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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>
46 <p><b>Table of Contents</b></p>
48 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#configuration_file_elements">Configuration File Elements</a></span></dt>
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#id2573606">Comment Syntax</a></span></dt>
53 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#Configuration_File_Grammar">Configuration File Grammar</a></span></dt>
55 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574305"><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
58 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574494"><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
61 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574923"><span><strong class="command">include</strong></span> Statement Grammar</a></span></dt>
62 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574940"><span><strong class="command">include</strong></span> Statement Definition and
64 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574964"><span><strong class="command">key</strong></span> Statement Grammar</a></span></dt>
65 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574987"><span><strong class="command">key</strong></span> Statement Definition and Usage</a></span></dt>
66 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575078"><span><strong class="command">logging</strong></span> Statement Grammar</a></span></dt>
67 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575204"><span><strong class="command">logging</strong></span> Statement Definition and
69 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577401"><span><strong class="command">lwres</strong></span> Statement Grammar</a></span></dt>
70 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577475"><span><strong class="command">lwres</strong></span> Statement Definition and Usage</a></span></dt>
71 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577539"><span><strong class="command">masters</strong></span> Statement Grammar</a></span></dt>
72 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577582"><span><strong class="command">masters</strong></span> Statement Definition and
74 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577597"><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
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
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#id2586907"><span><strong class="command">statistics-channels</strong></span> Statement Definition and
83 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2587062"><span><strong class="command">trusted-keys</strong></span> Statement Grammar</a></span></dt>
84 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2587113"><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#id2587195"><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#id2588600"><span><strong class="command">zone</strong></span> Statement Definition and Usage</a></span></dt>
92 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#id2591216">Zone File</a></span></dt>
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#id2593378">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#id2593993">Inverse Mapping in IPv4</a></span></dt>
98 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2594188">Other Zone File Directives</a></span></dt>
99 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2594461"><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>
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>
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
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.
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>.
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>
126 Following is a list of elements used throughout the <acronym class="acronym">BIND</acronym> configuration
129 <div class="informaltable"><table border="1">
138 <code class="varname">acl_name</code>
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.
151 <code class="varname">address_match_list</code>
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 “Address Match Lists”</a>.
167 <code class="varname">masters_list</code>
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>.
183 <code class="varname">domain_name</code>
188 A quoted string which will be used as
189 a DNS name, for example "<code class="literal">my.test.domain</code>".
196 <code class="varname">dotted_decimal</code>
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>.
210 <code class="varname">ip4_addr</code>
215 An IPv4 address with exactly four elements
216 in <code class="varname">dotted_decimal</code> notation.
223 <code class="varname">ip6_addr</code>
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
252 <code class="varname">ip_addr</code>
257 An <code class="varname">ip4_addr</code> or <code class="varname">ip6_addr</code>.
264 <code class="varname">ip_port</code>
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
274 In some cases, an asterisk (`*') character can be used as a
276 select a random high-numbered port.
283 <code class="varname">ip_prefix</code>
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
291 Trailing zeros in a <code class="varname">ip_addr</code>
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>.
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.
308 <code class="varname">key_id</code>
313 A <code class="varname">domain_name</code> representing
314 the name of a shared key, to be used for transaction
322 <code class="varname">key_list</code>
327 A list of one or more
328 <code class="varname">key_id</code>s,
329 separated by semicolons and ending with a semicolon.
336 <code class="varname">number</code>
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.
351 <code class="varname">path_name</code>
356 A quoted string which will be used as
357 a pathname, such as <code class="filename">zones/master/my.test.domain</code>.
364 <code class="varname">port_list</code>
369 A list of an <code class="varname">ip_port</code> or a port
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>.
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>.
391 <code class="varname">size_spec</code>
396 A number, the word <strong class="userinput"><code>unlimited</code></strong>,
397 or the word <strong class="userinput"><code>default</code></strong>.
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.
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>
409 <strong class="userinput"><code>M</code></strong> or <strong class="userinput"><code>m</code></strong>
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
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
420 to safely set a really large number.
427 <code class="varname">yes_or_no</code>
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>.
442 <code class="varname">dialup_option</code>
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.
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="id2573372"></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 } )
471 <div class="sect3" lang="en">
472 <div class="titlepage"><div><div><h4 class="title">
473 <a name="id2573468"></a>Definition and Usage</h4></div></div></div>
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:
481 <div class="itemizedlist"><ul type="disc">
482 <li>an IP address (IPv4 or IPv6)</li>
483 <li>an IP prefix (in `/' notation)</li>
485 a key ID, as defined by the <span><strong class="command">key</strong></span>
488 <li>the name of an address match list defined with
489 the <span><strong class="command">acl</strong></span> statement
491 <li>a nested address match list enclosed in braces</li>
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.
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.
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
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.
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.
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.
555 <div class="sect2" lang="en">
556 <div class="titlepage"><div><div><h3 class="title">
557 <a name="id2573606"></a>Comment Syntax</h3></div></div></div>
559 The <acronym class="acronym">BIND</acronym> 9 comment syntax allows for
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.
565 <div class="sect3" lang="en">
566 <div class="titlepage"><div><div><h4 class="title">
567 <a name="id2573621"></a>Syntax</h4></div></div></div>
570 <pre class="programlisting">/* This is a <acronym class="acronym">BIND</acronym> comment as in C */</pre>
573 <pre class="programlisting">// This is a <acronym class="acronym">BIND</acronym> comment as in C++</pre>
576 <pre class="programlisting"># This is a <acronym class="acronym">BIND</acronym> comment as in common UNIX shells and perl</pre>
580 <div class="sect3" lang="en">
581 <div class="titlepage"><div><div><h4 class="title">
582 <a name="id2573651"></a>Definition and Usage</h4></div></div></div>
584 Comments may appear anywhere that whitespace may appear in
585 a <acronym class="acronym">BIND</acronym> configuration file.
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.
594 C-style comments cannot be nested. For example, the following
595 is not valid because the entire comment ends with the first */:
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. */
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.
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.
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.
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.
642 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
643 <h3 class="title">Warning</h3>
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
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>
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.
666 The following statements are supported:
668 <div class="informaltable"><table border="1">
676 <p><span><strong class="command">acl</strong></span></p>
680 defines a named IP address
681 matching list, for access control and other uses.
687 <p><span><strong class="command">controls</strong></span></p>
691 declares control channels to be used
692 by the <span><strong class="command">rndc</strong></span> utility.
698 <p><span><strong class="command">include</strong></span></p>
708 <p><span><strong class="command">key</strong></span></p>
712 specifies key information for use in
713 authentication and authorization using TSIG.
719 <p><span><strong class="command">logging</strong></span></p>
723 specifies what the server logs, and where
724 the log messages are sent.
730 <p><span><strong class="command">lwres</strong></span></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>).
741 <p><span><strong class="command">masters</strong></span></p>
745 defines a named masters list for
746 inclusion in stub and slave zone masters clauses.
752 <p><span><strong class="command">options</strong></span></p>
756 controls global server configuration
757 options and sets defaults for other statements.
763 <p><span><strong class="command">server</strong></span></p>
767 sets certain configuration options on
774 <p><span><strong class="command">statistics-channels</strong></span></p>
778 declares communication channels to get access to
779 <span><strong class="command">named</strong></span> statistics.
785 <p><span><strong class="command">trusted-keys</strong></span></p>
789 defines trusted DNSSEC keys.
795 <p><span><strong class="command">view</strong></span></p>
805 <p><span><strong class="command">zone</strong></span></p>
816 The <span><strong class="command">logging</strong></span> and
817 <span><strong class="command">options</strong></span> statements may only occur once
821 <div class="sect2" lang="en">
822 <div class="titlepage"><div><div><h3 class="title">
823 <a name="id2574305"></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 {
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>
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).
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.
844 The following ACLs are built-in:
846 <div class="informaltable"><table border="1">
854 <p><span><strong class="command">any</strong></span></p>
864 <p><span><strong class="command">none</strong></span></p>
874 <p><span><strong class="command">localhost</strong></span></p>
878 Matches the IPv4 and IPv6 addresses of all network
879 interfaces on the system.
885 <p><span><strong class="command">localnets</strong></span></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
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>.
903 <div class="sect2" lang="en">
904 <div class="titlepage"><div><div><h3 class="title">
905 <a name="id2574494"></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> }; ]
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> }; ]
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>
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.
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.
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>.
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>
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.
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 “Administrative Tools”</a>)
969 for information about configuring keys in <span><strong class="command">rndc</strong></span>.
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>.
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.
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
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
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
1007 those things. The <code class="filename">rndc.key</code> file
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.
1012 desire greater flexibility in allowing other users to access
1013 <span><strong class="command">rndc</strong></span> commands, then you need to create
1015 <code class="filename">rndc.conf</code> file and make it group
1017 that contains the users who should have access.
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>.
1025 <div class="sect2" lang="en">
1026 <div class="titlepage"><div><div><h3 class="title">
1027 <a name="id2574923"></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>
1030 <div class="sect2" lang="en">
1031 <div class="titlepage"><div><div><h3 class="title">
1032 <a name="id2574940"></a><span><strong class="command">include</strong></span> Statement Definition and
1033 Usage</h3></div></div></div>
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
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.
1045 <div class="sect2" lang="en">
1046 <div class="titlepage"><div><div><h3 class="title">
1047 <a name="id2574964"></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>;
1054 <div class="sect2" lang="en">
1055 <div class="titlepage"><div><div><h3 class="title">
1056 <a name="id2574987"></a><span><strong class="command">key</strong></span> Statement Definition and Usage</h3></div></div></div>
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 “TSIG”</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 “<span><strong class="command">controls</strong></span> Statement Definition and
1066 The <span><strong class="command">key</strong></span> statement can occur at the
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 “<span><strong class="command">controls</strong></span> Statement Definition and
1075 must be defined at the top level.
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.
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
1101 <div class="sect2" lang="en">
1102 <div class="titlepage"><div><div><h3 class="title">
1103 <a name="id2575078"></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>; ]
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> ; ... ]
1125 <div class="sect2" lang="en">
1126 <div class="titlepage"><div><div><h3 class="title">
1127 <a name="id2575204"></a><span><strong class="command">logging</strong></span> Statement Definition and
1128 Usage</h3></div></div></div>
1130 The <span><strong class="command">logging</strong></span> statement configures a
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.
1138 Only one <span><strong class="command">logging</strong></span> statement is used to
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:
1143 <pre class="programlisting">logging {
1144 category default { default_syslog; default_debug; };
1145 category unmatched { null; };
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>
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
1159 <div class="sect3" lang="en">
1160 <div class="titlepage"><div><div><h4 class="title">
1161 <a name="id2575256"></a>The <span><strong class="command">channel</strong></span> Phrase</h4></div></div></div>
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.
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
1175 and/or severity level (the default is not to include any).
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.
1183 The <span><strong class="command">file</strong></span> destination clause directs
1185 to a disk file. It can include limitations
1186 both on how large the file is allowed to become, and how many
1188 of the file will be saved each time the file is opened.
1191 If you use the <span><strong class="command">versions</strong></span> log file
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
1197 of the file <code class="filename">lamers.log</code>, then just
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
1205 the number of versions.
1206 If a <span><strong class="command">size</strong></span> option is associated with
1208 then renaming is only done when the file being opened exceeds the
1209 indicated size. No backup versions are kept by default; any
1211 log file is simply appended.
1214 The <span><strong class="command">size</strong></span> option for files is used
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
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
1225 maximum size. The default behavior is not to limit the size of
1230 Example usage of the <span><strong class="command">size</strong></span> and
1231 <span><strong class="command">versions</strong></span> options:
1233 <pre class="programlisting">channel an_example_channel {
1234 file "example.log" versions 3 size 20m;
1240 The <span><strong class="command">syslog</strong></span> destination clause
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
1253 all operating systems.
1254 How <span><strong class="command">syslog</strong></span> will handle messages
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.
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
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.
1283 The <span><strong class="command">stderr</strong></span> destination clause
1285 channel to the server's standard error stream. This is intended
1287 use when the server is running as a foreground process, for
1289 when debugging a configuration.
1292 The server can supply extensive debugging information when
1293 it is in debugging mode. If the server's global debug level is
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:
1305 <pre class="programlisting">channel specific_debug_level {
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>
1315 server's global debug level to determine what messages to print.
1318 If <span><strong class="command">print-time</strong></span> has been turned on,
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,
1323 pointless since <span><strong class="command">syslog</strong></span> also logs
1325 time. If <span><strong class="command">print-category</strong></span> is
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
1331 order: time, category, severity. Here is an example where all
1332 three <span><strong class="command">print-</strong></span> options
1336 <code class="computeroutput">28-Feb-2000 15:05:32.863 general: notice: running</code>
1339 There are four predefined channels that are used for
1340 <span><strong class="command">named</strong></span>'s default logging as follows.
1342 used is described in <a href="Bv9ARM.ch06.html#the_category_phrase" title="The category Phrase">the section called “The <span><strong class="command">category</strong></span> Phrase”</a>.
1344 <pre class="programlisting">channel default_syslog {
1345 syslog daemon; // send to syslog's daemon
1347 severity info; // only send priority info
1351 channel default_debug {
1352 file "named.run"; // write to named.run in
1353 // the working directory
1354 // Note: stderr is used instead
1356 // if the server is started
1357 // with the '-f' option.
1358 severity dynamic; // log at the server's
1359 // current debug level
1362 channel default_stderr {
1363 stderr; // writes to stderr
1364 severity info; // only send priority info
1369 null; // toss anything sent to
1374 The <span><strong class="command">default_debug</strong></span> channel has the
1376 property that it only produces output when the server's debug
1378 nonzero. It normally writes to a file called <code class="filename">named.run</code>
1379 in the server's working directory.
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
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.
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
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>
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
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:
1410 <pre class="programlisting">category default { default_syslog; default_debug; };
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:
1417 <pre class="programlisting">channel my_security_channel {
1418 file "my_security_file";
1422 my_security_channel;
1427 To discard all messages in a category, specify the <span><strong class="command">null</strong></span> channel:
1429 <pre class="programlisting">category xfer-out { null; };
1430 category notify { null; };
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.
1437 <div class="informaltable"><table border="1">
1445 <p><span><strong class="command">default</strong></span></p>
1449 The default category defines the logging
1450 options for those categories where no specific
1451 configuration has been
1458 <p><span><strong class="command">general</strong></span></p>
1462 The catch-all. Many things still aren't
1463 classified into categories, and they all end up here.
1469 <p><span><strong class="command">database</strong></span></p>
1473 Messages relating to the databases used
1474 internally by the name server to store zone and cache
1481 <p><span><strong class="command">security</strong></span></p>
1485 Approval and denial of requests.
1491 <p><span><strong class="command">config</strong></span></p>
1495 Configuration file parsing and processing.
1501 <p><span><strong class="command">resolver</strong></span></p>
1505 DNS resolution, such as the recursive
1506 lookups performed on behalf of clients by a caching name
1513 <p><span><strong class="command">xfer-in</strong></span></p>
1517 Zone transfers the server is receiving.
1523 <p><span><strong class="command">xfer-out</strong></span></p>
1527 Zone transfers the server is sending.
1533 <p><span><strong class="command">notify</strong></span></p>
1537 The NOTIFY protocol.
1543 <p><span><strong class="command">client</strong></span></p>
1547 Processing of client requests.
1553 <p><span><strong class="command">unmatched</strong></span></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.
1568 <p><span><strong class="command">network</strong></span></p>
1578 <p><span><strong class="command">update</strong></span></p>
1588 <p><span><strong class="command">update-security</strong></span></p>
1592 Approval and denial of update requests.
1598 <p><span><strong class="command">queries</strong></span></p>
1602 Specify where queries should be logged to.
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
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
1622 <code class="computeroutput">client 127.0.0.1#62536: query: www.example.com IN AAAA +SE</code>
1625 <code class="computeroutput">client ::1#62537: query: www.example.net IN AAAA -SE</code>
1631 <p><span><strong class="command">query-errors</strong></span></p>
1635 Information about queries that resulted in some
1642 <p><span><strong class="command">dispatch</strong></span></p>
1646 Dispatching of incoming packets to the
1647 server modules where they are to be processed.
1653 <p><span><strong class="command">dnssec</strong></span></p>
1657 DNSSEC and TSIG protocol processing.
1663 <p><span><strong class="command">lame-servers</strong></span></p>
1667 Lame servers. These are misconfigurations
1668 in remote servers, discovered by BIND 9 when trying to
1669 query those servers during resolution.
1675 <p><span><strong class="command">delegation-only</strong></span></p>
1679 Delegation only. Logs queries that have been
1680 forced to NXDOMAIN as the result of a
1681 delegation-only zone or a
1682 <span><strong class="command">delegation-only</strong></span> in a hint
1683 or stub zone declaration.
1689 <p><span><strong class="command">edns-disabled</strong></span></p>
1693 Log queries that have been forced to use plain
1694 DNS due to timeouts. This is often due to
1695 the remote servers not being RFC 1034 compliant
1696 (not always returning FORMERR or similar to
1697 EDNS queries and other extensions to the DNS
1698 when they are not understood). In other words, this is
1699 targeted at servers that fail to respond to
1700 DNS queries that they don't understand.
1703 Note: the log message can also be due to
1704 packet loss. Before reporting servers for
1705 non-RFC 1034 compliance they should be re-tested
1706 to determine the nature of the non-compliance.
1707 This testing should prevent or reduce the
1708 number of false-positive reports.
1711 Note: eventually <span><strong class="command">named</strong></span> will have to stop
1712 treating such timeouts as due to RFC 1034 non
1713 compliance and start treating it as plain
1714 packet loss. Falsely classifying packet
1715 loss as due to RFC 1034 non compliance impacts
1716 on DNSSEC validation which requires EDNS for
1717 the DNSSEC records to be returned.
1724 <div class="sect3" lang="en">
1725 <div class="titlepage"><div><div><h4 class="title">
1726 <a name="id2576820"></a>The <span><strong class="command">query-errors</strong></span> Category</h4></div></div></div>
1728 The <span><strong class="command">query-errors</strong></span> category is
1729 specifically intended for debugging purposes: To identify
1730 why and how specific queries result in responses which
1732 Messages of this category are therefore only logged
1733 with <span><strong class="command">debug</strong></span> levels.
1736 At the debug levels of 1 or higher, each response with the
1737 rcode of SERVFAIL is logged as follows:
1740 <code class="computeroutput">client 127.0.0.1#61502: query failed (SERVFAIL) for www.example.com/IN/AAAA at query.c:3880</code>
1743 This means an error resulting in SERVFAIL was
1744 detected at line 3880 of source file
1745 <code class="filename">query.c</code>.
1746 Log messages of this level will particularly
1747 help identify the cause of SERVFAIL for an
1748 authoritative server.
1751 At the debug levels of 2 or higher, detailed context
1752 information of recursive resolutions that resulted in
1754 The log message will look like as follows:
1757 <code class="computeroutput">fetch completed at resolver.c:2970 for www.example.com/A in 30.000183: timed out/success [domain:example.com,referral:2,restart:7,qrysent:8,timeout:5,lame:0,neterr:0,badresp:1,adberr:0,findfail:0,valfail:0]</code>
1760 The first part before the colon shows that a recursive
1761 resolution for AAAA records of www.example.com completed
1762 in 30.000183 seconds and the final result that led to the
1763 SERVFAIL was determined at line 2970 of source file
1764 <code class="filename">resolver.c</code>.
1767 The following part shows the detected final result and the
1768 latest result of DNSSEC validation.
1769 The latter is always success when no validation attempt
1771 In this example, this query resulted in SERVFAIL probably
1772 because all name servers are down or unreachable, leading
1773 to a timeout in 30 seconds.
1774 DNSSEC validation was probably not attempted.
1777 The last part enclosed in square brackets shows statistics
1778 information collected for this particular resolution
1780 The <code class="varname">domain</code> field shows the deepest zone
1781 that the resolver reached;
1782 it is the zone where the error was finally detected.
1783 The meaning of the other fields is summarized in the
1786 <div class="informaltable"><table border="1">
1794 <p><code class="varname">referral</code></p>
1798 The number of referrals the resolver received
1799 throughout the resolution process.
1800 In the above example this is 2, which are most
1801 likely com and example.com.
1807 <p><code class="varname">restart</code></p>
1811 The number of cycles that the resolver tried
1812 remote servers at the <code class="varname">domain</code>
1814 In each cycle the resolver sends one query
1815 (possibly resending it, depending on the response)
1816 to each known name server of
1817 the <code class="varname">domain</code> zone.
1823 <p><code class="varname">qrysent</code></p>
1827 The number of queries the resolver sent at the
1828 <code class="varname">domain</code> zone.
1834 <p><code class="varname">timeout</code></p>
1838 The number of timeouts since the resolver
1839 received the last response.
1845 <p><code class="varname">lame</code></p>
1849 The number of lame servers the resolver detected
1850 at the <code class="varname">domain</code> zone.
1851 A server is detected to be lame either by an
1852 invalid response or as a result of lookup in
1853 BIND9's address database (ADB), where lame
1860 <p><code class="varname">neterr</code></p>
1864 The number of erroneous results that the
1865 resolver encountered in sending queries
1866 at the <code class="varname">domain</code> zone.
1867 One common case is the remote server is
1868 unreachable and the resolver receives an ICMP
1869 unreachable error message.
1875 <p><code class="varname">badresp</code></p>
1879 The number of unexpected responses (other than
1880 <code class="varname">lame</code>) to queries sent by the
1881 resolver at the <code class="varname">domain</code> zone.
1887 <p><code class="varname">adberr</code></p>
1891 Failures in finding remote server addresses
1892 of the <code class="varname">domain</code> zone in the ADB.
1893 One common case of this is that the remote
1894 server's name does not have any address records.
1900 <p><code class="varname">findfail</code></p>
1904 Failures of resolving remote server addresses.
1905 This is a total number of failures throughout
1906 the resolution process.
1912 <p><code class="varname">valfail</code></p>
1916 Failures of DNSSEC validation.
1917 Validation failures are counted throughout
1918 the resolution process (not limited to
1919 the <code class="varname">domain</code> zone), but should
1920 only happen in <code class="varname">domain</code>.
1927 At the debug levels of 3 or higher, the same messages
1928 as those at the debug 1 level are logged for other errors
1930 Note that negative responses such as NXDOMAIN are not
1931 regarded as errors here.
1934 At the debug levels of 4 or higher, the same messages
1935 as those at the debug 2 level are logged for other errors
1937 Unlike the above case of level 3, messages are logged for
1939 This is because any unexpected results can be difficult to
1940 debug in the recursion case.
1944 <div class="sect2" lang="en">
1945 <div class="titlepage"><div><div><h3 class="title">
1946 <a name="id2577401"></a><span><strong class="command">lwres</strong></span> Statement Grammar</h3></div></div></div>
1948 This is the grammar of the <span><strong class="command">lwres</strong></span>
1949 statement in the <code class="filename">named.conf</code> file:
1951 <pre class="programlisting"><span><strong class="command">lwres</strong></span> {
1952 [<span class="optional"> listen-on { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
1953 [<span class="optional"> view <em class="replaceable"><code>view_name</code></em>; </span>]
1954 [<span class="optional"> search { <em class="replaceable"><code>domain_name</code></em> ; [<span class="optional"> <em class="replaceable"><code>domain_name</code></em> ; ... </span>] }; </span>]
1955 [<span class="optional"> ndots <em class="replaceable"><code>number</code></em>; </span>]
1959 <div class="sect2" lang="en">
1960 <div class="titlepage"><div><div><h3 class="title">
1961 <a name="id2577475"></a><span><strong class="command">lwres</strong></span> Statement Definition and Usage</h3></div></div></div>
1963 The <span><strong class="command">lwres</strong></span> statement configures the
1965 server to also act as a lightweight resolver server. (See
1966 <a href="Bv9ARM.ch05.html#lwresd" title="Running a Resolver Daemon">the section called “Running a Resolver Daemon”</a>.) There may be multiple
1967 <span><strong class="command">lwres</strong></span> statements configuring
1968 lightweight resolver servers with different properties.
1971 The <span><strong class="command">listen-on</strong></span> statement specifies a
1973 addresses (and ports) that this instance of a lightweight resolver
1975 should accept requests on. If no port is specified, port 921 is
1977 If this statement is omitted, requests will be accepted on
1982 The <span><strong class="command">view</strong></span> statement binds this
1984 lightweight resolver daemon to a view in the DNS namespace, so that
1986 response will be constructed in the same manner as a normal DNS
1988 matching this view. If this statement is omitted, the default view
1990 used, and if there is no default view, an error is triggered.
1993 The <span><strong class="command">search</strong></span> statement is equivalent to
1995 <span><strong class="command">search</strong></span> statement in
1996 <code class="filename">/etc/resolv.conf</code>. It provides a
1998 which are appended to relative names in queries.
2001 The <span><strong class="command">ndots</strong></span> statement is equivalent to
2003 <span><strong class="command">ndots</strong></span> statement in
2004 <code class="filename">/etc/resolv.conf</code>. It indicates the
2006 number of dots in a relative domain name that should result in an
2007 exact match lookup before search path elements are appended.
2010 <div class="sect2" lang="en">
2011 <div class="titlepage"><div><div><h3 class="title">
2012 <a name="id2577539"></a><span><strong class="command">masters</strong></span> Statement Grammar</h3></div></div></div>
2013 <pre class="programlisting">
2014 <span><strong class="command">masters</strong></span> <em class="replaceable"><code>name</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { ( <em class="replaceable"><code>masters_list</code></em> | <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] };
2017 <div class="sect2" lang="en">
2018 <div class="titlepage"><div><div><h3 class="title">
2019 <a name="id2577582"></a><span><strong class="command">masters</strong></span> Statement Definition and
2020 Usage</h3></div></div></div>
2021 <p><span><strong class="command">masters</strong></span>
2022 lists allow for a common set of masters to be easily used by
2023 multiple stub and slave zones.
