
7008                         <code class="literal">ISI.EDU.</code>
7009                       </p>
7010                     </td>
7011 <td>
7012                       <p>
7013                         <code class="literal">MX</code>
7014                       </p>
7015                     </td>
7016 <td>
7017                       <p>
7018                         <code class="literal">10 VENERA.ISI.EDU.</code>
7019                       </p>
7020                     </td>
7021 </tr>
7022 <tr>
7023 <td>
7024                       <p></p>
7025                     </td>
7026 <td>
7027                       <p>
7028                         <code class="literal">MX</code>
7029                       </p>
7030                     </td>
7031 <td>
7032                       <p>
7033                         <code class="literal">10 VAXA.ISI.EDU</code>
7034                       </p>
7035                     </td>
7036 </tr>
7037 <tr>
7038 <td>
7039                       <p>
7040                         <code class="literal">VENERA.ISI.EDU</code>
7041                       </p>
7042                     </td>
7043 <td>
7044                       <p>
7045                         <code class="literal">A</code>
7046                       </p>
7047                     </td>
7048 <td>
7049                       <p>
7050                         <code class="literal">128.9.0.32</code>
7051                       </p>
7052                     </td>
7053 </tr>
7054 <tr>
7055 <td>
7056                       <p></p>
7057                     </td>
7058 <td>
7059                       <p>
7060                         <code class="literal">A</code>
7061                       </p>
7062                     </td>
7063 <td>
7064                       <p>
7065                         <code class="literal">10.1.0.52</code>
7066                       </p>
7067                     </td>
7068 </tr>
7069 <tr>
7070 <td>
7071                       <p>
7072                         <code class="literal">VAXA.ISI.EDU</code>
7073                       </p>
7074                     </td>
7075 <td>
7076                       <p>
7077                         <code class="literal">A</code>
7078                       </p>
7079                     </td>
7080 <td>
7081                       <p>
7082                         <code class="literal">10.2.0.27</code>
7083                       </p>
7084                     </td>
7085 </tr>
7086 <tr>
7087 <td>
7088                       <p></p>
7089                     </td>
7090 <td>
7091                       <p>
7092                         <code class="literal">A</code>
7093                       </p>
7094                     </td>
7095 <td>
7096                       <p>
7097                         <code class="literal">128.9.0.33</code>
7098                       </p>
7099                     </td>
7100 </tr>
7101 </tbody>
7102 </table></div>
7103 <p>
7104               The MX RRs have an RDATA section which consists of a 16-bit
7105               number followed by a domain name.  The address RRs use a
7106               standard
7107               IP address format to contain a 32-bit internet address.
7108             </p>
7109 <p>
7110               The above example shows six RRs, with two RRs at each of three
7111               domain names.
7112             </p>
7113 <p>
7114               Similarly we might see:
7115             </p>
7116 <div class="informaltable"><table border="1">
7117 <colgroup>
7118 <col>
7119 <col>
7120 <col>
7121 </colgroup>
7122 <tbody>
7123 <tr>
7124 <td>
7125                       <p>
7126                         <code class="literal">XX.LCS.MIT.EDU.</code>
7127                       </p>
7128                     </td>
7129 <td>
7130                       <p>
7131                         <code class="literal">IN A</code>
7132                       </p>
7133                     </td>
7134 <td>
7135                       <p>
7136                         <code class="literal">10.0.0.44</code>
7137                       </p>
7138                     </td>
7139 </tr>
7140 <tr>
7141 <td> </td>
7142 <td>
7143                       <p>
7144                         <code class="literal">CH A</code>
7145                       </p>
7146                     </td>
7147 <td>
7148                       <p>
7149                         <code class="literal">MIT.EDU. 2420</code>
7150                       </p>
7151                     </td>
7152 </tr>
7153 </tbody>
7154 </table></div>
7155 <p>
7156               This example shows two addresses for
7157               <code class="literal">XX.LCS.MIT.EDU</code>, each of a different class.
7158             </p>
7159 </div>
7160 </div>
7161 <div class="sect2" lang="en">
7162 <div class="titlepage"><div><div><h3 class="title">
7163 <a name="id2593203"></a>Discussion of MX Records</h3></div></div></div>
7164 <p>
7165             As described above, domain servers store information as a
7166             series of resource records, each of which contains a particular
7167             piece of information about a given domain name (which is usually,
7168             but not always, a host). The simplest way to think of a RR is as
7169             a typed pair of data, a domain name matched with a relevant datum,
7170             and stored with some additional type information to help systems
7171             determine when the RR is relevant.
7172           </p>
7173 <p>
7174             MX records are used to control delivery of email. The data
7175             specified in the record is a priority and a domain name. The
7176             priority
7177             controls the order in which email delivery is attempted, with the
7178             lowest number first. If two priorities are the same, a server is
7179             chosen randomly. If no servers at a given priority are responding,
7180             the mail transport agent will fall back to the next largest
7181             priority.
7182             Priority numbers do not have any absolute meaning &#8212; they are
7183             relevant
7184             only respective to other MX records for that domain name. The
7185             domain
7186             name given is the machine to which the mail will be delivered.
7187             It <span class="emphasis"><em>must</em></span> have an associated address record
7188             (A or AAAA) &#8212; CNAME is not sufficient.
7189           </p>
7190 <p>
7191             For a given domain, if there is both a CNAME record and an
7192             MX record, the MX record is in error, and will be ignored.
7193             Instead,
7194             the mail will be delivered to the server specified in the MX
7195             record
7196             pointed to by the CNAME.
7197             For example:
7198           </p>
7199 <div class="informaltable"><table border="1">
7200 <colgroup>
7201 <col>
7202 <col>
7203 <col>
7204 <col>
7205 <col>
7206 </colgroup>
7207 <tbody>
7208 <tr>
7209 <td>
7210                     <p>
7211                       <code class="literal">example.com.</code>
7212                     </p>
7213                   </td>
7214 <td>
7215                     <p>
7216                       <code class="literal">IN</code>
7217                     </p>
7218                   </td>
7219 <td>
7220                     <p>
7221                       <code class="literal">MX</code>
7222                     </p>
7223                   </td>
7224 <td>
7225                     <p>
7226                       <code class="literal">10</code>
7227                     </p>
7228                   </td>
7229 <td>
7230                     <p>
7231                       <code class="literal">mail.example.com.</code>
7232                     </p>
7233                   </td>
7234 </tr>
7235 <tr>
7236 <td>
7237                     <p></p>
7238                   </td>
7239 <td>
7240                     <p>
7241                       <code class="literal">IN</code>
7242                     </p>
7243                   </td>
7244 <td>
7245                     <p>
7246                       <code class="literal">MX</code>
7247                     </p>
7248                   </td>
7249 <td>
7250                     <p>
7251                       <code class="literal">10</code>
7252                     </p>
7253                   </td>
7254 <td>
7255                     <p>
7256                       <code class="literal">mail2.example.com.</code>
7257                     </p>
7258                   </td>
7259 </tr>
7260 <tr>
7261 <td>
7262                     <p></p>
7263                   </td>
7264 <td>
7265                     <p>
7266                       <code class="literal">IN</code>
7267                     </p>
7268                   </td>
7269 <td>
7270                     <p>
7271                       <code class="literal">MX</code>
7272                     </p>
7273                   </td>
7274 <td>
7275                     <p>
7276                       <code class="literal">20</code>
7277                     </p>
7278                   </td>
7279 <td>
7280                     <p>
7281                       <code class="literal">mail.backup.org.</code>
7282                     </p>
7283                   </td>
7284 </tr>
7285 <tr>
7286 <td>
7287                     <p>
7288                       <code class="literal">mail.example.com.</code>
7289                     </p>
7290                   </td>
7291 <td>
7292                     <p>
7293                       <code class="literal">IN</code>
7294                     </p>
7295                   </td>
7296 <td>
7297                     <p>
7298                       <code class="literal">A</code>
7299                     </p>
7300                   </td>
7301 <td>
7302                     <p>
7303                       <code class="literal">10.0.0.1</code>
7304                     </p>
7305                   </td>
7306 <td>
7307                     <p></p>
7308                   </td>
7309 </tr>
7310 <tr>
7311 <td>
7312                     <p>
7313                       <code class="literal">mail2.example.com.</code>
7314                     </p>
7315                   </td>
7316 <td>
7317                     <p>
7318                       <code class="literal">IN</code>
7319                     </p>
7320                   </td>
7321 <td>
7322                     <p>
7323                       <code class="literal">A</code>
7324                     </p>
7325                   </td>
7326 <td>
7327                     <p>
7328                       <code class="literal">10.0.0.2</code>
7329                     </p>
7330                   </td>
7331 <td>
7332                     <p></p>
7333                   </td>
7334 </tr>
7335 </tbody>
7336 </table></div>
7337 <p>
7338             Mail delivery will be attempted to <code class="literal">mail.example.com</code> and
7339             <code class="literal">mail2.example.com</code> (in
7340             any order), and if neither of those succeed, delivery to <code class="literal">mail.backup.org</code> will
7341             be attempted.
