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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#id2574290">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#id2574944"><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#id2575133"><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#id2575425"><span><strong class="command">include</strong></span> Statement Grammar</a></span></dt>
62 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575442"><span><strong class="command">include</strong></span> Statement Definition and
64 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575465"><span><strong class="command">key</strong></span> Statement Grammar</a></span></dt>
65 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575489"><span><strong class="command">key</strong></span> Statement Definition and Usage</a></span></dt>
66 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575648"><span><strong class="command">logging</strong></span> Statement Grammar</a></span></dt>
67 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575842"><span><strong class="command">logging</strong></span> Statement Definition and
69 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577841"><span><strong class="command">lwres</strong></span> Statement Grammar</a></span></dt>
70 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577982"><span><strong class="command">lwres</strong></span> Statement Definition and Usage</a></span></dt>
71 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578046"><span><strong class="command">masters</strong></span> Statement Grammar</a></span></dt>
72 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578090"><span><strong class="command">masters</strong></span> Statement Definition and
74 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578105"><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#id2589239"><span><strong class="command">statistics-channels</strong></span> Statement Definition and
83 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#trusted-keys"><span><strong class="command">trusted-keys</strong></span> Statement Grammar</a></span></dt>
84 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2589379"><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#id2589494"><span><strong class="command">managed-keys</strong></span> Statement Grammar</a></span></dt>
87 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#managed-keys"><span><strong class="command">managed-keys</strong></span> Statement Definition
88 and Usage</a></span></dt>
89 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#view_statement_grammar"><span><strong class="command">view</strong></span> Statement Grammar</a></span></dt>
90 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2589851"><span><strong class="command">view</strong></span> Statement Definition and Usage</a></span></dt>
91 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#zone_statement_grammar"><span><strong class="command">zone</strong></span>
92 Statement Grammar</a></span></dt>
93 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2591396"><span><strong class="command">zone</strong></span> Statement Definition and Usage</a></span></dt>
95 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#id2594660">Zone File</a></span></dt>
97 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#types_of_resource_records_and_when_to_use_them">Types of Resource Records and When to Use Them</a></span></dt>
98 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2596822">Discussion of MX Records</a></span></dt>
99 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#Setting_TTLs">Setting TTLs</a></span></dt>
100 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2597574">Inverse Mapping in IPv4</a></span></dt>
101 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2597701">Other Zone File Directives</a></span></dt>
102 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2597974"><acronym class="acronym">BIND</acronym> Master File Extension: the <span><strong class="command">$GENERATE</strong></span> Directive</a></span></dt>
103 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#zonefile_format">Additional File Formats</a></span></dt>
105 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#statistics">BIND9 Statistics</a></span></dt>
106 <dd><dl><dt><span class="sect2"><a href="Bv9ARM.ch06.html#statistics_counters">Statistics Counters</a></span></dt></dl></dd>
110 <acronym class="acronym">BIND</acronym> 9 configuration is broadly similar
111 to <acronym class="acronym">BIND</acronym> 8; however, there are a few new
113 of configuration, such as views. <acronym class="acronym">BIND</acronym>
114 8 configuration files should work with few alterations in <acronym class="acronym">BIND</acronym>
115 9, although more complex configurations should be reviewed to check
116 if they can be more efficiently implemented using the new features
117 found in <acronym class="acronym">BIND</acronym> 9.
120 <acronym class="acronym">BIND</acronym> 4 configuration files can be
121 converted to the new format
122 using the shell script
123 <code class="filename">contrib/named-bootconf/named-bootconf.sh</code>.
125 <div class="sect1" lang="en">
126 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
127 <a name="configuration_file_elements"></a>Configuration File Elements</h2></div></div></div>
129 Following is a list of elements used throughout the <acronym class="acronym">BIND</acronym> configuration
132 <div class="informaltable"><table border="1">
141 <code class="varname">acl_name</code>
146 The name of an <code class="varname">address_match_list</code> as
147 defined by the <span><strong class="command">acl</strong></span> statement.
154 <code class="varname">address_match_list</code>
159 A list of one or more
160 <code class="varname">ip_addr</code>,
161 <code class="varname">ip_prefix</code>, <code class="varname">key_id</code>,
162 or <code class="varname">acl_name</code> elements, see
163 <a href="Bv9ARM.ch06.html#address_match_lists" title="Address Match Lists">the section called “Address Match Lists”</a>.
170 <code class="varname">masters_list</code>
175 A named list of one or more <code class="varname">ip_addr</code>
176 with optional <code class="varname">key_id</code> and/or
177 <code class="varname">ip_port</code>.
178 A <code class="varname">masters_list</code> may include other
179 <code class="varname">masters_lists</code>.
186 <code class="varname">domain_name</code>
191 A quoted string which will be used as
192 a DNS name, for example "<code class="literal">my.test.domain</code>".
199 <code class="varname">namelist</code>
204 A list of one or more <code class="varname">domain_name</code>
212 <code class="varname">dotted_decimal</code>
217 One to four integers valued 0 through
218 255 separated by dots (`.'), such as <span><strong class="command">123</strong></span>,
219 <span><strong class="command">45.67</strong></span> or <span><strong class="command">89.123.45.67</strong></span>.
226 <code class="varname">ip4_addr</code>
231 An IPv4 address with exactly four elements
232 in <code class="varname">dotted_decimal</code> notation.
239 <code class="varname">ip6_addr</code>
244 An IPv6 address, such as <span><strong class="command">2001:db8::1234</strong></span>.
245 IPv6 scoped addresses that have ambiguity on their
246 scope zones must be disambiguated by an appropriate
247 zone ID with the percent character (`%') as
248 delimiter. It is strongly recommended to use
249 string zone names rather than numeric identifiers,
250 in order to be robust against system configuration
251 changes. However, since there is no standard
252 mapping for such names and identifier values,
253 currently only interface names as link identifiers
254 are supported, assuming one-to-one mapping between
255 interfaces and links. For example, a link-local
256 address <span><strong class="command">fe80::1</strong></span> on the link
257 attached to the interface <span><strong class="command">ne0</strong></span>
258 can be specified as <span><strong class="command">fe80::1%ne0</strong></span>.
259 Note that on most systems link-local addresses
260 always have the ambiguity, and need to be
268 <code class="varname">ip_addr</code>
273 An <code class="varname">ip4_addr</code> or <code class="varname">ip6_addr</code>.
280 <code class="varname">ip_port</code>
285 An IP port <code class="varname">number</code>.
286 The <code class="varname">number</code> is limited to 0
287 through 65535, with values
288 below 1024 typically restricted to use by processes running
290 In some cases, an asterisk (`*') character can be used as a
292 select a random high-numbered port.
299 <code class="varname">ip_prefix</code>
304 An IP network specified as an <code class="varname">ip_addr</code>,
305 followed by a slash (`/') and then the number of bits in the
307 Trailing zeros in a <code class="varname">ip_addr</code>
309 For example, <span><strong class="command">127/8</strong></span> is the
310 network <span><strong class="command">127.0.0.0</strong></span> with
311 netmask <span><strong class="command">255.0.0.0</strong></span> and <span><strong class="command">1.2.3.0/28</strong></span> is
312 network <span><strong class="command">1.2.3.0</strong></span> with netmask <span><strong class="command">255.255.255.240</strong></span>.
315 When specifying a prefix involving a IPv6 scoped address
316 the scope may be omitted. In that case the prefix will
317 match packets from any scope.
324 <code class="varname">key_id</code>
329 A <code class="varname">domain_name</code> representing
330 the name of a shared key, to be used for transaction
338 <code class="varname">key_list</code>
343 A list of one or more
344 <code class="varname">key_id</code>s,
345 separated by semicolons and ending with a semicolon.
352 <code class="varname">number</code>
357 A non-negative 32-bit integer
358 (i.e., a number between 0 and 4294967295, inclusive).
359 Its acceptable value might further
360 be limited by the context in which it is used.
367 <code class="varname">path_name</code>
372 A quoted string which will be used as
373 a pathname, such as <code class="filename">zones/master/my.test.domain</code>.
380 <code class="varname">port_list</code>
385 A list of an <code class="varname">ip_port</code> or a port
387 A port range is specified in the form of
388 <strong class="userinput"><code>range</code></strong> followed by
389 two <code class="varname">ip_port</code>s,
390 <code class="varname">port_low</code> and
391 <code class="varname">port_high</code>, which represents
392 port numbers from <code class="varname">port_low</code> through
393 <code class="varname">port_high</code>, inclusive.
394 <code class="varname">port_low</code> must not be larger than
395 <code class="varname">port_high</code>.
397 <strong class="userinput"><code>range 1024 65535</code></strong> represents
398 ports from 1024 through 65535.
399 In either case an asterisk (`*') character is not
400 allowed as a valid <code class="varname">ip_port</code>.
407 <code class="varname">size_spec</code>
412 A number, the word <strong class="userinput"><code>unlimited</code></strong>,
413 or the word <strong class="userinput"><code>default</code></strong>.
416 An <code class="varname">unlimited</code> <code class="varname">size_spec</code> requests unlimited
417 use, or the maximum available amount. A <code class="varname">default size_spec</code> uses
418 the limit that was in force when the server was started.
421 A <code class="varname">number</code> can optionally be
422 followed by a scaling factor:
423 <strong class="userinput"><code>K</code></strong> or <strong class="userinput"><code>k</code></strong>
425 <strong class="userinput"><code>M</code></strong> or <strong class="userinput"><code>m</code></strong>
427 <strong class="userinput"><code>G</code></strong> or <strong class="userinput"><code>g</code></strong> for gigabytes,
428 which scale by 1024, 1024*1024, and 1024*1024*1024
432 The value must be representable as a 64-bit unsigned integer
433 (0 to 18446744073709551615, inclusive).
434 Using <code class="varname">unlimited</code> is the best
436 to safely set a really large number.
443 <code class="varname">yes_or_no</code>
448 Either <strong class="userinput"><code>yes</code></strong> or <strong class="userinput"><code>no</code></strong>.
449 The words <strong class="userinput"><code>true</code></strong> and <strong class="userinput"><code>false</code></strong> are
450 also accepted, as are the numbers <strong class="userinput"><code>1</code></strong>
451 and <strong class="userinput"><code>0</code></strong>.
458 <code class="varname">dialup_option</code>
463 One of <strong class="userinput"><code>yes</code></strong>,
464 <strong class="userinput"><code>no</code></strong>, <strong class="userinput"><code>notify</code></strong>,
465 <strong class="userinput"><code>notify-passive</code></strong>, <strong class="userinput"><code>refresh</code></strong> or
466 <strong class="userinput"><code>passive</code></strong>.
467 When used in a zone, <strong class="userinput"><code>notify-passive</code></strong>,
468 <strong class="userinput"><code>refresh</code></strong>, and <strong class="userinput"><code>passive</code></strong>
469 are restricted to slave and stub zones.
475 <div class="sect2" lang="en">
476 <div class="titlepage"><div><div><h3 class="title">
477 <a name="address_match_lists"></a>Address Match Lists</h3></div></div></div>
478 <div class="sect3" lang="en">
479 <div class="titlepage"><div><div><h4 class="title">
480 <a name="id2574056"></a>Syntax</h4></div></div></div>
481 <pre class="programlisting"><code class="varname">address_match_list</code> = address_match_list_element ;
482 [<span class="optional"> address_match_list_element; ... </span>]
483 <code class="varname">address_match_list_element</code> = [<span class="optional"> ! </span>] (ip_address [<span class="optional">/length</span>] |
484 key key_id | acl_name | { address_match_list } )
487 <div class="sect3" lang="en">
488 <div class="titlepage"><div><div><h4 class="title">
489 <a name="id2574084"></a>Definition and Usage</h4></div></div></div>
491 Address match lists are primarily used to determine access
492 control for various server operations. They are also used in
493 the <span><strong class="command">listen-on</strong></span> and <span><strong class="command">sortlist</strong></span>
494 statements. The elements which constitute an address match
495 list can be any of the following:
497 <div class="itemizedlist"><ul type="disc">
498 <li>an IP address (IPv4 or IPv6)</li>
499 <li>an IP prefix (in `/' notation)</li>
501 a key ID, as defined by the <span><strong class="command">key</strong></span>
504 <li>the name of an address match list defined with
505 the <span><strong class="command">acl</strong></span> statement
507 <li>a nested address match list enclosed in braces</li>
510 Elements can be negated with a leading exclamation mark (`!'),
511 and the match list names "any", "none", "localhost", and
512 "localnets" are predefined. More information on those names
513 can be found in the description of the acl statement.
516 The addition of the key clause made the name of this syntactic
517 element something of a misnomer, since security keys can be used
518 to validate access without regard to a host or network address.