2026 <div class="sect2" lang="en">
2027 <div class="titlepage"><div><div><h3 class="title">
2028 <a name="id2577597"></a><span><strong class="command">options</strong></span> Statement Grammar</h3></div></div></div>
2030 This is the grammar of the <span><strong class="command">options</strong></span>
2031 statement in the <code class="filename">named.conf</code> file:
2033 <pre class="programlisting"><span><strong class="command">options</strong></span> {
2034 [<span class="optional"> version <em class="replaceable"><code>version_string</code></em>; </span>]
2035 [<span class="optional"> hostname <em class="replaceable"><code>hostname_string</code></em>; </span>]
2036 [<span class="optional"> server-id <em class="replaceable"><code>server_id_string</code></em>; </span>]
2037 [<span class="optional"> directory <em class="replaceable"><code>path_name</code></em>; </span>]
2038 [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>]
2039 [<span class="optional"> named-xfer <em class="replaceable"><code>path_name</code></em>; </span>]
2040 [<span class="optional"> tkey-gssapi-credential <em class="replaceable"><code>principal</code></em>; </span>]
2041 [<span class="optional"> tkey-domain <em class="replaceable"><code>domainname</code></em>; </span>]
2042 [<span class="optional"> tkey-dhkey <em class="replaceable"><code>key_name</code></em> <em class="replaceable"><code>key_tag</code></em>; </span>]
2043 [<span class="optional"> cache-file <em class="replaceable"><code>path_name</code></em>; </span>]
2044 [<span class="optional"> dump-file <em class="replaceable"><code>path_name</code></em>; </span>]
2045 [<span class="optional"> memstatistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2046 [<span class="optional"> memstatistics-file <em class="replaceable"><code>path_name</code></em>; </span>]
2047 [<span class="optional"> pid-file <em class="replaceable"><code>path_name</code></em>; </span>]
2048 [<span class="optional"> recursing-file <em class="replaceable"><code>path_name</code></em>; </span>]
2049 [<span class="optional"> statistics-file <em class="replaceable"><code>path_name</code></em>; </span>]
2050 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2051 [<span class="optional"> auth-nxdomain <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2052 [<span class="optional"> deallocate-on-exit <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2053 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em>; </span>]
2054 [<span class="optional"> fake-iquery <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2055 [<span class="optional"> fetch-glue <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2056 [<span class="optional"> flush-zones-on-shutdown <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2057 [<span class="optional"> has-old-clients <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2058 [<span class="optional"> host-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2059 [<span class="optional"> host-statistics-max <em class="replaceable"><code>number</code></em>; </span>]
2060 [<span class="optional"> minimal-responses <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2061 [<span class="optional"> multiple-cnames <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2062 [<span class="optional"> notify <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>explicit</code></em> | <em class="replaceable"><code>master-only</code></em>; </span>]
2063 [<span class="optional"> recursion <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2064 [<span class="optional"> rfc2308-type1 <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2065 [<span class="optional"> use-id-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2066 [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2067 [<span class="optional"> ixfr-from-differences (<em class="replaceable"><code>yes_or_no</code></em> | <code class="constant">master</code> | <code class="constant">slave</code>); </span>]
2068 [<span class="optional"> dnssec-enable <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2069 [<span class="optional"> dnssec-validation <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2070 [<span class="optional"> dnssec-lookaside <em class="replaceable"><code>domain</code></em> trust-anchor <em class="replaceable"><code>domain</code></em>; </span>]
2071 [<span class="optional"> dnssec-must-be-secure <em class="replaceable"><code>domain yes_or_no</code></em>; </span>]
2072 [<span class="optional"> dnssec-accept-expired <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2073 [<span class="optional"> forward ( <em class="replaceable"><code>only</code></em> | <em class="replaceable"><code>first</code></em> ); </span>]
2074 [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
2075 [<span class="optional"> dual-stack-servers [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] {
2076 ( <em class="replaceable"><code>domain_name</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] |
2077 <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ) ;
2079 [<span class="optional"> check-names ( <em class="replaceable"><code>master</code></em> | <em class="replaceable"><code>slave</code></em> | <em class="replaceable"><code>response</code></em> )
2080 ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2081 [<span class="optional"> check-mx ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2082 [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2083 [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2084 [<span class="optional"> check-mx-cname ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2085 [<span class="optional"> check-srv-cname ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2086 [<span class="optional"> check-sibling <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2087 [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2088 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2089 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2090 [<span class="optional"> allow-query-cache { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2091 [<span class="optional"> allow-query-cache-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2092 [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2093 [<span class="optional"> allow-recursion { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2094 [<span class="optional"> allow-recursion-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2095 [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2096 [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2097 [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2098 [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2099 [<span class="optional"> allow-v6-synthesis { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2100 [<span class="optional"> blackhole { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2101 [<span class="optional"> use-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2102 [<span class="optional"> avoid-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2103 [<span class="optional"> use-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2104 [<span class="optional"> avoid-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2105 [<span class="optional"> listen-on [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em> </span>] { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2106 [<span class="optional"> listen-on-v6 [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em> </span>] { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2107 [<span class="optional"> query-source ( ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> )
2108 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] |
2109 [<span class="optional"> address ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
2110 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>]
2111 [<span class="optional"> query-source-v6 ( ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> )
2112 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] |
2113 [<span class="optional"> address ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
2114 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>]
2115 [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2116 [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>]
2117 [<span class="optional"> queryport-pool-updateinterval <em class="replaceable"><code>number</code></em>; </span>]
2118 [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em>; </span>]
2119 [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em>; </span>]
2120 [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em>; </span>]
2121 [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em>; </span>]
2122 [<span class="optional"> tcp-clients <em class="replaceable"><code>number</code></em>; </span>]
2123 [<span class="optional"> reserved-sockets <em class="replaceable"><code>number</code></em>; </span>]
2124 [<span class="optional"> recursive-clients <em class="replaceable"><code>number</code></em>; </span>]
2125 [<span class="optional"> serial-query-rate <em class="replaceable"><code>number</code></em>; </span>]
2126 [<span class="optional"> serial-queries <em class="replaceable"><code>number</code></em>; </span>]
2127 [<span class="optional"> tcp-listen-queue <em class="replaceable"><code>number</code></em>; </span>]
2128 [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em>; </span>]
2129 [<span class="optional"> transfers-in <em class="replaceable"><code>number</code></em>; </span>]
2130 [<span class="optional"> transfers-out <em class="replaceable"><code>number</code></em>; </span>]
2131 [<span class="optional"> transfers-per-ns <em class="replaceable"><code>number</code></em>; </span>]
2132 [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2133 [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2134 [<span class="optional"> alt-transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2135 [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2136 [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2137 [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
2138 [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2139 [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2140 [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2141 [<span class="optional"> also-notify { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>]
2142 [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em>; </span>]
2143 [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
2144 [<span class="optional"> coresize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2145 [<span class="optional"> datasize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2146 [<span class="optional"> files <em class="replaceable"><code>size_spec</code></em> ; </span>]
2147 [<span class="optional"> stacksize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2148 [<span class="optional"> cleaning-interval <em class="replaceable"><code>number</code></em>; </span>]
2149 [<span class="optional"> heartbeat-interval <em class="replaceable"><code>number</code></em>; </span>]
2150 [<span class="optional"> interface-interval <em class="replaceable"><code>number</code></em>; </span>]
2151 [<span class="optional"> statistics-interval <em class="replaceable"><code>number</code></em>; </span>]
2152 [<span class="optional"> topology { <em class="replaceable"><code>address_match_list</code></em> }</span>];
2153 [<span class="optional"> sortlist { <em class="replaceable"><code>address_match_list</code></em> }</span>];
2154 [<span class="optional"> rrset-order { <em class="replaceable"><code>order_spec</code></em> ; [<span class="optional"> <em class="replaceable"><code>order_spec</code></em> ; ... </span>] </span>] };
2155 [<span class="optional"> lame-ttl <em class="replaceable"><code>number</code></em>; </span>]
2156 [<span class="optional"> max-ncache-ttl <em class="replaceable"><code>number</code></em>; </span>]
2157 [<span class="optional"> max-cache-ttl <em class="replaceable"><code>number</code></em>; </span>]
2158 [<span class="optional"> sig-validity-interval <em class="replaceable"><code>number</code></em> [<span class="optional"><em class="replaceable"><code>number</code></em></span>] ; </span>]
2159 [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>]
2160 [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>]
2161 [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>]
2162 [<span class="optional"> min-roots <em class="replaceable"><code>number</code></em>; </span>]
2163 [<span class="optional"> use-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2164 [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2165 [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2166 [<span class="optional"> treat-cr-as-space <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2167 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
2168 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
2169 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
2170 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
2171 [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em>; </span>]
2172 [<span class="optional"> additional-from-auth <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2173 [<span class="optional"> additional-from-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2174 [<span class="optional"> random-device <em class="replaceable"><code>path_name</code></em> ; </span>]
2175 [<span class="optional"> max-cache-size <em class="replaceable"><code>size_spec</code></em> ; </span>]
2176 [<span class="optional"> match-mapped-addresses <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2177 [<span class="optional"> preferred-glue ( <em class="replaceable"><code>A</code></em> | <em class="replaceable"><code>AAAA</code></em> | <em class="replaceable"><code>NONE</code></em> ); </span>]
2178 [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em>; </span>]
2179 [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em>; </span>]
2180 [<span class="optional"> root-delegation-only [<span class="optional"> exclude { <em class="replaceable"><code>namelist</code></em> } </span>] ; </span>]
2181 [<span class="optional"> querylog <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2182 [<span class="optional"> disable-algorithms <em class="replaceable"><code>domain</code></em> { <em class="replaceable"><code>algorithm</code></em>; [<span class="optional"> <em class="replaceable"><code>algorithm</code></em>; </span>] }; </span>]
2183 [<span class="optional"> acache-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2184 [<span class="optional"> acache-cleaning-interval <em class="replaceable"><code>number</code></em>; </span>]
2185 [<span class="optional"> max-acache-size <em class="replaceable"><code>size_spec</code></em> ; </span>]
2186 [<span class="optional"> clients-per-query <em class="replaceable"><code>number</code></em> ; </span>]
2187 [<span class="optional"> max-clients-per-query <em class="replaceable"><code>number</code></em> ; </span>]
2188 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
2189 [<span class="optional"> empty-server <em class="replaceable"><code>name</code></em> ; </span>]
2190 [<span class="optional"> empty-contact <em class="replaceable"><code>name</code></em> ; </span>]
2191 [<span class="optional"> empty-zones-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2192 [<span class="optional"> disable-empty-zone <em class="replaceable"><code>zone_name</code></em> ; </span>]
2193 [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2194 [<span class="optional"> zero-no-soa-ttl-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2198 <div class="sect2" lang="en">
2199 <div class="titlepage"><div><div><h3 class="title">
2200 <a name="options"></a><span><strong class="command">options</strong></span> Statement Definition and
2201 Usage</h3></div></div></div>
2203 The <span><strong class="command">options</strong></span> statement sets up global
2205 to be used by <acronym class="acronym">BIND</acronym>. This statement
2207 once in a configuration file. If there is no <span><strong class="command">options</strong></span>
2208 statement, an options block with each option set to its default will
2211 <div class="variablelist"><dl>
2212 <dt><span class="term"><span><strong class="command">directory</strong></span></span></dt>
2214 The working directory of the server.
2215 Any non-absolute pathnames in the configuration file will be
2217 as relative to this directory. The default location for most
2219 output files (e.g. <code class="filename">named.run</code>)
2221 If a directory is not specified, the working directory
2222 defaults to `<code class="filename">.</code>', the directory from
2224 was started. The directory specified should be an absolute
2227 <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt>
2229 When performing dynamic update of secure zones, the
2230 directory where the public and private DNSSEC key files
2231 should be found, if different than the current working
2232 directory. The directory specified must be an absolute
2233 path. (Note that this option has no effect on the paths
2234 for files containing non-DNSSEC keys such as the
2235 <code class="filename">rndc.key</code>.
2237 <dt><span class="term"><span><strong class="command">named-xfer</strong></span></span></dt>
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.
2246 <dt><span class="term"><span><strong class="command">tkey-gssapi-credential</strong></span></span></dt>
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>
2259 <dt><span class="term"><span><strong class="command">tkey-domain</strong></span></span></dt>
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.
2276 <dt><span class="term"><span><strong class="command">tkey-dhkey</strong></span></span></dt>
2278 The Diffie-Hellman key used by the server
2279 to generate shared keys with clients using the Diffie-Hellman
2281 of <span><strong class="command">TKEY</strong></span>. The server must be
2283 public and private keys from files in the working directory.
2285 most cases, the keyname should be the server's host name.
2287 <dt><span class="term"><span><strong class="command">cache-file</strong></span></span></dt>
2289 This is for testing only. Do not use.
2291 <dt><span class="term"><span><strong class="command">dump-file</strong></span></span></dt>
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>.
2298 <dt><span class="term"><span><strong class="command">memstatistics-file</strong></span></span></dt>
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>.
2304 <dt><span class="term"><span><strong class="command">pid-file</strong></span></span></dt>
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
2311 name server. Specifying <span><strong class="command">pid-file none</strong></span> disables the
2312 use of a PID file — 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
2318 <dt><span class="term"><span><strong class="command">recursing-file</strong></span></span></dt>
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>.
2325 <dt><span class="term"><span><strong class="command">statistics-file</strong></span></span></dt>
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
2332 in <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called “The Statistics File”</a>.
2334 <dt><span class="term"><span><strong class="command">port</strong></span></span></dt>
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
2340 a server using a port other than 53 will not be able to
2344 <dt><span class="term"><span><strong class="command">random-device</strong></span></span></dt>
2346 The source of entropy to be used by the server. Entropy is
2348 for DNSSEC operations, such as TKEY transactions and dynamic
2350 zones. This options specifies the device (or file) from which
2352 entropy. If this is a file, operations requiring entropy will
2354 file has been exhausted. If not specified, the default value
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
2360 the initial configuration load at server startup time and
2361 is ignored on subsequent reloads.
2363 <dt><span class="term"><span><strong class="command">preferred-glue</strong></span></span></dt>
2365 If specified, the listed type (A or AAAA) will be emitted
2367 in the additional section of a query response.
2368 The default is not to prefer any type (NONE).
2371 <a name="root_delegation_only"></a><span class="term"><span><strong class="command">root-delegation-only</strong></span></span>
2375 Turn on enforcement of delegation-only in TLDs
2376 (top level domains) and root zones with an optional
2380 DS queries are expected to be made to and be answered by
2381 delegation only zones. Such queries and responses are
2382 treated as a exception to delegation-only processing
2383 and are not converted to NXDOMAIN responses provided
2384 a CNAME is not discovered at the query name.
2387 If a delegation only zone server also serves a child
2388 zone it is not always possible to determine whether
2389 a answer comes from the delegation only zone or the
2390 child zone. SOA NS and DNSKEY records are apex
2391 only records and a matching response that contains
2392 these records or DS is treated as coming from a
2393 child zone. RRSIG records are also examined to see
2394 if they are signed by a child zone or not. The
2395 authority section is also examined to see if there
2396 is evidence that the answer is from the child zone.
2397 Answers that are determined to be from a child zone
2398 are not converted to NXDOMAIN responses. Despite
2399 all these checks there is still a possibility of
2400 false negatives when a child zone is being served.
2403 Similarly false positives can arise from empty nodes
2404 (no records at the name) in the delegation only zone
2405 when the query type is not ANY.
2408 Note some TLDs are not delegation only (e.g. "DE", "LV",
2409 "US" and "MUSEUM"). This list is not exhaustive.
2411 <pre class="programlisting">
2413 root-delegation-only exclude { "de"; "lv"; "us"; "museum"; };
2417 <dt><span class="term"><span><strong class="command">disable-algorithms</strong></span></span></dt>
2419 Disable the specified DNSSEC algorithms at and below the
2421 Multiple <span><strong class="command">disable-algorithms</strong></span>
2422 statements are allowed.
2423 Only the most specific will be applied.
2425 <dt><span class="term"><span><strong class="command">dnssec-lookaside</strong></span></span></dt>
2427 When set, <span><strong class="command">dnssec-lookaside</strong></span>
2429 validator with an alternate method to validate DNSKEY records
2431 top of a zone. When a DNSKEY is at or below a domain
2433 deepest <span><strong class="command">dnssec-lookaside</strong></span>, and
2434 the normal DNSSEC validation
2435 has left the key untrusted, the trust-anchor will be append to
2437 name and a DLV record will be looked up to see if it can
2439 key. If the DLV record validates a DNSKEY (similarly to the
2441 record does) the DNSKEY RRset is deemed to be trusted.
2443 <dt><span class="term"><span><strong class="command">dnssec-must-be-secure</strong></span></span></dt>
2445 Specify hierarchies which must be or may not be secure (signed and
2447 If <strong class="userinput"><code>yes</code></strong>, then <span><strong class="command">named</strong></span> will only accept
2450 If <strong class="userinput"><code>no</code></strong>, then normal DNSSEC validation
2452 allowing for insecure answers to be accepted.
2453 The specified domain must be under a <span><strong class="command">trusted-key</strong></span> or
2454 <span><strong class="command">dnssec-lookaside</strong></span> must be
2458 <div class="sect3" lang="en">
2459 <div class="titlepage"><div><div><h4 class="title">
2460 <a name="boolean_options"></a>Boolean Options</h4></div></div></div>
2461 <div class="variablelist"><dl>
2462 <dt><span class="term"><span><strong class="command">auth-nxdomain</strong></span></span></dt>
2464 If <strong class="userinput"><code>yes</code></strong>, then the <span><strong class="command">AA</strong></span> bit
2465 is always set on NXDOMAIN responses, even if the server is
2467 authoritative. The default is <strong class="userinput"><code>no</code></strong>;
2469 a change from <acronym class="acronym">BIND</acronym> 8. If you
2470 are using very old DNS software, you
2471 may need to set it to <strong class="userinput"><code>yes</code></strong>.
2473 <dt><span class="term"><span><strong class="command">deallocate-on-exit</strong></span></span></dt>
2475 This option was used in <acronym class="acronym">BIND</acronym>
2476 8 to enable checking
2477 for memory leaks on exit. <acronym class="acronym">BIND</acronym> 9 ignores the option and always performs
2480 <dt><span class="term"><span><strong class="command">memstatistics</strong></span></span></dt>
2482 Write memory statistics to the file specified by
2483 <span><strong class="command">memstatistics-file</strong></span> at exit.
2484 The default is <strong class="userinput"><code>no</code></strong> unless
2485 '-m record' is specified on the command line in
2486 which case it is <strong class="userinput"><code>yes</code></strong>.
2488 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
2491 If <strong class="userinput"><code>yes</code></strong>, then the
2492 server treats all zones as if they are doing zone transfers
2494 a dial-on-demand dialup link, which can be brought up by
2496 originating from this server. This has different effects
2498 to zone type and concentrates the zone maintenance so that
2500 happens in a short interval, once every <span><strong class="command">heartbeat-interval</strong></span> and
2501 hopefully during the one call. It also suppresses some of
2503 zone maintenance traffic. The default is <strong class="userinput"><code>no</code></strong>.
2506 The <span><strong class="command">dialup</strong></span> option
2507 may also be specified in the <span><strong class="command">view</strong></span> and
2508 <span><strong class="command">zone</strong></span> statements,
2509 in which case it overrides the global <span><strong class="command">dialup</strong></span>
2513 If the zone is a master zone, then the server will send out a
2515 request to all the slaves (default). This should trigger the
2517 number check in the slave (providing it supports NOTIFY)
2519 to verify the zone while the connection is active.
2520 The set of servers to which NOTIFY is sent can be controlled
2522 <span><strong class="command">notify</strong></span> and <span><strong class="command">also-notify</strong></span>.
2526 zone is a slave or stub zone, then the server will suppress
2528 "zone up to date" (refresh) queries and only perform them
2530 <span><strong class="command">heartbeat-interval</strong></span> expires in
2535 Finer control can be achieved by using
2536 <strong class="userinput"><code>notify</code></strong> which only sends NOTIFY
2538 <strong class="userinput"><code>notify-passive</code></strong> which sends NOTIFY
2540 suppresses the normal refresh queries, <strong class="userinput"><code>refresh</code></strong>
2541 which suppresses normal refresh processing and sends refresh
2543 when the <span><strong class="command">heartbeat-interval</strong></span>
2545 <strong class="userinput"><code>passive</code></strong> which just disables normal
2549 <div class="informaltable"><table border="1">
2581 <p><span><strong class="command">no</strong></span> (default)</p>
2601 <p><span><strong class="command">yes</strong></span></p>
2621 <p><span><strong class="command">notify</strong></span></p>
2641 <p><span><strong class="command">refresh</strong></span></p>
2661 <p><span><strong class="command">passive</strong></span></p>
2681 <p><span><strong class="command">notify-passive</strong></span></p>
2702 Note that normal NOTIFY processing is not affected by
2703 <span><strong class="command">dialup</strong></span>.
2706 <dt><span class="term"><span><strong class="command">fake-iquery</strong></span></span></dt>
2708 In <acronym class="acronym">BIND</acronym> 8, this option
2709 enabled simulating the obsolete DNS query type
2710 IQUERY. <acronym class="acronym">BIND</acronym> 9 never does
2713 <dt><span class="term"><span><strong class="command">fetch-glue</strong></span></span></dt>
2715 This option is obsolete.
2716 In BIND 8, <strong class="userinput"><code>fetch-glue yes</code></strong>
2717 caused the server to attempt to fetch glue resource records
2719 didn't have when constructing the additional
2720 data section of a response. This is now considered a bad
2722 and BIND 9 never does it.
2724 <dt><span class="term"><span><strong class="command">flush-zones-on-shutdown</strong></span></span></dt>
2726 When the nameserver exits due receiving SIGTERM,
2727 flush or do not flush any pending zone writes. The default
2729 <span><strong class="command">flush-zones-on-shutdown</strong></span> <strong class="userinput"><code>no</code></strong>.
2731 <dt><span class="term"><span><strong class="command">has-old-clients</strong></span></span></dt>
2733 This option was incorrectly implemented
2734 in <acronym class="acronym">BIND</acronym> 8, and is ignored by <acronym class="acronym">BIND</acronym> 9.
2735 To achieve the intended effect
2737 <span><strong class="command">has-old-clients</strong></span> <strong class="userinput"><code>yes</code></strong>, specify
2738 the two separate options <span><strong class="command">auth-nxdomain</strong></span> <strong class="userinput"><code>yes</code></strong>
2739 and <span><strong class="command">rfc2308-type1</strong></span> <strong class="userinput"><code>no</code></strong> instead.
2741 <dt><span class="term"><span><strong class="command">host-statistics</strong></span></span></dt>
2743 In BIND 8, this enables keeping of
2744 statistics for every host that the name server interacts
2746 Not implemented in BIND 9.
2748 <dt><span class="term"><span><strong class="command">maintain-ixfr-base</strong></span></span></dt>
2750 <span class="emphasis"><em>This option is obsolete</em></span>.
2751 It was used in <acronym class="acronym">BIND</acronym> 8 to
2752 determine whether a transaction log was
2753 kept for Incremental Zone Transfer. <acronym class="acronym">BIND</acronym> 9 maintains a transaction
2754 log whenever possible. If you need to disable outgoing
2756 transfers, use <span><strong class="command">provide-ixfr</strong></span> <strong class="userinput"><code>no</code></strong>.
2758 <dt><span class="term"><span><strong class="command">minimal-responses</strong></span></span></dt>
2760 If <strong class="userinput"><code>yes</code></strong>, then when generating
2761 responses the server will only add records to the authority
2762 and additional data sections when they are required (e.g.
2763 delegations, negative responses). This may improve the
2764 performance of the server.
2765 The default is <strong class="userinput"><code>no</code></strong>.
2767 <dt><span class="term"><span><strong class="command">multiple-cnames</strong></span></span></dt>
2769 This option was used in <acronym class="acronym">BIND</acronym> 8 to allow
2770 a domain name to have multiple CNAME records in violation of
2771 the DNS standards. <acronym class="acronym">BIND</acronym> 9.2 onwards
2772 always strictly enforces the CNAME rules both in master
2773 files and dynamic updates.
2775 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
2778 If <strong class="userinput"><code>yes</code></strong> (the default),
2779 DNS NOTIFY messages are sent when a zone the server is
2781 changes, see <a href="Bv9ARM.ch04.html#notify" title="Notify">the section called “Notify”</a>. The messages are
2783 servers listed in the zone's NS records (except the master
2785 in the SOA MNAME field), and to any servers listed in the
2786 <span><strong class="command">also-notify</strong></span> option.
2789 If <strong class="userinput"><code>master-only</code></strong>, notifies are only
2792 If <strong class="userinput"><code>explicit</code></strong>, notifies are sent only
2794 servers explicitly listed using <span><strong class="command">also-notify</strong></span>.
2795 If <strong class="userinput"><code>no</code></strong>, no notifies are sent.
2798 The <span><strong class="command">notify</strong></span> option may also be
2799 specified in the <span><strong class="command">zone</strong></span>
2801 in which case it overrides the <span><strong class="command">options notify</strong></span> statement.
2802 It would only be necessary to turn off this option if it
2807 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
2809 If <strong class="userinput"><code>yes</code></strong> do not check the nameservers
2810 in the NS RRset against the SOA MNAME. Normally a NOTIFY
2811 message is not sent to the SOA MNAME (SOA ORIGIN) as it is
2812 supposed to contain the name of the ultimate master.
2813 Sometimes, however, a slave is listed as the SOA MNAME in
2814 hidden master configurations and in that case you would
2815 want the ultimate master to still send NOTIFY messages to
2816 all the nameservers listed in the NS RRset.
2818 <dt><span class="term"><span><strong class="command">recursion</strong></span></span></dt>
2820 If <strong class="userinput"><code>yes</code></strong>, and a
2821 DNS query requests recursion, then the server will attempt
2823 all the work required to answer the query. If recursion is
2825 and the server does not already know the answer, it will
2827 referral response. The default is
2828 <strong class="userinput"><code>yes</code></strong>.
2829 Note that setting <span><strong class="command">recursion no</strong></span> does not prevent
2830 clients from getting data from the server's cache; it only
2831 prevents new data from being cached as an effect of client
2833 Caching may still occur as an effect the server's internal
2834 operation, such as NOTIFY address lookups.
2835 See also <span><strong class="command">fetch-glue</strong></span> above.
2837 <dt><span class="term"><span><strong class="command">rfc2308-type1</strong></span></span></dt>
2840 Setting this to <strong class="userinput"><code>yes</code></strong> will
2841 cause the server to send NS records along with the SOA
2843 answers. The default is <strong class="userinput"><code>no</code></strong>.
2845 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
2846 <h3 class="title">Note</h3>
2848 Not yet implemented in <acronym class="acronym">BIND</acronym>
2853 <dt><span class="term"><span><strong class="command">use-id-pool</strong></span></span></dt>
2855 <span class="emphasis"><em>This option is obsolete</em></span>.
2856 <acronym class="acronym">BIND</acronym> 9 always allocates query
2859 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
2861 If <strong class="userinput"><code>yes</code></strong>, the server will collect
2862 statistical data on all zones (unless specifically turned
2864 on a per-zone basis by specifying <span><strong class="command">zone-statistics no</strong></span>
2865 in the <span><strong class="command">zone</strong></span> statement).
2866 These statistics may be accessed
2867 using <span><strong class="command">rndc stats</strong></span>, which will
2868 dump them to the file listed
2869 in the <span><strong class="command">statistics-file</strong></span>. See
2870 also <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called “The Statistics File”</a>.