7342           </p>
7343 </div>
7344 <div class="sect2" lang="en">
7345 <div class="titlepage"><div><div><h3 class="title">
7346 <a name="Setting_TTLs"></a>Setting TTLs</h3></div></div></div>
7347 <p>
7348             The time-to-live of the RR field is a 32-bit integer represented
7349             in units of seconds, and is primarily used by resolvers when they
7350             cache RRs. The TTL describes how long a RR can be cached before it
7351             should be discarded. The following three types of TTL are
7352             currently
7353             used in a zone file.
7354           </p>
7355 <div class="informaltable"><table border="1">
7356 <colgroup>
7357 <col>
7358 <col>
7359 </colgroup>
7360 <tbody>
7361 <tr>
7362 <td>
7363                     <p>
7364                       SOA
7365                     </p>
7366                   </td>
7367 <td>
7368                     <p>
7369                       The last field in the SOA is the negative
7370                       caching TTL. This controls how long other servers will
7371                       cache no-such-domain
7372                       (NXDOMAIN) responses from you.
7373                     </p>
7374                     <p>
7375                       The maximum time for
7376                       negative caching is 3 hours (3h).
7377                     </p>
7378                   </td>
7379 </tr>
7380 <tr>
7381 <td>
7382                     <p>
7383                       $TTL
7384                     </p>
7385                   </td>
7386 <td>
7387                     <p>
7388                       The $TTL directive at the top of the
7389                       zone file (before the SOA) gives a default TTL for every
7390                       RR without
7391                       a specific TTL set.
7392                     </p>
7393                   </td>
7394 </tr>
7395 <tr>
7396 <td>
7397                     <p>
7398                       RR TTLs
7399                     </p>
7400                   </td>
7401 <td>
7402                     <p>
7403                       Each RR can have a TTL as the second
7404                       field in the RR, which will control how long other
7405                       servers can cache
7406                       the it.
7407                     </p>
7408                   </td>
7409 </tr>
7410 </tbody>
7411 </table></div>
7412 <p>
7413             All of these TTLs default to units of seconds, though units
7414             can be explicitly specified, for example, <code class="literal">1h30m</code>.
7415           </p>
7416 </div>
7417 <div class="sect2" lang="en">
7418 <div class="titlepage"><div><div><h3 class="title">
7419 <a name="id2593886"></a>Inverse Mapping in IPv4</h3></div></div></div>
7420 <p>
7421             Reverse name resolution (that is, translation from IP address
7422             to name) is achieved by means of the <span class="emphasis"><em>in-addr.arpa</em></span> domain
7423             and PTR records. Entries in the in-addr.arpa domain are made in
7424             least-to-most significant order, read left to right. This is the
7425             opposite order to the way IP addresses are usually written. Thus,
7426             a machine with an IP address of 10.1.2.3 would have a
7427             corresponding
7428             in-addr.arpa name of
7429             3.2.1.10.in-addr.arpa. This name should have a PTR resource record
7430             whose data field is the name of the machine or, optionally,
7431             multiple
7432             PTR records if the machine has more than one name. For example,
7433             in the [<span class="optional">example.com</span>] domain:
7434           </p>
7435 <div class="informaltable"><table border="1">
7436 <colgroup>
7437 <col>
7438 <col>
7439 </colgroup>
7440 <tbody>
7441 <tr>
7442 <td>
7443                     <p>
7444                       <code class="literal">$ORIGIN</code>
7445                     </p>
7446                   </td>
7447 <td>
7448                     <p>
7449                       <code class="literal">2.1.10.in-addr.arpa</code>
7450                     </p>
7451                   </td>
7452 </tr>
7453 <tr>
7454 <td>
7455                     <p>
7456                       <code class="literal">3</code>
7457                     </p>
7458                   </td>
7459 <td>
7460                     <p>
7461                       <code class="literal">IN PTR foo.example.com.</code>
7462                     </p>
7463                   </td>
7464 </tr>
7465 </tbody>
7466 </table></div>
7467 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7468 <h3 class="title">Note</h3>
7469 <p>
7470               The <span><strong class="command">$ORIGIN</strong></span> lines in the examples
7471               are for providing context to the examples only &#8212; they do not
7472               necessarily
7473               appear in the actual usage. They are only used here to indicate
7474               that the example is relative to the listed origin.
7475             </p>
7476 </div>
7477 </div>
7478 <div class="sect2" lang="en">
7479 <div class="titlepage"><div><div><h3 class="title">
7480 <a name="id2594013"></a>Other Zone File Directives</h3></div></div></div>
7481 <p>
7482             The Master File Format was initially defined in RFC 1035 and
7483             has subsequently been extended. While the Master File Format
7484             itself
7485             is class independent all records in a Master File must be of the
7486             same
7487             class.
7488           </p>
7489 <p>
7490             Master File Directives include <span><strong class="command">$ORIGIN</strong></span>, <span><strong class="command">$INCLUDE</strong></span>,
7491             and <span><strong class="command">$TTL.</strong></span>
7492           </p>
7493 <div class="sect3" lang="en">
7494 <div class="titlepage"><div><div><h4 class="title">
7495 <a name="id2594036"></a>The <span><strong class="command">$ORIGIN</strong></span> Directive</h4></div></div></div>
7496 <p>
7497               Syntax: <span><strong class="command">$ORIGIN</strong></span>
7498               <em class="replaceable"><code>domain-name</code></em>
7499               [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
7500             </p>
7501 <p><span><strong class="command">$ORIGIN</strong></span>
7502               sets the domain name that will be appended to any
7503               unqualified records. When a zone is first read in there
7504               is an implicit <span><strong class="command">$ORIGIN</strong></span>
7505               &lt;<code class="varname">zone-name</code>&gt;<span><strong class="command">.</strong></span>
7506               The current <span><strong class="command">$ORIGIN</strong></span> is appended to
7507               the domain specified in the <span><strong class="command">$ORIGIN</strong></span>
7508               argument if it is not absolute.
7509             </p>
7510 <pre class="programlisting">
7511 $ORIGIN example.com.
7512 WWW     CNAME   MAIN-SERVER
7513 </pre>
7514 <p>
7515               is equivalent to
7516             </p>
7517 <pre class="programlisting">
7518 WWW.EXAMPLE.COM. CNAME MAIN-SERVER.EXAMPLE.COM.
7519 </pre>
7520 </div>
7521 <div class="sect3" lang="en">
7522 <div class="titlepage"><div><div><h4 class="title">
7523 <a name="id2594097"></a>The <span><strong class="command">$INCLUDE</strong></span> Directive</h4></div></div></div>
7524 <p>
7525               Syntax: <span><strong class="command">$INCLUDE</strong></span>
7526               <em class="replaceable"><code>filename</code></em>
7527               [<span class="optional">
7528 <em class="replaceable"><code>origin</code></em> </span>]
7529               [<span class="optional"> <em class="replaceable"><code>comment</code></em> </span>]
7530             </p>
7531 <p>
7532               Read and process the file <code class="filename">filename</code> as
7533               if it were included into the file at this point.  If <span><strong class="command">origin</strong></span> is
7534               specified the file is processed with <span><strong class="command">$ORIGIN</strong></span> set
7535               to that value, otherwise the current <span><strong class="command">$ORIGIN</strong></span> is
7536               used.
7537             </p>
7538 <p>
7539               The origin and the current domain name
7540               revert to the values they had prior to the <span><strong class="command">$INCLUDE</strong></span> once
7541               the file has been read.
7542             </p>
7543 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7544 <h3 class="title">Note</h3>
7545 <p>
7546                 RFC 1035 specifies that the current origin should be restored
7547                 after
7548                 an <span><strong class="command">$INCLUDE</strong></span>, but it is silent
7549                 on whether the current
7550                 domain name should also be restored.  BIND 9 restores both of
7551                 them.
7552                 This could be construed as a deviation from RFC 1035, a
7553                 feature, or both.
7554               </p>
7555 </div>
7556 </div>
7557 <div class="sect3" lang="en">
7558 <div class="titlepage"><div><div><h4 class="title">
7559 <a name="id2594234"></a>The <span><strong class="command">$TTL</strong></span> Directive</h4></div></div></div>
7560 <p>
7561               Syntax: <span><strong class="command">$TTL</strong></span>
7562               <em class="replaceable"><code>default-ttl</code></em>
7563               [<span class="optional">
7564 <em class="replaceable"><code>comment</code></em> </span>]
7565             </p>
7566 <p>
7567               Set the default Time To Live (TTL) for subsequent records
7568               with undefined TTLs. Valid TTLs are of the range 0-2147483647
7569               seconds.
7570             </p>
7571 <p><span><strong class="command">$TTL</strong></span>
7572                is defined in RFC 2308.