519 Nonetheless, the term "address match list" is still used
520 throughout the documentation.
523 When a given IP address or prefix is compared to an address
524 match list, the comparison takes place in approximately O(1)
525 time. However, key comparisons require that the list of keys
526 be traversed until a matching key is found, and therefore may
530 The interpretation of a match depends on whether the list is being
531 used for access control, defining <span><strong class="command">listen-on</strong></span> ports, or in a
532 <span><strong class="command">sortlist</strong></span>, and whether the element was negated.
535 When used as an access control list, a non-negated match
536 allows access and a negated match denies access. If
537 there is no match, access is denied. The clauses
538 <span><strong class="command">allow-notify</strong></span>,
539 <span><strong class="command">allow-recursion</strong></span>,
540 <span><strong class="command">allow-recursion-on</strong></span>,
541 <span><strong class="command">allow-query</strong></span>,
542 <span><strong class="command">allow-query-on</strong></span>,
543 <span><strong class="command">allow-query-cache</strong></span>,
544 <span><strong class="command">allow-query-cache-on</strong></span>,
545 <span><strong class="command">allow-transfer</strong></span>,
546 <span><strong class="command">allow-update</strong></span>,
547 <span><strong class="command">allow-update-forwarding</strong></span>, and
548 <span><strong class="command">blackhole</strong></span> all use address match
549 lists. Similarly, the <span><strong class="command">listen-on</strong></span> option will cause the
550 server to refuse queries on any of the machine's
551 addresses which do not match the list.
554 Order of insertion is significant. If more than one element
555 in an ACL is found to match a given IP address or prefix,
556 preference will be given to the one that came
557 <span class="emphasis"><em>first</em></span> in the ACL definition.
558 Because of this first-match behavior, an element that
559 defines a subset of another element in the list should
560 come before the broader element, regardless of whether
561 either is negated. For example, in
562 <span><strong class="command">1.2.3/24; ! 1.2.3.13;</strong></span>
563 the 1.2.3.13 element is completely useless because the
564 algorithm will match any lookup for 1.2.3.13 to the 1.2.3/24
565 element. Using <span><strong class="command">! 1.2.3.13; 1.2.3/24</strong></span> fixes
566 that problem by having 1.2.3.13 blocked by the negation, but
567 all other 1.2.3.* hosts fall through.
571 <div class="sect2" lang="en">
572 <div class="titlepage"><div><div><h3 class="title">
573 <a name="id2574290"></a>Comment Syntax</h3></div></div></div>
575 The <acronym class="acronym">BIND</acronym> 9 comment syntax allows for
577 anywhere that whitespace may appear in a <acronym class="acronym">BIND</acronym> configuration
578 file. To appeal to programmers of all kinds, they can be written
579 in the C, C++, or shell/perl style.
581 <div class="sect3" lang="en">
582 <div class="titlepage"><div><div><h4 class="title">
583 <a name="id2574305"></a>Syntax</h4></div></div></div>
586 <pre class="programlisting">/* This is a <acronym class="acronym">BIND</acronym> comment as in C */</pre>
589 <pre class="programlisting">// This is a <acronym class="acronym">BIND</acronym> comment as in C++</pre>
592 <pre class="programlisting"># This is a <acronym class="acronym">BIND</acronym> comment as in common UNIX shells
597 <div class="sect3" lang="en">
598 <div class="titlepage"><div><div><h4 class="title">
599 <a name="id2574334"></a>Definition and Usage</h4></div></div></div>
601 Comments may appear anywhere that whitespace may appear in
602 a <acronym class="acronym">BIND</acronym> configuration file.
605 C-style comments start with the two characters /* (slash,
606 star) and end with */ (star, slash). Because they are completely
607 delimited with these characters, they can be used to comment only
608 a portion of a line or to span multiple lines.
611 C-style comments cannot be nested. For example, the following
612 is not valid because the entire comment ends with the first */:
617 <pre class="programlisting">/* This is the start of a comment.
618 This is still part of the comment.
619 /* This is an incorrect attempt at nesting a comment. */
620 This is no longer in any comment. */
626 C++-style comments start with the two characters // (slash,
627 slash) and continue to the end of the physical line. They cannot
628 be continued across multiple physical lines; to have one logical
629 comment span multiple lines, each line must use the // pair.
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.
643 Shell-style (or perl-style, if you prefer) comments start
644 with the character <code class="literal">#</code> (number sign)
645 and continue to the end of the
646 physical line, as in C++ comments.
652 <pre class="programlisting"># This is the start of a comment. The next line
653 # is a new comment, even though it is logically
654 # part of the previous comment.
659 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
660 <h3 class="title">Warning</h3>
662 You cannot use the semicolon (`;') character
663 to start a comment such as you would in a zone file. The
664 semicolon indicates the end of a configuration
671 <div class="sect1" lang="en">
672 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
673 <a name="Configuration_File_Grammar"></a>Configuration File Grammar</h2></div></div></div>
675 A <acronym class="acronym">BIND</acronym> 9 configuration consists of
676 statements and comments.
677 Statements end with a semicolon. Statements and comments are the
678 only elements that can appear without enclosing braces. Many
679 statements contain a block of sub-statements, which are also
680 terminated with a semicolon.
683 The following statements are supported:
685 <div class="informaltable"><table border="1">
693 <p><span><strong class="command">acl</strong></span></p>
697 defines a named IP address
698 matching list, for access control and other uses.
704 <p><span><strong class="command">controls</strong></span></p>
708 declares control channels to be used
709 by the <span><strong class="command">rndc</strong></span> utility.
715 <p><span><strong class="command">include</strong></span></p>
725 <p><span><strong class="command">key</strong></span></p>
729 specifies key information for use in
730 authentication and authorization using TSIG.
736 <p><span><strong class="command">logging</strong></span></p>
740 specifies what the server logs, and where
741 the log messages are sent.
747 <p><span><strong class="command">lwres</strong></span></p>
751 configures <span><strong class="command">named</strong></span> to
752 also act as a light-weight resolver daemon (<span><strong class="command">lwresd</strong></span>).
758 <p><span><strong class="command">masters</strong></span></p>
762 defines a named masters list for
763 inclusion in stub and slave zone masters clauses.
769 <p><span><strong class="command">options</strong></span></p>
773 controls global server configuration
774 options and sets defaults for other statements.
780 <p><span><strong class="command">server</strong></span></p>
784 sets certain configuration options on
791 <p><span><strong class="command">statistics-channels</strong></span></p>
795 declares communication channels to get access to
796 <span><strong class="command">named</strong></span> statistics.
802 <p><span><strong class="command">trusted-keys</strong></span></p>
806 defines trusted DNSSEC keys.
812 <p><span><strong class="command">managed-keys</strong></span></p>
816 lists DNSSEC keys to be kept up to date
817 using RFC 5011 trust anchor maintenance.
823 <p><span><strong class="command">view</strong></span></p>
833 <p><span><strong class="command">zone</strong></span></p>
844 The <span><strong class="command">logging</strong></span> and
845 <span><strong class="command">options</strong></span> statements may only occur once
849 <div class="sect2" lang="en">
850 <div class="titlepage"><div><div><h3 class="title">
851 <a name="id2574944"></a><span><strong class="command">acl</strong></span> Statement Grammar</h3></div></div></div>
852 <pre class="programlisting"><span><strong class="command">acl</strong></span> acl-name {
857 <div class="sect2" lang="en">
858 <div class="titlepage"><div><div><h3 class="title">
859 <a name="acl"></a><span><strong class="command">acl</strong></span> Statement Definition and
860 Usage</h3></div></div></div>
862 The <span><strong class="command">acl</strong></span> statement assigns a symbolic
863 name to an address match list. It gets its name from a primary
864 use of address match lists: Access Control Lists (ACLs).
867 Note that an address match list's name must be defined
868 with <span><strong class="command">acl</strong></span> before it can be used
869 elsewhere; no forward references are allowed.
872 The following ACLs are built-in:
874 <div class="informaltable"><table border="1">
882 <p><span><strong class="command">any</strong></span></p>
892 <p><span><strong class="command">none</strong></span></p>
902 <p><span><strong class="command">localhost</strong></span></p>
906 Matches the IPv4 and IPv6 addresses of all network
907 interfaces on the system.
913 <p><span><strong class="command">localnets</strong></span></p>
917 Matches any host on an IPv4 or IPv6 network
918 for which the system has an interface.
919 Some systems do not provide a way to determine the prefix
921 local IPv6 addresses.
922 In such a case, <span><strong class="command">localnets</strong></span>
923 only matches the local
924 IPv6 addresses, just like <span><strong class="command">localhost</strong></span>.
931 <div class="sect2" lang="en">
932 <div class="titlepage"><div><div><h3 class="title">
933 <a name="id2575133"></a><span><strong class="command">controls</strong></span> Statement Grammar</h3></div></div></div>
934 <pre class="programlisting"><span><strong class="command">controls</strong></span> {
935 [ inet ( ip_addr | * ) [ port ip_port ]
936 allow { <em class="replaceable"><code> address_match_list </code></em> }
937 keys { <em class="replaceable"><code>key_list</code></em> }; ]
939 [ 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>
940 keys { <em class="replaceable"><code>key_list</code></em> }; ]
945 <div class="sect2" lang="en">
946 <div class="titlepage"><div><div><h3 class="title">
947 <a name="controls_statement_definition_and_usage"></a><span><strong class="command">controls</strong></span> Statement Definition and
948 Usage</h3></div></div></div>
950 The <span><strong class="command">controls</strong></span> statement declares control
951 channels to be used by system administrators to control the
952 operation of the name server. These control channels are
953 used by the <span><strong class="command">rndc</strong></span> utility to send
954 commands to and retrieve non-DNS results from a name server.
957 An <span><strong class="command">inet</strong></span> control channel is a TCP socket
958 listening at the specified <span><strong class="command">ip_port</strong></span> on the
959 specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6
960 address. An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is
961 interpreted as the IPv4 wildcard address; connections will be
962 accepted on any of the system's IPv4 addresses.
963 To listen on the IPv6 wildcard address,
964 use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>.
965 If you will only use <span><strong class="command">rndc</strong></span> on the local host,
966 using the loopback address (<code class="literal">127.0.0.1</code>
967 or <code class="literal">::1</code>) is recommended for maximum security.
970 If no port is specified, port 953 is used. The asterisk
971 "<code class="literal">*</code>" cannot be used for <span><strong class="command">ip_port</strong></span>.
974 The ability to issue commands over the control channel is
975 restricted by the <span><strong class="command">allow</strong></span> and
976 <span><strong class="command">keys</strong></span> clauses.
977 Connections to the control channel are permitted based on the
978 <span><strong class="command">address_match_list</strong></span>. This is for simple
979 IP address based filtering only; any <span><strong class="command">key_id</strong></span>
980 elements of the <span><strong class="command">address_match_list</strong></span>
984 A <span><strong class="command">unix</strong></span> control channel is a UNIX domain
985 socket listening at the specified path in the file system.
986 Access to the socket is specified by the <span><strong class="command">perm</strong></span>,
987 <span><strong class="command">owner</strong></span> and <span><strong class="command">group</strong></span> clauses.
988 Note on some platforms (SunOS and Solaris) the permissions
989 (<span><strong class="command">perm</strong></span>) are applied to the parent directory
990 as the permissions on the socket itself are ignored.
993 The primary authorization mechanism of the command
994 channel is the <span><strong class="command">key_list</strong></span>, which
995 contains a list of <span><strong class="command">key_id</strong></span>s.
996 Each <span><strong class="command">key_id</strong></span> in the <span><strong class="command">key_list</strong></span>
997 is authorized to execute commands over the control channel.
998 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>)
999 for information about configuring keys in <span><strong class="command">rndc</strong></span>.
1002 If no <span><strong class="command">controls</strong></span> statement is present,
1003 <span><strong class="command">named</strong></span> will set up a default
1004 control channel listening on the loopback address 127.0.0.1
1005 and its IPv6 counterpart ::1.
1006 In this case, and also when the <span><strong class="command">controls</strong></span> statement
1007 is present but does not have a <span><strong class="command">keys</strong></span> clause,
1008 <span><strong class="command">named</strong></span> will attempt to load the command channel key
1009 from the file <code class="filename">rndc.key</code> in
1010 <code class="filename">/etc</code> (or whatever <code class="varname">sysconfdir</code>
1011 was specified as when <acronym class="acronym">BIND</acronym> was built).
1012 To create a <code class="filename">rndc.key</code> file, run
1013 <strong class="userinput"><code>rndc-confgen -a</code></strong>.