2872 <dt><span class="term"><span><strong class="command">use-ixfr</strong></span></span></dt>
2874 <span class="emphasis"><em>This option is obsolete</em></span>.
2875 If you need to disable IXFR to a particular server or
2877 the information on the <span><strong class="command">provide-ixfr</strong></span> option
2878 in <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
2879 Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and
2882 <a href="Bv9ARM.ch04.html#incremental_zone_transfers" title="Incremental Zone Transfers (IXFR)">the section called “Incremental Zone Transfers (IXFR)”</a>.
2884 <dt><span class="term"><span><strong class="command">provide-ixfr</strong></span></span></dt>
2886 See the description of
2887 <span><strong class="command">provide-ixfr</strong></span> in
2888 <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
2889 Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and
2892 <dt><span class="term"><span><strong class="command">request-ixfr</strong></span></span></dt>
2894 See the description of
2895 <span><strong class="command">request-ixfr</strong></span> in
2896 <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
2897 Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and
2900 <dt><span class="term"><span><strong class="command">treat-cr-as-space</strong></span></span></dt>
2902 This option was used in <acronym class="acronym">BIND</acronym>
2904 the server treat carriage return ("<span><strong class="command">\r</strong></span>") characters the same way
2905 as a space or tab character,
2906 to facilitate loading of zone files on a UNIX system that
2908 on an NT or DOS machine. In <acronym class="acronym">BIND</acronym> 9, both UNIX "<span><strong class="command">\n</strong></span>"
2909 and NT/DOS "<span><strong class="command">\r\n</strong></span>" newlines
2910 are always accepted,
2911 and the option is ignored.
2914 <span class="term"><span><strong class="command">additional-from-auth</strong></span>, </span><span class="term"><span><strong class="command">additional-from-cache</strong></span></span>
2918 These options control the behavior of an authoritative
2920 answering queries which have additional data, or when
2925 When both of these options are set to <strong class="userinput"><code>yes</code></strong>
2927 query is being answered from authoritative data (a zone
2928 configured into the server), the additional data section of
2930 reply will be filled in using data from other authoritative
2932 and from the cache. In some situations this is undesirable,
2934 as when there is concern over the correctness of the cache,
2936 in servers where slave zones may be added and modified by
2937 untrusted third parties. Also, avoiding
2938 the search for this additional data will speed up server
2940 at the possible expense of additional queries to resolve
2942 otherwise be provided in the additional section.
2945 For example, if a query asks for an MX record for host <code class="literal">foo.example.com</code>,
2946 and the record found is "<code class="literal">MX 10 mail.example.net</code>", normally the address
2947 records (A and AAAA) for <code class="literal">mail.example.net</code> will be provided as well,
2948 if known, even though they are not in the example.com zone.
2949 Setting these options to <span><strong class="command">no</strong></span>
2950 disables this behavior and makes
2951 the server only search for additional data in the zone it
2955 These options are intended for use in authoritative-only
2956 servers, or in authoritative-only views. Attempts to set
2957 them to <span><strong class="command">no</strong></span> without also
2959 <span><strong class="command">recursion no</strong></span> will cause the
2961 ignore the options and log a warning message.
2964 Specifying <span><strong class="command">additional-from-cache no</strong></span> actually
2965 disables the use of the cache not only for additional data
2967 but also when looking up the answer. This is usually the
2969 behavior in an authoritative-only server where the
2971 the cached data is an issue.
2974 When a name server is non-recursively queried for a name
2976 below the apex of any served zone, it normally answers with
2978 "upwards referral" to the root servers or the servers of
2980 known parent of the query name. Since the data in an
2982 comes from the cache, the server will not be able to provide
2984 referrals when <span><strong class="command">additional-from-cache no</strong></span>
2985 has been specified. Instead, it will respond to such
2987 with REFUSED. This should not cause any problems since
2988 upwards referrals are not required for the resolution
2992 <dt><span class="term"><span><strong class="command">match-mapped-addresses</strong></span></span></dt>
2995 If <strong class="userinput"><code>yes</code></strong>, then an
2996 IPv4-mapped IPv6 address will match any address match
2997 list entries that match the corresponding IPv4 address.
3000 This option was introduced to work around a kernel quirk
3001 in some operating systems that causes IPv4 TCP
3002 connections, such as zone transfers, to be accepted on an
3003 IPv6 socket using mapped addresses. This caused address
3004 match lists designed for IPv4 to fail to match. However,
3005 <span><strong class="command">named</strong></span> now solves this problem
3006 internally. The use of this option is discouraged.
3009 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
3012 When <strong class="userinput"><code>yes</code></strong> and the server loads a new version of a master
3013 zone from its zone file or receives a new version of a slave
3014 file by a non-incremental zone transfer, it will compare
3015 the new version to the previous one and calculate a set
3016 of differences. The differences are then logged in the
3017 zone's journal file such that the changes can be transmitted
3018 to downstream slaves as an incremental zone transfer.
3021 By allowing incremental zone transfers to be used for
3022 non-dynamic zones, this option saves bandwidth at the
3023 expense of increased CPU and memory consumption at the
3025 In particular, if the new version of a zone is completely
3026 different from the previous one, the set of differences
3027 will be of a size comparable to the combined size of the
3028 old and new zone version, and the server will need to
3029 temporarily allocate memory to hold this complete
3032 <p><span><strong class="command">ixfr-from-differences</strong></span>
3033 also accepts <span><strong class="command">master</strong></span> and
3034 <span><strong class="command">slave</strong></span> at the view and options
3036 <span><strong class="command">ixfr-from-differences</strong></span> to be enabled for
3037 all <span><strong class="command">master</strong></span> or
3038 <span><strong class="command">slave</strong></span> zones respectively.
3039 It is off by default.
3042 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
3044 This should be set when you have multiple masters for a zone
3046 addresses refer to different machines. If <strong class="userinput"><code>yes</code></strong>, <span><strong class="command">named</strong></span> will
3048 when the serial number on the master is less than what <span><strong class="command">named</strong></span>
3050 has. The default is <strong class="userinput"><code>no</code></strong>.
3052 <dt><span class="term"><span><strong class="command">dnssec-enable</strong></span></span></dt>
3054 Enable DNSSEC support in <span><strong class="command">named</strong></span>. Unless set to <strong class="userinput"><code>yes</code></strong>,
3055 <span><strong class="command">named</strong></span> behaves as if it does not support DNSSEC.
3056 The default is <strong class="userinput"><code>yes</code></strong>.
3058 <dt><span class="term"><span><strong class="command">dnssec-validation</strong></span></span></dt>
3060 Enable DNSSEC validation in <span><strong class="command">named</strong></span>.
3061 Note <span><strong class="command">dnssec-enable</strong></span> also needs to be
3062 set to <strong class="userinput"><code>yes</code></strong> to be effective.
3063 The default is <strong class="userinput"><code>yes</code></strong>.
3065 <dt><span class="term"><span><strong class="command">dnssec-accept-expired</strong></span></span></dt>
3067 Accept expired signatures when verifying DNSSEC signatures.
3068 The default is <strong class="userinput"><code>no</code></strong>.
3069 Setting this option to "yes" leaves <span><strong class="command">named</strong></span> vulnerable to replay attacks.
3071 <dt><span class="term"><span><strong class="command">querylog</strong></span></span></dt>
3073 Specify whether query logging should be started when <span><strong class="command">named</strong></span>
3075 If <span><strong class="command">querylog</strong></span> is not specified,
3076 then the query logging
3077 is determined by the presence of the logging category <span><strong class="command">queries</strong></span>.
3079 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
3082 This option is used to restrict the character set and syntax
3084 certain domain names in master files and/or DNS responses
3086 from the network. The default varies according to usage
3088 <span><strong class="command">master</strong></span> zones the default is <span><strong class="command">fail</strong></span>.
3089 For <span><strong class="command">slave</strong></span> zones the default
3090 is <span><strong class="command">warn</strong></span>.
3091 For answers received from the network (<span><strong class="command">response</strong></span>)
3092 the default is <span><strong class="command">ignore</strong></span>.
3095 The rules for legal hostnames and mail domains are derived
3096 from RFC 952 and RFC 821 as modified by RFC 1123.
3098 <p><span><strong class="command">check-names</strong></span>
3099 applies to the owner names of A, AAAA and MX records.
3100 It also applies to the domain names in the RDATA of NS, SOA,
3101 MX, and SRV records.
3102 It also applies to the RDATA of PTR records where the owner
3103 name indicated that it is a reverse lookup of a hostname
3104 (the owner name ends in IN-ADDR.ARPA, IP6.ARPA, or IP6.INT).
3107 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
3109 Check whether the MX record appears to refer to a IP address.
3110 The default is to <span><strong class="command">warn</strong></span>. Other possible
3111 values are <span><strong class="command">fail</strong></span> and
3112 <span><strong class="command">ignore</strong></span>.
3114 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
3116 This option is used to check for non-terminal wildcards.
3117 The use of non-terminal wildcards is almost always as a
3119 to understand the wildcard matching algorithm (RFC 1034).
3121 affects master zones. The default (<span><strong class="command">yes</strong></span>) is to check
3122 for non-terminal wildcards and issue a warning.
3124 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
3126 Perform post load zone integrity checks on master
3127 zones. This checks that MX and SRV records refer
3128 to address (A or AAAA) records and that glue
3129 address records exist for delegated zones. For
3130 MX and SRV records only in-zone hostnames are
3131 checked (for out-of-zone hostnames use
3132 <span><strong class="command">named-checkzone</strong></span>).
3133 For NS records only names below top of zone are
3134 checked (for out-of-zone names and glue consistency
3135 checks use <span><strong class="command">named-checkzone</strong></span>).
3136 The default is <span><strong class="command">yes</strong></span>.
3138 <dt><span class="term"><span><strong class="command">check-mx-cname</strong></span></span></dt>
3140 If <span><strong class="command">check-integrity</strong></span> is set then
3141 fail, warn or ignore MX records that refer
3142 to CNAMES. The default is to <span><strong class="command">warn</strong></span>.
3144 <dt><span class="term"><span><strong class="command">check-srv-cname</strong></span></span></dt>
3146 If <span><strong class="command">check-integrity</strong></span> is set then
3147 fail, warn or ignore SRV records that refer
3148 to CNAMES. The default is to <span><strong class="command">warn</strong></span>.
3150 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
3152 When performing integrity checks, also check that
3153 sibling glue exists. The default is <span><strong class="command">yes</strong></span>.
3155 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
3157 When returning authoritative negative responses to
3158 SOA queries set the TTL of the SOA record returned in
3159 the authority section to zero.
3160 The default is <span><strong class="command">yes</strong></span>.
3162 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl-cache</strong></span></span></dt>
3164 When caching a negative response to a SOA query
3165 set the TTL to zero.
3166 The default is <span><strong class="command">no</strong></span>.
3168 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
3170 When regenerating the RRSIGs following a UPDATE
3171 request to a secure zone, check the KSK flag on
3172 the DNSKEY RR to determine if this key should be
3173 used to generate the RRSIG. This flag is ignored
3174 if there are not DNSKEY RRs both with and without
3176 The default is <span><strong class="command">yes</strong></span>.
3178 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
3180 Try to refresh the zone using TCP if UDP queries fail.
3181 For BIND 8 compatibility, the default is
3182 <span><strong class="command">yes</strong></span>.
3186 <div class="sect3" lang="en">
3187 <div class="titlepage"><div><div><h4 class="title">
3188 <a name="id2581856"></a>Forwarding</h4></div></div></div>
3190 The forwarding facility can be used to create a large site-wide
3191 cache on a few servers, reducing traffic over links to external
3192 name servers. It can also be used to allow queries by servers that
3193 do not have direct access to the Internet, but wish to look up
3195 names anyway. Forwarding occurs only on those queries for which
3196 the server is not authoritative and does not have the answer in
3199 <div class="variablelist"><dl>
3200 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
3202 This option is only meaningful if the
3203 forwarders list is not empty. A value of <code class="varname">first</code>,
3204 the default, causes the server to query the forwarders
3206 if that doesn't answer the question, the server will then
3208 the answer itself. If <code class="varname">only</code> is
3210 server will only query the forwarders.
3212 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
3214 Specifies the IP addresses to be used
3215 for forwarding. The default is the empty list (no
3220 Forwarding can also be configured on a per-domain basis, allowing
3221 for the global forwarding options to be overridden in a variety
3222 of ways. You can set particular domains to use different
3224 or have a different <span><strong class="command">forward only/first</strong></span> behavior,
3225 or not forward at all, see <a href="Bv9ARM.ch06.html#zone_statement_grammar" title="zone
3226 Statement Grammar">the section called “<span><strong class="command">zone</strong></span>
3227 Statement Grammar”</a>.
3230 <div class="sect3" lang="en">
3231 <div class="titlepage"><div><div><h4 class="title">
3232 <a name="id2581914"></a>Dual-stack Servers</h4></div></div></div>
3234 Dual-stack servers are used as servers of last resort to work
3236 problems in reachability due the lack of support for either IPv4
3238 on the host machine.
3240 <div class="variablelist"><dl>
3241 <dt><span class="term"><span><strong class="command">dual-stack-servers</strong></span></span></dt>
3243 Specifies host names or addresses of machines with access to
3244 both IPv4 and IPv6 transports. If a hostname is used, the
3246 to resolve the name using only the transport it has. If the
3248 stacked, then the <span><strong class="command">dual-stack-servers</strong></span> have no effect unless
3249 access to a transport has been disabled on the command line
3250 (e.g. <span><strong class="command">named -4</strong></span>).
3254 <div class="sect3" lang="en">
3255 <div class="titlepage"><div><div><h4 class="title">
3256 <a name="access_control"></a>Access Control</h4></div></div></div>
3258 Access to the server can be restricted based on the IP address
3259 of the requesting system. See <a href="Bv9ARM.ch06.html#address_match_lists" title="Address Match Lists">the section called “Address Match Lists”</a> for
3260 details on how to specify IP address lists.
3262 <div class="variablelist"><dl>
3263 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
3265 Specifies which hosts are allowed to
3266 notify this server, a slave, of zone changes in addition
3267 to the zone masters.
3268 <span><strong class="command">allow-notify</strong></span> may also be
3270 <span><strong class="command">zone</strong></span> statement, in which case
3272 <span><strong class="command">options allow-notify</strong></span>
3273 statement. It is only meaningful
3274 for a slave zone. If not specified, the default is to
3275 process notify messages
3276 only from a zone's master.
3278 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
3281 Specifies which hosts are allowed to ask ordinary
3282 DNS questions. <span><strong class="command">allow-query</strong></span> may
3283 also be specified in the <span><strong class="command">zone</strong></span>
3284 statement, in which case it overrides the
3285 <span><strong class="command">options allow-query</strong></span> statement.
3286 If not specified, the default is to allow queries
3289 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3290 <h3 class="title">Note</h3>
3292 <span><strong class="command">allow-query-cache</strong></span> is now
3293 used to specify access to the cache.
3297 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
3300 Specifies which local addresses can accept ordinary
3301 DNS questions. This makes it possible, for instance,
3302 to allow queries on internal-facing interfaces but
3303 disallow them on external-facing ones, without
3304 necessarily knowing the internal network's addresses.
3307 <span><strong class="command">allow-query-on</strong></span> may
3308 also be specified in the <span><strong class="command">zone</strong></span>
3309 statement, in which case it overrides the
3310 <span><strong class="command">options allow-query-on</strong></span> statement.
3313 If not specified, the default is to allow queries
3316 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3317 <h3 class="title">Note</h3>
3319 <span><strong class="command">allow-query-cache</strong></span> is
3320 used to specify access to the cache.
3324 <dt><span class="term"><span><strong class="command">allow-query-cache</strong></span></span></dt>
3326 Specifies which hosts are allowed to get answers
3327 from the cache. If <span><strong class="command">allow-query-cache</strong></span>
3328 is not set then <span><strong class="command">allow-recursion</strong></span>
3329 is used if set, otherwise <span><strong class="command">allow-query</strong></span>
3330 is used if set unless <span><strong class="command">recursion no;</strong></span> is
3331 set in which case <span><strong class="command">none;</strong></span> is used,
3332 otherwise the default (<span><strong class="command">localnets;</strong></span>
3333 <span><strong class="command">localhost;</strong></span>) is used.
3335 <dt><span class="term"><span><strong class="command">allow-query-cache-on</strong></span></span></dt>
3337 Specifies which local addresses can give answers
3338 from the cache. If not specified, the default is
3339 to allow cache queries on any address,
3340 <span><strong class="command">localnets</strong></span> and
3341 <span><strong class="command">localhost</strong></span>.
3343 <dt><span class="term"><span><strong class="command">allow-recursion</strong></span></span></dt>
3345 Specifies which hosts are allowed to make recursive
3346 queries through this server. If
3347 <span><strong class="command">allow-recursion</strong></span> is not set
3348 then <span><strong class="command">allow-query-cache</strong></span> is
3349 used if set, otherwise <span><strong class="command">allow-query</strong></span>
3350 is used if set, otherwise the default
3351 (<span><strong class="command">localnets;</strong></span>
3352 <span><strong class="command">localhost;</strong></span>) is used.
3354 <dt><span class="term"><span><strong class="command">allow-recursion-on</strong></span></span></dt>
3356 Specifies which local addresses can accept recursive
3357 queries. If not specified, the default is to allow
3358 recursive queries on all addresses.
3360 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
3362 Specifies which hosts are allowed to
3363 submit Dynamic DNS updates for master zones. The default is
3365 updates from all hosts. Note that allowing updates based
3366 on the requestor's IP address is insecure; see
3367 <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called “Dynamic Update Security”</a> for details.
3369 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
3372 Specifies which hosts are allowed to
3373 submit Dynamic DNS updates to slave zones to be forwarded to
3375 master. The default is <strong class="userinput"><code>{ none; }</code></strong>,
3377 means that no update forwarding will be performed. To
3379 update forwarding, specify
3380 <strong class="userinput"><code>allow-update-forwarding { any; };</code></strong>.
3381 Specifying values other than <strong class="userinput"><code>{ none; }</code></strong> or
3382 <strong class="userinput"><code>{ any; }</code></strong> is usually
3383 counterproductive, since
3384 the responsibility for update access control should rest
3386 master server, not the slaves.
3389 Note that enabling the update forwarding feature on a slave
3391 may expose master servers relying on insecure IP address
3393 access control to attacks; see <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called “Dynamic Update Security”</a>
3397 <dt><span class="term"><span><strong class="command">allow-v6-synthesis</strong></span></span></dt>
3399 This option was introduced for the smooth transition from
3401 to A6 and from "nibble labels" to binary labels.
3402 However, since both A6 and binary labels were then
3404 this option was also deprecated.
3405 It is now ignored with some warning messages.
3407 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
3409 Specifies which hosts are allowed to
3410 receive zone transfers from the server. <span><strong class="command">allow-transfer</strong></span> may
3411 also be specified in the <span><strong class="command">zone</strong></span>
3413 case it overrides the <span><strong class="command">options allow-transfer</strong></span> statement.
3414 If not specified, the default is to allow transfers to all
3417 <dt><span class="term"><span><strong class="command">blackhole</strong></span></span></dt>
3419 Specifies a list of addresses that the
3420 server will not accept queries from or use to resolve a
3422 from these addresses will not be responded to. The default
3423 is <strong class="userinput"><code>none</code></strong>.
3427 <div class="sect3" lang="en">
3428 <div class="titlepage"><div><div><h4 class="title">
3429 <a name="id2582420"></a>Interfaces</h4></div></div></div>
3431 The interfaces and ports that the server will answer queries
3432 from may be specified using the <span><strong class="command">listen-on</strong></span> option. <span><strong class="command">listen-on</strong></span> takes
3433 an optional port and an <code class="varname">address_match_list</code>.
3434 The server will listen on all interfaces allowed by the address
3435 match list. If a port is not specified, port 53 will be used.
3438 Multiple <span><strong class="command">listen-on</strong></span> statements are
3442 <pre class="programlisting">listen-on { 5.6.7.8; };
3443 listen-on port 1234 { !1.2.3.4; 1.2/16; };
3446 will enable the name server on port 53 for the IP address
3447 5.6.7.8, and on port 1234 of an address on the machine in net
3448 1.2 that is not 1.2.3.4.
3451 If no <span><strong class="command">listen-on</strong></span> is specified, the
3452 server will listen on port 53 on all IPv4 interfaces.
3455 The <span><strong class="command">listen-on-v6</strong></span> option is used to
3456 specify the interfaces and the ports on which the server will
3458 for incoming queries sent using IPv6.
3462 <pre class="programlisting">{ any; }</pre>
3465 as the <code class="varname">address_match_list</code> for the
3466 <span><strong class="command">listen-on-v6</strong></span> option,
3467 the server does not bind a separate socket to each IPv6 interface
3468 address as it does for IPv4 if the operating system has enough API
3469 support for IPv6 (specifically if it conforms to RFC 3493 and RFC
3471 Instead, it listens on the IPv6 wildcard address.
3472 If the system only has incomplete API support for IPv6, however,
3473 the behavior is the same as that for IPv4.
3476 A list of particular IPv6 addresses can also be specified, in
3478 the server listens on a separate socket for each specified
3480 regardless of whether the desired API is supported by the system.
3483 Multiple <span><strong class="command">listen-on-v6</strong></span> options can
3487 <pre class="programlisting">listen-on-v6 { any; };
3488 listen-on-v6 port 1234 { !2001:db8::/32; any; };
3491 will enable the name server on port 53 for any IPv6 addresses
3492 (with a single wildcard socket),
3493 and on port 1234 of IPv6 addresses that is not in the prefix
3494 2001:db8::/32 (with separate sockets for each matched address.)
3497 To make the server not listen on any IPv6 address, use
3499 <pre class="programlisting">listen-on-v6 { none; };
3502 If no <span><strong class="command">listen-on-v6</strong></span> option is
3503 specified, the server will not listen on any IPv6 address
3504 unless <span><strong class="command">-6</strong></span> is specified when <span><strong class="command">named</strong></span> is
3505 invoked. If <span><strong class="command">-6</strong></span> is specified then
3506 <span><strong class="command">named</strong></span> will listen on port 53 on all IPv6 interfaces by default.
3509 <div class="sect3" lang="en">
3510 <div class="titlepage"><div><div><h4 class="title">
3511 <a name="query_address"></a>Query Address</h4></div></div></div>
3513 If the server doesn't know the answer to a question, it will
3514 query other name servers. <span><strong class="command">query-source</strong></span> specifies
3515 the address and port used for such queries. For queries sent over
3516 IPv6, there is a separate <span><strong class="command">query-source-v6</strong></span> option.
3517 If <span><strong class="command">address</strong></span> is <span><strong class="command">*</strong></span> (asterisk) or is omitted,
3518 a wildcard IP address (<span><strong class="command">INADDR_ANY</strong></span>)
3522 If <span><strong class="command">port</strong></span> is <span><strong class="command">*</strong></span> or is omitted,
3523 a random port number from a pre-configured
3524 range is picked up and will be used for each query.
3525 The port range(s) is that specified in
3526 the <span><strong class="command">use-v4-udp-ports</strong></span> (for IPv4)
3527 and <span><strong class="command">use-v6-udp-ports</strong></span> (for IPv6)
3528 options, excluding the ranges specified in
3529 the <span><strong class="command">avoid-v4-udp-ports</strong></span>
3530 and <span><strong class="command">avoid-v6-udp-ports</strong></span> options, respectively.
3533 The defaults of the <span><strong class="command">query-source</strong></span> and
3534 <span><strong class="command">query-source-v6</strong></span> options
3537 <pre class="programlisting">query-source address * port *;
3538 query-source-v6 address * port *;
3541 If <span><strong class="command">use-v4-udp-ports</strong></span> or
3542 <span><strong class="command">use-v6-udp-ports</strong></span> is unspecified,
3543 <span><strong class="command">named</strong></span> will check if the operating
3544 system provides a programming interface to retrieve the
3545 system's default range for ephemeral ports.
3546 If such an interface is available,
3547 <span><strong class="command">named</strong></span> will use the corresponding system
3548 default range; otherwise, it will use its own defaults:
3550 <pre class="programlisting">use-v4-udp-ports { range 1024 65535; };
3551 use-v6-udp-ports { range 1024 65535; };
3554 Note: make sure the ranges be sufficiently large for
3555 security. A desirable size depends on various parameters,
3556 but we generally recommend it contain at least 16384 ports
3557 (14 bits of entropy).
3558 Note also that the system's default range when used may be
3559 too small for this purpose, and that the range may even be
3560 changed while <span><strong class="command">named</strong></span> is running; the new
3561 range will automatically be applied when <span><strong class="command">named</strong></span>
3564 configure <span><strong class="command">use-v4-udp-ports</strong></span> and
3565 <span><strong class="command">use-v6-udp-ports</strong></span> explicitly so that the
3566 ranges are sufficiently large and are reasonably
3567 independent from the ranges used by other applications.
3570 Note: the operational configuration
3571 where <span><strong class="command">named</strong></span> runs may prohibit the use
3572 of some ports. For example, UNIX systems will not allow
3573 <span><strong class="command">named</strong></span> running without a root privilege
3574 to use ports less than 1024.
3575 If such ports are included in the specified (or detected)
3576 set of query ports, the corresponding query attempts will
3577 fail, resulting in resolution failures or delay.
3578 It is therefore important to configure the set of ports
3579 that can be safely used in the expected operational environment.
3582 The defaults of the <span><strong class="command">avoid-v4-udp-ports</strong></span> and
3583 <span><strong class="command">avoid-v6-udp-ports</strong></span> options
3586 <pre class="programlisting">avoid-v4-udp-ports {};
3587 avoid-v6-udp-ports {};
3590 Note: BIND 9.5.0 introduced
3591 the <span><strong class="command">use-queryport-pool</strong></span>
3592 option to support a pool of such random ports, but this
3593 option is now obsolete because reusing the same ports in
3594 the pool may not be sufficiently secure.
3595 For the same reason, it is generally strongly discouraged to
3596 specify a particular port for the
3597 <span><strong class="command">query-source</strong></span> or
3598 <span><strong class="command">query-source-v6</strong></span> options;
3599 it implicitly disables the use of randomized port numbers.
3601 <div class="variablelist"><dl>
3602 <dt><span class="term"><span><strong class="command">use-queryport-pool</strong></span></span></dt>
3604 This option is obsolete.
3606 <dt><span class="term"><span><strong class="command">queryport-pool-ports</strong></span></span></dt>
3608 This option is obsolete.
3610 <dt><span class="term"><span><strong class="command">queryport-pool-updateinterval</strong></span></span></dt>
3612 This option is obsolete.
3615 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3616 <h3 class="title">Note</h3>
3618 The address specified in the <span><strong class="command">query-source</strong></span> option
3619 is used for both UDP and TCP queries, but the port applies only
3620 to UDP queries. TCP queries always use a random
3624 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3625 <h3 class="title">Note</h3>
3627 Solaris 2.5.1 and earlier does not support setting the source
3628 address for TCP sockets.