7573             </p>
7574 </div>
7575 </div>
7576 <div class="sect2" lang="en">
7577 <div class="titlepage"><div><div><h3 class="title">
7578 <a name="id2594270"></a><acronym class="acronym">BIND</acronym> Master File Extension: the  <span><strong class="command">$GENERATE</strong></span> Directive</h3></div></div></div>
7579 <p>
7580             Syntax: <span><strong class="command">$GENERATE</strong></span>
7581             <em class="replaceable"><code>range</code></em>
7582             <em class="replaceable"><code>lhs</code></em>
7583             [<span class="optional"><em class="replaceable"><code>ttl</code></em></span>]
7584             [<span class="optional"><em class="replaceable"><code>class</code></em></span>]
7585             <em class="replaceable"><code>type</code></em>
7586             <em class="replaceable"><code>rhs</code></em>
7587             [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
7588           </p>
7589 <p><span><strong class="command">$GENERATE</strong></span>
7590             is used to create a series of resource records that only
7591             differ from each other by an
7592             iterator. <span><strong class="command">$GENERATE</strong></span> can be used to
7593             easily generate the sets of records required to support
7594             sub /24 reverse delegations described in RFC 2317:
7595             Classless IN-ADDR.ARPA delegation.
7596           </p>
7597 <pre class="programlisting">$ORIGIN 0.0.192.IN-ADDR.ARPA.
7598 $GENERATE 1-2 0 NS SERVER$.EXAMPLE.
7599 $GENERATE 1-127 $ CNAME $.0</pre>
7600 <p>
7601             is equivalent to
7602           </p>
7603 <pre class="programlisting">0.0.0.192.IN-ADDR.ARPA. NS SERVER1.EXAMPLE.
7604 0.0.0.192.IN-ADDR.ARPA. NS SERVER2.EXAMPLE.
7605 1.0.0.192.IN-ADDR.ARPA. CNAME 1.0.0.0.192.IN-ADDR.ARPA.
7606 2.0.0.192.IN-ADDR.ARPA. CNAME 2.0.0.0.192.IN-ADDR.ARPA.
7607 ...
7608 127.0.0.192.IN-ADDR.ARPA. CNAME 127.0.0.0.192.IN-ADDR.ARPA.
7609 </pre>
7610 <div class="informaltable"><table border="1">
7611 <colgroup>
7612 <col>
7613 <col>
7614 </colgroup>
7615 <tbody>
7616 <tr>
7617 <td>
7618                     <p><span><strong class="command">range</strong></span></p>
7619                   </td>
7620 <td>
7621                     <p>
7622                       This can be one of two forms: start-stop
7623                       or start-stop/step. If the first form is used, then step
7624                       is set to
7625                       1. All of start, stop and step must be positive.
7626                     </p>
7627                   </td>
7628 </tr>
7629 <tr>
7630 <td>
7631                     <p><span><strong class="command">lhs</strong></span></p>
7632                   </td>
7633 <td>
7634                     <p>This
7635                       describes the owner name of the resource records
7636                       to be created.  Any single <span><strong class="command">$</strong></span>
7637                       (dollar sign)
7638                       symbols within the <span><strong class="command">lhs</strong></span> string
7639                       are replaced by the iterator value.
7640
7641                       To get a $ in the output, you need to escape the
7642                       <span><strong class="command">$</strong></span> using a backslash
7643                       <span><strong class="command">\</strong></span>,
7644                       e.g. <span><strong class="command">\$</strong></span>. The
7645                       <span><strong class="command">$</strong></span> may optionally be followed
7646                       by modifiers which change the offset from the
7647                       iterator, field width and base.
7648
7649                       Modifiers are introduced by a
7650                       <span><strong class="command">{</strong></span> (left brace) immediately following the
7651                       <span><strong class="command">$</strong></span> as
7652                       <span><strong class="command">${offset[,width[,base]]}</strong></span>.
7653                       For example, <span><strong class="command">${-20,3,d}</strong></span>
7654                       subtracts 20 from the current value, prints the
7655                       result as a decimal in a zero-padded field of
7656                       width 3.
7657
7658                       Available output forms are decimal
7659                       (<span><strong class="command">d</strong></span>), octal
7660                       (<span><strong class="command">o</strong></span>) and hexadecimal
7661                       (<span><strong class="command">x</strong></span> or <span><strong class="command">X</strong></span>
7662                       for uppercase).  The default modifier is
7663                       <span><strong class="command">${0,0,d}</strong></span>.  If the
7664                       <span><strong class="command">lhs</strong></span> is not absolute, the
7665                       current <span><strong class="command">$ORIGIN</strong></span> is appended
7666                       to the name.
7667                     </p>
7668                     <p>
7669                       For compatibility with earlier versions, <span><strong class="command">$$</strong></span> is still
7670                       recognized as indicating a literal $ in the output.
7671                     </p>
7672                   </td>
7673 </tr>
7674 <tr>
7675 <td>
7676                     <p><span><strong class="command">ttl</strong></span></p>
7677                   </td>
7678 <td>
7679                     <p>
7680                       Specifies the time-to-live of the generated records. If
7681                       not specified this will be inherited using the
7682                       normal TTL inheritance rules.
7683                     </p>
7684                     <p><span><strong class="command">class</strong></span>
7685                       and <span><strong class="command">ttl</strong></span> can be
7686                       entered in either order.
7687                     </p>
7688                   </td>
7689 </tr>
7690 <tr>
7691 <td>
7692                     <p><span><strong class="command">class</strong></span></p>
7693                   </td>
7694 <td>
7695                     <p>
7696                       Specifies the class of the generated records.
7697                       This must match the zone class if it is
7698                       specified.
7699                     </p>
7700                     <p><span><strong class="command">class</strong></span>
7701                       and <span><strong class="command">ttl</strong></span> can be
7702                       entered in either order.
7703                     </p>
7704                   </td>
7705 </tr>
7706 <tr>
7707 <td>
7708                     <p><span><strong class="command">type</strong></span></p>
7709                   </td>
7710 <td>
7711                     <p>
7712                       At present the only supported types are
7713                       PTR, CNAME, DNAME, A, AAAA and NS.
7714                     </p>
7715                   </td>
7716 </tr>
7717 <tr>
7718 <td>
7719                     <p><span><strong class="command">rhs</strong></span></p>
7720                   </td>
7721 <td>
7722                     <p>
7723                       <span><strong class="command">rhs</strong></span> is a domain name. It is processed
7724                       similarly to lhs.
7725                     </p>
7726                   </td>
7727 </tr>
7728 </tbody>
7729 </table></div>
7730 <p>
7731             The <span><strong class="command">$GENERATE</strong></span> directive is a <acronym class="acronym">BIND</acronym> extension
7732             and not part of the standard zone file format.
7733           </p>
7734 <p>
7735             BIND 8 does not support the optional TTL and CLASS fields.
7736           </p>
7737 </div>
7738 <div class="sect2" lang="en">
7739 <div class="titlepage"><div><div><h3 class="title">
7740 <a name="zonefile_format"></a>Additional File Formats</h3></div></div></div>
7741 <p>
7742             In addition to the standard textual format, BIND 9
7743             supports the ability to read or dump to zone files in
7744             other formats.  The <code class="constant">raw</code> format is
7745             currently available as an additional format.  It is a
7746             binary format representing BIND 9's internal data
7747             structure directly, thereby remarkably improving the
7748             loading time.
7749           </p>
7750 <p>
7751             For a primary server, a zone file in the
7752             <code class="constant">raw</code> format is expected to be
7753             generated from a textual zone file by the
7754             <span><strong class="command">named-compilezone</strong></span> command.  For a
7755             secondary server or for a dynamic zone, it is automatically
7756             generated (if this format is specified by the
7757             <span><strong class="command">masterfile-format</strong></span> option) when
7758             <span><strong class="command">named</strong></span> dumps the zone contents after
7759             zone transfer or when applying prior updates.
7760           </p>
7761 <p>
7762             If a zone file in a binary format needs manual modification,
7763             it first must be converted to a textual form by the
7764             <span><strong class="command">named-compilezone</strong></span> command.  All
7765             necessary modification should go to the text file, which
7766             should then be converted to the binary form by the
7767             <span><strong class="command">named-compilezone</strong></span> command again.
7768           </p>
7769 <p>
7770              Although the <code class="constant">raw</code> format uses the
7771              network byte order and avoids architecture-dependent
7772              data alignment so that it is as much portable as
7773              possible, it is primarily expected to be used inside
7774              the same single system.  In order to export a zone
7775              file in the <code class="constant">raw</code> format or make a
7776              portable backup of the file, it is recommended to
7777              convert the file to the standard textual representation.
7778           </p>
7779 </div>
7780 </div>
7781 <div class="sect1" lang="en">
7782 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
7783 <a name="statistics"></a>BIND9 Statistics</h2></div></div></div>
7784 <p>
7785           <acronym class="acronym">BIND</acronym> 9 maintains lots of statistics
7786           information and provides several interfaces for users to
7787           get access to the statistics.
7788           The available statistics include all statistics counters
7789           that were available in <acronym class="acronym">BIND</acronym> 8 and
7790           are meaningful in <acronym class="acronym">BIND</acronym> 9,
7791           and other information that is considered useful.
7792         </p>
7793 <p>
7794           The statistics information is categorized into the following
7795           sections.