1016 The <code class="filename">rndc.key</code> feature was created to
1017 ease the transition of systems from <acronym class="acronym">BIND</acronym> 8,
1018 which did not have digital signatures on its command channel
1019 messages and thus did not have a <span><strong class="command">keys</strong></span> clause.
1021 It makes it possible to use an existing <acronym class="acronym">BIND</acronym> 8
1022 configuration file in <acronym class="acronym">BIND</acronym> 9 unchanged,
1023 and still have <span><strong class="command">rndc</strong></span> work the same way
1024 <span><strong class="command">ndc</strong></span> worked in BIND 8, simply by executing the
1025 command <strong class="userinput"><code>rndc-confgen -a</code></strong> after BIND 9 is
1029 Since the <code class="filename">rndc.key</code> feature
1030 is only intended to allow the backward-compatible usage of
1031 <acronym class="acronym">BIND</acronym> 8 configuration files, this
1033 have a high degree of configurability. You cannot easily change
1034 the key name or the size of the secret, so you should make a
1035 <code class="filename">rndc.conf</code> with your own key if you
1037 those things. The <code class="filename">rndc.key</code> file
1039 permissions set such that only the owner of the file (the user that
1040 <span><strong class="command">named</strong></span> is running as) can access it.
1042 desire greater flexibility in allowing other users to access
1043 <span><strong class="command">rndc</strong></span> commands, then you need to create
1045 <code class="filename">rndc.conf</code> file and make it group
1047 that contains the users who should have access.
1050 To disable the command channel, use an empty
1051 <span><strong class="command">controls</strong></span> statement:
1052 <span><strong class="command">controls { };</strong></span>.
1055 <div class="sect2" lang="en">
1056 <div class="titlepage"><div><div><h3 class="title">
1057 <a name="id2575425"></a><span><strong class="command">include</strong></span> Statement Grammar</h3></div></div></div>
1058 <pre class="programlisting"><span><strong class="command">include</strong></span> <em class="replaceable"><code>filename</code></em>;</pre>
1060 <div class="sect2" lang="en">
1061 <div class="titlepage"><div><div><h3 class="title">
1062 <a name="id2575442"></a><span><strong class="command">include</strong></span> Statement Definition and
1063 Usage</h3></div></div></div>
1065 The <span><strong class="command">include</strong></span> statement inserts the
1066 specified file at the point where the <span><strong class="command">include</strong></span>
1067 statement is encountered. The <span><strong class="command">include</strong></span>
1068 statement facilitates the administration of configuration
1070 by permitting the reading or writing of some things but not
1071 others. For example, the statement could include private keys
1072 that are readable only by the name server.
1075 <div class="sect2" lang="en">
1076 <div class="titlepage"><div><div><h3 class="title">
1077 <a name="id2575465"></a><span><strong class="command">key</strong></span> Statement Grammar</h3></div></div></div>
1078 <pre class="programlisting"><span><strong class="command">key</strong></span> <em class="replaceable"><code>key_id</code></em> {
1079 algorithm <em class="replaceable"><code>string</code></em>;
1080 secret <em class="replaceable"><code>string</code></em>;
1084 <div class="sect2" lang="en">
1085 <div class="titlepage"><div><div><h3 class="title">
1086 <a name="id2575489"></a><span><strong class="command">key</strong></span> Statement Definition and Usage</h3></div></div></div>
1088 The <span><strong class="command">key</strong></span> statement defines a shared
1089 secret key for use with TSIG (see <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called “TSIG”</a>)
1090 or the command channel
1091 (see <a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and
1092 Usage">the section called “<span><strong class="command">controls</strong></span> Statement Definition and
1096 The <span><strong class="command">key</strong></span> statement can occur at the
1098 of the configuration file or inside a <span><strong class="command">view</strong></span>
1099 statement. Keys defined in top-level <span><strong class="command">key</strong></span>
1100 statements can be used in all views. Keys intended for use in
1101 a <span><strong class="command">controls</strong></span> statement
1102 (see <a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and
1103 Usage">the section called “<span><strong class="command">controls</strong></span> Statement Definition and
1105 must be defined at the top level.
1108 The <em class="replaceable"><code>key_id</code></em>, also known as the
1109 key name, is a domain name uniquely identifying the key. It can
1110 be used in a <span><strong class="command">server</strong></span>
1111 statement to cause requests sent to that
1112 server to be signed with this key, or in address match lists to
1113 verify that incoming requests have been signed with a key
1114 matching this name, algorithm, and secret.
1117 The <em class="replaceable"><code>algorithm_id</code></em> is a string
1118 that specifies a security/authentication algorithm. Named
1119 supports <code class="literal">hmac-md5</code>,
1120 <code class="literal">hmac-sha1</code>, <code class="literal">hmac-sha224</code>,
1121 <code class="literal">hmac-sha256</code>, <code class="literal">hmac-sha384</code>
1122 and <code class="literal">hmac-sha512</code> TSIG authentication.
1123 Truncated hashes are supported by appending the minimum
1124 number of required bits preceded by a dash, e.g.
1125 <code class="literal">hmac-sha1-80</code>. The
1126 <em class="replaceable"><code>secret_string</code></em> is the secret
1127 to be used by the algorithm, and is treated as a base-64
1131 <div class="sect2" lang="en">
1132 <div class="titlepage"><div><div><h3 class="title">
1133 <a name="id2575648"></a><span><strong class="command">logging</strong></span> Statement Grammar</h3></div></div></div>
1134 <pre class="programlisting"><span><strong class="command">logging</strong></span> {
1135 [ <span><strong class="command">channel</strong></span> <em class="replaceable"><code>channel_name</code></em> {
1136 ( <span><strong class="command">file</strong></span> <em class="replaceable"><code>path_name</code></em>
1137 [ <span><strong class="command">versions</strong></span> ( <em class="replaceable"><code>number</code></em> | <span><strong class="command">unlimited</strong></span> ) ]
1138 [ <span><strong class="command">size</strong></span> <em class="replaceable"><code>size spec</code></em> ]
1139 | <span><strong class="command">syslog</strong></span> <em class="replaceable"><code>syslog_facility</code></em>
1140 | <span><strong class="command">stderr</strong></span>
1141 | <span><strong class="command">null</strong></span> );
1142 [ <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> |
1143 <code class="option">info</code> | <code class="option">debug</code> [ <em class="replaceable"><code>level</code></em> ] | <code class="option">dynamic</code> ); ]
1144 [ <span><strong class="command">print-category</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ]
1145 [ <span><strong class="command">print-severity</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ]
1146 [ <span><strong class="command">print-time</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ]
1148 [ <span><strong class="command">category</strong></span> <em class="replaceable"><code>category_name</code></em> {
1149 <em class="replaceable"><code>channel_name</code></em> ; [ <em class="replaceable"><code>channel_name</code></em> ; ... ]
1155 <div class="sect2" lang="en">
1156 <div class="titlepage"><div><div><h3 class="title">
1157 <a name="id2575842"></a><span><strong class="command">logging</strong></span> Statement Definition and
1158 Usage</h3></div></div></div>
1160 The <span><strong class="command">logging</strong></span> statement configures a
1162 variety of logging options for the name server. Its <span><strong class="command">channel</strong></span> phrase
1163 associates output methods, format options and severity levels with
1164 a name that can then be used with the <span><strong class="command">category</strong></span> phrase
1165 to select how various classes of messages are logged.
1168 Only one <span><strong class="command">logging</strong></span> statement is used to
1170 as many channels and categories as are wanted. If there is no <span><strong class="command">logging</strong></span> statement,
1171 the logging configuration will be:
1173 <pre class="programlisting">logging {
1174 category default { default_syslog; default_debug; };
1175 category unmatched { null; };
1179 In <acronym class="acronym">BIND</acronym> 9, the logging configuration
1180 is only established when
1181 the entire configuration file has been parsed. In <acronym class="acronym">BIND</acronym> 8, it was
1182 established as soon as the <span><strong class="command">logging</strong></span>
1184 was parsed. When the server is starting up, all logging messages
1185 regarding syntax errors in the configuration file go to the default
1186 channels, or to standard error if the "<code class="option">-g</code>" option
1189 <div class="sect3" lang="en">
1190 <div class="titlepage"><div><div><h4 class="title">
1191 <a name="id2575894"></a>The <span><strong class="command">channel</strong></span> Phrase</h4></div></div></div>
1193 All log output goes to one or more <span class="emphasis"><em>channels</em></span>;
1194 you can make as many of them as you want.
1197 Every channel definition must include a destination clause that
1198 says whether messages selected for the channel go to a file, to a
1199 particular syslog facility, to the standard error stream, or are
1200 discarded. It can optionally also limit the message severity level
1201 that will be accepted by the channel (the default is
1202 <span><strong class="command">info</strong></span>), and whether to include a
1203 <span><strong class="command">named</strong></span>-generated time stamp, the
1205 and/or severity level (the default is not to include any).
1208 The <span><strong class="command">null</strong></span> destination clause
1209 causes all messages sent to the channel to be discarded;
1210 in that case, other options for the channel are meaningless.
1213 The <span><strong class="command">file</strong></span> destination clause directs
1215 to a disk file. It can include limitations
1216 both on how large the file is allowed to become, and how many
1218 of the file will be saved each time the file is opened.
1221 If you use the <span><strong class="command">versions</strong></span> log file
1223 <span><strong class="command">named</strong></span> will retain that many backup
1224 versions of the file by
1225 renaming them when opening. For example, if you choose to keep
1227 of the file <code class="filename">lamers.log</code>, then just
1229 <code class="filename">lamers.log.1</code> is renamed to
1230 <code class="filename">lamers.log.2</code>, <code class="filename">lamers.log.0</code> is renamed
1231 to <code class="filename">lamers.log.1</code>, and <code class="filename">lamers.log</code> is
1232 renamed to <code class="filename">lamers.log.0</code>.
1233 You can say <span><strong class="command">versions unlimited</strong></span> to
1235 the number of versions.
1236 If a <span><strong class="command">size</strong></span> option is associated with
1238 then renaming is only done when the file being opened exceeds the
1239 indicated size. No backup versions are kept by default; any
1241 log file is simply appended.
1244 The <span><strong class="command">size</strong></span> option for files is used
1246 growth. If the file ever exceeds the size, then <span><strong class="command">named</strong></span> will
1247 stop writing to the file unless it has a <span><strong class="command">versions</strong></span> option
1248 associated with it. If backup versions are kept, the files are
1250 described above and a new one begun. If there is no
1251 <span><strong class="command">versions</strong></span> option, no more data will
1252 be written to the log
1253 until some out-of-band mechanism removes or truncates the log to
1255 maximum size. The default behavior is not to limit the size of
1260 Example usage of the <span><strong class="command">size</strong></span> and
1261 <span><strong class="command">versions</strong></span> options:
1263 <pre class="programlisting">channel an_example_channel {
1264 file "example.log" versions 3 size 20m;
1270 The <span><strong class="command">syslog</strong></span> destination clause
1272 channel to the system log. Its argument is a
1273 syslog facility as described in the <span><strong class="command">syslog</strong></span> man
1274 page. Known facilities are <span><strong class="command">kern</strong></span>, <span><strong class="command">user</strong></span>,
1275 <span><strong class="command">mail</strong></span>, <span><strong class="command">daemon</strong></span>, <span><strong class="command">auth</strong></span>,
1276 <span><strong class="command">syslog</strong></span>, <span><strong class="command">lpr</strong></span>, <span><strong class="command">news</strong></span>,
1277 <span><strong class="command">uucp</strong></span>, <span><strong class="command">cron</strong></span>, <span><strong class="command">authpriv</strong></span>,
1278 <span><strong class="command">ftp</strong></span>, <span><strong class="command">local0</strong></span>, <span><strong class="command">local1</strong></span>,
1279 <span><strong class="command">local2</strong></span>, <span><strong class="command">local3</strong></span>, <span><strong class="command">local4</strong></span>,
1280 <span><strong class="command">local5</strong></span>, <span><strong class="command">local6</strong></span> and
1281 <span><strong class="command">local7</strong></span>, however not all facilities
1283 all operating systems.
1284 How <span><strong class="command">syslog</strong></span> will handle messages
1286 this facility is described in the <span><strong class="command">syslog.conf</strong></span> man
1287 page. If you have a system which uses a very old version of <span><strong class="command">syslog</strong></span> that
1288 only uses two arguments to the <span><strong class="command">openlog()</strong></span> function,
1289 then this clause is silently ignored.
1292 The <span><strong class="command">severity</strong></span> clause works like <span><strong class="command">syslog</strong></span>'s
1293 "priorities", except that they can also be used if you are writing
1294 straight to a file rather than using <span><strong class="command">syslog</strong></span>.