3631 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3632 <h3 class="title">Note</h3>
3634 See also <span><strong class="command">transfer-source</strong></span> and
3635 <span><strong class="command">notify-source</strong></span>.
3639 <div class="sect3" lang="en">
3640 <div class="titlepage"><div><div><h4 class="title">
3641 <a name="zone_transfers"></a>Zone Transfers</h4></div></div></div>
3643 <acronym class="acronym">BIND</acronym> has mechanisms in place to
3644 facilitate zone transfers
3645 and set limits on the amount of load that transfers place on the
3646 system. The following options apply to zone transfers.
3648 <div class="variablelist"><dl>
3649 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
3651 Defines a global list of IP addresses of name servers
3652 that are also sent NOTIFY messages whenever a fresh copy of
3654 zone is loaded, in addition to the servers listed in the
3656 This helps to ensure that copies of the zones will
3657 quickly converge on stealth servers.
3658 Optionally, a port may be specified with each
3659 <span><strong class="command">also-notify</strong></span> address to send
3660 the notify messages to a port other than the
3662 If an <span><strong class="command">also-notify</strong></span> list
3663 is given in a <span><strong class="command">zone</strong></span> statement,
3665 the <span><strong class="command">options also-notify</strong></span>
3666 statement. When a <span><strong class="command">zone notify</strong></span>
3668 is set to <span><strong class="command">no</strong></span>, the IP
3669 addresses in the global <span><strong class="command">also-notify</strong></span> list will
3670 not be sent NOTIFY messages for that zone. The default is
3672 list (no global notification list).
3674 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
3676 Inbound zone transfers running longer than
3677 this many minutes will be terminated. The default is 120
3679 (2 hours). The maximum value is 28 days (40320 minutes).
3681 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
3683 Inbound zone transfers making no progress
3684 in this many minutes will be terminated. The default is 60
3686 (1 hour). The maximum value is 28 days (40320 minutes).
3688 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
3690 Outbound zone transfers running longer than
3691 this many minutes will be terminated. The default is 120
3693 (2 hours). The maximum value is 28 days (40320 minutes).
3695 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
3697 Outbound zone transfers making no progress
3698 in this many minutes will be terminated. The default is 60
3700 hour). The maximum value is 28 days (40320 minutes).
3702 <dt><span class="term"><span><strong class="command">serial-query-rate</strong></span></span></dt>
3704 Slave servers will periodically query master servers
3705 to find out if zone serial numbers have changed. Each such
3707 a minute amount of the slave server's network bandwidth. To
3709 amount of bandwidth used, BIND 9 limits the rate at which
3711 sent. The value of the <span><strong class="command">serial-query-rate</strong></span> option,
3712 an integer, is the maximum number of queries sent per
3716 <dt><span class="term"><span><strong class="command">serial-queries</strong></span></span></dt>
3718 In BIND 8, the <span><strong class="command">serial-queries</strong></span>
3720 set the maximum number of concurrent serial number queries
3721 allowed to be outstanding at any given time.
3722 BIND 9 does not limit the number of outstanding
3723 serial queries and ignores the <span><strong class="command">serial-queries</strong></span> option.
3724 Instead, it limits the rate at which the queries are sent
3725 as defined using the <span><strong class="command">serial-query-rate</strong></span> option.
3727 <dt><span class="term"><span><strong class="command">transfer-format</strong></span></span></dt>
3729 Zone transfers can be sent using two different formats,
3730 <span><strong class="command">one-answer</strong></span> and
3731 <span><strong class="command">many-answers</strong></span>.
3732 The <span><strong class="command">transfer-format</strong></span> option is used
3733 on the master server to determine which format it sends.
3734 <span><strong class="command">one-answer</strong></span> uses one DNS message per
3735 resource record transferred.
3736 <span><strong class="command">many-answers</strong></span> packs as many resource
3737 records as possible into a message.
3738 <span><strong class="command">many-answers</strong></span> is more efficient, but is
3739 only supported by relatively new slave servers,
3740 such as <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
3741 8.x and <acronym class="acronym">BIND</acronym> 4.9.5 onwards.
3742 The <span><strong class="command">many-answers</strong></span> format is also supported by
3743 recent Microsoft Windows nameservers.
3744 The default is <span><strong class="command">many-answers</strong></span>.
3745 <span><strong class="command">transfer-format</strong></span> may be overridden on a
3746 per-server basis by using the <span><strong class="command">server</strong></span>
3749 <dt><span class="term"><span><strong class="command">transfers-in</strong></span></span></dt>
3751 The maximum number of inbound zone transfers
3752 that can be running concurrently. The default value is <code class="literal">10</code>.
3753 Increasing <span><strong class="command">transfers-in</strong></span> may
3754 speed up the convergence
3755 of slave zones, but it also may increase the load on the
3758 <dt><span class="term"><span><strong class="command">transfers-out</strong></span></span></dt>
3760 The maximum number of outbound zone transfers
3761 that can be running concurrently. Zone transfer requests in
3763 of the limit will be refused. The default value is <code class="literal">10</code>.
3765 <dt><span class="term"><span><strong class="command">transfers-per-ns</strong></span></span></dt>
3767 The maximum number of inbound zone transfers
3768 that can be concurrently transferring from a given remote
3770 The default value is <code class="literal">2</code>.
3771 Increasing <span><strong class="command">transfers-per-ns</strong></span>
3773 speed up the convergence of slave zones, but it also may
3775 the load on the remote name server. <span><strong class="command">transfers-per-ns</strong></span> may
3776 be overridden on a per-server basis by using the <span><strong class="command">transfers</strong></span> phrase
3777 of the <span><strong class="command">server</strong></span> statement.
3779 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
3781 <p><span><strong class="command">transfer-source</strong></span>
3782 determines which local address will be bound to IPv4
3783 TCP connections used to fetch zones transferred
3784 inbound by the server. It also determines the
3785 source IPv4 address, and optionally the UDP port,
3786 used for the refresh queries and forwarded dynamic
3787 updates. If not set, it defaults to a system
3788 controlled value which will usually be the address
3789 of the interface "closest to" the remote end. This
3790 address must appear in the remote end's
3791 <span><strong class="command">allow-transfer</strong></span> option for the
3792 zone being transferred, if one is specified. This
3794 <span><strong class="command">transfer-source</strong></span> for all zones,
3795 but can be overridden on a per-view or per-zone
3796 basis by including a
3797 <span><strong class="command">transfer-source</strong></span> statement within
3798 the <span><strong class="command">view</strong></span> or
3799 <span><strong class="command">zone</strong></span> block in the configuration
3802 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3803 <h3 class="title">Note</h3>
3805 Solaris 2.5.1 and earlier does not support setting the
3806 source address for TCP sockets.
3810 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
3812 The same as <span><strong class="command">transfer-source</strong></span>,
3813 except zone transfers are performed using IPv6.
3815 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
3818 An alternate transfer source if the one listed in
3819 <span><strong class="command">transfer-source</strong></span> fails and
3820 <span><strong class="command">use-alt-transfer-source</strong></span> is
3823 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3824 <h3 class="title">Note</h3>
3825 If you do not wish the alternate transfer source
3826 to be used, you should set
3827 <span><strong class="command">use-alt-transfer-source</strong></span>
3828 appropriately and you should not depend upon
3829 getting an answer back to the first refresh
3833 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
3835 An alternate transfer source if the one listed in
3836 <span><strong class="command">transfer-source-v6</strong></span> fails and
3837 <span><strong class="command">use-alt-transfer-source</strong></span> is
3840 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
3842 Use the alternate transfer sources or not. If views are
3843 specified this defaults to <span><strong class="command">no</strong></span>
3844 otherwise it defaults to
3845 <span><strong class="command">yes</strong></span> (for BIND 8
3848 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
3850 <p><span><strong class="command">notify-source</strong></span>
3851 determines which local source address, and
3852 optionally UDP port, will be used to send NOTIFY
3853 messages. This address must appear in the slave
3854 server's <span><strong class="command">masters</strong></span> zone clause or
3855 in an <span><strong class="command">allow-notify</strong></span> clause. This
3856 statement sets the <span><strong class="command">notify-source</strong></span>
3857 for all zones, but can be overridden on a per-zone or
3858 per-view basis by including a
3859 <span><strong class="command">notify-source</strong></span> statement within
3860 the <span><strong class="command">zone</strong></span> or
3861 <span><strong class="command">view</strong></span> block in the configuration
3864 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3865 <h3 class="title">Note</h3>
3867 Solaris 2.5.1 and earlier does not support setting the
3868 source address for TCP sockets.
3872 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
3874 Like <span><strong class="command">notify-source</strong></span>,
3875 but applies to notify messages sent to IPv6 addresses.
3879 <div class="sect3" lang="en">
3880 <div class="titlepage"><div><div><h4 class="title">
3881 <a name="id2583691"></a>UDP Port Lists</h4></div></div></div>
3883 <span><strong class="command">use-v4-udp-ports</strong></span>,
3884 <span><strong class="command">avoid-v4-udp-ports</strong></span>,
3885 <span><strong class="command">use-v6-udp-ports</strong></span>, and
3886 <span><strong class="command">avoid-v6-udp-ports</strong></span>
3887 specify a list of IPv4 and IPv6 UDP ports that will be
3888 used or not used as source ports for UDP messages.
3889 See <a href="Bv9ARM.ch06.html#query_address" title="Query Address">the section called “Query Address”</a> about how the
3890 available ports are determined.
3891 For example, with the following configuration
3893 <pre class="programlisting">
3894 use-v6-udp-ports { range 32768 65535; };
3895 avoid-v6-udp-ports { 40000; range 50000 60000; };
3898 UDP ports of IPv6 messages sent
3899 from <span><strong class="command">named</strong></span> will be in one
3900 of the following ranges: 32768 to 39999, 40001 to 49999,
3904 <span><strong class="command">avoid-v4-udp-ports</strong></span> and
3905 <span><strong class="command">avoid-v6-udp-ports</strong></span> can be used
3906 to prevent <span><strong class="command">named</strong></span> from choosing as its random source port a
3907 port that is blocked by your firewall or a port that is
3908 used by other applications;
3909 if a query went out with a source port blocked by a
3911 answer would not get by the firewall and the name server would
3912 have to query again.
3913 Note: the desired range can also be represented only with
3914 <span><strong class="command">use-v4-udp-ports</strong></span> and
3915 <span><strong class="command">use-v6-udp-ports</strong></span>, and the
3916 <span><strong class="command">avoid-</strong></span> options are redundant in that
3917 sense; they are provided for backward compatibility and
3918 to possibly simplify the port specification.
3921 <div class="sect3" lang="en">
3922 <div class="titlepage"><div><div><h4 class="title">
3923 <a name="id2583751"></a>Operating System Resource Limits</h4></div></div></div>
3925 The server's usage of many system resources can be limited.
3926 Scaled values are allowed when specifying resource limits. For
3927 example, <span><strong class="command">1G</strong></span> can be used instead of
3928 <span><strong class="command">1073741824</strong></span> to specify a limit of
3930 gigabyte. <span><strong class="command">unlimited</strong></span> requests
3931 unlimited use, or the
3932 maximum available amount. <span><strong class="command">default</strong></span>
3934 that was in force when the server was started. See the description
3935 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 “Configuration File Elements”</a>.
3938 The following options set operating system resource limits for
3939 the name server process. Some operating systems don't support
3941 any of the limits. On such systems, a warning will be issued if
3943 unsupported limit is used.
3945 <div class="variablelist"><dl>
3946 <dt><span class="term"><span><strong class="command">coresize</strong></span></span></dt>
3948 The maximum size of a core dump. The default
3949 is <code class="literal">default</code>.
3951 <dt><span class="term"><span><strong class="command">datasize</strong></span></span></dt>
3953 The maximum amount of data memory the server
3954 may use. The default is <code class="literal">default</code>.
3955 This is a hard limit on server memory usage.
3956 If the server attempts to allocate memory in excess of this
3957 limit, the allocation will fail, which may in turn leave
3958 the server unable to perform DNS service. Therefore,
3959 this option is rarely useful as a way of limiting the
3960 amount of memory used by the server, but it can be used
3961 to raise an operating system data size limit that is
3962 too small by default. If you wish to limit the amount
3963 of memory used by the server, use the
3964 <span><strong class="command">max-cache-size</strong></span> and
3965 <span><strong class="command">recursive-clients</strong></span>
3968 <dt><span class="term"><span><strong class="command">files</strong></span></span></dt>
3970 The maximum number of files the server
3971 may have open concurrently. The default is <code class="literal">unlimited</code>.
3973 <dt><span class="term"><span><strong class="command">stacksize</strong></span></span></dt>
3975 The maximum amount of stack memory the server
3976 may use. The default is <code class="literal">default</code>.
3980 <div class="sect3" lang="en">
3981 <div class="titlepage"><div><div><h4 class="title">
3982 <a name="server_resource_limits"></a>Server Resource Limits</h4></div></div></div>
3984 The following options set limits on the server's
3985 resource consumption that are enforced internally by the
3986 server rather than the operating system.
3988 <div class="variablelist"><dl>
3989 <dt><span class="term"><span><strong class="command">max-ixfr-log-size</strong></span></span></dt>
3991 This option is obsolete; it is accepted
3992 and ignored for BIND 8 compatibility. The option
3993 <span><strong class="command">max-journal-size</strong></span> performs a
3994 similar function in BIND 9.
3996 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
3998 Sets a maximum size for each journal file
3999 (see <a href="Bv9ARM.ch04.html#journal" title="The journal file">the section called “The journal file”</a>). When the journal file
4001 the specified size, some of the oldest transactions in the
4003 will be automatically removed. The default is
4004 <code class="literal">unlimited</code>.
4005 This may also be set on a per-zone basis.
4007 <dt><span class="term"><span><strong class="command">host-statistics-max</strong></span></span></dt>
4009 In BIND 8, specifies the maximum number of host statistics
4011 Not implemented in BIND 9.
4013 <dt><span class="term"><span><strong class="command">recursive-clients</strong></span></span></dt>
4015 The maximum number of simultaneous recursive lookups
4016 the server will perform on behalf of clients. The default
4018 <code class="literal">1000</code>. Because each recursing
4020 bit of memory, on the order of 20 kilobytes, the value of
4022 <span><strong class="command">recursive-clients</strong></span> option may
4023 have to be decreased
4024 on hosts with limited memory.
4026 <dt><span class="term"><span><strong class="command">tcp-clients</strong></span></span></dt>
4028 The maximum number of simultaneous client TCP
4029 connections that the server will accept.
4030 The default is <code class="literal">100</code>.
4032 <dt><span class="term"><span><strong class="command">reserved-sockets</strong></span></span></dt>
4035 The number of file descriptors reserved for TCP, stdio,
4036 etc. This needs to be big enough to cover the number of
4037 interfaces <span><strong class="command">named</strong></span> listens on, <span><strong class="command">tcp-clients</strong></span> as well as
4038 to provide room for outgoing TCP queries and incoming zone
4039 transfers. The default is <code class="literal">512</code>.
4040 The minimum value is <code class="literal">128</code> and the
4041 maximum value is <code class="literal">128</code> less than
4042 maxsockets (-S). This option may be removed in the future.
4045 This option has little effect on Windows.
4048 <dt><span class="term"><span><strong class="command">max-cache-size</strong></span></span></dt>
4050 The maximum amount of memory to use for the
4051 server's cache, in bytes.
4052 When the amount of data in the cache
4053 reaches this limit, the server will cause records to expire
4054 prematurely based on an LRU based strategy so that
4055 the limit is not exceeded.
4056 A value of 0 is special, meaning that
4057 records are purged from the cache only when their
4059 Another special keyword <strong class="userinput"><code>unlimited</code></strong>
4060 means the maximum value of 32-bit unsigned integers
4061 (0xffffffff), which may not have the same effect as
4062 0 on machines that support more than 32 bits of
4064 Any positive values less than 2MB will be ignored reset
4066 In a server with multiple views, the limit applies
4067 separately to the cache of each view.
4070 <dt><span class="term"><span><strong class="command">tcp-listen-queue</strong></span></span></dt>
4072 The listen queue depth. The default and minimum is 3.
4073 If the kernel supports the accept filter "dataready" this
4075 many TCP connections that will be queued in kernel space
4077 some data before being passed to accept. Values less than 3
4083 <div class="sect3" lang="en">
4084 <div class="titlepage"><div><div><h4 class="title">
4085 <a name="id2584173"></a>Periodic Task Intervals</h4></div></div></div>
4086 <div class="variablelist"><dl>
4087 <dt><span class="term"><span><strong class="command">cleaning-interval</strong></span></span></dt>
4089 This interval is effectively obsolete. Previously,
4090 the server would remove expired resource records
4091 from the cache every <span><strong class="command">cleaning-interval</strong></span> minutes.
4092 <acronym class="acronym">BIND</acronym> 9 now manages cache
4093 memory in a more sophisticated manner and does not
4094 rely on the periodic cleaning any more.
4095 Specifying this option therefore has no effect on
4096 the server's behavior.
4098 <dt><span class="term"><span><strong class="command">heartbeat-interval</strong></span></span></dt>
4100 The server will perform zone maintenance tasks
4101 for all zones marked as <span><strong class="command">dialup</strong></span> whenever this
4102 interval expires. The default is 60 minutes. Reasonable
4104 to 1 day (1440 minutes). The maximum value is 28 days
4106 If set to 0, no zone maintenance for these zones will occur.
4108 <dt><span class="term"><span><strong class="command">interface-interval</strong></span></span></dt>
4110 The server will scan the network interface list
4111 every <span><strong class="command">interface-interval</strong></span>
4112 minutes. The default
4113 is 60 minutes. The maximum value is 28 days (40320 minutes).
4114 If set to 0, interface scanning will only occur when
4115 the configuration file is loaded. After the scan, the
4117 begin listening for queries on any newly discovered
4118 interfaces (provided they are allowed by the
4119 <span><strong class="command">listen-on</strong></span> configuration), and
4121 stop listening on interfaces that have gone away.
4123 <dt><span class="term"><span><strong class="command">statistics-interval</strong></span></span></dt>
4126 Name server statistics will be logged
4127 every <span><strong class="command">statistics-interval</strong></span>
4128 minutes. The default is
4129 60. The maximum value is 28 days (40320 minutes).
4130 If set to 0, no statistics will be logged.
4132 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4133 <h3 class="title">Note</h3>
4135 Not yet implemented in
4136 <acronym class="acronym">BIND</acronym> 9.
4142 <div class="sect3" lang="en">
4143 <div class="titlepage"><div><div><h4 class="title">
4144 <a name="topology"></a>Topology</h4></div></div></div>
4146 All other things being equal, when the server chooses a name
4148 to query from a list of name servers, it prefers the one that is
4149 topologically closest to itself. The <span><strong class="command">topology</strong></span> statement
4150 takes an <span><strong class="command">address_match_list</strong></span> and
4152 in a special way. Each top-level list element is assigned a
4154 Non-negated elements get a distance based on their position in the
4155 list, where the closer the match is to the start of the list, the
4156 shorter the distance is between it and the server. A negated match
4157 will be assigned the maximum distance from the server. If there
4158 is no match, the address will get a distance which is further than
4159 any non-negated list element, and closer than any negated element.
4162 <pre class="programlisting">topology {
4168 will prefer servers on network 10 the most, followed by hosts
4169 on network 1.2.0.0 (netmask 255.255.0.0) and network 3, with the
4170 exception of hosts on network 1.2.3 (netmask 255.255.255.0), which
4171 is preferred least of all.
4174 The default topology is
4176 <pre class="programlisting"> topology { localhost; localnets; };
4178 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4179 <h3 class="title">Note</h3>
4181 The <span><strong class="command">topology</strong></span> option
4182 is not implemented in <acronym class="acronym">BIND</acronym> 9.
4186 <div class="sect3" lang="en">
4187 <div class="titlepage"><div><div><h4 class="title">
4188 <a name="the_sortlist_statement"></a>The <span><strong class="command">sortlist</strong></span> Statement</h4></div></div></div>
4190 The response to a DNS query may consist of multiple resource
4191 records (RRs) forming a resource records set (RRset).
4192 The name server will normally return the
4193 RRs within the RRset in an indeterminate order
4194 (but see the <span><strong class="command">rrset-order</strong></span>
4195 statement in <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called “RRset Ordering”</a>).
4196 The client resolver code should rearrange the RRs as appropriate,
4197 that is, using any addresses on the local net in preference to
4199 However, not all resolvers can do this or are correctly
4201 When a client is using a local server, the sorting can be performed
4202 in the server, based on the client's address. This only requires
4203 configuring the name servers, not all the clients.
4206 The <span><strong class="command">sortlist</strong></span> statement (see below)
4208 an <span><strong class="command">address_match_list</strong></span> and
4210 more specifically than the <span><strong class="command">topology</strong></span>
4212 does (<a href="Bv9ARM.ch06.html#topology" title="Topology">the section called “Topology”</a>).
4213 Each top level statement in the <span><strong class="command">sortlist</strong></span> must
4214 itself be an explicit <span><strong class="command">address_match_list</strong></span> with
4215 one or two elements. The first element (which may be an IP
4217 an IP prefix, an ACL name or a nested <span><strong class="command">address_match_list</strong></span>)
4218 of each top level list is checked against the source address of
4219 the query until a match is found.
4222 Once the source address of the query has been matched, if
4223 the top level statement contains only one element, the actual
4225 element that matched the source address is used to select the
4227 in the response to move to the beginning of the response. If the
4228 statement is a list of two elements, then the second element is
4229 treated the same as the <span><strong class="command">address_match_list</strong></span> in
4230 a <span><strong class="command">topology</strong></span> statement. Each top
4232 is assigned a distance and the address in the response with the
4234 distance is moved to the beginning of the response.
4237 In the following example, any queries received from any of
4238 the addresses of the host itself will get responses preferring
4240 on any of the locally connected networks. Next most preferred are
4242 on the 192.168.1/24 network, and after that either the
4245 192.168.3/24 network with no preference shown between these two
4246 networks. Queries received from a host on the 192.168.1/24 network
4247 will prefer other addresses on that network to the 192.168.2/24
4249 192.168.3/24 networks. Queries received from a host on the
4251 or the 192.168.5/24 network will only prefer other addresses on
4252 their directly connected networks.
4254 <pre class="programlisting">sortlist {
4255 { localhost; // IF the local host
4256 { localnets; // THEN first fit on the
4257 192.168.1/24; // following nets
4258 { 192.168.2/24; 192.168.3/24; }; }; };
4259 { 192.168.1/24; // IF on class C 192.168.1
4260 { 192.168.1/24; // THEN use .1, or .2 or .3
4261 { 192.168.2/24; 192.168.3/24; }; }; };
4262 { 192.168.2/24; // IF on class C 192.168.2
4263 { 192.168.2/24; // THEN use .2, or .1 or .3
4264 { 192.168.1/24; 192.168.3/24; }; }; };
4265 { 192.168.3/24; // IF on class C 192.168.3
4266 { 192.168.3/24; // THEN use .3, or .1 or .2
4267 { 192.168.1/24; 192.168.2/24; }; }; };
4268 { { 192.168.4/24; 192.168.5/24; }; // if .4 or .5, prefer that net
4272 The following example will give reasonable behavior for the
4273 local host and hosts on directly connected networks. It is similar
4274 to the behavior of the address sort in <acronym class="acronym">BIND</acronym> 4.9.x. Responses sent
4275 to queries from the local host will favor any of the directly
4277 networks. Responses sent to queries from any other hosts on a
4279 connected network will prefer addresses on that same network.
4281 to other queries will not be sorted.
4283 <pre class="programlisting">sortlist {
4284 { localhost; localnets; };
4289 <div class="sect3" lang="en">
4290 <div class="titlepage"><div><div><h4 class="title">
4291 <a name="rrset_ordering"></a>RRset Ordering</h4></div></div></div>
4293 When multiple records are returned in an answer it may be
4294 useful to configure the order of the records placed into the
4296 The <span><strong class="command">rrset-order</strong></span> statement permits
4298 of the ordering of the records in a multiple record response.
4299 See also the <span><strong class="command">sortlist</strong></span> statement,
4300 <a href="Bv9ARM.ch06.html#the_sortlist_statement" title="The sortlist Statement">the section called “The <span><strong class="command">sortlist</strong></span> Statement”</a>.
4303 An <span><strong class="command">order_spec</strong></span> is defined as
4307 [<span class="optional">class <em class="replaceable"><code>class_name</code></em></span>]
4308 [<span class="optional">type <em class="replaceable"><code>type_name</code></em></span>]
4309 [<span class="optional">name <em class="replaceable"><code>"domain_name"</code></em></span>]
4310 order <em class="replaceable"><code>ordering</code></em>
4313 If no class is specified, the default is <span><strong class="command">ANY</strong></span>.
4314 If no type is specified, the default is <span><strong class="command">ANY</strong></span>.
4315 If no name is specified, the default is "<span><strong class="command">*</strong></span>" (asterisk).
4318 The legal values for <span><strong class="command">ordering</strong></span> are:
4320 <div class="informaltable"><table border="1">
4328 <p><span><strong class="command">fixed</strong></span></p>
4332 Records are returned in the order they
4333 are defined in the zone file.
4339 <p><span><strong class="command">random</strong></span></p>
4343 Records are returned in some random order.
4349 <p><span><strong class="command">cyclic</strong></span></p>
4353 Records are returned in a cyclic round-robin order.
4356 If <acronym class="acronym">BIND</acronym> is configured with the
4357 "--enable-fixed-rrset" option at compile time, then
4358 the initial ordering of the RRset will match the
4359 one specified in the zone file.
4368 <pre class="programlisting">rrset-order {
4369 class IN type A name "host.example.com" order random;
4374 will cause any responses for type A records in class IN that
4375 have "<code class="literal">host.example.com</code>" as a
4376 suffix, to always be returned
4377 in random order. All other records are returned in cyclic order.
4380 If multiple <span><strong class="command">rrset-order</strong></span> statements
4382 they are not combined — the last one applies.
4384 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4385 <h3 class="title">Note</h3>
4387 In this release of <acronym class="acronym">BIND</acronym> 9, the
4388 <span><strong class="command">rrset-order</strong></span> statement does not support
4389 "fixed" ordering by default. Fixed ordering can be enabled
4390 at compile time by specifying "--enable-fixed-rrset" on
4391 the "configure" command line.