7796         </p>
7797 <div class="informaltable"><table border="1">
7798 <colgroup>
7799 <col>
7800 <col>
7801 </colgroup>
7802 <tbody>
7803 <tr>
7804 <td>
7805                   <p>Incoming Requests</p>
7806                 </td>
7807 <td>
7808                   <p>
7809                     The number of incoming DNS requests for each OPCODE.
7810                   </p>
7811                 </td>
7812 </tr>
7813 <tr>
7814 <td>
7815                   <p>Incoming Queries</p>
7816                 </td>
7817 <td>
7818                   <p>
7819                     The number of incoming queries for each RR type.
7820                   </p>
7821                 </td>
7822 </tr>
7823 <tr>
7824 <td>
7825                   <p>Outgoing Queries</p>
7826                 </td>
7827 <td>
7828                   <p>
7829                     The number of outgoing queries for each RR
7830                     type sent from the internal resolver.
7831                     Maintained per view.
7832                   </p>
7833                 </td>
7834 </tr>
7835 <tr>
7836 <td>
7837                   <p>Name Server Statistics</p>
7838                 </td>
7839 <td>
7840                   <p>
7841                     Statistics counters about incoming request processing.
7842                   </p>
7843                 </td>
7844 </tr>
7845 <tr>
7846 <td>
7847                   <p>Zone Maintenance Statistics</p>
7848                 </td>
7849 <td>
7850                   <p>
7851                     Statistics counters regarding zone maintenance
7852                     operations such as zone transfers.
7853                   </p>
7854                 </td>
7855 </tr>
7856 <tr>
7857 <td>
7858                   <p>Resolver Statistics</p>
7859                 </td>
7860 <td>
7861                   <p>
7862                     Statistics counters about name resolution
7863                     performed in the internal resolver.
7864                     Maintained per view.
7865                   </p>
7866                 </td>
7867 </tr>
7868 <tr>
7869 <td>
7870                   <p>Cache DB RRsets</p>
7871                 </td>
7872 <td>
7873                   <p>
7874                     The number of RRsets per RR type (positive
7875                     or negative) and nonexistent names stored in the
7876                     cache database.
7877                     Maintained per view.
7878                   </p>
7879                 </td>
7880 </tr>
7881 <tr>
7882 <td>
7883                   <p>Socket I/O Statistics</p>
7884                 </td>
7885 <td>
7886                   <p>
7887                     Statistics counters about network related events.
7888                   </p>
7889                 </td>
7890 </tr>
7891 </tbody>
7892 </table></div>
7893 <p>
7894           A subset of Name Server Statistics is collected and shown
7895           per zone for which the server has the authority when
7896           <span><strong class="command">zone-statistics</strong></span> is set to
7897           <strong class="userinput"><code>yes</code></strong>.
7898           These statistics counters are shown with their zone and view
7899           names.
7900           In some cases the view names are omitted for the default view.
7901         </p>
7902 <p>
7903           There are currently two user interfaces to get access to the
7904           statistics.
7905           One is in the plain text format dumped to the file specified
7906           by the <span><strong class="command">statistics-file</strong></span> configuration option.
7907           The other is remotely accessible via a statistics channel
7908           when the <span><strong class="command">statistics-channels</strong></span> statement
7909           is specified in the configuration file
7910           (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>.)
7911         </p>
7912 <div class="sect3" lang="en">
7913 <div class="titlepage"><div><div><h4 class="title">
7914 <a name="statsfile"></a>The Statistics File</h4></div></div></div>
7915 <p>
7916             The text format statistics dump begins with a line, like:
7917           </p>
7918 <p>
7919             <span><strong class="command">+++ Statistics Dump +++ (973798949)</strong></span>
7920           </p>
7921 <p>
7922             The number in parentheses is a standard
7923             Unix-style timestamp, measured as seconds since January 1, 1970.
7924
7925             Following
7926             that line is a set of statistics information, which is categorized
7927             as described above.
7928             Each section begins with a line, like:
7929           </p>
7930 <p>
7931             <span><strong class="command">++ Name Server Statistics ++</strong></span>
7932           </p>
7933 <p>
7934             Each section consists of lines, each containing the statistics
7935             counter value followed by its textual description.
7936             See below for available counters.
7937             For brevity, counters that have a value of 0 are not shown
7938             in the statistics file.
7939           </p>
7940 <p>
7941             The statistics dump ends with the line where the
7942             number is identical to the number in the beginning line; for example:
7943           </p>
7944 <p>
7945             <span><strong class="command">--- Statistics Dump --- (973798949)</strong></span>
7946           </p>
7947 </div>
7948 <div class="sect2" lang="en">
7949 <div class="titlepage"><div><div><h3 class="title">
7950 <a name="statistics_counters"></a>Statistics Counters</h3></div></div></div>
7951 <p>
7952             The following tables summarize statistics counters that
7953             <acronym class="acronym">BIND</acronym> 9 provides.
7954             For each row of the tables, the leftmost column is the
7955             abbreviated symbol name of that counter.
7956             These symbols are shown in the statistics information
7957             accessed via an HTTP statistics channel.
7958             The rightmost column gives the description of the counter,
7959             which is also shown in the statistics file
7960             (but, in this document, possibly with slight modification
7961             for better readability).
7962             Additional notes may also be provided in this column.
7963             When a middle column exists between these two columns,
7964             it gives the corresponding counter name of the
7965             <acronym class="acronym">BIND</acronym> 8 statistics, if applicable.
7966           </p>
7967 <div class="sect3" lang="en">
7968 <div class="titlepage"><div><div><h4 class="title">
7969 <a name="id2595267"></a>Name Server Statistics Counters</h4></div></div></div>
7970 <div class="informaltable"><table border="1">
7971 <colgroup>
7972 <col>
7973 <col>
7974 <col>
7975 </colgroup>
7976 <tbody>
7977 <tr>
7978 <td>
7979                       <p>
7980                         <span class="emphasis"><em>Symbol</em></span>
7981                       </p>
7982                     </td>
7983 <td>
7984                       <p>
7985                         <span class="emphasis"><em>BIND8 Symbol</em></span>
7986                       </p>
7987                     </td>
7988 <td>
7989                       <p>
7990                         <span class="emphasis"><em>Description</em></span>
7991                       </p>
7992                     </td>
7993 </tr>
7994 <tr>
7995 <td>
7996                       <p><span><strong class="command">Requestv4</strong></span></p>
7997                     </td>
7998 <td>
7999                       <p><span><strong class="command">RQ</strong></span></p>
8000                     </td>
8001 <td>
8002                       <p>
8003                         IPv4 requests received.
8004                         Note: this also counts non query requests.
8005                       </p>
8006                     </td>
8007 </tr>
8008 <tr>
8009 <td>
8010                       <p><span><strong class="command">Requestv6</strong></span></p>
8011                     </td>
8012 <td>
8013                       <p><span><strong class="command">RQ</strong></span></p>
8014                     </td>
8015 <td>
8016                       <p>
8017                         IPv6 requests received.
8018                         Note: this also counts non query requests.
8019                       </p>
8020                     </td>
8021 </tr>
8022 <tr>
8023 <td>
8024                       <p><span><strong class="command">ReqEdns0</strong></span></p>
8025                     </td>
8026 <td>
8027                       <p><span><strong class="command"></strong></span></p>
8028                     </td>
8029 <td>
8030                       <p>
8031                         Requests with EDNS(0) received.
8032                       </p>
8033                     </td>
8034 </tr>
8035 <tr>
8036 <td>
8037                       <p><span><strong class="command">ReqBadEDNSVer</strong></span></p>
8038                     </td>
8039 <td>
8040                       <p><span><strong class="command"></strong></span></p>
8041                     </td>
8042 <td>
8043                       <p>
8044                         Requests with unsupported EDNS version received.
8045                       </p>
8046                     </td>
8047 </tr>
8048 <tr>
8049 <td>
8050                       <p><span><strong class="command">ReqTSIG</strong></span></p>
8051                     </td>
8052 <td>
8053                       <p><span><strong class="command"></strong></span></p>
8054                     </td>
8055 <td>
8056                       <p>
8057                         Requests with TSIG received.
8058                       </p>
8059                     </td>
8060 </tr>
8061 <tr>
8062 <td>
8063                       <p><span><strong class="command">ReqSIG0</strong></span></p>
8064                     </td>
8065 <td>
8066                       <p><span><strong class="command"></strong></span></p>
8067                     </td>
8068 <td>
8069                       <p>
8070                         Requests with SIG(0) received.
8071                       </p>
8072                     </td>
8073 </tr>
8074 <tr>
8075 <td>
8076                       <p><span><strong class="command">ReqBadSIG</strong></span></p>
8077                     </td>
8078 <td>
8079                       <p><span><strong class="command"></strong></span></p>
8080                     </td>
8081 <td>
8082                       <p>
8083                         Requests with invalid (TSIG or SIG(0)) signature.
8084                       </p>
8085                     </td>
8086 </tr>
8087 <tr>
8088 <td>
8089                       <p><span><strong class="command">ReqTCP</strong></span></p>
8090                     </td>
8091 <td>
8092                       <p><span><strong class="command">RTCP</strong></span></p>