1295 Messages which are not at least of the severity level given will
1296 not be selected for the channel; messages of higher severity
1301 If you are using <span><strong class="command">syslog</strong></span>, then the <span><strong class="command">syslog.conf</strong></span> priorities
1302 will also determine what eventually passes through. For example,
1303 defining a channel facility and severity as <span><strong class="command">daemon</strong></span> and <span><strong class="command">debug</strong></span> but
1304 only logging <span><strong class="command">daemon.warning</strong></span> via <span><strong class="command">syslog.conf</strong></span> will
1305 cause messages of severity <span><strong class="command">info</strong></span> and
1306 <span><strong class="command">notice</strong></span> to
1307 be dropped. If the situation were reversed, with <span><strong class="command">named</strong></span> writing
1308 messages of only <span><strong class="command">warning</strong></span> or higher,
1309 then <span><strong class="command">syslogd</strong></span> would
1310 print all messages it received from the channel.
1313 The <span><strong class="command">stderr</strong></span> destination clause
1315 channel to the server's standard error stream. This is intended
1317 use when the server is running as a foreground process, for
1319 when debugging a configuration.
1322 The server can supply extensive debugging information when
1323 it is in debugging mode. If the server's global debug level is
1325 than zero, then debugging mode will be active. The global debug
1326 level is set either by starting the <span><strong class="command">named</strong></span> server
1327 with the <code class="option">-d</code> flag followed by a positive integer,
1328 or by running <span><strong class="command">rndc trace</strong></span>.
1329 The global debug level
1330 can be set to zero, and debugging mode turned off, by running <span><strong class="command">rndc
1331 notrace</strong></span>. All debugging messages in the server have a debug
1332 level, and higher debug levels give more detailed output. Channels
1333 that specify a specific debug severity, for example:
1335 <pre class="programlisting">channel specific_debug_level {
1341 will get debugging output of level 3 or less any time the
1342 server is in debugging mode, regardless of the global debugging
1343 level. Channels with <span><strong class="command">dynamic</strong></span>
1345 server's global debug level to determine what messages to print.
1348 If <span><strong class="command">print-time</strong></span> has been turned on,
1350 the date and time will be logged. <span><strong class="command">print-time</strong></span> may
1351 be specified for a <span><strong class="command">syslog</strong></span> channel,
1353 pointless since <span><strong class="command">syslog</strong></span> also logs
1355 time. If <span><strong class="command">print-category</strong></span> is
1357 category of the message will be logged as well. Finally, if <span><strong class="command">print-severity</strong></span> is
1358 on, then the severity level of the message will be logged. The <span><strong class="command">print-</strong></span> options may
1359 be used in any combination, and will always be printed in the
1361 order: time, category, severity. Here is an example where all
1362 three <span><strong class="command">print-</strong></span> options
1366 <code class="computeroutput">28-Feb-2000 15:05:32.863 general: notice: running</code>
1369 There are four predefined channels that are used for
1370 <span><strong class="command">named</strong></span>'s default logging as follows.
1372 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>.
1374 <pre class="programlisting">channel default_syslog {
1375 // send to syslog's daemon facility
1377 // only send priority info and higher
1380 channel default_debug {
1381 // write to named.run in the working directory
1382 // Note: stderr is used instead of "named.run" if
1383 // the server is started with the '-f' option.
1385 // log at the server's current debug level
1389 channel default_stderr {
1392 // only send priority info and higher
1397 // toss anything sent to this channel
1402 The <span><strong class="command">default_debug</strong></span> channel has the
1404 property that it only produces output when the server's debug
1406 nonzero. It normally writes to a file called <code class="filename">named.run</code>
1407 in the server's working directory.
1410 For security reasons, when the "<code class="option">-u</code>"
1411 command line option is used, the <code class="filename">named.run</code> file
1412 is created only after <span><strong class="command">named</strong></span> has
1414 new UID, and any debug output generated while <span><strong class="command">named</strong></span> is
1415 starting up and still running as root is discarded. If you need
1416 to capture this output, you must run the server with the "<code class="option">-g</code>"
1417 option and redirect standard error to a file.
1420 Once a channel is defined, it cannot be redefined. Thus you
1421 cannot alter the built-in channels directly, but you can modify
1422 the default logging by pointing categories at channels you have
1426 <div class="sect3" lang="en">
1427 <div class="titlepage"><div><div><h4 class="title">
1428 <a name="the_category_phrase"></a>The <span><strong class="command">category</strong></span> Phrase</h4></div></div></div>
1430 There are many categories, so you can send the logs you want
1431 to see wherever you want, without seeing logs you don't want. If
1432 you don't specify a list of channels for a category, then log
1434 in that category will be sent to the <span><strong class="command">default</strong></span> category
1435 instead. If you don't specify a default category, the following
1436 "default default" is used:
1438 <pre class="programlisting">category default { default_syslog; default_debug; };
1441 As an example, let's say you want to log security events to
1442 a file, but you also want keep the default logging behavior. You'd
1443 specify the following:
1445 <pre class="programlisting">channel my_security_channel {
1446 file "my_security_file";
1450 my_security_channel;
1455 To discard all messages in a category, specify the <span><strong class="command">null</strong></span> channel:
1457 <pre class="programlisting">category xfer-out { null; };
1458 category notify { null; };
1461 Following are the available categories and brief descriptions
1462 of the types of log information they contain. More
1463 categories may be added in future <acronym class="acronym">BIND</acronym> releases.
1465 <div class="informaltable"><table border="1">
1473 <p><span><strong class="command">default</strong></span></p>
1477 The default category defines the logging
1478 options for those categories where no specific
1479 configuration has been
1486 <p><span><strong class="command">general</strong></span></p>
1490 The catch-all. Many things still aren't
1491 classified into categories, and they all end up here.
1497 <p><span><strong class="command">database</strong></span></p>
1501 Messages relating to the databases used
1502 internally by the name server to store zone and cache
1509 <p><span><strong class="command">security</strong></span></p>
1513 Approval and denial of requests.
1519 <p><span><strong class="command">config</strong></span></p>
1523 Configuration file parsing and processing.
1529 <p><span><strong class="command">resolver</strong></span></p>
1533 DNS resolution, such as the recursive
1534 lookups performed on behalf of clients by a caching name
1541 <p><span><strong class="command">xfer-in</strong></span></p>
1545 Zone transfers the server is receiving.
1551 <p><span><strong class="command">xfer-out</strong></span></p>
1555 Zone transfers the server is sending.
1561 <p><span><strong class="command">notify</strong></span></p>
1565 The NOTIFY protocol.
1571 <p><span><strong class="command">client</strong></span></p>
1575 Processing of client requests.
1581 <p><span><strong class="command">unmatched</strong></span></p>
1585 Messages that <span><strong class="command">named</strong></span> was unable to determine the
1586 class of or for which there was no matching <span><strong class="command">view</strong></span>.
1587 A one line summary is also logged to the <span><strong class="command">client</strong></span> category.
1588 This category is best sent to a file or stderr, by
1589 default it is sent to
1590 the <span><strong class="command">null</strong></span> channel.
1596 <p><span><strong class="command">network</strong></span></p>
1606 <p><span><strong class="command">update</strong></span></p>
1616 <p><span><strong class="command">update-security</strong></span></p>
1620 Approval and denial of update requests.
1626 <p><span><strong class="command">queries</strong></span></p>
1630 Specify where queries should be logged to.
1633 At startup, specifying the category <span><strong class="command">queries</strong></span> will also
1634 enable query logging unless <span><strong class="command">querylog</strong></span> option has been
1639 The query log entry reports the client's IP
1640 address and port number, and the query name,
1641 class and type. Next it reports whether the
1642 Recursion Desired flag was set (+ if set, -
1643 if not set), if the query was signed (S),
1644 EDNS was in use (E), if TCP was used (T), if
1645 DO (DNSSEC Ok) was set (D), or if CD (Checking
1646 Disabled) was set (C). After this the
1647 destination address the query was sent to is
1652 <code class="computeroutput">client 127.0.0.1#62536: query: www.example.com IN AAAA +SE</code>
1655 <code class="computeroutput">client ::1#62537: query: www.example.net IN AAAA -SE</code>
1661 <p><span><strong class="command">query-errors</strong></span></p>
1665 Information about queries that resulted in some
1672 <p><span><strong class="command">dispatch</strong></span></p>
1676 Dispatching of incoming packets to the
1677 server modules where they are to be processed.
1683 <p><span><strong class="command">dnssec</strong></span></p>
1687 DNSSEC and TSIG protocol processing.
1693 <p><span><strong class="command">lame-servers</strong></span></p>
1697 Lame servers. These are misconfigurations
1698 in remote servers, discovered by BIND 9 when trying to
1699 query those servers during resolution.
1705 <p><span><strong class="command">delegation-only</strong></span></p>
1709 Delegation only. Logs queries that have been
1710 forced to NXDOMAIN as the result of a
1711 delegation-only zone or a
1712 <span><strong class="command">delegation-only</strong></span> in a hint
1713 or stub zone declaration.
1719 <p><span><strong class="command">edns-disabled</strong></span></p>
1723 Log queries that have been forced to use plain
1724 DNS due to timeouts. This is often due to
1725 the remote servers not being RFC 1034 compliant
1726 (not always returning FORMERR or similar to
1727 EDNS queries and other extensions to the DNS
1728 when they are not understood). In other words, this is
1729 targeted at servers that fail to respond to
1730 DNS queries that they don't understand.
1733 Note: the log message can also be due to
1734 packet loss. Before reporting servers for
1735 non-RFC 1034 compliance they should be re-tested
1736 to determine the nature of the non-compliance.
1737 This testing should prevent or reduce the
1738 number of false-positive reports.
1741 Note: eventually <span><strong class="command">named</strong></span> will have to stop
1742 treating such timeouts as due to RFC 1034 non
1743 compliance and start treating it as plain
1744 packet loss. Falsely classifying packet
1745 loss as due to RFC 1034 non compliance impacts
1746 on DNSSEC validation which requires EDNS for
1747 the DNSSEC records to be returned.
1754 <div class="sect3" lang="en">
1755 <div class="titlepage"><div><div><h4 class="title">
1756 <a name="id2577253"></a>The <span><strong class="command">query-errors</strong></span> Category</h4></div></div></div>
1758 The <span><strong class="command">query-errors</strong></span> category is
1759 specifically intended for debugging purposes: To identify
1760 why and how specific queries result in responses which
1762 Messages of this category are therefore only logged
1763 with <span><strong class="command">debug</strong></span> levels.
1766 At the debug levels of 1 or higher, each response with the
1767 rcode of SERVFAIL is logged as follows:
1770 <code class="computeroutput">client 127.0.0.1#61502: query failed (SERVFAIL) for www.example.com/IN/AAAA at query.c:3880</code>
1773 This means an error resulting in SERVFAIL was
1774 detected at line 3880 of source file
1775 <code class="filename">query.c</code>.
1776 Log messages of this level will particularly
1777 help identify the cause of SERVFAIL for an
1778 authoritative server.
1781 At the debug levels of 2 or higher, detailed context
1782 information of recursive resolutions that resulted in
1784 The log message will look like as follows:
1789 <pre class="programlisting">
1790 fetch completed at resolver.c:2970 for www.example.com/A
1791 in 30.000183: timed out/success [domain:example.com,
1792 referral:2,restart:7,qrysent:8,timeout:5,lame:0,neterr:0,
1793 badresp:1,adberr:0,findfail:0,valfail:0]
1798 The first part before the colon shows that a recursive
1799 resolution for AAAA records of www.example.com completed
1800 in 30.000183 seconds and the final result that led to the
1801 SERVFAIL was determined at line 2970 of source file
1802 <code class="filename">resolver.c</code>.
1805 The following part shows the detected final result and the
1806 latest result of DNSSEC validation.
1807 The latter is always success when no validation attempt
1809 In this example, this query resulted in SERVFAIL probably
1810 because all name servers are down or unreachable, leading
1811 to a timeout in 30 seconds.
1812 DNSSEC validation was probably not attempted.
1815 The last part enclosed in square brackets shows statistics
1816 information collected for this particular resolution
1818 The <code class="varname">domain</code> field shows the deepest zone
1819 that the resolver reached;
1820 it is the zone where the error was finally detected.
1821 The meaning of the other fields is summarized in the
1824 <div class="informaltable"><table border="1">
1832 <p><code class="varname">referral</code></p>
1836 The number of referrals the resolver received
1837 throughout the resolution process.
1838 In the above example this is 2, which are most
1839 likely com and example.com.
1845 <p><code class="varname">restart</code></p>
1849 The number of cycles that the resolver tried
1850 remote servers at the <code class="varname">domain</code>
1852 In each cycle the resolver sends one query
1853 (possibly resending it, depending on the response)
1854 to each known name server of
1855 the <code class="varname">domain</code> zone.