4395 <div class="sect3" lang="en">
4396 <div class="titlepage"><div><div><h4 class="title">
4397 <a name="tuning"></a>Tuning</h4></div></div></div>
4398 <div class="variablelist"><dl>
4399 <dt><span class="term"><span><strong class="command">lame-ttl</strong></span></span></dt>
4402 Sets the number of seconds to cache a
4403 lame server indication. 0 disables caching. (This is
4404 <span class="bold"><strong>NOT</strong></span> recommended.)
4405 The default is <code class="literal">600</code> (10 minutes) and the
4407 <code class="literal">1800</code> (30 minutes).
4410 Lame-ttl also controls the amount of time DNSSEC
4411 validation failures are cached. There is a minimum
4412 of 30 seconds applied to bad cache entries if the
4413 lame-ttl is set to less than 30 seconds.
4416 <dt><span class="term"><span><strong class="command">max-ncache-ttl</strong></span></span></dt>
4418 To reduce network traffic and increase performance,
4419 the server stores negative answers. <span><strong class="command">max-ncache-ttl</strong></span> is
4420 used to set a maximum retention time for these answers in
4422 in seconds. The default
4423 <span><strong class="command">max-ncache-ttl</strong></span> is <code class="literal">10800</code> seconds (3 hours).
4424 <span><strong class="command">max-ncache-ttl</strong></span> cannot exceed
4426 be silently truncated to 7 days if set to a greater value.
4428 <dt><span class="term"><span><strong class="command">max-cache-ttl</strong></span></span></dt>
4430 Sets the maximum time for which the server will
4431 cache ordinary (positive) answers. The default is
4433 A value of zero may cause all queries to return
4434 SERVFAIL, because of lost caches of intermediate
4435 RRsets (such as NS and glue AAAA/A records) in the
4438 <dt><span class="term"><span><strong class="command">min-roots</strong></span></span></dt>
4441 The minimum number of root servers that
4442 is required for a request for the root servers to be
4443 accepted. The default
4444 is <strong class="userinput"><code>2</code></strong>.
4446 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4447 <h3 class="title">Note</h3>
4449 Not implemented in <acronym class="acronym">BIND</acronym> 9.
4453 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
4456 Specifies the number of days into the future when
4457 DNSSEC signatures automatically generated as a
4458 result of dynamic updates (<a href="Bv9ARM.ch04.html#dynamic_update" title="Dynamic Update">the section called “Dynamic Update”</a>) will expire. There
4459 is a optional second field which specifies how
4460 long before expiry that the signatures will be
4461 regenerated. If not specified, the signatures will
4462 be regenerated at 1/4 of base interval. The second
4463 field is specified in days if the base interval is
4464 greater than 7 days otherwise it is specified in hours.
4465 The default base interval is <code class="literal">30</code> days
4466 giving a re-signing interval of 7 1/2 days. The maximum
4467 values are 10 years (3660 days).
4470 The signature inception time is unconditionally
4471 set to one hour before the current time to allow
4472 for a limited amount of clock skew.
4475 The <span><strong class="command">sig-validity-interval</strong></span>
4476 should be, at least, several multiples of the SOA
4477 expire interval to allow for reasonable interaction
4478 between the various timer and expiry dates.
4481 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
4483 Specify the maximum number of nodes to be
4484 examined in each quantum when signing a zone with
4485 a new DNSKEY. The default is
4486 <code class="literal">100</code>.
4488 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
4490 Specify a threshold number of signatures that
4491 will terminate processing a quantum when signing
4492 a zone with a new DNSKEY. The default is
4493 <code class="literal">10</code>.
4495 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
4498 Specify a private RDATA type to be used when generating
4499 key signing records. The default is
4500 <code class="literal">65535</code>.
4503 It is expected that this parameter may be removed
4504 in a future version once there is a standard type.
4508 <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>
4512 These options control the server's behavior on refreshing a
4514 (querying for SOA changes) or retrying failed transfers.
4515 Usually the SOA values for the zone are used, but these
4517 are set by the master, giving slave server administrators
4519 control over their contents.
4522 These options allow the administrator to set a minimum and
4524 refresh and retry time either per-zone, per-view, or
4526 These options are valid for slave and stub zones,
4527 and clamp the SOA refresh and retry times to the specified
4531 The following defaults apply.
4532 <span><strong class="command">min-refresh-time</strong></span> 300 seconds,
4533 <span><strong class="command">max-refresh-time</strong></span> 2419200 seconds
4534 (4 weeks), <span><strong class="command">min-retry-time</strong></span> 500 seconds,
4535 and <span><strong class="command">max-retry-time</strong></span> 1209600 seconds
4539 <dt><span class="term"><span><strong class="command">edns-udp-size</strong></span></span></dt>
4541 Sets the advertised EDNS UDP buffer size in bytes
4542 to control the size of packets received.
4543 Valid values are 512 to 4096 (values outside this range
4544 will be silently adjusted). The default value
4545 is 4096. The usual reason for setting
4546 <span><strong class="command">edns-udp-size</strong></span> to a non-default
4547 value is to get UDP answers to pass through broken
4548 firewalls that block fragmented packets and/or
4549 block UDP packets that are greater than 512 bytes.
4551 <dt><span class="term"><span><strong class="command">max-udp-size</strong></span></span></dt>
4553 Sets the maximum EDNS UDP message size <span><strong class="command">named</strong></span> will
4554 send in bytes. Valid values are 512 to 4096 (values outside
4555 this range will be silently adjusted). The default
4556 value is 4096. The usual reason for setting
4557 <span><strong class="command">max-udp-size</strong></span> to a non-default value is to get UDP
4558 answers to pass through broken firewalls that
4559 block fragmented packets and/or block UDP packets
4560 that are greater than 512 bytes.
4561 This is independent of the advertised receive
4562 buffer (<span><strong class="command">edns-udp-size</strong></span>).
4564 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
4566 the file format of zone files (see
4567 <a href="Bv9ARM.ch06.html#zonefile_format" title="Additional File Formats">the section called “Additional File Formats”</a>).
4568 The default value is <code class="constant">text</code>, which is the
4569 standard textual representation. Files in other formats
4570 than <code class="constant">text</code> are typically expected
4571 to be generated by the <span><strong class="command">named-compilezone</strong></span> tool.
4572 Note that when a zone file in a different format than
4573 <code class="constant">text</code> is loaded, <span><strong class="command">named</strong></span>
4574 may omit some of the checks which would be performed for a
4575 file in the <code class="constant">text</code> format. In particular,
4576 <span><strong class="command">check-names</strong></span> checks do not apply
4577 for the <code class="constant">raw</code> format. This means
4578 a zone file in the <code class="constant">raw</code> format
4579 must be generated with the same check level as that
4580 specified in the <span><strong class="command">named</strong></span> configuration
4581 file. This statement sets the
4582 <span><strong class="command">masterfile-format</strong></span> for all zones,
4583 but can be overridden on a per-zone or per-view basis
4584 by including a <span><strong class="command">masterfile-format</strong></span>
4585 statement within the <span><strong class="command">zone</strong></span> or
4586 <span><strong class="command">view</strong></span> block in the configuration
4590 <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>
4594 initial value (minimum) and maximum number of recursive
4595 simultaneous clients for any given query
4596 (<qname,qtype,qclass>) that the server will accept
4597 before dropping additional clients. <span><strong class="command">named</strong></span> will attempt to
4598 self tune this value and changes will be logged. The
4599 default values are 10 and 100.
4602 This value should reflect how many queries come in for
4603 a given name in the time it takes to resolve that name.
4604 If the number of queries exceed this value, <span><strong class="command">named</strong></span> will
4605 assume that it is dealing with a non-responsive zone
4606 and will drop additional queries. If it gets a response
4607 after dropping queries, it will raise the estimate. The
4608 estimate will then be lowered in 20 minutes if it has
4612 If <span><strong class="command">clients-per-query</strong></span> is set to zero,
4613 then there is no limit on the number of clients per query
4614 and no queries will be dropped.
4617 If <span><strong class="command">max-clients-per-query</strong></span> is set to zero,
4618 then there is no upper bound other than imposed by
4619 <span><strong class="command">recursive-clients</strong></span>.
4622 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
4624 The delay, in seconds, between sending sets of notify
4625 messages for a zone. The default is five (5) seconds.
4629 <div class="sect3" lang="en">
4630 <div class="titlepage"><div><div><h4 class="title">
4631 <a name="builtin"></a>Built-in server information zones</h4></div></div></div>
4633 The server provides some helpful diagnostic information
4634 through a number of built-in zones under the
4635 pseudo-top-level-domain <code class="literal">bind</code> in the
4636 <span><strong class="command">CHAOS</strong></span> class. These zones are part
4638 built-in view (see <a href="Bv9ARM.ch06.html#view_statement_grammar" title="view Statement Grammar">the section called “<span><strong class="command">view</strong></span> Statement Grammar”</a>) of
4640 <span><strong class="command">CHAOS</strong></span> which is separate from the
4642 class <span><strong class="command">IN</strong></span>; therefore, any global
4644 such as <span><strong class="command">allow-query</strong></span> do not apply
4646 If you feel the need to disable these zones, use the options
4647 below, or hide the built-in <span><strong class="command">CHAOS</strong></span>
4649 defining an explicit view of class <span><strong class="command">CHAOS</strong></span>
4650 that matches all clients.
4652 <div class="variablelist"><dl>
4653 <dt><span class="term"><span><strong class="command">version</strong></span></span></dt>
4655 The version the server should report
4656 via a query of the name <code class="literal">version.bind</code>
4657 with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
4658 The default is the real version number of this server.
4659 Specifying <span><strong class="command">version none</strong></span>
4660 disables processing of the queries.
4662 <dt><span class="term"><span><strong class="command">hostname</strong></span></span></dt>
4664 The hostname the server should report via a query of
4665 the name <code class="filename">hostname.bind</code>
4666 with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
4667 This defaults to the hostname of the machine hosting the
4669 found by the gethostname() function. The primary purpose of such queries
4671 identify which of a group of anycast servers is actually
4672 answering your queries. Specifying <span><strong class="command">hostname none;</strong></span>
4673 disables processing of the queries.
4675 <dt><span class="term"><span><strong class="command">server-id</strong></span></span></dt>
4677 The ID the server should report when receiving a Name
4678 Server Identifier (NSID) query, or a query of the name
4679 <code class="filename">ID.SERVER</code> with type
4680 <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
4681 The primary purpose of such queries is to
4682 identify which of a group of anycast servers is actually
4683 answering your queries. Specifying <span><strong class="command">server-id none;</strong></span>
4684 disables processing of the queries.
4685 Specifying <span><strong class="command">server-id hostname;</strong></span> will cause <span><strong class="command">named</strong></span> to
4686 use the hostname as found by the gethostname() function.
4687 The default <span><strong class="command">server-id</strong></span> is <span><strong class="command">none</strong></span>.
4691 <div class="sect3" lang="en">
4692 <div class="titlepage"><div><div><h4 class="title">
4693 <a name="empty"></a>Built-in Empty Zones</h4></div></div></div>
4695 Named has some built-in empty zones (SOA and NS records only).
4696 These are for zones that should normally be answered locally
4697 and which queries should not be sent to the Internet's root
4698 servers. The official servers which cover these namespaces
4699 return NXDOMAIN responses to these queries. In particular,
4700 these cover the reverse namespace for addresses from RFC 1918 and
4701 RFC 3330. They also include the reverse namespace for IPv6 local
4702 address (locally assigned), IPv6 link local addresses, the IPv6
4703 loopback address and the IPv6 unknown address.
4706 Named will attempt to determine if a built-in zone already exists
4707 or is active (covered by a forward-only forwarding declaration)
4708 and will not create a empty zone in that case.
4711 The current list of empty zones is:
4713 <div class="itemizedlist"><ul type="disc">
4714 <li>0.IN-ADDR.ARPA</li>
4715 <li>127.IN-ADDR.ARPA</li>
4716 <li>254.169.IN-ADDR.ARPA</li>
4717 <li>2.0.192.IN-ADDR.ARPA</li>
4718 <li>100.51.198.IN-ADDR.ARPA</li>
4719 <li>113.0.203.IN-ADDR.ARPA</li>
4720 <li>255.255.255.255.IN-ADDR.ARPA</li>
4721 <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>
4722 <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>
4723 <li>8.B.D.0.1.0.0.2.IP6.ARPA</li>
4724 <li>D.F.IP6.ARPA</li>
4725 <li>8.E.F.IP6.ARPA</li>
4726 <li>9.E.F.IP6.ARPA</li>
4727 <li>A.E.F.IP6.ARPA</li>
4728 <li>B.E.F.IP6.ARPA</li>
4733 Empty zones are settable at the view level and only apply to
4734 views of class IN. Disabled empty zones are only inherited
4735 from options if there are no disabled empty zones specified
4736 at the view level. To override the options list of disabled
4737 zones, you can disable the root zone at the view level, for example:
4739 <pre class="programlisting">
4740 disable-empty-zone ".";
4745 If you are using the address ranges covered here, you should
4746 already have reverse zones covering the addresses you use.
4747 In practice this appears to not be the case with many queries
4748 being made to the infrastructure servers for names in these
4749 spaces. So many in fact that sacrificial servers were needed
4750 to be deployed to channel the query load away from the
4751 infrastructure servers.
4753 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4754 <h3 class="title">Note</h3>
4755 The real parent servers for these zones should disable all
4756 empty zone under the parent zone they serve. For the real
4757 root servers, this is all built-in empty zones. This will
4758 enable them to return referrals to deeper in the tree.
4760 <div class="variablelist"><dl>
4761 <dt><span class="term"><span><strong class="command">empty-server</strong></span></span></dt>
4763 Specify what server name will appear in the returned
4764 SOA record for empty zones. If none is specified, then
4765 the zone's name will be used.
4767 <dt><span class="term"><span><strong class="command">empty-contact</strong></span></span></dt>
4769 Specify what contact name will appear in the returned
4770 SOA record for empty zones. If none is specified, then
4773 <dt><span class="term"><span><strong class="command">empty-zones-enable</strong></span></span></dt>
4775 Enable or disable all empty zones. By default, they
4778 <dt><span class="term"><span><strong class="command">disable-empty-zone</strong></span></span></dt>
4780 Disable individual empty zones. By default, none are
4781 disabled. This option can be specified multiple times.
4785 <div class="sect3" lang="en">
4786 <div class="titlepage"><div><div><h4 class="title">
4787 <a name="acache"></a>Additional Section Caching</h4></div></div></div>
4789 The additional section cache, also called <span><strong class="command">acache</strong></span>,
4790 is an internal cache to improve the response performance of BIND 9.
4791 When additional section caching is enabled, BIND 9 will
4792 cache an internal short-cut to the additional section content for
4794 Note that <span><strong class="command">acache</strong></span> is an internal caching
4795 mechanism of BIND 9, and is not related to the DNS caching
4799 Additional section caching does not change the
4800 response content (except the RRsets ordering of the additional
4801 section, see below), but can improve the response performance
4803 It is particularly effective when BIND 9 acts as an authoritative
4804 server for a zone that has many delegations with many glue RRs.
4807 In order to obtain the maximum performance improvement
4808 from additional section caching, setting
4809 <span><strong class="command">additional-from-cache</strong></span>
4810 to <span><strong class="command">no</strong></span> is recommended, since the current
4811 implementation of <span><strong class="command">acache</strong></span>
4812 does not short-cut of additional section information from the
4816 One obvious disadvantage of <span><strong class="command">acache</strong></span> is
4817 that it requires much more
4818 memory for the internal cached data.
4819 Thus, if the response performance does not matter and memory
4820 consumption is much more critical, the
4821 <span><strong class="command">acache</strong></span> mechanism can be
4822 disabled by setting <span><strong class="command">acache-enable</strong></span> to
4823 <span><strong class="command">no</strong></span>.
4824 It is also possible to specify the upper limit of memory
4826 for acache by using <span><strong class="command">max-acache-size</strong></span>.
4829 Additional section caching also has a minor effect on the
4830 RRset ordering in the additional section.
4831 Without <span><strong class="command">acache</strong></span>,
4832 <span><strong class="command">cyclic</strong></span> order is effective for the additional
4833 section as well as the answer and authority sections.
4834 However, additional section caching fixes the ordering when it
4835 first caches an RRset for the additional section, and the same
4836 ordering will be kept in succeeding responses, regardless of the
4837 setting of <span><strong class="command">rrset-order</strong></span>.
4838 The effect of this should be minor, however, since an
4839 RRset in the additional section
4840 typically only contains a small number of RRs (and in many cases
4841 it only contains a single RR), in which case the
4842 ordering does not matter much.
4845 The following is a summary of options related to
4846 <span><strong class="command">acache</strong></span>.
4848 <div class="variablelist"><dl>
4849 <dt><span class="term"><span><strong class="command">acache-enable</strong></span></span></dt>
4851 If <span><strong class="command">yes</strong></span>, additional section caching is
4852 enabled. The default value is <span><strong class="command">no</strong></span>.
4854 <dt><span class="term"><span><strong class="command">acache-cleaning-interval</strong></span></span></dt>
4856 The server will remove stale cache entries, based on an LRU
4858 algorithm, every <span><strong class="command">acache-cleaning-interval</strong></span> minutes.
4859 The default is 60 minutes.
4860 If set to 0, no periodic cleaning will occur.
4862 <dt><span class="term"><span><strong class="command">max-acache-size</strong></span></span></dt>
4864 The maximum amount of memory in bytes to use for the server's acache.
4865 When the amount of data in the acache reaches this limit,
4867 will clean more aggressively so that the limit is not
4869 In a server with multiple views, the limit applies
4871 acache of each view.
4872 The default is <code class="literal">16M</code>.
4877 <div class="sect2" lang="en">
4878 <div class="titlepage"><div><div><h3 class="title">
4879 <a name="server_statement_grammar"></a><span><strong class="command">server</strong></span> Statement Grammar</h3></div></div></div>
4880 <pre class="programlisting"><span><strong class="command">server</strong></span> <em class="replaceable"><code>ip_addr[/prefixlen]</code></em> {
4881 [<span class="optional"> bogus <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4882 [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4883 [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4884 [<span class="optional"> edns <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
4885 [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
4886 [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
4887 [<span class="optional"> transfers <em class="replaceable"><code>number</code></em> ; </span>]
4888 [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em> ; ]</span>]
4889 [<span class="optional"> keys <em class="replaceable"><code>{ string ; [<span class="optional"> string ; [<span class="optional">...</span>]</span>] }</code></em> ; </span>]
4890 [<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>]
4891 [<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>]
4892 [<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>]
4893 [<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>]
4894 [<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>]
4895 [<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>]
4896 [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
4897 [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>]
4898 [<span class="optional"> queryport-pool-updateinterval <em class="replaceable"><code>number</code></em>; </span>]
4902 <div class="sect2" lang="en">
4903 <div class="titlepage"><div><div><h3 class="title">
4904 <a name="server_statement_definition_and_usage"></a><span><strong class="command">server</strong></span> Statement Definition and
4905 Usage</h3></div></div></div>
4907 The <span><strong class="command">server</strong></span> statement defines
4909 to be associated with a remote name server. If a prefix length is
4910 specified, then a range of servers is covered. Only the most
4912 server clause applies regardless of the order in
4913 <code class="filename">named.conf</code>.
4916 The <span><strong class="command">server</strong></span> statement can occur at
4917 the top level of the
4918 configuration file or inside a <span><strong class="command">view</strong></span>
4920 If a <span><strong class="command">view</strong></span> statement contains
4921 one or more <span><strong class="command">server</strong></span> statements, only
4923 apply to the view and any top-level ones are ignored.
4924 If a view contains no <span><strong class="command">server</strong></span>
4926 any top-level <span><strong class="command">server</strong></span> statements are
4931 If you discover that a remote server is giving out bad data,
4932 marking it as bogus will prevent further queries to it. The
4934 value of <span><strong class="command">bogus</strong></span> is <span><strong class="command">no</strong></span>.
4937 The <span><strong class="command">provide-ixfr</strong></span> clause determines
4939 the local server, acting as master, will respond with an
4941 zone transfer when the given remote server, a slave, requests it.
4942 If set to <span><strong class="command">yes</strong></span>, incremental transfer
4944 whenever possible. If set to <span><strong class="command">no</strong></span>,
4946 to the remote server will be non-incremental. If not set, the
4948 of the <span><strong class="command">provide-ixfr</strong></span> option in the
4950 global options block is used as a default.
4953 The <span><strong class="command">request-ixfr</strong></span> clause determines
4955 the local server, acting as a slave, will request incremental zone
4956 transfers from the given remote server, a master. If not set, the
4957 value of the <span><strong class="command">request-ixfr</strong></span> option in
4959 global options block is used as a default.
4962 IXFR requests to servers that do not support IXFR will
4964 fall back to AXFR. Therefore, there is no need to manually list
4965 which servers support IXFR and which ones do not; the global
4967 of <span><strong class="command">yes</strong></span> should always work.
4968 The purpose of the <span><strong class="command">provide-ixfr</strong></span> and
4969 <span><strong class="command">request-ixfr</strong></span> clauses is
4970 to make it possible to disable the use of IXFR even when both
4972 and slave claim to support it, for example if one of the servers
4973 is buggy and crashes or corrupts data when IXFR is used.
4976 The <span><strong class="command">edns</strong></span> clause determines whether
4977 the local server will attempt to use EDNS when communicating
4978 with the remote server. The default is <span><strong class="command">yes</strong></span>.
4981 The <span><strong class="command">edns-udp-size</strong></span> option sets the EDNS UDP size
4982 that is advertised by <span><strong class="command">named</strong></span> when querying the remote server.
4983 Valid values are 512 to 4096 bytes (values outside this range will be
4984 silently adjusted). This option is useful when you wish to
4985 advertises a different value to this server than the value you
4986 advertise globally, for example, when there is a firewall at the
4987 remote site that is blocking large replies.
4990 The <span><strong class="command">max-udp-size</strong></span> option sets the
4991 maximum EDNS UDP message size <span><strong class="command">named</strong></span> will send. Valid
4992 values are 512 to 4096 bytes (values outside this range will
4993 be silently adjusted). This option is useful when you
4994 know that there is a firewall that is blocking large
4995 replies from <span><strong class="command">named</strong></span>.
4998 The server supports two zone transfer methods. The first, <span><strong class="command">one-answer</strong></span>,
4999 uses one DNS message per resource record transferred. <span><strong class="command">many-answers</strong></span> packs
5000 as many resource records as possible into a message. <span><strong class="command">many-answers</strong></span> is
5001 more efficient, but is only known to be understood by <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
5002 8.x, and patched versions of <acronym class="acronym">BIND</acronym>
5003 4.9.5. You can specify which method
5004 to use for a server with the <span><strong class="command">transfer-format</strong></span> option.
5005 If <span><strong class="command">transfer-format</strong></span> is not
5006 specified, the <span><strong class="command">transfer-format</strong></span>
5008 by the <span><strong class="command">options</strong></span> statement will be
5011 <p><span><strong class="command">transfers</strong></span>
5012 is used to limit the number of concurrent inbound zone
5013 transfers from the specified server. If no
5014 <span><strong class="command">transfers</strong></span> clause is specified, the
5015 limit is set according to the
5016 <span><strong class="command">transfers-per-ns</strong></span> option.
5019 The <span><strong class="command">keys</strong></span> clause identifies a
5020 <span><strong class="command">key_id</strong></span> defined by the <span><strong class="command">key</strong></span> statement,
5021 to be used for transaction security (TSIG, <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called “TSIG”</a>)
5022 when talking to the remote server.
5023 When a request is sent to the remote server, a request signature
5024 will be generated using the key specified here and appended to the
5025 message. A request originating from the remote server is not
5027 to be signed by this key.
5030 Although the grammar of the <span><strong class="command">keys</strong></span>
5032 allows for multiple keys, only a single key per server is
5037 The <span><strong class="command">transfer-source</strong></span> and
5038 <span><strong class="command">transfer-source-v6</strong></span> clauses specify
5039 the IPv4 and IPv6 source
5040 address to be used for zone transfer with the remote server,
5042 For an IPv4 remote server, only <span><strong class="command">transfer-source</strong></span> can
5044 Similarly, for an IPv6 remote server, only
5045 <span><strong class="command">transfer-source-v6</strong></span> can be
5047 For more details, see the description of
5048 <span><strong class="command">transfer-source</strong></span> and
5049 <span><strong class="command">transfer-source-v6</strong></span> in
5050 <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5053 The <span><strong class="command">notify-source</strong></span> and
5054 <span><strong class="command">notify-source-v6</strong></span> clauses specify the
5055 IPv4 and IPv6 source address to be used for notify
5056 messages sent to remote servers, respectively. For an
5057 IPv4 remote server, only <span><strong class="command">notify-source</strong></span>
5058 can be specified. Similarly, for an IPv6 remote server,
5059 only <span><strong class="command">notify-source-v6</strong></span> can be specified.
5062 The <span><strong class="command">query-source</strong></span> and
5063 <span><strong class="command">query-source-v6</strong></span> clauses specify the
5064 IPv4 and IPv6 source address to be used for queries
5065 sent to remote servers, respectively. For an IPv4
5066 remote server, only <span><strong class="command">query-source</strong></span> can
5067 be specified. Similarly, for an IPv6 remote server,
5068 only <span><strong class="command">query-source-v6</strong></span> can be specified.
5071 <div class="sect2" lang="en">
5072 <div class="titlepage"><div><div><h3 class="title">
5073 <a name="statschannels"></a><span><strong class="command">statistics-channels</strong></span> Statement Grammar</h3></div></div></div>
5074 <pre class="programlisting"><span><strong class="command">statistics-channels</strong></span> {
5075 [ inet ( ip_addr | * ) [ port ip_port ] [allow { <em class="replaceable"><code> address_match_list </code></em> } ]; ]
5080 <div class="sect2" lang="en">
5081 <div class="titlepage"><div><div><h3 class="title">
5082 <a name="id2586907"></a><span><strong class="command">statistics-channels</strong></span> Statement Definition and
5083 Usage</h3></div></div></div>
5085 The <span><strong class="command">statistics-channels</strong></span> statement
5086 declares communication channels to be used by system
5087 administrators to get access to statistics information of
5091 This statement intends to be flexible to support multiple
5092 communication protocols in the future, but currently only
5093 HTTP access is supported.
5094 It requires that BIND 9 be compiled with libxml2;
5095 the <span><strong class="command">statistics-channels</strong></span> statement is
5096 still accepted even if it is built without the library,
5097 but any HTTP access will fail with an error.
5100 An <span><strong class="command">inet</strong></span> control channel is a TCP socket
5101 listening at the specified <span><strong class="command">ip_port</strong></span> on the
5102 specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6
5103 address. An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is
5104 interpreted as the IPv4 wildcard address; connections will be
5105 accepted on any of the system's IPv4 addresses.