8093                     </td>
8094 <td>
8095                       <p>
8096                         TCP requests received.
8097                       </p>
8098                     </td>
8099 </tr>
8100 <tr>
8101 <td>
8102                       <p><span><strong class="command">AuthQryRej</strong></span></p>
8103                     </td>
8104 <td>
8105                       <p><span><strong class="command">RUQ</strong></span></p>
8106                     </td>
8107 <td>
8108                       <p>
8109                         Authoritative (non recursive) queries rejected.
8110                       </p>
8111                     </td>
8112 </tr>
8113 <tr>
8114 <td>
8115                       <p><span><strong class="command">RecQryRej</strong></span></p>
8116                     </td>
8117 <td>
8118                       <p><span><strong class="command">RURQ</strong></span></p>
8119                     </td>
8120 <td>
8121                       <p>
8122                         Recursive queries rejected.
8123                       </p>
8124                     </td>
8125 </tr>
8126 <tr>
8127 <td>
8128                       <p><span><strong class="command">XfrRej</strong></span></p>
8129                     </td>
8130 <td>
8131                       <p><span><strong class="command">RUXFR</strong></span></p>
8132                     </td>
8133 <td>
8134                       <p>
8135                         Zone transfer requests rejected.
8136                       </p>
8137                     </td>
8138 </tr>
8139 <tr>
8140 <td>
8141                       <p><span><strong class="command">UpdateRej</strong></span></p>
8142                     </td>
8143 <td>
8144                       <p><span><strong class="command">RUUpd</strong></span></p>
8145                     </td>
8146 <td>
8147                       <p>
8148                         Dynamic update requests rejected.
8149                       </p>
8150                     </td>
8151 </tr>
8152 <tr>
8153 <td>
8154                       <p><span><strong class="command">Response</strong></span></p>
8155                     </td>
8156 <td>
8157                       <p><span><strong class="command">SAns</strong></span></p>
8158                     </td>
8159 <td>
8160                       <p>
8161                         Responses sent.
8162                       </p>
8163                     </td>
8164 </tr>
8165 <tr>
8166 <td>
8167                       <p><span><strong class="command">RespTruncated</strong></span></p>
8168                     </td>
8169 <td>
8170                       <p><span><strong class="command"></strong></span></p>
8171                     </td>
8172 <td>
8173                       <p>
8174                         Truncated responses sent.
8175                       </p>
8176                     </td>
8177 </tr>
8178 <tr>
8179 <td>
8180                       <p><span><strong class="command">RespEDNS0</strong></span></p>
8181                     </td>
8182 <td>
8183                       <p><span><strong class="command"></strong></span></p>
8184                     </td>
8185 <td>
8186                       <p>
8187                         Responses with EDNS(0) sent.
8188                       </p>
8189                     </td>
8190 </tr>
8191 <tr>
8192 <td>
8193                       <p><span><strong class="command">RespTSIG</strong></span></p>
8194                     </td>
8195 <td>
8196                       <p><span><strong class="command"></strong></span></p>
8197                     </td>
8198 <td>
8199                       <p>
8200                         Responses with TSIG sent.
8201                       </p>
8202                     </td>
8203 </tr>
8204 <tr>
8205 <td>
8206                       <p><span><strong class="command">RespSIG0</strong></span></p>
8207                     </td>
8208 <td>
8209                       <p><span><strong class="command"></strong></span></p>
8210                     </td>
8211 <td>
8212                       <p>
8213                         Responses with SIG(0) sent.
8214                       </p>
8215                     </td>
8216 </tr>
8217 <tr>
8218 <td>
8219                       <p><span><strong class="command">QrySuccess</strong></span></p>
8220                     </td>
8221 <td>
8222                       <p><span><strong class="command"></strong></span></p>
8223                     </td>
8224 <td>
8225                       <p>
8226                         Queries resulted in a successful answer.
8227                         This means the query which returns a NOERROR response
8228                         with at least one answer RR.
8229                         This corresponds to the
8230                         <span><strong class="command">success</strong></span> counter
8231                         of previous versions of
8232                         <acronym class="acronym">BIND</acronym> 9.
8233                       </p>
8234                     </td>
8235 </tr>
8236 <tr>
8237 <td>
8238                       <p><span><strong class="command">QryAuthAns</strong></span></p>
8239                     </td>
8240 <td>
8241                       <p><span><strong class="command"></strong></span></p>
8242                     </td>
8243 <td>
8244                       <p>
8245                         Queries resulted in authoritative answer.
8246                       </p>
8247                     </td>
8248 </tr>
8249 <tr>
8250 <td>
8251                       <p><span><strong class="command">QryNoauthAns</strong></span></p>
8252                     </td>
8253 <td>
8254                       <p><span><strong class="command">SNaAns</strong></span></p>
8255                     </td>
8256 <td>
8257                       <p>
8258                         Queries resulted in non authoritative answer.
8259                       </p>
8260                     </td>
8261 </tr>
8262 <tr>
8263 <td>
8264                       <p><span><strong class="command">QryReferral</strong></span></p>
8265                     </td>
8266 <td>
8267                       <p><span><strong class="command"></strong></span></p>
8268                     </td>
8269 <td>
8270                       <p>
8271                         Queries resulted in referral answer.
8272                         This corresponds to the
8273                         <span><strong class="command">referral</strong></span> counter
8274                         of previous versions of
8275                         <acronym class="acronym">BIND</acronym> 9.
8276                       </p>
8277                     </td>
8278 </tr>
8279 <tr>
8280 <td>
8281                       <p><span><strong class="command">QryNxrrset</strong></span></p>
8282                     </td>
8283 <td>
8284                       <p><span><strong class="command"></strong></span></p>
8285                     </td>
8286 <td>
8287                       <p>
8288                         Queries resulted in NOERROR responses with no data.
8289                         This corresponds to the
8290                         <span><strong class="command">nxrrset</strong></span> counter
8291                         of previous versions of
8292                         <acronym class="acronym">BIND</acronym> 9.
8293                       </p>
8294                     </td>
8295 </tr>
8296 <tr>
8297 <td>
8298                       <p><span><strong class="command">QrySERVFAIL</strong></span></p>
8299                     </td>
8300 <td>
8301                       <p><span><strong class="command">SFail</strong></span></p>
8302                     </td>
8303 <td>
8304                       <p>
8305                         Queries resulted in SERVFAIL.
8306                       </p>
8307                     </td>
8308 </tr>
8309 <tr>
8310 <td>
8311                       <p><span><strong class="command">QryFORMERR</strong></span></p>
8312                     </td>
8313 <td>
8314                       <p><span><strong class="command">SFErr</strong></span></p>
8315                     </td>
8316 <td>
8317                       <p>
8318                         Queries resulted in FORMERR.
8319                       </p>
8320                     </td>
8321 </tr>
8322 <tr>
8323 <td>
8324                       <p><span><strong class="command">QryNXDOMAIN</strong></span></p>
8325                     </td>
8326 <td>
8327                       <p><span><strong class="command">SNXD</strong></span></p>
8328                     </td>
8329 <td>
8330                       <p>
8331                         Queries resulted in NXDOMAIN.
8332                         This corresponds to the
8333                         <span><strong class="command">nxdomain</strong></span> counter
8334                         of previous versions of
8335                         <acronym class="acronym">BIND</acronym> 9.
8336                       </p>
8337                     </td>
8338 </tr>
8339 <tr>
8340 <td>
8341                       <p><span><strong class="command">QryRecursion</strong></span></p>
8342                     </td>
8343 <td>
8344                       <p><span><strong class="command">RFwdQ</strong></span></p>
8345                     </td>
8346 <td>
8347                       <p>
8348                         Queries which caused the server
8349                         to perform recursion in order to find the final answer.
8350                         This corresponds to the
8351                         <span><strong class="command">recursion</strong></span> counter
8352                         of previous versions of
8353                         <acronym class="acronym">BIND</acronym> 9.
8354                       </p>
8355                     </td>
8356 </tr>
8357 <tr>
8358 <td>
8359                       <p><span><strong class="command">QryDuplicate</strong></span></p>
8360                     </td>
8361 <td>
8362                       <p><span><strong class="command">RDupQ</strong></span></p>
8363                     </td>
8364 <td>
8365                       <p>
8366                         Queries which the server attempted to
8367                         recurse but discovered an existing query with the same
8368                         IP address, port, query ID, name, type and class
8369                         already being processed.
8370                         This corresponds to the
8371                         <span><strong class="command">duplicate</strong></span> counter
8372                         of previous versions of
8373                         <acronym class="acronym">BIND</acronym> 9.
8374                       </p>
8375                     </td>
8376 </tr>
8377 <tr>
8378 <td>
8379                       <p><span><strong class="command">QryDropped</strong></span></p>
8380                     </td>
8381 <td>
8382                       <p><span><strong class="command"></strong></span></p>
8383                     </td>
8384 <td>
8385                       <p>
8386                         Recursive queries for which the server
8387                         discovered an excessive number of existing
8388                         recursive queries for the same name, type and
8389                         class and were subsequently dropped.
8390                         This is the number of dropped queries due to
8391                         the reason explained with the
8392                         <span><strong class="command">clients-per-query</strong></span>
8393                         and
8394                         <span><strong class="command">max-clients-per-query</strong></span>
8395                         options
8396                         (see the description about
8397                         <a href="Bv9ARM.ch06.html#clients-per-query"><span><strong class="command">clients-per-query</strong></span></a>.)