1861 <p><code class="varname">qrysent</code></p>
1865 The number of queries the resolver sent at the
1866 <code class="varname">domain</code> zone.
1872 <p><code class="varname">timeout</code></p>
1876 The number of timeouts since the resolver
1877 received the last response.
1883 <p><code class="varname">lame</code></p>
1887 The number of lame servers the resolver detected
1888 at the <code class="varname">domain</code> zone.
1889 A server is detected to be lame either by an
1890 invalid response or as a result of lookup in
1891 BIND9's address database (ADB), where lame
1898 <p><code class="varname">neterr</code></p>
1902 The number of erroneous results that the
1903 resolver encountered in sending queries
1904 at the <code class="varname">domain</code> zone.
1905 One common case is the remote server is
1906 unreachable and the resolver receives an ICMP
1907 unreachable error message.
1913 <p><code class="varname">badresp</code></p>
1917 The number of unexpected responses (other than
1918 <code class="varname">lame</code>) to queries sent by the
1919 resolver at the <code class="varname">domain</code> zone.
1925 <p><code class="varname">adberr</code></p>
1929 Failures in finding remote server addresses
1930 of the <code class="varname">domain</code> zone in the ADB.
1931 One common case of this is that the remote
1932 server's name does not have any address records.
1938 <p><code class="varname">findfail</code></p>
1942 Failures of resolving remote server addresses.
1943 This is a total number of failures throughout
1944 the resolution process.
1950 <p><code class="varname">valfail</code></p>
1954 Failures of DNSSEC validation.
1955 Validation failures are counted throughout
1956 the resolution process (not limited to
1957 the <code class="varname">domain</code> zone), but should
1958 only happen in <code class="varname">domain</code>.
1965 At the debug levels of 3 or higher, the same messages
1966 as those at the debug 1 level are logged for other errors
1968 Note that negative responses such as NXDOMAIN are not
1969 regarded as errors here.
1972 At the debug levels of 4 or higher, the same messages
1973 as those at the debug 2 level are logged for other errors
1975 Unlike the above case of level 3, messages are logged for
1977 This is because any unexpected results can be difficult to
1978 debug in the recursion case.
1982 <div class="sect2" lang="en">
1983 <div class="titlepage"><div><div><h3 class="title">
1984 <a name="id2577841"></a><span><strong class="command">lwres</strong></span> Statement Grammar</h3></div></div></div>
1986 This is the grammar of the <span><strong class="command">lwres</strong></span>
1987 statement in the <code class="filename">named.conf</code> file:
1989 <pre class="programlisting"><span><strong class="command">lwres</strong></span> {
1990 [<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>] ;
1991 [<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>]
1992 [<span class="optional"> view <em class="replaceable"><code>view_name</code></em>; </span>]
1993 [<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>]
1994 [<span class="optional"> ndots <em class="replaceable"><code>number</code></em>; </span>]
1998 <div class="sect2" lang="en">
1999 <div class="titlepage"><div><div><h3 class="title">
2000 <a name="id2577982"></a><span><strong class="command">lwres</strong></span> Statement Definition and Usage</h3></div></div></div>
2002 The <span><strong class="command">lwres</strong></span> statement configures the
2004 server to also act as a lightweight resolver server. (See
2005 <a href="Bv9ARM.ch05.html#lwresd" title="Running a Resolver Daemon">the section called “Running a Resolver Daemon”</a>.) There may be multiple
2006 <span><strong class="command">lwres</strong></span> statements configuring
2007 lightweight resolver servers with different properties.
2010 The <span><strong class="command">listen-on</strong></span> statement specifies a
2012 addresses (and ports) that this instance of a lightweight resolver
2014 should accept requests on. If no port is specified, port 921 is
2016 If this statement is omitted, requests will be accepted on
2021 The <span><strong class="command">view</strong></span> statement binds this
2023 lightweight resolver daemon to a view in the DNS namespace, so that
2025 response will be constructed in the same manner as a normal DNS
2027 matching this view. If this statement is omitted, the default view
2029 used, and if there is no default view, an error is triggered.
2032 The <span><strong class="command">search</strong></span> statement is equivalent to
2034 <span><strong class="command">search</strong></span> statement in
2035 <code class="filename">/etc/resolv.conf</code>. It provides a
2037 which are appended to relative names in queries.
2040 The <span><strong class="command">ndots</strong></span> statement is equivalent to
2042 <span><strong class="command">ndots</strong></span> statement in
2043 <code class="filename">/etc/resolv.conf</code>. It indicates the
2045 number of dots in a relative domain name that should result in an
2046 exact match lookup before search path elements are appended.
2049 <div class="sect2" lang="en">
2050 <div class="titlepage"><div><div><h3 class="title">
2051 <a name="id2578046"></a><span><strong class="command">masters</strong></span> Statement Grammar</h3></div></div></div>
2052 <pre class="programlisting">
2053 <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> |
2054 <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>] };
2057 <div class="sect2" lang="en">
2058 <div class="titlepage"><div><div><h3 class="title">
2059 <a name="id2578090"></a><span><strong class="command">masters</strong></span> Statement Definition and
2060 Usage</h3></div></div></div>
2061 <p><span><strong class="command">masters</strong></span>
2062 lists allow for a common set of masters to be easily used by
2063 multiple stub and slave zones.
2066 <div class="sect2" lang="en">
2067 <div class="titlepage"><div><div><h3 class="title">
2068 <a name="id2578105"></a><span><strong class="command">options</strong></span> Statement Grammar</h3></div></div></div>
2070 This is the grammar of the <span><strong class="command">options</strong></span>
2071 statement in the <code class="filename">named.conf</code> file:
2073 <pre class="programlisting"><span><strong class="command">options</strong></span> {
2074 [<span class="optional"> attach-cache <em class="replaceable"><code>cache_name</code></em>; </span>]
2075 [<span class="optional"> version <em class="replaceable"><code>version_string</code></em>; </span>]
2076 [<span class="optional"> hostname <em class="replaceable"><code>hostname_string</code></em>; </span>]
2077 [<span class="optional"> server-id <em class="replaceable"><code>server_id_string</code></em>; </span>]
2078 [<span class="optional"> directory <em class="replaceable"><code>path_name</code></em>; </span>]
2079 [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>]
2080 [<span class="optional"> managed-keys-directory <em class="replaceable"><code>path_name</code></em>; </span>]
2081 [<span class="optional"> named-xfer <em class="replaceable"><code>path_name</code></em>; </span>]
2082 [<span class="optional"> tkey-gssapi-keytab <em class="replaceable"><code>path_name</code></em>; </span>]
2083 [<span class="optional"> tkey-gssapi-credential <em class="replaceable"><code>principal</code></em>; </span>]
2084 [<span class="optional"> tkey-domain <em class="replaceable"><code>domainname</code></em>; </span>]
2085 [<span class="optional"> tkey-dhkey <em class="replaceable"><code>key_name</code></em> <em class="replaceable"><code>key_tag</code></em>; </span>]
2086 [<span class="optional"> cache-file <em class="replaceable"><code>path_name</code></em>; </span>]
2087 [<span class="optional"> dump-file <em class="replaceable"><code>path_name</code></em>; </span>]
2088 [<span class="optional"> bindkeys-file <em class="replaceable"><code>path_name</code></em>; </span>]
2089 [<span class="optional"> memstatistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2090 [<span class="optional"> memstatistics-file <em class="replaceable"><code>path_name</code></em>; </span>]
2091 [<span class="optional"> pid-file <em class="replaceable"><code>path_name</code></em>; </span>]
2092 [<span class="optional"> recursing-file <em class="replaceable"><code>path_name</code></em>; </span>]
2093 [<span class="optional"> statistics-file <em class="replaceable"><code>path_name</code></em>; </span>]
2094 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2095 [<span class="optional"> auth-nxdomain <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2096 [<span class="optional"> deallocate-on-exit <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2097 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em>; </span>]
2098 [<span class="optional"> fake-iquery <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2099 [<span class="optional"> fetch-glue <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2100 [<span class="optional"> flush-zones-on-shutdown <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2101 [<span class="optional"> has-old-clients <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2102 [<span class="optional"> host-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2103 [<span class="optional"> host-statistics-max <em class="replaceable"><code>number</code></em>; </span>]
2104 [<span class="optional"> minimal-responses <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2105 [<span class="optional"> multiple-cnames <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2106 [<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>]
2107 [<span class="optional"> recursion <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2108 [<span class="optional"> rfc2308-type1 <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2109 [<span class="optional"> use-id-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2110 [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2111 [<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>]
2112 [<span class="optional"> dnssec-enable <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2113 [<span class="optional"> dnssec-validation (<em class="replaceable"><code>yes_or_no</code></em> | <code class="constant">auto</code>); </span>]
2114 [<span class="optional"> dnssec-lookaside ( <em class="replaceable"><code>auto</code></em> |
2115 <em class="replaceable"><code>domain</code></em> trust-anchor <em class="replaceable"><code>domain</code></em> ); </span>]
2116 [<span class="optional"> dnssec-must-be-secure <em class="replaceable"><code>domain yes_or_no</code></em>; </span>]
2117 [<span class="optional"> dnssec-accept-expired <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2118 [<span class="optional"> forward ( <em class="replaceable"><code>only</code></em> | <em class="replaceable"><code>first</code></em> ); </span>]
2119 [<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>]
2120 [<span class="optional"> dual-stack-servers [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] {
2121 ( <em class="replaceable"><code>domain_name</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] |
2122 <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ) ;
2124 [<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> )
2125 ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2126 [<span class="optional"> check-dup-records ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>]
2127 [<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>]
2128 [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2129 [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2130 [<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>]
2131 [<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>]
2132 [<span class="optional"> check-sibling <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2133 [<span class="optional"> allow-new-zones { <em class="replaceable"><code>yes_or_no</code></em> }; </span>]
2134 [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2135 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2136 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2137 [<span class="optional"> allow-query-cache { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2138 [<span class="optional"> allow-query-cache-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2139 [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2140 [<span class="optional"> allow-recursion { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2141 [<span class="optional"> allow-recursion-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2142 [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2143 [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2144 [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2145 [<span class="optional"> dnssec-dnskey-kskonly <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2146 [<span class="optional"> dnssec-secure-to-insecure <em class="replaceable"><code>yes_or_no</code></em> ;</span>]
2147 [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2148 [<span class="optional"> allow-v6-synthesis { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2149 [<span class="optional"> blackhole { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2150 [<span class="optional"> use-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2151 [<span class="optional"> avoid-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2152 [<span class="optional"> use-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2153 [<span class="optional"> avoid-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>]
2154 [<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>]
2155 [<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>]
2156 [<span class="optional"> query-source ( ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> )
2157 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] |
2158 [<span class="optional"> address ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
2159 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>]
2160 [<span class="optional"> query-source-v6 ( ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> )
2161 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] |
2162 [<span class="optional"> address ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
2163 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>]
2164 [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2165 [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>]
2166 [<span class="optional"> queryport-pool-updateinterval <em class="replaceable"><code>number</code></em>; </span>]
2167 [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em>; </span>]
2168 [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em>; </span>]
2169 [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em>; </span>]
2170 [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em>; </span>]
2171 [<span class="optional"> tcp-clients <em class="replaceable"><code>number</code></em>; </span>]
2172 [<span class="optional"> reserved-sockets <em class="replaceable"><code>number</code></em>; </span>]
2173 [<span class="optional"> recursive-clients <em class="replaceable"><code>number</code></em>; </span>]
2174 [<span class="optional"> serial-query-rate <em class="replaceable"><code>number</code></em>; </span>]
2175 [<span class="optional"> serial-queries <em class="replaceable"><code>number</code></em>; </span>]
2176 [<span class="optional"> tcp-listen-queue <em class="replaceable"><code>number</code></em>; </span>]
2177 [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em>; </span>]
2178 [<span class="optional"> transfers-in <em class="replaceable"><code>number</code></em>; </span>]
2179 [<span class="optional"> transfers-out <em class="replaceable"><code>number</code></em>; </span>]
2180 [<span class="optional"> transfers-per-ns <em class="replaceable"><code>number</code></em>; </span>]
2181 [<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>]
2182 [<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>]
2183 [<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>]
2184 [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>)