5106 To listen on the IPv6 wildcard address,
5107 use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>.
5110 If no port is specified, port 80 is used for HTTP channels.
5111 The asterisk "<code class="literal">*</code>" cannot be used for
5112 <span><strong class="command">ip_port</strong></span>.
5115 The attempt of opening a statistics channel is
5116 restricted by the optional <span><strong class="command">allow</strong></span> clause.
5117 Connections to the statistics channel are permitted based on the
5118 <span><strong class="command">address_match_list</strong></span>.
5119 If no <span><strong class="command">allow</strong></span> clause is present,
5120 <span><strong class="command">named</strong></span> accepts connection
5121 attempts from any address; since the statistics may
5122 contain sensitive internal information, it is highly
5123 recommended to restrict the source of connection requests
5127 If no <span><strong class="command">statistics-channels</strong></span> statement is present,
5128 <span><strong class="command">named</strong></span> will not open any communication channels.
5131 <div class="sect2" lang="en">
5132 <div class="titlepage"><div><div><h3 class="title">
5133 <a name="id2587062"></a><span><strong class="command">trusted-keys</strong></span> Statement Grammar</h3></div></div></div>
5134 <pre class="programlisting"><span><strong class="command">trusted-keys</strong></span> {
5135 <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> ;
5136 [<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>]
5140 <div class="sect2" lang="en">
5141 <div class="titlepage"><div><div><h3 class="title">
5142 <a name="id2587113"></a><span><strong class="command">trusted-keys</strong></span> Statement Definition
5143 and Usage</h3></div></div></div>
5145 The <span><strong class="command">trusted-keys</strong></span> statement defines
5146 DNSSEC security roots. DNSSEC is described in <a href="Bv9ARM.ch04.html#DNSSEC" title="DNSSEC">the section called “DNSSEC”</a>. A security root is defined when the
5147 public key for a non-authoritative zone is known, but
5148 cannot be securely obtained through DNS, either because
5149 it is the DNS root zone or because its parent zone is
5150 unsigned. Once a key has been configured as a trusted
5151 key, it is treated as if it had been validated and
5152 proven secure. The resolver attempts DNSSEC validation
5153 on all DNS data in subdomains of a security root.
5156 All keys (and corresponding zones) listed in
5157 <span><strong class="command">trusted-keys</strong></span> are deemed to exist regardless
5158 of what parent zones say. Similarly for all keys listed in
5159 <span><strong class="command">trusted-keys</strong></span> only those keys are
5160 used to validate the DNSKEY RRset. The parent's DS RRset
5164 The <span><strong class="command">trusted-keys</strong></span> statement can contain
5165 multiple key entries, each consisting of the key's
5166 domain name, flags, protocol, algorithm, and the Base-64
5167 representation of the key data.
5168 Spaces, tabs, newlines and carriage returns are ignored
5169 in the key data, so the configuration may be split up into
5173 <div class="sect2" lang="en">
5174 <div class="titlepage"><div><div><h3 class="title">
5175 <a name="view_statement_grammar"></a><span><strong class="command">view</strong></span> Statement Grammar</h3></div></div></div>
5176 <pre class="programlisting"><span><strong class="command">view</strong></span> <em class="replaceable"><code>view_name</code></em>
5177 [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5178 match-clients { <em class="replaceable"><code>address_match_list</code></em> };
5179 match-destinations { <em class="replaceable"><code>address_match_list</code></em> };
5180 match-recursive-only <em class="replaceable"><code>yes_or_no</code></em> ;
5181 [<span class="optional"> <em class="replaceable"><code>view_option</code></em>; ...</span>]
5182 [<span class="optional"> <em class="replaceable"><code>zone_statement</code></em>; ...</span>]
5186 <div class="sect2" lang="en">
5187 <div class="titlepage"><div><div><h3 class="title">
5188 <a name="id2587195"></a><span><strong class="command">view</strong></span> Statement Definition and Usage</h3></div></div></div>
5190 The <span><strong class="command">view</strong></span> statement is a powerful
5192 of <acronym class="acronym">BIND</acronym> 9 that lets a name server
5193 answer a DNS query differently
5194 depending on who is asking. It is particularly useful for
5196 split DNS setups without having to run multiple servers.
5199 Each <span><strong class="command">view</strong></span> statement defines a view
5201 DNS namespace that will be seen by a subset of clients. A client
5203 a view if its source IP address matches the
5204 <code class="varname">address_match_list</code> of the view's
5205 <span><strong class="command">match-clients</strong></span> clause and its
5206 destination IP address matches
5207 the <code class="varname">address_match_list</code> of the
5209 <span><strong class="command">match-destinations</strong></span> clause. If not
5211 <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
5212 default to matching all addresses. In addition to checking IP
5214 <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
5215 can also take <span><strong class="command">keys</strong></span> which provide an
5217 client to select the view. A view can also be specified
5218 as <span><strong class="command">match-recursive-only</strong></span>, which
5219 means that only recursive
5220 requests from matching clients will match that view.
5221 The order of the <span><strong class="command">view</strong></span> statements is
5223 a client request will be resolved in the context of the first
5224 <span><strong class="command">view</strong></span> that it matches.
5227 Zones defined within a <span><strong class="command">view</strong></span>
5229 only be accessible to clients that match the <span><strong class="command">view</strong></span>.
5230 By defining a zone of the same name in multiple views, different
5231 zone data can be given to different clients, for example,
5233 and "external" clients in a split DNS setup.
5236 Many of the options given in the <span><strong class="command">options</strong></span> statement
5237 can also be used within a <span><strong class="command">view</strong></span>
5239 apply only when resolving queries with that view. When no
5241 value is given, the value in the <span><strong class="command">options</strong></span> statement
5242 is used as a default. Also, zone options can have default values
5244 in the <span><strong class="command">view</strong></span> statement; these
5245 view-specific defaults
5246 take precedence over those in the <span><strong class="command">options</strong></span> statement.
5249 Views are class specific. If no class is given, class IN
5250 is assumed. Note that all non-IN views must contain a hint zone,
5251 since only the IN class has compiled-in default hints.
5254 If there are no <span><strong class="command">view</strong></span> statements in
5256 file, a default view that matches any client is automatically
5258 in class IN. Any <span><strong class="command">zone</strong></span> statements
5260 the top level of the configuration file are considered to be part
5262 this default view, and the <span><strong class="command">options</strong></span>
5264 apply to the default view. If any explicit <span><strong class="command">view</strong></span>
5265 statements are present, all <span><strong class="command">zone</strong></span>
5267 occur inside <span><strong class="command">view</strong></span> statements.
5270 Here is an example of a typical split DNS setup implemented
5271 using <span><strong class="command">view</strong></span> statements:
5273 <pre class="programlisting">view "internal" {
5274 // This should match our internal networks.
5275 match-clients { 10.0.0.0/8; };
5277 // Provide recursive service to internal clients only.
5280 // Provide a complete view of the example.com zone
5281 // including addresses of internal hosts.
5282 zone "example.com" {
5284 file "example-internal.db";
5289 // Match all clients not matched by the previous view.
5290 match-clients { any; };
5292 // Refuse recursive service to external clients.
5295 // Provide a restricted view of the example.com zone
5296 // containing only publicly accessible hosts.
5297 zone "example.com" {
5299 file "example-external.db";
5304 <div class="sect2" lang="en">
5305 <div class="titlepage"><div><div><h3 class="title">
5306 <a name="zone_statement_grammar"></a><span><strong class="command">zone</strong></span>
5307 Statement Grammar</h3></div></div></div>
5308 <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>] {
5310 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5311 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5312 [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5313 [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5314 [<span class="optional"> update-policy { <em class="replaceable"><code>update_policy_rule</code></em> [<span class="optional">...</span>] }; </span>]
5315 [<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>]
5316 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5317 [<span class="optional"> check-mx (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5318 [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5319 [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5320 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
5321 [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
5322 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
5323 [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>]
5324 [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
5325 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5326 [<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>]
5327 [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>]
5328 [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5329 [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>]
5330 [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5331 [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
5332 [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
5333 [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
5334 [<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>]
5335 [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
5336 [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5337 [<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>]
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"> sig-validity-interval <em class="replaceable"><code>number</code></em> [<span class="optional"><em class="replaceable"><code>number</code></em></span>] ; </span>]
5342 [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>]
5343 [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>]
5344 [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>]
5345 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
5346 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5347 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5348 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5349 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5350 [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>]
5351 [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5354 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5356 [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5357 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5358 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5359 [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5360 [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5361 [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5362 [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5363 [<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>]
5364 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5365 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
5366 [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
5367 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
5368 [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>]
5369 [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
5370 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5371 [<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>]
5372 [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>]
5373 [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5374 [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>]
5375 [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5376 [<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>]
5377 [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
5378 [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
5379 [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
5380 [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
5381 [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
5382 [<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>]
5383 [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
5384 [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5385 [<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>]
5386 [<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>]
5387 [<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>]
5388 [<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>]
5389 [<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>]
5390 [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5391 [<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>]
5392 [<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>]
5393 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5394 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
5395 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5396 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5397 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5398 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5399 [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5400 [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5403 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5405 file <em class="replaceable"><code>string</code></em> ;
5406 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5407 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; // Not Implemented. </span>]
5410 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5412 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5413 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
5414 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
5415 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
5416 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5417 [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
5418 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
5419 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5420 [<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>]
5421 [<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>]
5422 [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
5423 [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
5424 [<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>]
5425 [<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>]
5426 [<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>]
5427 [<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>]
5428 [<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>]
5429 [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5430 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5431 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
5432 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5433 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
5434 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5435 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
5436 [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5439 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5441 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
5442 [<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>]
5443 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5446 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
5447 type delegation-only;
5452 <div class="sect2" lang="en">
5453 <div class="titlepage"><div><div><h3 class="title">
5454 <a name="id2588600"></a><span><strong class="command">zone</strong></span> Statement Definition and Usage</h3></div></div></div>
5455 <div class="sect3" lang="en">
5456 <div class="titlepage"><div><div><h4 class="title">
5457 <a name="id2588608"></a>Zone Types</h4></div></div></div>
5458 <div class="informaltable"><table border="1">
5467 <code class="varname">master</code>
5472 The server has a master copy of the data
5473 for the zone and will be able to provide authoritative
5482 <code class="varname">slave</code>
5487 A slave zone is a replica of a master
5488 zone. The <span><strong class="command">masters</strong></span> list
5489 specifies one or more IP addresses
5490 of master servers that the slave contacts to update
5491 its copy of the zone.
5492 Masters list elements can also be names of other
5494 By default, transfers are made from port 53 on the
5496 be changed for all servers by specifying a port number
5498 list of IP addresses, or on a per-server basis after
5500 Authentication to the master can also be done with
5501 per-server TSIG keys.
5502 If a file is specified, then the
5503 replica will be written to this file whenever the zone
5505 and reloaded from this file on a server restart. Use
5507 recommended, since it often speeds server startup and
5509 a needless waste of bandwidth. Note that for large
5511 tens or hundreds of thousands) of zones per server, it
5513 use a two-level naming scheme for zone filenames. For
5515 a slave server for the zone <code class="literal">example.com</code> might place
5516 the zone contents into a file called
5517 <code class="filename">ex/example.com</code> where <code class="filename">ex/</code> is
5518 just the first two letters of the zone name. (Most
5520 behave very slowly if you put 100000 files into
5521 a single directory.)
5528 <code class="varname">stub</code>
5533 A stub zone is similar to a slave zone,
5534 except that it replicates only the NS records of a
5536 of the entire zone. Stub zones are not a standard part
5538 they are a feature specific to the <acronym class="acronym">BIND</acronym> implementation.
5542 Stub zones can be used to eliminate the need for glue
5544 in a parent zone at the expense of maintaining a stub
5546 a set of name server addresses in <code class="filename">named.conf</code>.
5547 This usage is not recommended for new configurations,
5549 supports it only in a limited way.
5550 In <acronym class="acronym">BIND</acronym> 4/8, zone
5551 transfers of a parent zone
5552 included the NS records from stub children of that
5554 that, in some cases, users could get away with
5555 configuring child stubs
5556 only in the master server for the parent zone. <acronym class="acronym">BIND</acronym>
5557 9 never mixes together zone data from different zones
5559 way. Therefore, if a <acronym class="acronym">BIND</acronym> 9 master serving a parent
5560 zone has child stub zones configured, all the slave
5562 parent zone also need to have the same child stub
5568 Stub zones can also be used as a way of forcing the
5570 of a given domain to use a particular set of
5571 authoritative servers.
5572 For example, the caching name servers on a private
5574 RFC1918 addressing may be configured with stub zones
5576 <code class="literal">10.in-addr.arpa</code>
5577 to use a set of internal name servers as the
5579 servers for that domain.
5586 <code class="varname">forward</code>
5591 A "forward zone" is a way to configure
5592 forwarding on a per-domain basis. A <span><strong class="command">zone</strong></span> statement
5593 of type <span><strong class="command">forward</strong></span> can
5594 contain a <span><strong class="command">forward</strong></span>
5595 and/or <span><strong class="command">forwarders</strong></span>
5597 which will apply to queries within the domain given by
5599 name. If no <span><strong class="command">forwarders</strong></span>
5600 statement is present or
5601 an empty list for <span><strong class="command">forwarders</strong></span> is given, then no
5602 forwarding will be done for the domain, canceling the
5604 any forwarders in the <span><strong class="command">options</strong></span> statement. Thus
5605 if you want to use this type of zone to change the
5607 global <span><strong class="command">forward</strong></span> option
5608 (that is, "forward first"
5609 to, then "forward only", or vice versa, but want to
5611 servers as set globally) you need to re-specify the
5619 <code class="varname">hint</code>
5624 The initial set of root name servers is
5625 specified using a "hint zone". When the server starts
5627 the root hints to find a root name server and get the
5629 list of root name servers. If no hint zone is
5631 IN, the server uses a compiled-in default set of root
5633 Classes other than IN have no built-in defaults hints.
5640 <code class="varname">delegation-only</code>
5645 This is used to enforce the delegation-only
5646 status of infrastructure zones (e.g. COM,
5647 NET, ORG). Any answer that is received
5648 without an explicit or implicit delegation
5649 in the authority section will be treated
5650 as NXDOMAIN. This does not apply to the
5651 zone apex. This should not be applied to
5655 <code class="varname">delegation-only</code> has no
5656 effect on answers received from forwarders.
5659 See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>.
5666 <div class="sect3" lang="en">
5667 <div class="titlepage"><div><div><h4 class="title">
5668 <a name="id2589104"></a>Class</h4></div></div></div>
5670 The zone's name may optionally be followed by a class. If
5671 a class is not specified, class <code class="literal">IN</code> (for <code class="varname">Internet</code>),
5672 is assumed. This is correct for the vast majority of cases.
5675 The <code class="literal">hesiod</code> class is
5676 named for an information service from MIT's Project Athena. It
5678 used to share information about various systems databases, such
5679 as users, groups, printers and so on. The keyword
5680 <code class="literal">HS</code> is
5681 a synonym for hesiod.
5684 Another MIT development is Chaosnet, a LAN protocol created
5685 in the mid-1970s. Zone data for it can be specified with the <code class="literal">CHAOS</code> class.
5688 <div class="sect3" lang="en">
5689 <div class="titlepage"><div><div><h4 class="title">
5690 <a name="id2589137"></a>Zone Options</h4></div></div></div>
5691 <div class="variablelist"><dl>
5692 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
5694 See the description of
5695 <span><strong class="command">allow-notify</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
5697 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
5699 See the description of
5700 <span><strong class="command">allow-query</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
5702 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
5704 See the description of
5705 <span><strong class="command">allow-query-on</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
5707 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
5709 See the description of <span><strong class="command">allow-transfer</strong></span>
5710 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
5712 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
5714 See the description of <span><strong class="command">allow-update</strong></span>
5715 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
5717 <dt><span class="term"><span><strong class="command">update-policy</strong></span></span></dt>
5719 Specifies a "Simple Secure Update" policy. See
5720 <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called “Dynamic Update Policies”</a>.
5722 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
5724 See the description of <span><strong class="command">allow-update-forwarding</strong></span>
5725 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
5727 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
5729 Only meaningful if <span><strong class="command">notify</strong></span>
5731 active for this zone. The set of machines that will
5733 <code class="literal">DNS NOTIFY</code> message
5734 for this zone is made up of all the listed name servers
5736 the primary master) for the zone plus any IP addresses
5738 with <span><strong class="command">also-notify</strong></span>. A port
5740 with each <span><strong class="command">also-notify</strong></span>
5741 address to send the notify
5742 messages to a port other than the default of 53.
5743 <span><strong class="command">also-notify</strong></span> is not
5744 meaningful for stub zones.
5745 The default is the empty list.
5747 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
5749 This option is used to restrict the character set and
5751 certain domain names in master files and/or DNS responses
5753 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>
5754 zones the default is <span><strong class="command">warn</strong></span>.
5756 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
5758 See the description of
5759 <span><strong class="command">check-mx</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
5761 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
5763 See the description of
5764 <span><strong class="command">check-wildcard</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
5766 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
5768 See the description of
5769 <span><strong class="command">check-integrity</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
5771 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
5773 See the description of
5774 <span><strong class="command">check-sibling</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
5776 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
5778 See the description of
5779 <span><strong class="command">zero-no-soa-ttl</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
5781 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
5783 See the description of
5784 <span><strong class="command">update-check-ksk</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
5786 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
5788 See the description of
5789 <span><strong class="command">try-tcp-refresh</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
5791 <dt><span class="term"><span><strong class="command">database</strong></span></span></dt>
5794 Specify the type of database to be used for storing the
5795 zone data. The string following the <span><strong class="command">database</strong></span> keyword
5796 is interpreted as a list of whitespace-delimited words.
5798 identifies the database type, and any subsequent words are
5800 as arguments to the database to be interpreted in a way
5802 to the database type.
5805 The default is <strong class="userinput"><code>"rbt"</code></strong>, BIND 9's
5807 red-black-tree database. This database does not take
5811 Other values are possible if additional database drivers
5812 have been linked into the server. Some sample drivers are
5814 with the distribution but none are linked in by default.
5817 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
5819 See the description of
5820 <span><strong class="command">dialup</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
5822 <dt><span class="term"><span><strong class="command">delegation-only</strong></span></span></dt>
5825 The flag only applies to hint and stub zones. If set
5826 to <strong class="userinput"><code>yes</code></strong>, then the zone will also be
5827 treated as if it is also a delegation-only type zone.
5830 See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>.
5833 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
5835 Only meaningful if the zone has a forwarders
5836 list. The <span><strong class="command">only</strong></span> value causes
5838 after trying the forwarders and getting no answer, while <span><strong class="command">first</strong></span> would
5839 allow a normal lookup to be tried.
5841 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
5843 Used to override the list of global forwarders.
5844 If it is not specified in a zone of type <span><strong class="command">forward</strong></span>,
5845 no forwarding is done for the zone and the global options are
5848 <dt><span class="term"><span><strong class="command">ixfr-base</strong></span></span></dt>
5850 Was used in <acronym class="acronym">BIND</acronym> 8 to
5852 of the transaction log (journal) file for dynamic update
5854 <acronym class="acronym">BIND</acronym> 9 ignores the option
5855 and constructs the name of the journal
5856 file by appending "<code class="filename">.jnl</code>"
5860 <dt><span class="term"><span><strong class="command">ixfr-tmp-file</strong></span></span></dt>
5862 Was an undocumented option in <acronym class="acronym">BIND</acronym> 8.
5863 Ignored in <acronym class="acronym">BIND</acronym> 9.
5865 <dt><span class="term"><span><strong class="command">journal</strong></span></span></dt>
5867 Allow the default journal's filename to be overridden.
5868 The default is the zone's filename with "<code class="filename">.jnl</code>" appended.
5869 This is applicable to <span><strong class="command">master</strong></span> and <span><strong class="command">slave</strong></span> zones.
5871 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
5873 See the description of
5874 <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 “Server Resource Limits”</a>.
5876 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
5878 See the description of
5879 <span><strong class="command">max-transfer-time-in</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5881 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
5883 See the description of
5884 <span><strong class="command">max-transfer-idle-in</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5886 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
5888 See the description of
5889 <span><strong class="command">max-transfer-time-out</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5891 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
5893 See the description of
5894 <span><strong class="command">max-transfer-idle-out</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5896 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
5898 See the description of
5899 <span><strong class="command">notify</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
5901 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
5903 See the description of
5904 <span><strong class="command">notify-delay</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
5906 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
5908 See the description of
5909 <span><strong class="command">notify-to-soa</strong></span> in
5910 <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
5912 <dt><span class="term"><span><strong class="command">pubkey</strong></span></span></dt>
5914 In <acronym class="acronym">BIND</acronym> 8, this option was
5915 intended for specifying
5916 a public zone key for verification of signatures in DNSSEC
5918 zones when they are loaded from disk. <acronym class="acronym">BIND</acronym> 9 does not verify signatures
5919 on load and ignores the option.
5921 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
5923 If <strong class="userinput"><code>yes</code></strong>, the server will keep
5925 information for this zone, which can be dumped to the
5926 <span><strong class="command">statistics-file</strong></span> defined in
5929 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
5931 See the description of
5932 <span><strong class="command">sig-validity-interval</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
5934 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
5936 See the description of
5937 <span><strong class="command">sig-signing-nodes</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
5939 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
5941 See the description of
5942 <span><strong class="command">sig-signing-signatures</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
5944 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
5946 See the description of
5947 <span><strong class="command">sig-signing-type</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
5949 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
5951 See the description of
5952 <span><strong class="command">transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5954 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
5956 See the description of
5957 <span><strong class="command">transfer-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5959 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
5961 See the description of
5962 <span><strong class="command">alt-transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5964 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
5966 See the description of
5967 <span><strong class="command">alt-transfer-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5969 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
5971 See the description of
5972 <span><strong class="command">use-alt-transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5974 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
5976 See the description of
5977 <span><strong class="command">notify-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5979 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
5981 See the description of
5982 <span><strong class="command">notify-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5985 <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>
5988 See the description in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
5990 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
5992 See the description of
5993 <span><strong class="command">ixfr-from-differences</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
5994 (Note that the <span><strong class="command">ixfr-from-differences</strong></span>
5995 <strong class="userinput"><code>master</code></strong> and
5996 <strong class="userinput"><code>slave</code></strong> choices are not
5997 available at the zone level.)
5999 <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt>
6001 See the description of
6002 <span><strong class="command">key-directory</strong></span> in <a href="Bv9ARM.ch06.html#options" title="options Statement Definition and
6003 Usage">the section called “<span><strong class="command">options</strong></span> Statement Definition and
6006 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
6008 See the description of <span><strong class="command">multi-master</strong></span> in
6009 <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
6011 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
6013 See the description of <span><strong class="command">masterfile-format</strong></span>
6014 in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
6018 <div class="sect3" lang="en">
6019 <div class="titlepage"><div><div><h4 class="title">
6020 <a name="dynamic_update_policies"></a>Dynamic Update Policies</h4></div></div></div>
6021 <p><acronym class="acronym">BIND</acronym> 9 supports two alternative
6022 methods of granting clients the right to perform
6023 dynamic updates to a zone, configured by the
6024 <span><strong class="command">allow-update</strong></span> and
6025 <span><strong class="command">update-policy</strong></span> option, respectively.
6028 The <span><strong class="command">allow-update</strong></span> clause works the
6029 same way as in previous versions of <acronym class="acronym">BIND</acronym>.
6030 It grants given clients the permission to update any
6031 record of any name in the zone.
6034 The <span><strong class="command">update-policy</strong></span> clause is new
6035 in <acronym class="acronym">BIND</acronym> 9 and allows more fine-grained
6036 control over what updates are allowed. A set of rules
6037 is specified, where each rule either grants or denies
6038 permissions for one or more names to be updated by
6039 one or more identities. If the dynamic update request
6040 message is signed (that is, it includes either a TSIG
6041 or SIG(0) record), the identity of the signer can be
6045 Rules are specified in the <span><strong class="command">update-policy</strong></span>
6046 zone option, and are only meaningful for master zones.
6047 When the <span><strong class="command">update-policy</strong></span> statement
6048 is present, it is a configuration error for the
6049 <span><strong class="command">allow-update</strong></span> statement to be
6050 present. The <span><strong class="command">update-policy</strong></span> statement
6051 only examines the signer of a message; the source
6052 address is not relevant.
6055 This is how a rule definition looks:
6057 <pre class="programlisting">
6058 ( <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>]
6061 Each rule grants or denies privileges. Once a message has
6062 successfully matched a rule, the operation is immediately
6064 or denied and no further rules are examined. A rule is matched
6065 when the signer matches the identity field, the name matches the
6066 name field in accordance with the nametype field, and the type
6068 the types specified in the type field.
6071 No signer is required for <em class="replaceable"><code>tcp-self</code></em>
6072 or <em class="replaceable"><code>6to4-self</code></em> however the standard
6073 reverse mapping / prefix conversion must match the identity
6077 The identity field specifies a name or a wildcard
6078 name. Normally, this is the name of the TSIG or
6079 SIG(0) key used to sign the update request. When a
6080 TKEY exchange has been used to create a shared secret,
6081 the identity of the shared secret is the same as the
6082 identity of the key used to authenticate the TKEY
6083 exchange. TKEY is also the negotiation method used
6084 by GSS-TSIG, which establishes an identity that is
6085 the Kerberos principal of the client, such as
6086 <strong class="userinput"><code>"user@host.domain"</code></strong>. When the
6087 <em class="replaceable"><code>identity</code></em> field specifies
6088 a wildcard name, it is subject to DNS wildcard
6089 expansion, so the rule will apply to multiple identities.
6090 The <em class="replaceable"><code>identity</code></em> field must
6091 contain a fully-qualified domain name.
6094 The <em class="replaceable"><code>nametype</code></em> field has 12
6096 <code class="varname">name</code>, <code class="varname">subdomain</code>,
6097 <code class="varname">wildcard</code>, <code class="varname">self</code>,
6098 <code class="varname">selfsub</code>, <code class="varname">selfwild</code>,
6099 <code class="varname">krb5-self</code>, <code class="varname">ms-self</code>,
6100 <code class="varname">krb5-subdomain</code>,
6101 <code class="varname">ms-subdomain</code>,
6102 <code class="varname">tcp-self</code> and <code class="varname">6to4-self</code>.
6104 <div class="informaltable"><table border="1">
6113 <code class="varname">name</code>
6118 Exact-match semantics. This rule matches
6119 when the name being updated is identical
6120 to the contents of the
6121 <em class="replaceable"><code>name</code></em> field.