8398                         This corresponds to the
8399                         <span><strong class="command">dropped</strong></span> counter
8400                         of previous versions of
8401                         <acronym class="acronym">BIND</acronym> 9.
8402                       </p>
8403                     </td>
8404 </tr>
8405 <tr>
8406 <td>
8407                       <p><span><strong class="command">QryFailure</strong></span></p>
8408                     </td>
8409 <td>
8410                       <p><span><strong class="command"></strong></span></p>
8411                     </td>
8412 <td>
8413                       <p>
8414                         Other query failures.
8415                         This corresponds to the
8416                         <span><strong class="command">failure</strong></span> counter
8417                         of previous versions of
8418                         <acronym class="acronym">BIND</acronym> 9.
8419                         Note: this counter is provided mainly for
8420                         backward compatibility with the previous versions.
8421                         Normally a more fine-grained counters such as
8422                         <span><strong class="command">AuthQryRej</strong></span> and
8423                         <span><strong class="command">RecQryRej</strong></span>
8424                         that would also fall into this counter are provided,
8425                         and so this counter would not be of much
8426                         interest in practice.
8427                       </p>
8428                     </td>
8429 </tr>
8430 <tr>
8431 <td>
8432                       <p><span><strong class="command">XfrReqDone</strong></span></p>
8433                     </td>
8434 <td>
8435                       <p><span><strong class="command"></strong></span></p>
8436                     </td>
8437 <td>
8438                       <p>
8439                         Requested zone transfers completed.
8440                       </p>
8441                     </td>
8442 </tr>
8443 <tr>
8444 <td>
8445                       <p><span><strong class="command">UpdateReqFwd</strong></span></p>
8446                     </td>
8447 <td>
8448                       <p><span><strong class="command"></strong></span></p>
8449                     </td>
8450 <td>
8451                       <p>
8452                         Update requests forwarded.
8453                       </p>
8454                     </td>
8455 </tr>
8456 <tr>
8457 <td>
8458                       <p><span><strong class="command">UpdateRespFwd</strong></span></p>
8459                     </td>
8460 <td>
8461                       <p><span><strong class="command"></strong></span></p>
8462                     </td>
8463 <td>
8464                       <p>
8465                         Update responses forwarded.
8466                       </p>
8467                     </td>
8468 </tr>
8469 <tr>
8470 <td>
8471                       <p><span><strong class="command">UpdateFwdFail</strong></span></p>
8472                     </td>
8473 <td>
8474                       <p><span><strong class="command"></strong></span></p>
8475                     </td>
8476 <td>
8477                       <p>
8478                         Dynamic update forward failed.
8479                       </p>
8480                     </td>
8481 </tr>
8482 <tr>
8483 <td>
8484                       <p><span><strong class="command">UpdateDone</strong></span></p>
8485                     </td>
8486 <td>
8487                       <p><span><strong class="command"></strong></span></p>
8488                     </td>
8489 <td>
8490                       <p>
8491                         Dynamic updates completed.
8492                       </p>
8493                     </td>
8494 </tr>
8495 <tr>
8496 <td>
8497                       <p><span><strong class="command">UpdateFail</strong></span></p>
8498                     </td>
8499 <td>
8500                       <p><span><strong class="command"></strong></span></p>
8501                     </td>
8502 <td>
8503                       <p>
8504                         Dynamic updates failed.
8505                       </p>
8506                     </td>
8507 </tr>
8508 <tr>
8509 <td>
8510                       <p><span><strong class="command">UpdateBadPrereq</strong></span></p>
8511                     </td>
8512 <td>
8513                       <p><span><strong class="command"></strong></span></p>
8514                     </td>
8515 <td>
8516                       <p>
8517                         Dynamic updates rejected due to prerequisite failure.
8518                       </p>
8519                     </td>
8520 </tr>
8521 </tbody>
8522 </table></div>
8523 </div>
8524 <div class="sect3" lang="en">
8525 <div class="titlepage"><div><div><h4 class="title">
8526 <a name="id2596808"></a>Zone Maintenance Statistics Counters</h4></div></div></div>
8527 <div class="informaltable"><table border="1">
8528 <colgroup>
8529 <col>
8530 <col>
8531 </colgroup>
8532 <tbody>
8533 <tr>
8534 <td>
8535                       <p>
8536                         <span class="emphasis"><em>Symbol</em></span>
8537                       </p>
8538                     </td>
8539 <td>
8540                       <p>
8541                         <span class="emphasis"><em>Description</em></span>
8542                       </p>
8543                     </td>
8544 </tr>
8545 <tr>
8546 <td>
8547                       <p><span><strong class="command">NotifyOutv4</strong></span></p>
8548                     </td>
8549 <td>
8550                       <p>
8551                         IPv4 notifies sent.
8552                       </p>
8553                     </td>
8554 </tr>
8555 <tr>
8556 <td>
8557                       <p><span><strong class="command">NotifyOutv6</strong></span></p>
8558                     </td>
8559 <td>
8560                       <p>
8561                         IPv6 notifies sent.
8562                       </p>
8563                     </td>
8564 </tr>
8565 <tr>
8566 <td>
8567                       <p><span><strong class="command">NotifyInv4</strong></span></p>
8568                     </td>
8569 <td>
8570                       <p>
8571                         IPv4 notifies received.
8572                       </p>
8573                     </td>
8574 </tr>
8575 <tr>
8576 <td>
8577                       <p><span><strong class="command">NotifyInv6</strong></span></p>
8578                     </td>
8579 <td>
8580                       <p>
8581                         IPv6 notifies received.
8582                       </p>
8583                     </td>
8584 </tr>
8585 <tr>
8586 <td>
8587                       <p><span><strong class="command">NotifyRej</strong></span></p>
8588                     </td>
8589 <td>
8590                       <p>
8591                         Incoming notifies rejected.
8592                       </p>
8593                     </td>
8594 </tr>
8595 <tr>
8596 <td>
8597                       <p><span><strong class="command">SOAOutv4</strong></span></p>
8598                     </td>
8599 <td>
8600                       <p>
8601                         IPv4 SOA queries sent.
8602                       </p>
8603                     </td>
8604 </tr>
8605 <tr>
8606 <td>
8607                       <p><span><strong class="command">SOAOutv6</strong></span></p>
8608                     </td>
8609 <td>
8610                       <p>
8611                         IPv6 SOA queries sent.
8612                       </p>
8613                     </td>
8614 </tr>
8615 <tr>
8616 <td>
8617                       <p><span><strong class="command">AXFRReqv4</strong></span></p>
8618                     </td>
8619 <td>
8620                       <p>
8621                         IPv4 AXFR requested.
8622                       </p>
8623                     </td>
8624 </tr>
8625 <tr>
8626 <td>
8627                       <p><span><strong class="command">AXFRReqv6</strong></span></p>
8628                     </td>
8629 <td>
8630                       <p>
8631                         IPv6 AXFR requested.
8632                       </p>
8633                     </td>
8634 </tr>
8635 <tr>
8636 <td>
8637                       <p><span><strong class="command">IXFRReqv4</strong></span></p>
8638                     </td>
8639 <td>
8640                       <p>
8641                         IPv4 IXFR requested.
8642                       </p>
8643                     </td>
8644 </tr>
8645 <tr>
8646 <td>
8647                       <p><span><strong class="command">IXFRReqv6</strong></span></p>
8648                     </td>
8649 <td>
8650                       <p>
8651                         IPv6 IXFR requested.
8652                       </p>
8653                     </td>
8654 </tr>
8655 <tr>
8656 <td>
8657                       <p><span><strong class="command">XfrSuccess</strong></span></p>
8658                     </td>
8659 <td>
8660                       <p>
8661                         Zone transfer requests succeeded.
8662                       </p>
8663                     </td>
8664 </tr>
8665 <tr>
8666 <td>
8667                       <p><span><strong class="command">XfrFail</strong></span></p>
8668                     </td>
8669 <td>
8670                       <p>
8671                         Zone transfer requests failed.
8672                       </p>
8673                     </td>
8674 </tr>
8675 </tbody>
8676 </table></div>
8677 </div>
8678 <div class="sect3" lang="en">
8679 <div class="titlepage"><div><div><h4 class="title">
8680 <a name="id2597191"></a>Resolver Statistics Counters</h4></div></div></div>
8681 <div class="informaltable"><table border="1">
8682 <colgroup>
8683 <col>
8684 <col>
8685 <col>
8686 </colgroup>
8687 <tbody>
8688 <tr>
8689 <td>
8690                       <p>
8691                         <span class="emphasis"><em>Symbol</em></span>
8692                       </p>
8693                     </td>
8694 <td>
8695                       <p>
8696                         <span class="emphasis"><em>BIND8 Symbol</em></span>
8697                       </p>
8698                     </td>
8699 <td>
8700                       <p>
8701                         <span class="emphasis"><em>Description</em></span>
8702                       </p>
8703                     </td>
8704 </tr>
8705 <tr>
8706 <td>
8707                       <p><span><strong class="command">Queryv4</strong></span></p>
8708                     </td>
8709 <td>
8710                       <p><span><strong class="command">SFwdQ</strong></span></p>