2185 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
2186 [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2187 [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
2188 [<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>]
2189 [<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>]
2190 [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2191 [<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>] ;
2192 [<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>]
2193 [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em>; </span>]
2194 [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
2195 [<span class="optional"> coresize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2196 [<span class="optional"> datasize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2197 [<span class="optional"> files <em class="replaceable"><code>size_spec</code></em> ; </span>]
2198 [<span class="optional"> stacksize <em class="replaceable"><code>size_spec</code></em> ; </span>]
2199 [<span class="optional"> cleaning-interval <em class="replaceable"><code>number</code></em>; </span>]
2200 [<span class="optional"> heartbeat-interval <em class="replaceable"><code>number</code></em>; </span>]
2201 [<span class="optional"> interface-interval <em class="replaceable"><code>number</code></em>; </span>]
2202 [<span class="optional"> statistics-interval <em class="replaceable"><code>number</code></em>; </span>]
2203 [<span class="optional"> topology { <em class="replaceable"><code>address_match_list</code></em> }</span>];
2204 [<span class="optional"> sortlist { <em class="replaceable"><code>address_match_list</code></em> }</span>];
2205 [<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>] };
2206 [<span class="optional"> lame-ttl <em class="replaceable"><code>number</code></em>; </span>]
2207 [<span class="optional"> max-ncache-ttl <em class="replaceable"><code>number</code></em>; </span>]
2208 [<span class="optional"> max-cache-ttl <em class="replaceable"><code>number</code></em>; </span>]
2209 [<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>]
2210 [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>]
2211 [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>]
2212 [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>]
2213 [<span class="optional"> min-roots <em class="replaceable"><code>number</code></em>; </span>]
2214 [<span class="optional"> use-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2215 [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2216 [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2217 [<span class="optional"> treat-cr-as-space <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2218 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
2219 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
2220 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
2221 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
2222 [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em>; </span>]
2223 [<span class="optional"> additional-from-auth <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2224 [<span class="optional"> additional-from-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2225 [<span class="optional"> random-device <em class="replaceable"><code>path_name</code></em> ; </span>]
2226 [<span class="optional"> max-cache-size <em class="replaceable"><code>size_spec</code></em> ; </span>]
2227 [<span class="optional"> match-mapped-addresses <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2228 [<span class="optional"> filter-aaaa-on-v4 ( <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>break-dnssec</code></em> ); </span>]
2229 [<span class="optional"> filter-aaaa { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2230 [<span class="optional"> dns64 <em class="replaceable"><code>IPv6-prefix</code></em> {
2231 [<span class="optional"> clients { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2232 [<span class="optional"> mapped { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2233 [<span class="optional"> exclude { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
2234 [<span class="optional"> suffix IPv6-address; </span>]
2235 [<span class="optional"> recursive-only <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2236 [<span class="optional"> break-dnssec <em class="replaceable"><code>yes_or_no</code></em>; </span>]
2238 [<span class="optional"> dns64-server <em class="replaceable"><code>name</code></em> </span>]
2239 [<span class="optional"> dns64-contact <em class="replaceable"><code>name</code></em> </span>]
2240 [<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>]
2241 [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em>; </span>]
2242 [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em>; </span>]
2243 [<span class="optional"> root-delegation-only [<span class="optional"> exclude { <em class="replaceable"><code>namelist</code></em> } </span>] ; </span>]
2244 [<span class="optional"> querylog <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2245 [<span class="optional"> disable-algorithms <em class="replaceable"><code>domain</code></em> { <em class="replaceable"><code>algorithm</code></em>;
2246 [<span class="optional"> <em class="replaceable"><code>algorithm</code></em>; </span>] }; </span>]
2247 [<span class="optional"> acache-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2248 [<span class="optional"> acache-cleaning-interval <em class="replaceable"><code>number</code></em>; </span>]
2249 [<span class="optional"> max-acache-size <em class="replaceable"><code>size_spec</code></em> ; </span>]
2250 [<span class="optional"> clients-per-query <em class="replaceable"><code>number</code></em> ; </span>]
2251 [<span class="optional"> max-clients-per-query <em class="replaceable"><code>number</code></em> ; </span>]
2252 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
2253 [<span class="optional"> empty-server <em class="replaceable"><code>name</code></em> ; </span>]
2254 [<span class="optional"> empty-contact <em class="replaceable"><code>name</code></em> ; </span>]
2255 [<span class="optional"> empty-zones-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2256 [<span class="optional"> disable-empty-zone <em class="replaceable"><code>zone_name</code></em> ; </span>]
2257 [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2258 [<span class="optional"> zero-no-soa-ttl-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
2259 [<span class="optional"> resolver-query-timeout <em class="replaceable"><code>number</code></em> ; </span>]
2260 [<span class="optional"> deny-answer-addresses { <em class="replaceable"><code>address_match_list</code></em> } [<span class="optional"> except-from { <em class="replaceable"><code>namelist</code></em> } </span>];</span>]
2261 [<span class="optional"> deny-answer-aliases { <em class="replaceable"><code>namelist</code></em> } [<span class="optional"> except-from { <em class="replaceable"><code>namelist</code></em> } </span>];</span>]
2262 [<span class="optional"> response-policy { <em class="replaceable"><code>zone_name</code></em> [<span class="optional"> policy <em class="replaceable"><code>given</code></em> | <em class="replaceable"><code>no-op</code></em> | <em class="replaceable"><code>nxdomain</code></em> | <em class="replaceable"><code>nodata</code></em> | <em class="replaceable"><code>cname domain</code></em> </span>] ; } ; </span>]
2266 <div class="sect2" lang="en">
2267 <div class="titlepage"><div><div><h3 class="title">
2268 <a name="options"></a><span><strong class="command">options</strong></span> Statement Definition and
2269 Usage</h3></div></div></div>
2271 The <span><strong class="command">options</strong></span> statement sets up global
2273 to be used by <acronym class="acronym">BIND</acronym>. This statement
2275 once in a configuration file. If there is no <span><strong class="command">options</strong></span>
2276 statement, an options block with each option set to its default will
2279 <div class="variablelist"><dl>
2280 <dt><span class="term"><span><strong class="command">attach-cache</strong></span></span></dt>
2283 Allows multiple views to share a single cache
2285 Each view has its own cache database by default, but
2286 if multiple views have the same operational policy
2287 for name resolution and caching, those views can
2288 share a single cache to save memory and possibly
2289 improve resolution efficiency by using this option.
2292 The <span><strong class="command">attach-cache</strong></span> option
2293 may also be specified in <span><strong class="command">view</strong></span>
2294 statements, in which case it overrides the
2295 global <span><strong class="command">attach-cache</strong></span> option.
2298 The <em class="replaceable"><code>cache_name</code></em> specifies
2299 the cache to be shared.
2300 When the <span><strong class="command">named</strong></span> server configures
2301 views which are supposed to share a cache, it
2302 creates a cache with the specified name for the
2303 first view of these sharing views.
2304 The rest of the views will simply refer to the
2305 already created cache.
2308 One common configuration to share a cache would be to
2309 allow all views to share a single cache.
2310 This can be done by specifying
2311 the <span><strong class="command">attach-cache</strong></span> as a global
2312 option with an arbitrary name.
2315 Another possible operation is to allow a subset of
2316 all views to share a cache while the others to
2317 retain their own caches.
2318 For example, if there are three views A, B, and C,
2319 and only A and B should share a cache, specify the
2320 <span><strong class="command">attach-cache</strong></span> option as a view A (or
2321 B)'s option, referring to the other view name:
2323 <pre class="programlisting">
2325 // this view has its own cache
2329 // this view refers to A's cache
2333 // this view has its own cache
2338 Views that share a cache must have the same policy
2339 on configurable parameters that may affect caching.
2340 The current implementation requires the following
2341 configurable options be consistent among these
2343 <span><strong class="command">check-names</strong></span>,
2344 <span><strong class="command">cleaning-interval</strong></span>,
2345 <span><strong class="command">dnssec-accept-expired</strong></span>,
2346 <span><strong class="command">dnssec-validation</strong></span>,
2347 <span><strong class="command">max-cache-ttl</strong></span>,
2348 <span><strong class="command">max-ncache-ttl</strong></span>,
2349 <span><strong class="command">max-cache-size</strong></span>, and
2350 <span><strong class="command">zero-no-soa-ttl</strong></span>.
2353 Note that there may be other parameters that may
2354 cause confusion if they are inconsistent for
2355 different views that share a single cache.
2356 For example, if these views define different sets of
2357 forwarders that can return different answers for the
2358 same question, sharing the answer does not make
2359 sense or could even be harmful.
2360 It is administrator's responsibility to ensure
2361 configuration differences in different views do
2362 not cause disruption with a shared cache.
2365 <dt><span class="term"><span><strong class="command">directory</strong></span></span></dt>
2367 The working directory of the server.
2368 Any non-absolute pathnames in the configuration file will be
2370 as relative to this directory. The default location for most
2372 output files (e.g. <code class="filename">named.run</code>)
2374 If a directory is not specified, the working directory
2375 defaults to `<code class="filename">.</code>', the directory from
2377 was started. The directory specified should be an absolute
2380 <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt>
2382 When performing dynamic update of secure zones, the
2383 directory where the public and private DNSSEC key files
2384 should be found, if different than the current working
2385 directory. (Note that this option has no effect on the
2386 paths for files containing non-DNSSEC keys such as
2387 <code class="filename">bind.keys</code>,
2388 <code class="filename">rndc.key</code> or
2389 <code class="filename">session.key</code>.)
2391 <dt><span class="term"><span><strong class="command">managed-keys-directory</strong></span></span></dt>
2393 The directory used to hold the files used to track managed keys.
2394 By default it is the working directory. It there are no
2395 views then the file <code class="filename">managed-keys.bind</code>
2396 otherwise a SHA256 hash of the view name is used with
2397 <code class="filename">.mkeys</code> extension added.
2399 <dt><span class="term"><span><strong class="command">named-xfer</strong></span></span></dt>
2401 <span class="emphasis"><em>This option is obsolete.</em></span> It
2402 was used in <acronym class="acronym">BIND</acronym> 8 to specify
2403 the pathname to the <span><strong class="command">named-xfer</strong></span>
2404 program. In <acronym class="acronym">BIND</acronym> 9, no separate
2405 <span><strong class="command">named-xfer</strong></span> program is needed;
2406 its functionality is built into the name server.
2408 <dt><span class="term"><span><strong class="command">tkey-gssapi-keytab</strong></span></span></dt>
2410 The KRB5 keytab file to use for GSS-TSIG updates. If
2411 this option is set and tkey-gssapi-credential is not
2412 set, then updates will be allowed with any key
2413 matching a principal in the specified keytab.
2415 <dt><span class="term"><span><strong class="command">tkey-gssapi-credential</strong></span></span></dt>
2417 The security credential with which the server should
2418 authenticate keys requested by the GSS-TSIG protocol.
2419 Currently only Kerberos 5 authentication is available
2420 and the credential is a Kerberos principal which the
2421 server can acquire through the default system key
2422 file, normally <code class="filename">/etc/krb5.keytab</code>.
2423 The location keytab file can be overridden using the
2424 tkey-gssapi-keytab option. Normally this principal is
2425 of the form "<strong class="userinput"><code>DNS/</code></strong><code class="varname">server.domain</code>".
2426 To use GSS-TSIG, <span><strong class="command">tkey-domain</strong></span> must
2427 also be set if a specific keytab is not set with
2430 <dt><span class="term"><span><strong class="command">tkey-domain</strong></span></span></dt>
2432 The domain appended to the names of all shared keys
2433 generated with <span><strong class="command">TKEY</strong></span>. When a
2434 client requests a <span><strong class="command">TKEY</strong></span> exchange,
2435 it may or may not specify the desired name for the
2436 key. If present, the name of the shared key will
2437 be <code class="varname">client specified part</code> +
2438 <code class="varname">tkey-domain</code>. Otherwise, the
2439 name of the shared key will be <code class="varname">random hex
2440 digits</code> + <code class="varname">tkey-domain</code>.
2441 In most cases, the <span><strong class="command">domainname</strong></span>
2442 should be the server's domain name, or an otherwise
2443 non-existent subdomain like
2444 "_tkey.<code class="varname">domainname</code>". If you are
2445 using GSS-TSIG, this variable must be defined, unless
2446 you specify a specific keytab using tkey-gssapi-keytab.
2448 <dt><span class="term"><span><strong class="command">tkey-dhkey</strong></span></span></dt>
2450 The Diffie-Hellman key used by the server
2451 to generate shared keys with clients using the Diffie-Hellman
2453 of <span><strong class="command">TKEY</strong></span>. The server must be
2455 public and private keys from files in the working directory.
2457 most cases, the keyname should be the server's host name.
2459 <dt><span class="term"><span><strong class="command">cache-file</strong></span></span></dt>
2461 This is for testing only. Do not use.
2463 <dt><span class="term"><span><strong class="command">dump-file</strong></span></span></dt>
2465 The pathname of the file the server dumps
2466 the database to when instructed to do so with
2467 <span><strong class="command">rndc dumpdb</strong></span>.