6128 <code class="varname">subdomain</code>
6133 This rule matches when the name being updated
6134 is a subdomain of, or identical to, the
6135 contents of the <em class="replaceable"><code>name</code></em>
6143 <code class="varname">wildcard</code>
6148 The <em class="replaceable"><code>name</code></em> field
6149 is subject to DNS wildcard expansion, and
6150 this rule matches when the name being updated
6151 name is a valid expansion of the wildcard.
6158 <code class="varname">self</code>
6163 This rule matches when the name being updated
6164 matches the contents of the
6165 <em class="replaceable"><code>identity</code></em> field.
6166 The <em class="replaceable"><code>name</code></em> field
6167 is ignored, but should be the same as the
6168 <em class="replaceable"><code>identity</code></em> field.
6169 The <code class="varname">self</code> nametype is
6170 most useful when allowing using one key per
6171 name to update, where the key has the same
6172 name as the name to be updated. The
6173 <em class="replaceable"><code>identity</code></em> would
6174 be specified as <code class="constant">*</code> (an asterisk) in
6182 <code class="varname">selfsub</code>
6187 This rule is similar to <code class="varname">self</code>
6188 except that subdomains of <code class="varname">self</code>
6189 can also be updated.
6196 <code class="varname">selfwild</code>
6201 This rule is similar to <code class="varname">self</code>
6202 except that only subdomains of
6203 <code class="varname">self</code> can be updated.
6210 <code class="varname">tcp-self</code>
6215 Allow updates that have been sent via TCP and
6216 for which the standard mapping from the initiating
6217 IP address into the IN-ADDR.ARPA and IP6.ARPA
6218 namespaces match the name to be updated.
6220 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
6221 <h3 class="title">Note</h3>
6222 It is theoretically possible to spoof these TCP
6230 <code class="varname">6to4-self</code>
6235 Allow the 6to4 prefix to be update by any TCP
6236 conection from the 6to4 network or from the
6237 corresponding IPv4 address. This is intended
6238 to allow NS or DNAME RRsets to be added to the
6241 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
6242 <h3 class="title">Note</h3>
6243 It is theoretically possible to spoof these TCP
6251 In all cases, the <em class="replaceable"><code>name</code></em>
6253 specify a fully-qualified domain name.
6256 If no types are explicitly specified, this rule matches
6257 all types except RRSIG, NS, SOA, NSEC and NSEC3. Types
6258 may be specified by name, including "ANY" (ANY matches
6259 all types except NSEC and NSEC3, which can never be
6260 updated). Note that when an attempt is made to delete
6261 all records associated with a name, the rules are
6262 checked for each existing record type.
6267 <div class="sect1" lang="en">
6268 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
6269 <a name="id2591216"></a>Zone File</h2></div></div></div>
6270 <div class="sect2" lang="en">
6271 <div class="titlepage"><div><div><h3 class="title">
6272 <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>
6274 This section, largely borrowed from RFC 1034, describes the
6275 concept of a Resource Record (RR) and explains when each is used.
6276 Since the publication of RFC 1034, several new RRs have been
6278 and implemented in the DNS. These are also included.
6280 <div class="sect3" lang="en">
6281 <div class="titlepage"><div><div><h4 class="title">
6282 <a name="id2591234"></a>Resource Records</h4></div></div></div>
6284 A domain name identifies a node. Each node has a set of
6285 resource information, which may be empty. The set of resource
6286 information associated with a particular name is composed of
6287 separate RRs. The order of RRs in a set is not significant and
6288 need not be preserved by name servers, resolvers, or other
6289 parts of the DNS. However, sorting of multiple RRs is
6290 permitted for optimization purposes, for example, to specify
6291 that a particular nearby server be tried first. See <a href="Bv9ARM.ch06.html#the_sortlist_statement" title="The sortlist Statement">the section called “The <span><strong class="command">sortlist</strong></span> Statement”</a> and <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called “RRset Ordering”</a>.
6294 The components of a Resource Record are:
6296 <div class="informaltable"><table border="1">
6310 The domain name where the RR is found.
6322 An encoded 16-bit value that specifies
6323 the type of the resource record.
6335 The time-to-live of the RR. This field
6336 is a 32-bit integer in units of seconds, and is
6338 resolvers when they cache RRs. The TTL describes how
6340 be cached before it should be discarded.
6352 An encoded 16-bit value that identifies
6353 a protocol family or instance of a protocol.
6365 The resource data. The format of the
6366 data is type (and sometimes class) specific.
6373 The following are <span class="emphasis"><em>types</em></span> of valid RRs:
6375 <div class="informaltable"><table border="1">
6389 A host address. In the IN class, this is a
6390 32-bit IP address. Described in RFC 1035.
6402 IPv6 address. Described in RFC 1886.
6414 IPv6 address. This can be a partial
6415 address (a suffix) and an indirection to the name
6416 where the rest of the
6417 address (the prefix) can be found. Experimental.
6418 Described in RFC 2874.
6430 Location of AFS database servers.
6431 Experimental. Described in RFC 1183.
6443 Address prefix list. Experimental.
6444 Described in RFC 3123.
6456 Holds a digital certificate.
6457 Described in RFC 2538.
6469 Identifies the canonical name of an alias.
6470 Described in RFC 1035.
6482 Is used for identifying which DHCP client is
6483 associated with this name. Described in RFC 4701.
6495 Replaces the domain name specified with
6496 another name to be looked up, effectively aliasing an
6498 subtree of the domain name space rather than a single
6500 as in the case of the CNAME RR.
6501 Described in RFC 2672.
6513 Stores a public key associated with a signed
6514 DNS zone. Described in RFC 4034.
6526 Stores the hash of a public key associated with a
6527 signed DNS zone. Described in RFC 4034.
6539 Specifies the global position. Superseded by LOC.
6551 Identifies the CPU and OS used by a host.
6552 Described in RFC 1035.
6564 Provides a method for storing IPsec keying material in
6565 DNS. Described in RFC 4025.
6577 Representation of ISDN addresses.
6578 Experimental. Described in RFC 1183.
6590 Stores a public key associated with a
6591 DNS name. Used in original DNSSEC; replaced
6592 by DNSKEY in DNSSECbis, but still used with
6593 SIG(0). Described in RFCs 2535 and 2931.
6605 Identifies a key exchanger for this
6606 DNS name. Described in RFC 2230.
6618 For storing GPS info. Described in RFC 1876.
6631 Identifies a mail exchange for the domain with
6632 a 16-bit preference value (lower is better)
6633 followed by the host name of the mail exchange.
6634 Described in RFC 974, RFC 1035.
6646 Name authority pointer. Described in RFC 2915.
6658 A network service access point.
6659 Described in RFC 1706.
6671 The authoritative name server for the
6672 domain. Described in RFC 1035.
6684 Used in DNSSECbis to securely indicate that
6685 RRs with an owner name in a certain name interval do
6687 a zone and indicate what RR types are present for an
6689 Described in RFC 4034.
6701 Used in DNSSECbis to securely indicate that
6702 RRs with an owner name in a certain name
6703 interval do not exist in a zone and indicate
6704 what RR types are present for an existing
6705 name. NSEC3 differs from NSEC in that it
6706 prevents zone enumeration but is more
6707 computationally expensive on both the server
6708 and the client than NSEC. Described in RFC
6721 Used in DNSSECbis to tell the authoritative
6722 server which NSEC3 chains are available to use.
6723 Described in RFC 5155.
6735 Used in DNSSEC to securely indicate that
6736 RRs with an owner name in a certain name interval do
6738 a zone and indicate what RR types are present for an
6740 Used in original DNSSEC; replaced by NSEC in
6742 Described in RFC 2535.
6754 A pointer to another part of the domain
6755 name space. Described in RFC 1035.
6767 Provides mappings between RFC 822 and X.400
6768 addresses. Described in RFC 2163.
6780 Information on persons responsible
6781 for the domain. Experimental. Described in RFC 1183.
6793 Contains DNSSECbis signature data. Described
6806 Route-through binding for hosts that
6807 do not have their own direct wide area network
6809 Experimental. Described in RFC 1183.
6821 Contains DNSSEC signature data. Used in
6822 original DNSSEC; replaced by RRSIG in
6823 DNSSECbis, but still used for SIG(0).
6824 Described in RFCs 2535 and 2931.
6836 Identifies the start of a zone of authority.
6837 Described in RFC 1035.
6849 Contains the Sender Policy Framework information
6850 for a given email domain. Described in RFC 4408.
6862 Information about well known network
6863 services (replaces WKS). Described in RFC 2782.
6875 Provides a way to securely publish a secure shell key's
6876 fingerprint. Described in RFC 4255.
6888 Text records. Described in RFC 1035.
6900 Information about which well known
6901 network services, such as SMTP, that a domain
6902 supports. Historical.
6914 Representation of X.25 network addresses.
6915 Experimental. Described in RFC 1183.
6922 The following <span class="emphasis"><em>classes</em></span> of resource records
6923 are currently valid in the DNS:
6925 <div class="informaltable"><table border="1">
6951 Chaosnet, a LAN protocol created at MIT in the
6953 Rarely used for its historical purpose, but reused for
6955 built-in server information zones, e.g.,
6956 <code class="literal">version.bind</code>.
6968 Hesiod, an information service
6969 developed by MIT's Project Athena. It is used to share
6971 about various systems databases, such as users,
6980 The owner name is often implicit, rather than forming an
6982 part of the RR. For example, many name servers internally form
6984 or hash structures for the name space, and chain RRs off nodes.
6985 The remaining RR parts are the fixed header (type, class, TTL)
6986 which is consistent for all RRs, and a variable part (RDATA)
6988 fits the needs of the resource being described.
6991 The meaning of the TTL field is a time limit on how long an
6992 RR can be kept in a cache. This limit does not apply to
6994 data in zones; it is also timed out, but by the refreshing
6996 for the zone. The TTL is assigned by the administrator for the
6997 zone where the data originates. While short TTLs can be used to
6998 minimize caching, and a zero TTL prohibits caching, the
7000 of Internet performance suggest that these times should be on
7002 order of days for the typical host. If a change can be
7004 the TTL can be reduced prior to the change to minimize
7006 during the change, and then increased back to its former value
7011 The data in the RDATA section of RRs is carried as a combination
7012 of binary strings and domain names. The domain names are
7014 used as "pointers" to other data in the DNS.
7017 <div class="sect3" lang="en">
7018 <div class="titlepage"><div><div><h4 class="title">
7019 <a name="id2592857"></a>Textual expression of RRs</h4></div></div></div>
7021 RRs are represented in binary form in the packets of the DNS
7022 protocol, and are usually represented in highly encoded form
7024 stored in a name server or resolver. In the examples provided
7026 RFC 1034, a style similar to that used in master files was
7028 in order to show the contents of RRs. In this format, most RRs
7029 are shown on a single line, although continuation lines are
7034 The start of the line gives the owner of the RR. If a line
7035 begins with a blank, then the owner is assumed to be the same as
7036 that of the previous RR. Blank lines are often included for
7040 Following the owner, we list the TTL, type, and class of the
7041 RR. Class and type use the mnemonics defined above, and TTL is
7042 an integer before the type field. In order to avoid ambiguity
7044 parsing, type and class mnemonics are disjoint, TTLs are
7046 and the type mnemonic is always last. The IN class and TTL
7048 are often omitted from examples in the interests of clarity.
7051 The resource data or RDATA section of the RR are given using
7052 knowledge of the typical representation for the data.
7055 For example, we might show the RRs carried in a message as:
7057 <div class="informaltable"><table border="1">
7067 <code class="literal">ISI.EDU.</code>
7072 <code class="literal">MX</code>
7077 <code class="literal">10 VENERA.ISI.EDU.</code>
7087 <code class="literal">MX</code>
7092 <code class="literal">10 VAXA.ISI.EDU</code>
7099 <code class="literal">VENERA.ISI.EDU</code>
7104 <code class="literal">A</code>
7109 <code class="literal">128.9.0.32</code>
7119 <code class="literal">A</code>
7124 <code class="literal">10.1.0.52</code>
7131 <code class="literal">VAXA.ISI.EDU</code>
7136 <code class="literal">A</code>
7141 <code class="literal">10.2.0.27</code>
7151 <code class="literal">A</code>
7156 <code class="literal">128.9.0.33</code>
7163 The MX RRs have an RDATA section which consists of a 16-bit
7164 number followed by a domain name. The address RRs use a
7166 IP address format to contain a 32-bit internet address.
7169 The above example shows six RRs, with two RRs at each of three
7173 Similarly we might see:
7175 <div class="informaltable"><table border="1">
7185 <code class="literal">XX.LCS.MIT.EDU.</code>
7190 <code class="literal">IN A</code>
7195 <code class="literal">10.0.0.44</code>
7203 <code class="literal">CH A</code>
7208 <code class="literal">MIT.EDU. 2420</code>
7215 This example shows two addresses for
7216 <code class="literal">XX.LCS.MIT.EDU</code>, each of a different class.
7220 <div class="sect2" lang="en">
7221 <div class="titlepage"><div><div><h3 class="title">
7222 <a name="id2593378"></a>Discussion of MX Records</h3></div></div></div>
7224 As described above, domain servers store information as a
7225 series of resource records, each of which contains a particular
7226 piece of information about a given domain name (which is usually,
7227 but not always, a host). The simplest way to think of a RR is as
7228 a typed pair of data, a domain name matched with a relevant datum,
7229 and stored with some additional type information to help systems
7230 determine when the RR is relevant.
7233 MX records are used to control delivery of email. The data
7234 specified in the record is a priority and a domain name. The
7236 controls the order in which email delivery is attempted, with the
7237 lowest number first. If two priorities are the same, a server is
7238 chosen randomly. If no servers at a given priority are responding,
7239 the mail transport agent will fall back to the next largest
7241 Priority numbers do not have any absolute meaning — they are
7243 only respective to other MX records for that domain name. The
7245 name given is the machine to which the mail will be delivered.
7246 It <span class="emphasis"><em>must</em></span> have an associated address record
7247 (A or AAAA) — CNAME is not sufficient.
7250 For a given domain, if there is both a CNAME record and an
7251 MX record, the MX record is in error, and will be ignored.
7253 the mail will be delivered to the server specified in the MX
7255 pointed to by the CNAME.
7258 <div class="informaltable"><table border="1">
7270 <code class="literal">example.com.</code>
7275 <code class="literal">IN</code>
7280 <code class="literal">MX</code>
7285 <code class="literal">10</code>
7290 <code class="literal">mail.example.com.</code>
7300 <code class="literal">IN</code>
7305 <code class="literal">MX</code>
7310 <code class="literal">10</code>
7315 <code class="literal">mail2.example.com.</code>
7325 <code class="literal">IN</code>
7330 <code class="literal">MX</code>
7335 <code class="literal">20</code>
7340 <code class="literal">mail.backup.org.</code>
7347 <code class="literal">mail.example.com.</code>
7352 <code class="literal">IN</code>
7357 <code class="literal">A</code>
7362 <code class="literal">10.0.0.1</code>
7372 <code class="literal">mail2.example.com.</code>
7377 <code class="literal">IN</code>
7382 <code class="literal">A</code>
7387 <code class="literal">10.0.0.2</code>
7397 Mail delivery will be attempted to <code class="literal">mail.example.com</code> and
7398 <code class="literal">mail2.example.com</code> (in
7399 any order), and if neither of those succeed, delivery to <code class="literal">mail.backup.org</code> will
7403 <div class="sect2" lang="en">
7404 <div class="titlepage"><div><div><h3 class="title">
7405 <a name="Setting_TTLs"></a>Setting TTLs</h3></div></div></div>
7407 The time-to-live of the RR field is a 32-bit integer represented
7408 in units of seconds, and is primarily used by resolvers when they
7409 cache RRs. The TTL describes how long a RR can be cached before it
7410 should be discarded. The following three types of TTL are
7412 used in a zone file.
7414 <div class="informaltable"><table border="1">
7428 The last field in the SOA is the negative
7429 caching TTL. This controls how long other servers will
7430 cache no-such-domain
7431 (NXDOMAIN) responses from you.
7434 The maximum time for
7435 negative caching is 3 hours (3h).
7447 The $TTL directive at the top of the
7448 zone file (before the SOA) gives a default TTL for every
7462 Each RR can have a TTL as the second
7463 field in the RR, which will control how long other
7472 All of these TTLs default to units of seconds, though units
7473 can be explicitly specified, for example, <code class="literal">1h30m</code>.
7476 <div class="sect2" lang="en">
7477 <div class="titlepage"><div><div><h3 class="title">
7478 <a name="id2593993"></a>Inverse Mapping in IPv4</h3></div></div></div>
7480 Reverse name resolution (that is, translation from IP address
7481 to name) is achieved by means of the <span class="emphasis"><em>in-addr.arpa</em></span> domain
7482 and PTR records. Entries in the in-addr.arpa domain are made in
7483 least-to-most significant order, read left to right. This is the
7484 opposite order to the way IP addresses are usually written. Thus,
7485 a machine with an IP address of 10.1.2.3 would have a
7487 in-addr.arpa name of
7488 3.2.1.10.in-addr.arpa. This name should have a PTR resource record
7489 whose data field is the name of the machine or, optionally,
7491 PTR records if the machine has more than one name. For example,
7492 in the [<span class="optional">example.com</span>] domain:
7494 <div class="informaltable"><table border="1">
7503 <code class="literal">$ORIGIN</code>
7508 <code class="literal">2.1.10.in-addr.arpa</code>
7515 <code class="literal">3</code>
7520 <code class="literal">IN PTR foo.example.com.</code>
7526 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7527 <h3 class="title">Note</h3>
7529 The <span><strong class="command">$ORIGIN</strong></span> lines in the examples
7530 are for providing context to the examples only — they do not
7532 appear in the actual usage. They are only used here to indicate
7533 that the example is relative to the listed origin.
7537 <div class="sect2" lang="en">
7538 <div class="titlepage"><div><div><h3 class="title">
7539 <a name="id2594188"></a>Other Zone File Directives</h3></div></div></div>
7541 The Master File Format was initially defined in RFC 1035 and
7542 has subsequently been extended. While the Master File Format
7544 is class independent all records in a Master File must be of the
7549 Master File Directives include <span><strong class="command">$ORIGIN</strong></span>, <span><strong class="command">$INCLUDE</strong></span>,
7550 and <span><strong class="command">$TTL.</strong></span>
7552 <div class="sect3" lang="en">
7553 <div class="titlepage"><div><div><h4 class="title">
7554 <a name="id2594211"></a>The <span><strong class="command">@</strong></span> (at-sign)</h4></div></div></div>
7556 When used in the label (or name) field, the asperand or
7557 at-sign (@) symbol represents the current origin.
7558 At the start of the zone file, it is the
7559 <<code class="varname">zone_name</code>> (followed by
7563 <div class="sect3" lang="en">
7564 <div class="titlepage"><div><div><h4 class="title">
7565 <a name="id2594227"></a>The <span><strong class="command">$ORIGIN</strong></span> Directive</h4></div></div></div>
7567 Syntax: <span><strong class="command">$ORIGIN</strong></span>
7568 <em class="replaceable"><code>domain-name</code></em>
7569 [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
7571 <p><span><strong class="command">$ORIGIN</strong></span>
7572 sets the domain name that will be appended to any
7573 unqualified records. When a zone is first read in there
7574 is an implicit <span><strong class="command">$ORIGIN</strong></span>
7575 <<code class="varname">zone_name</code>><span><strong class="command">.</strong></span>
7576 (followed by trailing dot).
7577 The current <span><strong class="command">$ORIGIN</strong></span> is appended to
7578 the domain specified in the <span><strong class="command">$ORIGIN</strong></span>
7579 argument if it is not absolute.
7581 <pre class="programlisting">
7582 $ORIGIN example.com.
7583 WWW CNAME MAIN-SERVER
7588 <pre class="programlisting">
7589 WWW.EXAMPLE.COM. CNAME MAIN-SERVER.EXAMPLE.COM.
7592 <div class="sect3" lang="en">
7593 <div class="titlepage"><div><div><h4 class="title">
7594 <a name="id2594356"></a>The <span><strong class="command">$INCLUDE</strong></span> Directive</h4></div></div></div>
7596 Syntax: <span><strong class="command">$INCLUDE</strong></span>
7597 <em class="replaceable"><code>filename</code></em>
7598 [<span class="optional">
7599 <em class="replaceable"><code>origin</code></em> </span>]
7600 [<span class="optional"> <em class="replaceable"><code>comment</code></em> </span>]
7603 Read and process the file <code class="filename">filename</code> as
7604 if it were included into the file at this point. If <span><strong class="command">origin</strong></span> is
7605 specified the file is processed with <span><strong class="command">$ORIGIN</strong></span> set
7606 to that value, otherwise the current <span><strong class="command">$ORIGIN</strong></span> is
7610 The origin and the current domain name
7611 revert to the values they had prior to the <span><strong class="command">$INCLUDE</strong></span> once
7612 the file has been read.
7614 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7615 <h3 class="title">Note</h3>
7617 RFC 1035 specifies that the current origin should be restored
7619 an <span><strong class="command">$INCLUDE</strong></span>, but it is silent
7620 on whether the current
7621 domain name should also be restored. BIND 9 restores both of
7623 This could be construed as a deviation from RFC 1035, a
7628 <div class="sect3" lang="en">
7629 <div class="titlepage"><div><div><h4 class="title">
7630 <a name="id2594425"></a>The <span><strong class="command">$TTL</strong></span> Directive</h4></div></div></div>
7632 Syntax: <span><strong class="command">$TTL</strong></span>
7633 <em class="replaceable"><code>default-ttl</code></em>
7634 [<span class="optional">
7635 <em class="replaceable"><code>comment</code></em> </span>]
7638 Set the default Time To Live (TTL) for subsequent records
7639 with undefined TTLs. Valid TTLs are of the range 0-2147483647
7642 <p><span><strong class="command">$TTL</strong></span>
7643 is defined in RFC 2308.
7647 <div class="sect2" lang="en">
7648 <div class="titlepage"><div><div><h3 class="title">
7649 <a name="id2594461"></a><acronym class="acronym">BIND</acronym> Master File Extension: the <span><strong class="command">$GENERATE</strong></span> Directive</h3></div></div></div>
7651 Syntax: <span><strong class="command">$GENERATE</strong></span>
7652 <em class="replaceable"><code>range</code></em>
7653 <em class="replaceable"><code>lhs</code></em>
7654 [<span class="optional"><em class="replaceable"><code>ttl</code></em></span>]
7655 [<span class="optional"><em class="replaceable"><code>class</code></em></span>]
7656 <em class="replaceable"><code>type</code></em>
7657 <em class="replaceable"><code>rhs</code></em>
7658 [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
7660 <p><span><strong class="command">$GENERATE</strong></span>
7661 is used to create a series of resource records that only
7662 differ from each other by an
7663 iterator. <span><strong class="command">$GENERATE</strong></span> can be used to
7664 easily generate the sets of records required to support
7665 sub /24 reverse delegations described in RFC 2317:
7666 Classless IN-ADDR.ARPA delegation.
7668 <pre class="programlisting">$ORIGIN 0.0.192.IN-ADDR.ARPA.
7669 $GENERATE 1-2 0 NS SERVER$.EXAMPLE.
7670 $GENERATE 1-127 $ CNAME $.0</pre>
7674 <pre class="programlisting">0.0.0.192.IN-ADDR.ARPA. NS SERVER1.EXAMPLE.
7675 0.0.0.192.IN-ADDR.ARPA. NS SERVER2.EXAMPLE.
7676 1.0.0.192.IN-ADDR.ARPA. CNAME 1.0.0.0.192.IN-ADDR.ARPA.
7677 2.0.0.192.IN-ADDR.ARPA. CNAME 2.0.0.0.192.IN-ADDR.ARPA.
7679 127.0.0.192.IN-ADDR.ARPA. CNAME 127.0.0.0.192.IN-ADDR.ARPA.
7681 <div class="informaltable"><table border="1">
7689 <p><span><strong class="command">range</strong></span></p>
7693 This can be one of two forms: start-stop
7694 or start-stop/step. If the first form is used, then step
7696 1. All of start, stop and step must be positive.
7702 <p><span><strong class="command">lhs</strong></span></p>
7706 describes the owner name of the resource records
7707 to be created. Any single <span><strong class="command">$</strong></span>
7709 symbols within the <span><strong class="command">lhs</strong></span> string
7710 are replaced by the iterator value.
7712 To get a $ in the output, you need to escape the
7713 <span><strong class="command">$</strong></span> using a backslash
7714 <span><strong class="command">\</strong></span>,
7715 e.g. <span><strong class="command">\$</strong></span>. The
7716 <span><strong class="command">$</strong></span> may optionally be followed
7717 by modifiers which change the offset from the
7718 iterator, field width and base.
7720 Modifiers are introduced by a
7721 <span><strong class="command">{</strong></span> (left brace) immediately following the
7722 <span><strong class="command">$</strong></span> as
7723 <span><strong class="command">${offset[,width[,base]]}</strong></span>.
7724 For example, <span><strong class="command">${-20,3,d}</strong></span>
7725 subtracts 20 from the current value, prints the
7726 result as a decimal in a zero-padded field of
7729 Available output forms are decimal
7730 (<span><strong class="command">d</strong></span>), octal
7731 (<span><strong class="command">o</strong></span>) and hexadecimal
7732 (<span><strong class="command">x</strong></span> or <span><strong class="command">X</strong></span>
7733 for uppercase). The default modifier is
7734 <span><strong class="command">${0,0,d}</strong></span>. If the
7735 <span><strong class="command">lhs</strong></span> is not absolute, the
7736 current <span><strong class="command">$ORIGIN</strong></span> is appended
7740 For compatibility with earlier versions, <span><strong class="command">$$</strong></span> is still
7741 recognized as indicating a literal $ in the output.
7747 <p><span><strong class="command">ttl</strong></span></p>
7751 Specifies the time-to-live of the generated records. If
7752 not specified this will be inherited using the
7753 normal TTL inheritance rules.
7755 <p><span><strong class="command">class</strong></span>
7756 and <span><strong class="command">ttl</strong></span> can be
7757 entered in either order.
7763 <p><span><strong class="command">class</strong></span></p>
7767 Specifies the class of the generated records.
7768 This must match the zone class if it is
7771 <p><span><strong class="command">class</strong></span>
7772 and <span><strong class="command">ttl</strong></span> can be
7773 entered in either order.
7779 <p><span><strong class="command">type</strong></span></p>
7783 At present the only supported types are
7784 PTR, CNAME, DNAME, A, AAAA and NS.
7790 <p><span><strong class="command">rhs</strong></span></p>
7794 <span><strong class="command">rhs</strong></span> is a domain name. It is processed
7802 The <span><strong class="command">$GENERATE</strong></span> directive is a <acronym class="acronym">BIND</acronym> extension
7803 and not part of the standard zone file format.