8711                     </td>
8712 <td>
8713                       <p>
8714                         IPv4 queries sent.
8715                       </p>
8716                     </td>
8717 </tr>
8718 <tr>
8719 <td>
8720                       <p><span><strong class="command">Queryv6</strong></span></p>
8721                     </td>
8722 <td>
8723                       <p><span><strong class="command">SFwdQ</strong></span></p>
8724                     </td>
8725 <td>
8726                       <p>
8727                         IPv6 queries sent.
8728                       </p>
8729                     </td>
8730 </tr>
8731 <tr>
8732 <td>
8733                       <p><span><strong class="command">Responsev4</strong></span></p>
8734                     </td>
8735 <td>
8736                       <p><span><strong class="command">RR</strong></span></p>
8737                     </td>
8738 <td>
8739                       <p>
8740                         IPv4 responses received.
8741                       </p>
8742                     </td>
8743 </tr>
8744 <tr>
8745 <td>
8746                       <p><span><strong class="command">Responsev6</strong></span></p>
8747                     </td>
8748 <td>
8749                       <p><span><strong class="command">RR</strong></span></p>
8750                     </td>
8751 <td>
8752                       <p>
8753                         IPv6 responses received.
8754                       </p>
8755                     </td>
8756 </tr>
8757 <tr>
8758 <td>
8759                       <p><span><strong class="command">NXDOMAIN</strong></span></p>
8760                     </td>
8761 <td>
8762                       <p><span><strong class="command">RNXD</strong></span></p>
8763                     </td>
8764 <td>
8765                       <p>
8766                         NXDOMAIN received.
8767                       </p>
8768                     </td>
8769 </tr>
8770 <tr>
8771 <td>
8772                       <p><span><strong class="command">SERVFAIL</strong></span></p>
8773                     </td>
8774 <td>
8775                       <p><span><strong class="command">RFail</strong></span></p>
8776                     </td>
8777 <td>
8778                       <p>
8779                         SERVFAIL received.
8780                       </p>
8781                     </td>
8782 </tr>
8783 <tr>
8784 <td>
8785                       <p><span><strong class="command">FORMERR</strong></span></p>
8786                     </td>
8787 <td>
8788                       <p><span><strong class="command">RFErr</strong></span></p>
8789                     </td>
8790 <td>
8791                       <p>
8792                         FORMERR received.
8793                       </p>
8794                     </td>
8795 </tr>
8796 <tr>
8797 <td>
8798                       <p><span><strong class="command">OtherError</strong></span></p>
8799                     </td>
8800 <td>
8801                       <p><span><strong class="command">RErr</strong></span></p>
8802                     </td>
8803 <td>
8804                       <p>
8805                         Other errors received.
8806                       </p>
8807                     </td>
8808 </tr>
8809 <tr>
8810 <td>
8811                       <p><span><strong class="command">EDNS0Fail</strong></span></p>
8812                                                  </td>
8813 <td>
8814                       <p><span><strong class="command"></strong></span></p>
8815                     </td>
8816 <td>
8817                       <p>
8818                         EDNS(0) query failures.
8819                       </p>
8820                     </td>
8821 </tr>
8822 <tr>
8823 <td>
8824                       <p><span><strong class="command">Mismatch</strong></span></p>
8825                     </td>
8826 <td>
8827                       <p><span><strong class="command">RDupR</strong></span></p>
8828                     </td>
8829 <td>
8830                       <p>
8831                         Mismatch responses received.
8832                       </p>
8833                     </td>
8834 </tr>
8835 <tr>
8836 <td>
8837                       <p><span><strong class="command">Truncated</strong></span></p>
8838                     </td>
8839 <td>
8840                       <p><span><strong class="command"></strong></span></p>
8841                     </td>
8842 <td>
8843                       <p>
8844                         Truncated responses received.
8845                       </p>
8846                     </td>
8847 </tr>
8848 <tr>
8849 <td>
8850                       <p><span><strong class="command">Lame</strong></span></p>
8851                     </td>
8852 <td>
8853                       <p><span><strong class="command">RLame</strong></span></p>
8854                     </td>
8855 <td>
8856                       <p>
8857                         Lame delegations received.
8858                       </p>
8859                     </td>
8860 </tr>
8861 <tr>
8862 <td>
8863                       <p><span><strong class="command">Retry</strong></span></p>
8864                     </td>
8865 <td>
8866                       <p><span><strong class="command">SDupQ</strong></span></p>
8867                     </td>
8868 <td>
8869                       <p>
8870                         Query retries performed.
8871                       </p>
8872                     </td>
8873 </tr>
8874 <tr>
8875 <td>
8876                       <p><span><strong class="command">QueryAbort</strong></span></p>
8877                     </td>
8878 <td>
8879                       <p><span><strong class="command"></strong></span></p>
8880                     </td>
8881 <td>
8882                       <p>
8883                         Queries aborted due to quota control.
8884                       </p>
8885                     </td>
8886 </tr>
8887 <tr>
8888 <td>
8889                       <p><span><strong class="command">QuerySockFail</strong></span></p>
8890                     </td>
8891 <td>
8892                       <p><span><strong class="command"></strong></span></p>
8893                     </td>
8894 <td>
8895                       <p>
8896                         Failures in opening query sockets.
8897                         One common reason for such failures is a
8898                         failure of opening a new socket due to a
8899                         limitation on file descriptors.
8900                       </p>
8901                     </td>
8902 </tr>
8903 <tr>
8904 <td>
8905                       <p><span><strong class="command">QueryTimeout</strong></span></p>
8906                     </td>
8907 <td>
8908                       <p><span><strong class="command"></strong></span></p>
8909                     </td>
8910 <td>
8911                       <p>
8912                         Query timeouts.
8913                       </p>
8914                     </td>
8915 </tr>
8916 <tr>
8917 <td>
8918                       <p><span><strong class="command">GlueFetchv4</strong></span></p>
8919                     </td>
8920 <td>
8921                       <p><span><strong class="command">SSysQ</strong></span></p>
8922                     </td>
8923 <td>
8924                       <p>
8925                         IPv4 NS address fetches invoked.
8926                       </p>
8927                     </td>
8928 </tr>
8929 <tr>
8930 <td>
8931                       <p><span><strong class="command">GlueFetchv6</strong></span></p>
8932                     </td>
8933 <td>
8934                       <p><span><strong class="command">SSysQ</strong></span></p>
8935                     </td>
8936 <td>
8937                       <p>
8938                         IPv6 NS address fetches invoked.
8939                       </p>
8940                     </td>
8941 </tr>
8942 <tr>
8943 <td>
8944                       <p><span><strong class="command">GlueFetchv4Fail</strong></span></p>
8945                     </td>
8946 <td>
8947                       <p><span><strong class="command"></strong></span></p>
8948                     </td>
8949 <td>
8950                       <p>
8951                         IPv4 NS address fetch failed.
8952                       </p>
8953                     </td>
8954 </tr>
8955 <tr>
8956 <td>
8957                       <p><span><strong class="command">GlueFetchv6Fail</strong></span></p>
8958                     </td>
8959 <td>
8960                       <p><span><strong class="command"></strong></span></p>
8961                     </td>
8962 <td>
8963                       <p>
8964                         IPv6 NS address fetch failed.
8965                       </p>
8966                     </td>
8967 </tr>
8968 <tr>
8969 <td>
8970                       <p><span><strong class="command">ValAttempt</strong></span></p>
8971                     </td>
8972 <td>
8973                       <p><span><strong class="command"></strong></span></p>
8974                     </td>
8975 <td>
8976                       <p>
8977                         DNSSEC validation attempted.
8978                       </p>
8979                     </td>
8980 </tr>
8981 <tr>
8982 <td>
8983                       <p><span><strong class="command">ValOk</strong></span></p>
8984                     </td>
8985 <td>
8986                       <p><span><strong class="command"></strong></span></p>
8987                     </td>
8988 <td>
8989                       <p>
8990                         DNSSEC validation succeeded.
8991                       </p>
8992                     </td>
8993 </tr>
8994 <tr>
8995 <td>
8996                       <p><span><strong class="command">ValNegOk</strong></span></p>
8997                     </td>
8998 <td>
8999                       <p><span><strong class="command"></strong></span></p>
9000                     </td>
9001 <td>
9002                       <p>
9003                         DNSSEC validation on negative information succeeded.
9004                       </p>
9005                     </td>
9006 </tr>
9007 <tr>
9008 <td>
9009                       <p><span><strong class="command">ValFail</strong></span></p>
9010                     </td>
9011 <td>
9012                       <p><span><strong class="command"></strong></span></p>
9013                     </td>
9014 <td>
9015                       <p>
9016                         DNSSEC validation failed.
9017                       </p>
9018                     </td>
9019 </tr>
9020 <tr>
9021 <td>
9022                       <p><span><strong class="command">QryRTTnn</strong></span></p>
9023                     </td>
9024 <td>
9025                       <p><span><strong class="command"></strong></span></p>
9026                     </td>
9027 <td>
9028                       <p>
9029                         Frequency table on round trip times (RTTs) of
9030                         queries.