2468 If not specified, the default is <code class="filename">named_dump.db</code>.
2470 <dt><span class="term"><span><strong class="command">memstatistics-file</strong></span></span></dt>
2472 The pathname of the file the server writes memory
2473 usage statistics to on exit. If not specified,
2474 the default is <code class="filename">named.memstats</code>.
2476 <dt><span class="term"><span><strong class="command">pid-file</strong></span></span></dt>
2478 The pathname of the file the server writes its process ID
2479 in. If not specified, the default is
2480 <code class="filename">/var/run/named/named.pid</code>.
2481 The PID file is used by programs that want to send signals to
2483 name server. Specifying <span><strong class="command">pid-file none</strong></span> disables the
2484 use of a PID file — no file will be written and any
2485 existing one will be removed. Note that <span><strong class="command">none</strong></span>
2486 is a keyword, not a filename, and therefore is not enclosed
2490 <dt><span class="term"><span><strong class="command">recursing-file</strong></span></span></dt>
2492 The pathname of the file the server dumps
2493 the queries that are currently recursing when instructed
2494 to do so with <span><strong class="command">rndc recursing</strong></span>.
2495 If not specified, the default is <code class="filename">named.recursing</code>.
2497 <dt><span class="term"><span><strong class="command">statistics-file</strong></span></span></dt>
2499 The pathname of the file the server appends statistics
2500 to when instructed to do so using <span><strong class="command">rndc stats</strong></span>.
2501 If not specified, the default is <code class="filename">named.stats</code> in the
2502 server's current directory. The format of the file is
2504 in <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called “The Statistics File”</a>.
2506 <dt><span class="term"><span><strong class="command">bindkeys-file</strong></span></span></dt>
2508 The pathname of a file to override the built-in trusted
2509 keys provided by <span><strong class="command">named</strong></span>.
2510 See the discussion of <span><strong class="command">dnssec-lookaside</strong></span>
2511 and <span><strong class="command">dnssec-validation</strong></span> for details.
2512 If not specified, the default is
2513 <code class="filename">/etc/bind.keys</code>.
2515 <dt><span class="term"><span><strong class="command">secroots-file</strong></span></span></dt>
2517 The pathname of the file the server dumps
2518 security roots to when instructed to do so with
2519 <span><strong class="command">rndc secroots</strong></span>.
2520 If not specified, the default is <code class="filename">named.secroots</code>.
2522 <dt><span class="term"><span><strong class="command">session-keyfile</strong></span></span></dt>
2524 The pathname of the file into which to write a TSIG
2525 session key generated by <span><strong class="command">named</strong></span> for use by
2526 <span><strong class="command">nsupdate -l</strong></span>. If not specified, the
2527 default is <code class="filename">/var/run/named/session.key</code>.
2528 (See <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called “Dynamic Update Policies”</a>, and in
2529 particular the discussion of the
2530 <span><strong class="command">update-policy</strong></span> statement's
2531 <strong class="userinput"><code>local</code></strong> option for more
2532 information about this feature.)
2534 <dt><span class="term"><span><strong class="command">session-keyname</strong></span></span></dt>
2536 The key name to use for the TSIG session key.
2537 If not specified, the default is "local-ddns".
2539 <dt><span class="term"><span><strong class="command">session-keyalg</strong></span></span></dt>
2541 The algorithm to use for the TSIG session key.
2542 Valid values are hmac-sha1, hmac-sha224, hmac-sha256,
2543 hmac-sha384, hmac-sha512 and hmac-md5. If not
2544 specified, the default is hmac-sha256.
2546 <dt><span class="term"><span><strong class="command">session-keyfile</strong></span></span></dt>
2548 The pathname of the file into which to write a session TSIG
2549 key for use by <span><strong class="command">nsupdate -l</strong></span>. (See the
2550 discussion of the <span><strong class="command">update-policy</strong></span>
2551 statement's <strong class="userinput"><code>local</code></strong> option for more
2552 details on this feature.)
2554 <dt><span class="term"><span><strong class="command">port</strong></span></span></dt>
2556 The UDP/TCP port number the server uses for
2557 receiving and sending DNS protocol traffic.
2558 The default is 53. This option is mainly intended for server
2560 a server using a port other than 53 will not be able to
2564 <dt><span class="term"><span><strong class="command">random-device</strong></span></span></dt>
2566 The source of entropy to be used by the server. Entropy is
2568 for DNSSEC operations, such as TKEY transactions and dynamic
2570 zones. This options specifies the device (or file) from which
2572 entropy. If this is a file, operations requiring entropy will
2574 file has been exhausted. If not specified, the default value
2576 <code class="filename">/dev/random</code>
2577 (or equivalent) when present, and none otherwise. The
2578 <span><strong class="command">random-device</strong></span> option takes
2580 the initial configuration load at server startup time and
2581 is ignored on subsequent reloads.
2583 <dt><span class="term"><span><strong class="command">preferred-glue</strong></span></span></dt>
2585 If specified, the listed type (A or AAAA) will be emitted
2587 in the additional section of a query response.
2588 The default is not to prefer any type (NONE).
2591 <a name="root_delegation_only"></a><span class="term"><span><strong class="command">root-delegation-only</strong></span></span>
2595 Turn on enforcement of delegation-only in TLDs
2596 (top level domains) and root zones with an optional
2600 DS queries are expected to be made to and be answered by
2601 delegation only zones. Such queries and responses are
2602 treated as an exception to delegation-only processing
2603 and are not converted to NXDOMAIN responses provided
2604 a CNAME is not discovered at the query name.
2607 If a delegation only zone server also serves a child
2608 zone it is not always possible to determine whether
2609 an answer comes from the delegation only zone or the
2610 child zone. SOA NS and DNSKEY records are apex
2611 only records and a matching response that contains
2612 these records or DS is treated as coming from a
2613 child zone. RRSIG records are also examined to see
2614 if they are signed by a child zone or not. The
2615 authority section is also examined to see if there
2616 is evidence that the answer is from the child zone.
2617 Answers that are determined to be from a child zone
2618 are not converted to NXDOMAIN responses. Despite
2619 all these checks there is still a possibility of
2620 false negatives when a child zone is being served.
2623 Similarly false positives can arise from empty nodes
2624 (no records at the name) in the delegation only zone
2625 when the query type is not ANY.
2628 Note some TLDs are not delegation only (e.g. "DE", "LV",
2629 "US" and "MUSEUM"). This list is not exhaustive.
2631 <pre class="programlisting">
2633 root-delegation-only exclude { "de"; "lv"; "us"; "museum"; };
2637 <dt><span class="term"><span><strong class="command">disable-algorithms</strong></span></span></dt>
2639 Disable the specified DNSSEC algorithms at and below the
2641 Multiple <span><strong class="command">disable-algorithms</strong></span>
2642 statements are allowed.
2643 Only the most specific will be applied.
2645 <dt><span class="term"><span><strong class="command">dnssec-lookaside</strong></span></span></dt>
2648 When set, <span><strong class="command">dnssec-lookaside</strong></span> provides the
2649 validator with an alternate method to validate DNSKEY
2650 records at the top of a zone. When a DNSKEY is at or
2651 below a domain specified by the deepest
2652 <span><strong class="command">dnssec-lookaside</strong></span>, and the normal DNSSEC
2653 validation has left the key untrusted, the trust-anchor
2654 will be appended to the key name and a DLV record will be
2655 looked up to see if it can validate the key. If the DLV
2656 record validates a DNSKEY (similarly to the way a DS
2657 record does) the DNSKEY RRset is deemed to be trusted.
2660 If <span><strong class="command">dnssec-lookaside</strong></span> is set to
2661 <strong class="userinput"><code>auto</code></strong>, then built-in default
2662 values for the DLV domain and trust anchor will be
2663 used, along with a built-in key for validation.
2666 The default DLV key is stored in the file
2667 <code class="filename">bind.keys</code>;
2668 <span><strong class="command">named</strong></span> will load that key at
2669 startup if <span><strong class="command">dnssec-lookaside</strong></span> is set to
2670 <code class="constant">auto</code>. A copy of the file is
2671 installed along with <acronym class="acronym">BIND</acronym> 9, and is
2672 current as of the release date. If the DLV key expires, a
2673 new copy of <code class="filename">bind.keys</code> can be downloaded
2674 from <a href="" target="_top">https://www.isc.org/solutions/dlv</a>.
2677 (To prevent problems if <code class="filename">bind.keys</code> is
2678 not found, the current key is also compiled in to
2679 <span><strong class="command">named</strong></span>. Relying on this is not
2680 recommended, however, as it requires <span><strong class="command">named</strong></span>
2681 to be recompiled with a new key when the DLV key expires.)
2684 NOTE: <span><strong class="command">named</strong></span> only loads certain specific
2685 keys from <code class="filename">bind.keys</code>: those for the
2686 DLV zone and for the DNS root zone. The file cannot be
2687 used to store keys for other zones.
2690 <dt><span class="term"><span><strong class="command">dnssec-must-be-secure</strong></span></span></dt>
2692 Specify hierarchies which must be or may not be secure
2693 (signed and validated). If <strong class="userinput"><code>yes</code></strong>,
2694 then <span><strong class="command">named</strong></span> will only accept answers if
2695 they are secure. If <strong class="userinput"><code>no</code></strong>, then normal
2696 DNSSEC validation applies allowing for insecure answers to
2697 be accepted. The specified domain must be under a
2698 <span><strong class="command">trusted-keys</strong></span> or
2699 <span><strong class="command">managed-keys</strong></span> statement, or
2700 <span><strong class="command">dnssec-lookaside</strong></span> must be active.
2702 <dt><span class="term"><span><strong class="command">dns64</strong></span></span></dt>
2705 This directive instructs <span><strong class="command">named</strong></span> to
2706 return mapped IPv4 addresses to AAAA queries when
2707 there are no AAAA records. It is intended to be
2708 used in conjunction with a NAT64. Each
2709 <span><strong class="command">dns64</strong></span> defines one DNS64 prefix.
2710 Multiple DNS64 prefixes can be defined.
2713 Compatible IPv6 prefixes have lengths of 32, 40, 48, 56,
2714 64 and 96 as per RFC 6052.
2717 Additionally a reverse IP6.ARPA zone will be created for
2718 the prefix to provide a mapping from the IP6.ARPA names
2719 to the corresponding IN-ADDR.ARPA names using synthesized
2720 CNAMEs. <span><strong class="command">dns64-server</strong></span> and
2721 <span><strong class="command">dns64-contact</strong></span> can be used to specify
2722 the name of the server and contact for the zones. These
2723 are settable at the view / options level. These are
2724 not settable on a per-prefix basis.
2727 Each <span><strong class="command">dns64</strong></span> supports an optional
2728 <span><strong class="command">clients</strong></span> ACL that determines which
2729 clients are affected by this directive. If not defined,
2730 it defaults to <strong class="userinput"><code>any;</code></strong>.
2733 Each <span><strong class="command">dns64</strong></span> supports an optional
2734 <span><strong class="command">mapped</strong></span> ACL that selects which
2735 IPv4 addresses are to be mapped in the corresponding
2736 A RRset. If not defined it defaults to
2737 <strong class="userinput"><code>any;</code></strong>.
2740 Each <span><strong class="command">dns64</strong></span> supports an optional
2741 <span><strong class="command">exclude</strong></span> ACL that selects which
2742 IPv6 addresses will be ignored for the purposes
2743 of determining whether dns64 is to be applied.
2744 Any non-matching address will prevent further
2745 DNS64 processing from occurring for this client.
2748 A optional <span><strong class="command">suffix</strong></span> can also
2749 be defined to set the bits trailing the mapped
2750 IPv4 address bits. By default these bits are
2751 set to <strong class="userinput"><code>::</code></strong>. The bits
2752 matching the prefix and mapped IPv4 address
2755 <pre class="programlisting">
2756 acl rfc1918 { 10/8; 192.168/16; 172.16/12; };
2758 dns64 64:FF9B::/96 {
2760 mapped { !rfc1918; any; };
2761 exclude { 64:FF9B::/96; ::ffff:0000:0000/96; };
2767 <div class="sect3" lang="en">
2768 <div class="titlepage"><div><div><h4 class="title">
2769 <a name="boolean_options"></a>Boolean Options</h4></div></div></div>
2770 <div class="variablelist"><dl>
2771 <dt><span class="term"><span><strong class="command">allow-new-zones</strong></span></span></dt>
2773 If <strong class="userinput"><code>yes</code></strong>, then zones can be
2774 added at runtime via <span><strong class="command">rndc addzone</strong></span>
2775 or deleted via <span><strong class="command">rndc delzone</strong></span>.