7806 BIND 8 does not support the optional TTL and CLASS fields.
7809 <div class="sect2" lang="en">
7810 <div class="titlepage"><div><div><h3 class="title">
7811 <a name="zonefile_format"></a>Additional File Formats</h3></div></div></div>
7813 In addition to the standard textual format, BIND 9
7814 supports the ability to read or dump to zone files in
7815 other formats. The <code class="constant">raw</code> format is
7816 currently available as an additional format. It is a
7817 binary format representing BIND 9's internal data
7818 structure directly, thereby remarkably improving the
7822 For a primary server, a zone file in the
7823 <code class="constant">raw</code> format is expected to be
7824 generated from a textual zone file by the
7825 <span><strong class="command">named-compilezone</strong></span> command. For a
7826 secondary server or for a dynamic zone, it is automatically
7827 generated (if this format is specified by the
7828 <span><strong class="command">masterfile-format</strong></span> option) when
7829 <span><strong class="command">named</strong></span> dumps the zone contents after
7830 zone transfer or when applying prior updates.
7833 If a zone file in a binary format needs manual modification,
7834 it first must be converted to a textual form by the
7835 <span><strong class="command">named-compilezone</strong></span> command. All
7836 necessary modification should go to the text file, which
7837 should then be converted to the binary form by the
7838 <span><strong class="command">named-compilezone</strong></span> command again.
7841 Although the <code class="constant">raw</code> format uses the
7842 network byte order and avoids architecture-dependent
7843 data alignment so that it is as much portable as
7844 possible, it is primarily expected to be used inside
7845 the same single system. In order to export a zone
7846 file in the <code class="constant">raw</code> format or make a
7847 portable backup of the file, it is recommended to
7848 convert the file to the standard textual representation.
7852 <div class="sect1" lang="en">
7853 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
7854 <a name="statistics"></a>BIND9 Statistics</h2></div></div></div>
7856 <acronym class="acronym">BIND</acronym> 9 maintains lots of statistics
7857 information and provides several interfaces for users to
7858 get access to the statistics.
7859 The available statistics include all statistics counters
7860 that were available in <acronym class="acronym">BIND</acronym> 8 and
7861 are meaningful in <acronym class="acronym">BIND</acronym> 9,
7862 and other information that is considered useful.
7865 The statistics information is categorized into the following
7868 <div class="informaltable"><table border="1">
7876 <p>Incoming Requests</p>
7880 The number of incoming DNS requests for each OPCODE.
7886 <p>Incoming Queries</p>
7890 The number of incoming queries for each RR type.
7896 <p>Outgoing Queries</p>
7900 The number of outgoing queries for each RR
7901 type sent from the internal resolver.
7902 Maintained per view.
7908 <p>Name Server Statistics</p>
7912 Statistics counters about incoming request processing.
7918 <p>Zone Maintenance Statistics</p>
7922 Statistics counters regarding zone maintenance
7923 operations such as zone transfers.
7929 <p>Resolver Statistics</p>
7933 Statistics counters about name resolution
7934 performed in the internal resolver.
7935 Maintained per view.
7941 <p>Cache DB RRsets</p>
7945 The number of RRsets per RR type (positive
7946 or negative) and nonexistent names stored in the
7948 Maintained per view.
7954 <p>Socket I/O Statistics</p>
7958 Statistics counters about network related events.
7965 A subset of Name Server Statistics is collected and shown
7966 per zone for which the server has the authority when
7967 <span><strong class="command">zone-statistics</strong></span> is set to
7968 <strong class="userinput"><code>yes</code></strong>.
7969 These statistics counters are shown with their zone and view
7971 In some cases the view names are omitted for the default view.
7974 There are currently two user interfaces to get access to the
7976 One is in the plain text format dumped to the file specified
7977 by the <span><strong class="command">statistics-file</strong></span> configuration option.
7978 The other is remotely accessible via a statistics channel
7979 when the <span><strong class="command">statistics-channels</strong></span> statement
7980 is specified in the configuration file
7981 (see <a href="Bv9ARM.ch06.html#statschannels" title="statistics-channels Statement Grammar">the section called “<span><strong class="command">statistics-channels</strong></span> Statement Grammar”</a>.)
7983 <div class="sect3" lang="en">
7984 <div class="titlepage"><div><div><h4 class="title">
7985 <a name="statsfile"></a>The Statistics File</h4></div></div></div>
7987 The text format statistics dump begins with a line, like:
7990 <span><strong class="command">+++ Statistics Dump +++ (973798949)</strong></span>
7993 The number in parentheses is a standard
7994 Unix-style timestamp, measured as seconds since January 1, 1970.
7997 that line is a set of statistics information, which is categorized
7999 Each section begins with a line, like:
8002 <span><strong class="command">++ Name Server Statistics ++</strong></span>
8005 Each section consists of lines, each containing the statistics
8006 counter value followed by its textual description.
8007 See below for available counters.
8008 For brevity, counters that have a value of 0 are not shown
8009 in the statistics file.
8012 The statistics dump ends with the line where the
8013 number is identical to the number in the beginning line; for example:
8016 <span><strong class="command">--- Statistics Dump --- (973798949)</strong></span>
8019 <div class="sect2" lang="en">
8020 <div class="titlepage"><div><div><h3 class="title">
8021 <a name="statistics_counters"></a>Statistics Counters</h3></div></div></div>
8023 The following tables summarize statistics counters that
8024 <acronym class="acronym">BIND</acronym> 9 provides.
8025 For each row of the tables, the leftmost column is the
8026 abbreviated symbol name of that counter.
8027 These symbols are shown in the statistics information
8028 accessed via an HTTP statistics channel.
8029 The rightmost column gives the description of the counter,
8030 which is also shown in the statistics file
8031 (but, in this document, possibly with slight modification
8032 for better readability).
8033 Additional notes may also be provided in this column.
8034 When a middle column exists between these two columns,
8035 it gives the corresponding counter name of the
8036 <acronym class="acronym">BIND</acronym> 8 statistics, if applicable.
8038 <div class="sect3" lang="en">
8039 <div class="titlepage"><div><div><h4 class="title">
8040 <a name="id2595458"></a>Name Server Statistics Counters</h4></div></div></div>
8041 <div class="informaltable"><table border="1">
8051 <span class="emphasis"><em>Symbol</em></span>
8056 <span class="emphasis"><em>BIND8 Symbol</em></span>
8061 <span class="emphasis"><em>Description</em></span>
8067 <p><span><strong class="command">Requestv4</strong></span></p>
8070 <p><span><strong class="command">RQ</strong></span></p>
8074 IPv4 requests received.
8075 Note: this also counts non query requests.
8081 <p><span><strong class="command">Requestv6</strong></span></p>
8084 <p><span><strong class="command">RQ</strong></span></p>
8088 IPv6 requests received.
8089 Note: this also counts non query requests.
8095 <p><span><strong class="command">ReqEdns0</strong></span></p>
8098 <p><span><strong class="command"></strong></span></p>
8102 Requests with EDNS(0) received.
8108 <p><span><strong class="command">ReqBadEDNSVer</strong></span></p>
8111 <p><span><strong class="command"></strong></span></p>
8115 Requests with unsupported EDNS version received.
8121 <p><span><strong class="command">ReqTSIG</strong></span></p>
8124 <p><span><strong class="command"></strong></span></p>
8128 Requests with TSIG received.
8134 <p><span><strong class="command">ReqSIG0</strong></span></p>
8137 <p><span><strong class="command"></strong></span></p>
8141 Requests with SIG(0) received.
8147 <p><span><strong class="command">ReqBadSIG</strong></span></p>
8150 <p><span><strong class="command"></strong></span></p>
8154 Requests with invalid (TSIG or SIG(0)) signature.
8160 <p><span><strong class="command">ReqTCP</strong></span></p>
8163 <p><span><strong class="command">RTCP</strong></span></p>
8167 TCP requests received.
8173 <p><span><strong class="command">AuthQryRej</strong></span></p>
8176 <p><span><strong class="command">RUQ</strong></span></p>
8180 Authoritative (non recursive) queries rejected.
8186 <p><span><strong class="command">RecQryRej</strong></span></p>
8189 <p><span><strong class="command">RURQ</strong></span></p>
8193 Recursive queries rejected.
8199 <p><span><strong class="command">XfrRej</strong></span></p>
8202 <p><span><strong class="command">RUXFR</strong></span></p>
8206 Zone transfer requests rejected.
8212 <p><span><strong class="command">UpdateRej</strong></span></p>
8215 <p><span><strong class="command">RUUpd</strong></span></p>
8219 Dynamic update requests rejected.
8225 <p><span><strong class="command">Response</strong></span></p>
8228 <p><span><strong class="command">SAns</strong></span></p>
8238 <p><span><strong class="command">RespTruncated</strong></span></p>
8241 <p><span><strong class="command"></strong></span></p>
8245 Truncated responses sent.
8251 <p><span><strong class="command">RespEDNS0</strong></span></p>
8254 <p><span><strong class="command"></strong></span></p>
8258 Responses with EDNS(0) sent.
8264 <p><span><strong class="command">RespTSIG</strong></span></p>
8267 <p><span><strong class="command"></strong></span></p>
8271 Responses with TSIG sent.
8277 <p><span><strong class="command">RespSIG0</strong></span></p>
8280 <p><span><strong class="command"></strong></span></p>
8284 Responses with SIG(0) sent.
8290 <p><span><strong class="command">QrySuccess</strong></span></p>
8293 <p><span><strong class="command"></strong></span></p>
8297 Queries resulted in a successful answer.
8298 This means the query which returns a NOERROR response
8299 with at least one answer RR.
8300 This corresponds to the
8301 <span><strong class="command">success</strong></span> counter
8302 of previous versions of
8303 <acronym class="acronym">BIND</acronym> 9.
8309 <p><span><strong class="command">QryAuthAns</strong></span></p>
8312 <p><span><strong class="command"></strong></span></p>
8316 Queries resulted in authoritative answer.
8322 <p><span><strong class="command">QryNoauthAns</strong></span></p>
8325 <p><span><strong class="command">SNaAns</strong></span></p>
8329 Queries resulted in non authoritative answer.
8335 <p><span><strong class="command">QryReferral</strong></span></p>
8338 <p><span><strong class="command"></strong></span></p>
8342 Queries resulted in referral answer.
8343 This corresponds to the
8344 <span><strong class="command">referral</strong></span> counter
8345 of previous versions of
8346 <acronym class="acronym">BIND</acronym> 9.
8352 <p><span><strong class="command">QryNxrrset</strong></span></p>
8355 <p><span><strong class="command"></strong></span></p>
8359 Queries resulted in NOERROR responses with no data.
8360 This corresponds to the
8361 <span><strong class="command">nxrrset</strong></span> counter
8362 of previous versions of
8363 <acronym class="acronym">BIND</acronym> 9.
8369 <p><span><strong class="command">QrySERVFAIL</strong></span></p>
8372 <p><span><strong class="command">SFail</strong></span></p>
8376 Queries resulted in SERVFAIL.
8382 <p><span><strong class="command">QryFORMERR</strong></span></p>
8385 <p><span><strong class="command">SFErr</strong></span></p>
8389 Queries resulted in FORMERR.
8395 <p><span><strong class="command">QryNXDOMAIN</strong></span></p>
8398 <p><span><strong class="command">SNXD</strong></span></p>
8402 Queries resulted in NXDOMAIN.
8403 This corresponds to the
8404 <span><strong class="command">nxdomain</strong></span> counter
8405 of previous versions of
8406 <acronym class="acronym">BIND</acronym> 9.
8412 <p><span><strong class="command">QryRecursion</strong></span></p>
8415 <p><span><strong class="command">RFwdQ</strong></span></p>
8419 Queries which caused the server
8420 to perform recursion in order to find the final answer.
8421 This corresponds to the
8422 <span><strong class="command">recursion</strong></span> counter
8423 of previous versions of
8424 <acronym class="acronym">BIND</acronym> 9.
8430 <p><span><strong class="command">QryDuplicate</strong></span></p>
8433 <p><span><strong class="command">RDupQ</strong></span></p>
8437 Queries which the server attempted to
8438 recurse but discovered an existing query with the same
8439 IP address, port, query ID, name, type and class
8440 already being processed.
8441 This corresponds to the
8442 <span><strong class="command">duplicate</strong></span> counter
8443 of previous versions of
8444 <acronym class="acronym">BIND</acronym> 9.
8450 <p><span><strong class="command">QryDropped</strong></span></p>
8453 <p><span><strong class="command"></strong></span></p>
8457 Recursive queries for which the server
8458 discovered an excessive number of existing
8459 recursive queries for the same name, type and
8460 class and were subsequently dropped.
8461 This is the number of dropped queries due to
8462 the reason explained with the
8463 <span><strong class="command">clients-per-query</strong></span>
8465 <span><strong class="command">max-clients-per-query</strong></span>
8467 (see the description about
8468 <a href="Bv9ARM.ch06.html#clients-per-query"><span><strong class="command">clients-per-query</strong></span></a>.)
8469 This corresponds to the
8470 <span><strong class="command">dropped</strong></span> counter
8471 of previous versions of
8472 <acronym class="acronym">BIND</acronym> 9.
8478 <p><span><strong class="command">QryFailure</strong></span></p>
8481 <p><span><strong class="command"></strong></span></p>
8485 Other query failures.
8486 This corresponds to the
8487 <span><strong class="command">failure</strong></span> counter
8488 of previous versions of
8489 <acronym class="acronym">BIND</acronym> 9.
8490 Note: this counter is provided mainly for
8491 backward compatibility with the previous versions.
8492 Normally a more fine-grained counters such as
8493 <span><strong class="command">AuthQryRej</strong></span> and
8494 <span><strong class="command">RecQryRej</strong></span>
8495 that would also fall into this counter are provided,
8496 and so this counter would not be of much
8497 interest in practice.
8503 <p><span><strong class="command">XfrReqDone</strong></span></p>
8506 <p><span><strong class="command"></strong></span></p>
8510 Requested zone transfers completed.
8516 <p><span><strong class="command">UpdateReqFwd</strong></span></p>
8519 <p><span><strong class="command"></strong></span></p>
8523 Update requests forwarded.
8529 <p><span><strong class="command">UpdateRespFwd</strong></span></p>
8532 <p><span><strong class="command"></strong></span></p>
8536 Update responses forwarded.
8542 <p><span><strong class="command">UpdateFwdFail</strong></span></p>
8545 <p><span><strong class="command"></strong></span></p>
8549 Dynamic update forward failed.
8555 <p><span><strong class="command">UpdateDone</strong></span></p>
8558 <p><span><strong class="command"></strong></span></p>
8562 Dynamic updates completed.
8568 <p><span><strong class="command">UpdateFail</strong></span></p>
8571 <p><span><strong class="command"></strong></span></p>
8575 Dynamic updates failed.
8581 <p><span><strong class="command">UpdateBadPrereq</strong></span></p>
8584 <p><span><strong class="command"></strong></span></p>
8588 Dynamic updates rejected due to prerequisite failure.
8595 <div class="sect3" lang="en">
8596 <div class="titlepage"><div><div><h4 class="title">
8597 <a name="id2596931"></a>Zone Maintenance Statistics Counters</h4></div></div></div>
8598 <div class="informaltable"><table border="1">
8607 <span class="emphasis"><em>Symbol</em></span>
8612 <span class="emphasis"><em>Description</em></span>
8618 <p><span><strong class="command">NotifyOutv4</strong></span></p>
8628 <p><span><strong class="command">NotifyOutv6</strong></span></p>
8638 <p><span><strong class="command">NotifyInv4</strong></span></p>
8642 IPv4 notifies received.
8648 <p><span><strong class="command">NotifyInv6</strong></span></p>
8652 IPv6 notifies received.
8658 <p><span><strong class="command">NotifyRej</strong></span></p>
8662 Incoming notifies rejected.
8668 <p><span><strong class="command">SOAOutv4</strong></span></p>
8672 IPv4 SOA queries sent.
8678 <p><span><strong class="command">SOAOutv6</strong></span></p>
8682 IPv6 SOA queries sent.
8688 <p><span><strong class="command">AXFRReqv4</strong></span></p>
8692 IPv4 AXFR requested.
8698 <p><span><strong class="command">AXFRReqv6</strong></span></p>
8702 IPv6 AXFR requested.
8708 <p><span><strong class="command">IXFRReqv4</strong></span></p>
8712 IPv4 IXFR requested.
8718 <p><span><strong class="command">IXFRReqv6</strong></span></p>
8722 IPv6 IXFR requested.
8728 <p><span><strong class="command">XfrSuccess</strong></span></p>
8732 Zone transfer requests succeeded.
8738 <p><span><strong class="command">XfrFail</strong></span></p>
8742 Zone transfer requests failed.
8749 <div class="sect3" lang="en">
8750 <div class="titlepage"><div><div><h4 class="title">
8751 <a name="id2597314"></a>Resolver Statistics Counters</h4></div></div></div>
8752 <div class="informaltable"><table border="1">
8762 <span class="emphasis"><em>Symbol</em></span>
8767 <span class="emphasis"><em>BIND8 Symbol</em></span>
8772 <span class="emphasis"><em>Description</em></span>
8778 <p><span><strong class="command">Queryv4</strong></span></p>
8781 <p><span><strong class="command">SFwdQ</strong></span></p>
8791 <p><span><strong class="command">Queryv6</strong></span></p>
8794 <p><span><strong class="command">SFwdQ</strong></span></p>
8804 <p><span><strong class="command">Responsev4</strong></span></p>
8807 <p><span><strong class="command">RR</strong></span></p>
8811 IPv4 responses received.
8817 <p><span><strong class="command">Responsev6</strong></span></p>
8820 <p><span><strong class="command">RR</strong></span></p>
8824 IPv6 responses received.
8830 <p><span><strong class="command">NXDOMAIN</strong></span></p>
8833 <p><span><strong class="command">RNXD</strong></span></p>
8843 <p><span><strong class="command">SERVFAIL</strong></span></p>
8846 <p><span><strong class="command">RFail</strong></span></p>
8856 <p><span><strong class="command">FORMERR</strong></span></p>
8859 <p><span><strong class="command">RFErr</strong></span></p>
8869 <p><span><strong class="command">OtherError</strong></span></p>
8872 <p><span><strong class="command">RErr</strong></span></p>
8876 Other errors received.
8882 <p><span><strong class="command">EDNS0Fail</strong></span></p>
8885 <p><span><strong class="command"></strong></span></p>
8889 EDNS(0) query failures.
8895 <p><span><strong class="command">Mismatch</strong></span></p>
8898 <p><span><strong class="command">RDupR</strong></span></p>
8902 Mismatch responses received.
8908 <p><span><strong class="command">Truncated</strong></span></p>
8911 <p><span><strong class="command"></strong></span></p>
8915 Truncated responses received.
8921 <p><span><strong class="command">Lame</strong></span></p>
8924 <p><span><strong class="command">RLame</strong></span></p>
8928 Lame delegations received.
8934 <p><span><strong class="command">Retry</strong></span></p>
8937 <p><span><strong class="command">SDupQ</strong></span></p>
8941 Query retries performed.
8947 <p><span><strong class="command">QueryAbort</strong></span></p>
8950 <p><span><strong class="command"></strong></span></p>
8954 Queries aborted due to quota control.
8960 <p><span><strong class="command">QuerySockFail</strong></span></p>
8963 <p><span><strong class="command"></strong></span></p>
8967 Failures in opening query sockets.
8968 One common reason for such failures is a
8969 failure of opening a new socket due to a
8970 limitation on file descriptors.
8976 <p><span><strong class="command">QueryTimeout</strong></span></p>
8979 <p><span><strong class="command"></strong></span></p>
8989 <p><span><strong class="command">GlueFetchv4</strong></span></p>
8992 <p><span><strong class="command">SSysQ</strong></span></p>
8996 IPv4 NS address fetches invoked.
9002 <p><span><strong class="command">GlueFetchv6</strong></span></p>
9005 <p><span><strong class="command">SSysQ</strong></span></p>
9009 IPv6 NS address fetches invoked.
9015 <p><span><strong class="command">GlueFetchv4Fail</strong></span></p>
9018 <p><span><strong class="command"></strong></span></p>
9022 IPv4 NS address fetch failed.
9028 <p><span><strong class="command">GlueFetchv6Fail</strong></span></p>
9031 <p><span><strong class="command"></strong></span></p>
9035 IPv6 NS address fetch failed.
9041 <p><span><strong class="command">ValAttempt</strong></span></p>
9044 <p><span><strong class="command"></strong></span></p>
9048 DNSSEC validation attempted.
9054 <p><span><strong class="command">ValOk</strong></span></p>
9057 <p><span><strong class="command"></strong></span></p>
9061 DNSSEC validation succeeded.
9067 <p><span><strong class="command">ValNegOk</strong></span></p>
9070 <p><span><strong class="command"></strong></span></p>
9074 DNSSEC validation on negative information succeeded.
9080 <p><span><strong class="command">ValFail</strong></span></p>
9083 <p><span><strong class="command"></strong></span></p>
9087 DNSSEC validation failed.
9093 <p><span><strong class="command">QryRTTnn</strong></span></p>
9096 <p><span><strong class="command"></strong></span></p>
9100 Frequency table on round trip times (RTTs) of
9102 Each <span><strong class="command">nn</strong></span> specifies the corresponding
9105 <span><strong class="command">nn_1</strong></span>,
9106 <span><strong class="command">nn_2</strong></span>,
9108 <span><strong class="command">nn_m</strong></span>,
9109 the value of <span><strong class="command">nn_i</strong></span> is the
9110 number of queries whose RTTs are between
9111 <span><strong class="command">nn_(i-1)</strong></span> (inclusive) and
9112 <span><strong class="command">nn_i</strong></span> (exclusive) milliseconds.
9113 For the sake of convenience we define
9114 <span><strong class="command">nn_0</strong></span> to be 0.
9115 The last entry should be represented as
9116 <span><strong class="command">nn_m+</strong></span>, which means the
9117 number of queries whose RTTs are equal to or over
9118 <span><strong class="command">nn_m</strong></span> milliseconds.
9125 <div class="sect3" lang="en">
9126 <div class="titlepage"><div><div><h4 class="title">
9127 <a name="id2598332"></a>Socket I/O Statistics Counters</h4></div></div></div>
9129 Socket I/O statistics counters are defined per socket
9131 <span><strong class="command">UDP4</strong></span> (UDP/IPv4),
9132 <span><strong class="command">UDP6</strong></span> (UDP/IPv6),
9133 <span><strong class="command">TCP4</strong></span> (TCP/IPv4),
9134 <span><strong class="command">TCP6</strong></span> (TCP/IPv6),
9135 <span><strong class="command">Unix</strong></span> (Unix Domain), and
9136 <span><strong class="command">FDwatch</strong></span> (sockets opened outside the
9138 In the following table <span><strong class="command"><TYPE></strong></span>
9139 represents a socket type.
9140 Not all counters are available for all socket types;
9141 exceptions are noted in the description field.
9143 <div class="informaltable"><table border="1">
9152 <span class="emphasis"><em>Symbol</em></span>
9157 <span class="emphasis"><em>Description</em></span>
9163 <p><span><strong class="command"><TYPE>Open</strong></span></p>
9167 Sockets opened successfully.
9168 This counter is not applicable to the
9169 <span><strong class="command">FDwatch</strong></span> type.
9175 <p><span><strong class="command"><TYPE>OpenFail</strong></span></p>
9179 Failures of opening sockets.
9180 This counter is not applicable to the
9181 <span><strong class="command">FDwatch</strong></span> type.
9187 <p><span><strong class="command"><TYPE>Close</strong></span></p>
9197 <p><span><strong class="command"><TYPE>BindFail</strong></span></p>
9201 Failures of binding sockets.
9207 <p><span><strong class="command"><TYPE>ConnFail</strong></span></p>
9211 Failures of connecting sockets.
9217 <p><span><strong class="command"><TYPE>Conn</strong></span></p>
9221 Connections established successfully.
9227 <p><span><strong class="command"><TYPE>AcceptFail</strong></span></p>
9231 Failures of accepting incoming connection requests.
9232 This counter is not applicable to the
9233 <span><strong class="command">UDP</strong></span> and
9234 <span><strong class="command">FDwatch</strong></span> types.
9240 <p><span><strong class="command"><TYPE>Accept</strong></span></p>
9244 Incoming connections successfully accepted.
9245 This counter is not applicable to the
9246 <span><strong class="command">UDP</strong></span> and
9247 <span><strong class="command">FDwatch</strong></span> types.
9253 <p><span><strong class="command"><TYPE>SendErr</strong></span></p>
9257 Errors in socket send operations.
9258 This counter corresponds
9259 to <span><strong class="command">SErr</strong></span> counter of
9260 <span><strong class="command">BIND</strong></span> 8.
9266 <p><span><strong class="command"><TYPE>RecvErr</strong></span></p>
9270 Errors in socket receive operations.
9271 This includes errors of send operations on a
9272 connected UDP socket notified by an ICMP error
9280 <div class="sect3" lang="en">
9281 <div class="titlepage"><div><div><h4 class="title">
9282 <a name="id2598842"></a>Compatibility with <span class="emphasis"><em>BIND</em></span> 8 Counters</h4></div></div></div>
9284 Most statistics counters that were available
9285 in <span><strong class="command">BIND</strong></span> 8 are also supported in
9286 <span><strong class="command">BIND</strong></span> 9 as shown in the above tables.
9287 Here are notes about other counters that do not appear
9290 <div class="variablelist"><dl>
9291 <dt><span class="term"><span><strong class="command">RFwdR,SFwdR</strong></span></span></dt>
9293 These counters are not supported
9294 because <span><strong class="command">BIND</strong></span> 9 does not adopt
9295 the notion of <span class="emphasis"><em>forwarding</em></span>
9296 as <span><strong class="command">BIND</strong></span> 8 did.
9298 <dt><span class="term"><span><strong class="command">RAXFR</strong></span></span></dt>
9300 This counter is accessible in the Incoming Queries section.
9302 <dt><span class="term"><span><strong class="command">RIQ</strong></span></span></dt>
9304 This counter is accessible in the Incoming Requests section.
9306 <dt><span class="term"><span><strong class="command">ROpts</strong></span></span></dt>
9308 This counter is not supported
9309 because <span><strong class="command">BIND</strong></span> 9 does not care
9310 about IP options in the first place.
9317 <div class="navfooter">
9319 <table width="100%" summary="Navigation footer">
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9328 <td width="40%" align="left" valign="top">Chapter 5. The <acronym class="acronym">BIND</acronym> 9 Lightweight Resolver </td>
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9330 <td width="40%" align="right" valign="top"> Chapter 7. <acronym class="acronym">BIND</acronym> 9 Security Considerations</td>