9031                         Each <span><strong class="command">nn</strong></span> specifies the corresponding
9032                         frequency.
9033                         In the sequence of
9034                         <span><strong class="command">nn_1</strong></span>,
9035                         <span><strong class="command">nn_2</strong></span>,
9036                         ...,
9037                         <span><strong class="command">nn_m</strong></span>,
9038                         the value of <span><strong class="command">nn_i</strong></span> is the
9039                         number of queries whose RTTs are between
9040                         <span><strong class="command">nn_(i-1)</strong></span> (inclusive) and
9041                         <span><strong class="command">nn_i</strong></span> (exclusive) milliseconds.
9042                         For the sake of convenience we define
9043                         <span><strong class="command">nn_0</strong></span> to be 0.
9044                         The last entry should be represented as
9045                         <span><strong class="command">nn_m+</strong></span>, which means the
9046                         number of queries whose RTTs are equal to or over
9047                         <span><strong class="command">nn_m</strong></span> milliseconds.
9048                       </p>
9049                     </td>
9050 </tr>
9051 </tbody>
9052 </table></div>
9053 </div>
9054 <div class="sect3" lang="en">
9055 <div class="titlepage"><div><div><h4 class="title">
9056 <a name="id2598210"></a>Socket I/O Statistics Counters</h4></div></div></div>
9057 <p>
9058               Socket I/O statistics counters are defined per socket
9059               types, which are
9060               <span><strong class="command">UDP4</strong></span> (UDP/IPv4),
9061               <span><strong class="command">UDP6</strong></span> (UDP/IPv6),
9062               <span><strong class="command">TCP4</strong></span> (TCP/IPv4),
9063               <span><strong class="command">TCP6</strong></span> (TCP/IPv6),
9064               <span><strong class="command">Unix</strong></span> (Unix Domain), and
9065               <span><strong class="command">FDwatch</strong></span> (sockets opened outside the
9066               socket module).
9067               In the following table <span><strong class="command">&lt;TYPE&gt;</strong></span>
9068               represents a socket type.
9069               Not all counters are available for all socket types;
9070               exceptions are noted in the description field.
9071             </p>
9072 <div class="informaltable"><table border="1">
9073 <colgroup>
9074 <col>
9075 <col>
9076 </colgroup>
9077 <tbody>
9078 <tr>
9079 <td>
9080                       <p>
9081                         <span class="emphasis"><em>Symbol</em></span>
9082                       </p>
9083                     </td>
9084 <td>
9085                       <p>
9086                         <span class="emphasis"><em>Description</em></span>
9087                       </p>
9088                     </td>
9089 </tr>
9090 <tr>
9091 <td>
9092                       <p><span><strong class="command">&lt;TYPE&gt;Open</strong></span></p>
9093                     </td>
9094 <td>
9095                       <p>
9096                         Sockets opened successfully.
9097                         This counter is not applicable to the
9098                         <span><strong class="command">FDwatch</strong></span> type.
9099                       </p>
9100                     </td>
9101 </tr>
9102 <tr>
9103 <td>
9104                       <p><span><strong class="command">&lt;TYPE&gt;OpenFail</strong></span></p>
9105                     </td>
9106 <td>
9107                       <p>
9108                         Failures of opening sockets.
9109                         This counter is not applicable to the
9110                         <span><strong class="command">FDwatch</strong></span> type.
9111                       </p>
9112                     </td>
9113 </tr>
9114 <tr>
9115 <td>
9116                       <p><span><strong class="command">&lt;TYPE&gt;Close</strong></span></p>
9117                     </td>
9118 <td>
9119                       <p>
9120                         Sockets closed.
9121                       </p>
9122                     </td>
9123 </tr>
9124 <tr>
9125 <td>
9126                       <p><span><strong class="command">&lt;TYPE&gt;BindFail</strong></span></p>
9127                     </td>
9128 <td>
9129                       <p>
9130                         Failures of binding sockets.
9131                       </p>
9132                     </td>
9133 </tr>
9134 <tr>
9135 <td>
9136                       <p><span><strong class="command">&lt;TYPE&gt;ConnFail</strong></span></p>
9137                     </td>
9138 <td>
9139                       <p>
9140                         Failures of connecting sockets.
9141                       </p>
9142                     </td>
9143 </tr>
9144 <tr>
9145 <td>
9146                       <p><span><strong class="command">&lt;TYPE&gt;Conn</strong></span></p>
9147                     </td>
9148 <td>
9149                       <p>
9150                         Connections established successfully.
9151                       </p>
9152                     </td>
9153 </tr>
9154 <tr>
9155 <td>
9156                       <p><span><strong class="command">&lt;TYPE&gt;AcceptFail</strong></span></p>
9157                     </td>
9158 <td>
9159                       <p>
9160                         Failures of accepting incoming connection requests.
9161                         This counter is not applicable to the
9162                         <span><strong class="command">UDP</strong></span> and
9163                         <span><strong class="command">FDwatch</strong></span> types.
9164                       </p>
9165                     </td>
9166 </tr>
9167 <tr>
9168 <td>
9169                       <p><span><strong class="command">&lt;TYPE&gt;Accept</strong></span></p>
9170                     </td>
9171 <td>
9172                       <p>
9173                         Incoming connections successfully accepted.
9174                         This counter is not applicable to the
9175                         <span><strong class="command">UDP</strong></span> and
9176                         <span><strong class="command">FDwatch</strong></span> types.
9177                       </p>
9178                     </td>
9179 </tr>
9180 <tr>
9181 <td>
9182                       <p><span><strong class="command">&lt;TYPE&gt;SendErr</strong></span></p>
9183                     </td>
9184 <td>
9185                       <p>
9186                         Errors in socket send operations.
9187                         This counter corresponds
9188                         to <span><strong class="command">SErr</strong></span> counter of
9189                         <span><strong class="command">BIND</strong></span> 8.
9190                       </p>
9191                     </td>
9192 </tr>
9193 <tr>
9194 <td>
9195                       <p><span><strong class="command">&lt;TYPE&gt;RecvErr</strong></span></p>
9196                     </td>
9197 <td>
9198                       <p>
9199                         Errors in socket receive operations.
9200                         This includes errors of send operations on a
9201                         connected UDP socket notified by an ICMP error
9202                         message.
9203                       </p>
9204                     </td>
9205 </tr>
9206 </tbody>
9207 </table></div>
9208 </div>
9209 <div class="sect3" lang="en">
9210 <div class="titlepage"><div><div><h4 class="title">
9211 <a name="id2598651"></a>Compatibility with <span class="emphasis"><em>BIND</em></span> 8 Counters</h4></div></div></div>
9212 <p>
9213               Most statistics counters that were available
9214               in <span><strong class="command">BIND</strong></span> 8 are also supported in
9215               <span><strong class="command">BIND</strong></span> 9 as shown in the above tables.
9216               Here are notes about other counters that do not appear
9217               in these tables.
9218             </p>
9219 <div class="variablelist"><dl>
9220 <dt><span class="term"><span><strong class="command">RFwdR,SFwdR</strong></span></span></dt>
9221 <dd><p>
9222                     These counters are not supported
9223                     because <span><strong class="command">BIND</strong></span> 9 does not adopt
9224                     the notion of <span class="emphasis"><em>forwarding</em></span>
9225                     as <span><strong class="command">BIND</strong></span> 8 did.
9226                   </p></dd>
9227 <dt><span class="term"><span><strong class="command">RAXFR</strong></span></span></dt>
9228 <dd><p>
9229                     This counter is accessible in the Incoming Queries section.
9230                   </p></dd>
9231 <dt><span class="term"><span><strong class="command">RIQ</strong></span></span></dt>
9232 <dd><p>
9233                     This counter is accessible in the Incoming Requests section.
9234                   </p></dd>
9235 <dt><span class="term"><span><strong class="command">ROpts</strong></span></span></dt>
9236 <dd><p>
9237                     This counter is not supported
9238                     because <span><strong class="command">BIND</strong></span> 9 does not care
9239                     about IP options in the first place.
9240                   </p></dd>
9241 </dl></div>
9242 </div>
9243 </div>
9244 </div>
9245 </div>
9246 <div class="navfooter">
9247 <hr>
9248 <table width="100%" summary="Navigation footer">
9249 <tr>
9250 <td width="40%" align="left">
9251 <a accesskey="p" href="Bv9ARM.ch05.html">Prev</a> </td>
9252 <td width="20%" align="center"> </td>
9253 <td width="40%" align="right"> <a accesskey="n" href="Bv9ARM.ch07.html">Next</a>
9254 </td>
9255 </tr>
9256 <tr>
9257 <td width="40%" align="left" valign="top">Chapter 5. The <acronym class="acronym">BIND</acronym> 9 Lightweight Resolver </td>
9258 <td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td>
9259 <td width="40%" align="right" valign="top"> Chapter 7. <acronym class="acronym">BIND</acronym> 9 Security Considerations</td>
9260 </tr>
9261 </table>
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