2776 The default is <strong class="userinput"><code>no</code></strong>.
2778 <dt><span class="term"><span><strong class="command">auth-nxdomain</strong></span></span></dt>
2780 If <strong class="userinput"><code>yes</code></strong>, then the <span><strong class="command">AA</strong></span> bit
2781 is always set on NXDOMAIN responses, even if the server is
2783 authoritative. The default is <strong class="userinput"><code>no</code></strong>;
2785 a change from <acronym class="acronym">BIND</acronym> 8. If you
2786 are using very old DNS software, you
2787 may need to set it to <strong class="userinput"><code>yes</code></strong>.
2789 <dt><span class="term"><span><strong class="command">deallocate-on-exit</strong></span></span></dt>
2791 This option was used in <acronym class="acronym">BIND</acronym>
2792 8 to enable checking
2793 for memory leaks on exit. <acronym class="acronym">BIND</acronym> 9 ignores the option and always performs
2796 <dt><span class="term"><span><strong class="command">memstatistics</strong></span></span></dt>
2798 Write memory statistics to the file specified by
2799 <span><strong class="command">memstatistics-file</strong></span> at exit.
2800 The default is <strong class="userinput"><code>no</code></strong> unless
2801 '-m record' is specified on the command line in
2802 which case it is <strong class="userinput"><code>yes</code></strong>.
2804 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
2807 If <strong class="userinput"><code>yes</code></strong>, then the
2808 server treats all zones as if they are doing zone transfers
2810 a dial-on-demand dialup link, which can be brought up by
2812 originating from this server. This has different effects
2814 to zone type and concentrates the zone maintenance so that
2816 happens in a short interval, once every <span><strong class="command">heartbeat-interval</strong></span> and
2817 hopefully during the one call. It also suppresses some of
2819 zone maintenance traffic. The default is <strong class="userinput"><code>no</code></strong>.
2822 The <span><strong class="command">dialup</strong></span> option
2823 may also be specified in the <span><strong class="command">view</strong></span> and
2824 <span><strong class="command">zone</strong></span> statements,
2825 in which case it overrides the global <span><strong class="command">dialup</strong></span>
2829 If the zone is a master zone, then the server will send out a
2831 request to all the slaves (default). This should trigger the
2833 number check in the slave (providing it supports NOTIFY)
2835 to verify the zone while the connection is active.
2836 The set of servers to which NOTIFY is sent can be controlled
2838 <span><strong class="command">notify</strong></span> and <span><strong class="command">also-notify</strong></span>.
2842 zone is a slave or stub zone, then the server will suppress
2844 "zone up to date" (refresh) queries and only perform them
2846 <span><strong class="command">heartbeat-interval</strong></span> expires in
2851 Finer control can be achieved by using
2852 <strong class="userinput"><code>notify</code></strong> which only sends NOTIFY
2854 <strong class="userinput"><code>notify-passive</code></strong> which sends NOTIFY
2856 suppresses the normal refresh queries, <strong class="userinput"><code>refresh</code></strong>
2857 which suppresses normal refresh processing and sends refresh
2859 when the <span><strong class="command">heartbeat-interval</strong></span>
2861 <strong class="userinput"><code>passive</code></strong> which just disables normal
2865 <div class="informaltable"><table border="1">
2897 <p><span><strong class="command">no</strong></span> (default)</p>
2917 <p><span><strong class="command">yes</strong></span></p>
2937 <p><span><strong class="command">notify</strong></span></p>
2957 <p><span><strong class="command">refresh</strong></span></p>
2977 <p><span><strong class="command">passive</strong></span></p>
2997 <p><span><strong class="command">notify-passive</strong></span></p>
3018 Note that normal NOTIFY processing is not affected by
3019 <span><strong class="command">dialup</strong></span>.
3022 <dt><span class="term"><span><strong class="command">fake-iquery</strong></span></span></dt>
3024 In <acronym class="acronym">BIND</acronym> 8, this option
3025 enabled simulating the obsolete DNS query type
3026 IQUERY. <acronym class="acronym">BIND</acronym> 9 never does
3029 <dt><span class="term"><span><strong class="command">fetch-glue</strong></span></span></dt>
3031 This option is obsolete.
3032 In BIND 8, <strong class="userinput"><code>fetch-glue yes</code></strong>
3033 caused the server to attempt to fetch glue resource records
3035 didn't have when constructing the additional
3036 data section of a response. This is now considered a bad
3038 and BIND 9 never does it.
3040 <dt><span class="term"><span><strong class="command">flush-zones-on-shutdown</strong></span></span></dt>
3042 When the nameserver exits due receiving SIGTERM,
3043 flush or do not flush any pending zone writes. The default
3045 <span><strong class="command">flush-zones-on-shutdown</strong></span> <strong class="userinput"><code>no</code></strong>.
3047 <dt><span class="term"><span><strong class="command">has-old-clients</strong></span></span></dt>
3049 This option was incorrectly implemented
3050 in <acronym class="acronym">BIND</acronym> 8, and is ignored by <acronym class="acronym">BIND</acronym> 9.
3051 To achieve the intended effect
3053 <span><strong class="command">has-old-clients</strong></span> <strong class="userinput"><code>yes</code></strong>, specify
3054 the two separate options <span><strong class="command">auth-nxdomain</strong></span> <strong class="userinput"><code>yes</code></strong>
3055 and <span><strong class="command">rfc2308-type1</strong></span> <strong class="userinput"><code>no</code></strong> instead.
3057 <dt><span class="term"><span><strong class="command">host-statistics</strong></span></span></dt>
3059 In BIND 8, this enables keeping of
3060 statistics for every host that the name server interacts
3062 Not implemented in BIND 9.
3064 <dt><span class="term"><span><strong class="command">maintain-ixfr-base</strong></span></span></dt>
3066 <span class="emphasis"><em>This option is obsolete</em></span>.
3067 It was used in <acronym class="acronym">BIND</acronym> 8 to
3068 determine whether a transaction log was
3069 kept for Incremental Zone Transfer. <acronym class="acronym">BIND</acronym> 9 maintains a transaction
3070 log whenever possible. If you need to disable outgoing
3072 transfers, use <span><strong class="command">provide-ixfr</strong></span> <strong class="userinput"><code>no</code></strong>.
3074 <dt><span class="term"><span><strong class="command">minimal-responses</strong></span></span></dt>
3076 If <strong class="userinput"><code>yes</code></strong>, then when generating
3077 responses the server will only add records to the authority
3078 and additional data sections when they are required (e.g.
3079 delegations, negative responses). This may improve the
3080 performance of the server.
3081 The default is <strong class="userinput"><code>no</code></strong>.
3083 <dt><span class="term"><span><strong class="command">multiple-cnames</strong></span></span></dt>
3085 This option was used in <acronym class="acronym">BIND</acronym> 8 to allow
3086 a domain name to have multiple CNAME records in violation of
3087 the DNS standards. <acronym class="acronym">BIND</acronym> 9.2 onwards
3088 always strictly enforces the CNAME rules both in master
3089 files and dynamic updates.
3091 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
3094 If <strong class="userinput"><code>yes</code></strong> (the default),
3095 DNS NOTIFY messages are sent when a zone the server is
3097 changes, see <a href="Bv9ARM.ch04.html#notify" title="Notify">the section called “Notify”</a>. The messages are
3099 servers listed in the zone's NS records (except the master
3101 in the SOA MNAME field), and to any servers listed in the
3102 <span><strong class="command">also-notify</strong></span> option.
3105 If <strong class="userinput"><code>master-only</code></strong>, notifies are only
3108 If <strong class="userinput"><code>explicit</code></strong>, notifies are sent only
3110 servers explicitly listed using <span><strong class="command">also-notify</strong></span>.
3111 If <strong class="userinput"><code>no</code></strong>, no notifies are sent.
3114 The <span><strong class="command">notify</strong></span> option may also be
3115 specified in the <span><strong class="command">zone</strong></span>
3117 in which case it overrides the <span><strong class="command">options notify</strong></span> statement.
3118 It would only be necessary to turn off this option if it
3123 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
3125 If <strong class="userinput"><code>yes</code></strong> do not check the nameservers
3126 in the NS RRset against the SOA MNAME. Normally a NOTIFY
3127 message is not sent to the SOA MNAME (SOA ORIGIN) as it is
3128 supposed to contain the name of the ultimate master.
3129 Sometimes, however, a slave is listed as the SOA MNAME in
3130 hidden master configurations and in that case you would
3131 want the ultimate master to still send NOTIFY messages to
3132 all the nameservers listed in the NS RRset.
3134 <dt><span class="term"><span><strong class="command">recursion</strong></span></span></dt>
3136 If <strong class="userinput"><code>yes</code></strong>, and a
3137 DNS query requests recursion, then the server will attempt
3139 all the work required to answer the query. If recursion is
3141 and the server does not already know the answer, it will
3143 referral response. The default is
3144 <strong class="userinput"><code>yes</code></strong>.
3145 Note that setting <span><strong class="command">recursion no</strong></span> does not prevent
3146 clients from getting data from the server's cache; it only
3147 prevents new data from being cached as an effect of client
3149 Caching may still occur as an effect the server's internal
3150 operation, such as NOTIFY address lookups.
3151 See also <span><strong class="command">fetch-glue</strong></span> above.
3153 <dt><span class="term"><span><strong class="command">rfc2308-type1</strong></span></span></dt>
3156 Setting this to <strong class="userinput"><code>yes</code></strong> will
3157 cause the server to send NS records along with the SOA
3159 answers. The default is <strong class="userinput"><code>no</code></strong>.
3161 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3162 <h3 class="title">Note</h3>
3164 Not yet implemented in <acronym class="acronym">BIND</acronym>
3169 <dt><span class="term"><span><strong class="command">use-id-pool</strong></span></span></dt>
3171 <span class="emphasis"><em>This option is obsolete</em></span>.
3172 <acronym class="acronym">BIND</acronym> 9 always allocates query
3175 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
3177 If <strong class="userinput"><code>yes</code></strong>, the server will collect
3178 statistical data on all zones (unless specifically turned
3180 on a per-zone basis by specifying <span><strong class="command">zone-statistics no</strong></span>
3181 in the <span><strong class="command">zone</strong></span> statement).
3182 The default is <strong class="userinput"><code>no</code></strong>.
3183 These statistics may be accessed
3184 using <span><strong class="command">rndc stats</strong></span>, which will
3185 dump them to the file listed
3186 in the <span><strong class="command">statistics-file</strong></span>. See
3187 also <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called “The Statistics File”</a>.
3189 <dt><span class="term"><span><strong class="command">use-ixfr</strong></span></span></dt>
3191 <span class="emphasis"><em>This option is obsolete</em></span>.
3192 If you need to disable IXFR to a particular server or
3194 the information on the <span><strong class="command">provide-ixfr</strong></span> option
3195 in <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
3196 Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and
3199 <a href="Bv9ARM.ch04.html#incremental_zone_transfers" title="Incremental Zone Transfers (IXFR)">the section called “Incremental Zone Transfers (IXFR)”</a>.
3201 <dt><span class="term"><span><strong class="command">provide-ixfr</strong></span></span></dt>
3203 See the description of
3204 <span><strong class="command">provide-ixfr</strong></span> in
3205 <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
3206 Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and
3209 <dt><span class="term"><span><strong class="command">request-ixfr</strong></span></span></dt>
3211 See the description of
3212 <span><strong class="command">request-ixfr</strong></span> in
3213 <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
3214 Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and
3217 <dt><span class="term"><span><strong class="command">treat-cr-as-space</strong></span></span></dt>
3219 This option was used in <acronym class="acronym">BIND</acronym>
3221 the server treat carriage return ("<span><strong class="command">\r</strong></span>") characters the same way
3222 as a space or tab character,
3223 to facilitate loading of zone files on a UNIX system that
3225 on an NT or DOS machine. In <acronym class="acronym">BIND</acronym> 9, both UNIX "<span><strong class="command">\n</strong></span>"
3226 and NT/DOS "<span><strong class="command">\r\n</strong></span>" newlines
3227 are always accepted,
3228 and the option is ignored.
3231 <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>
3235 These options control the behavior of an authoritative
3237 answering queries which have additional data, or when
3242 When both of these options are set to <strong class="userinput"><code>yes</code></strong>
3244 query is being answered from authoritative data (a zone
3245 configured into the server), the additional data section of
3247 reply will be filled in using data from other authoritative
3249 and from the cache. In some situations this is undesirable,
3251 as when there is concern over the correctness of the cache,
3253 in servers where slave zones may be added and modified by
3254 untrusted third parties. Also, avoiding
3255 the search for this additional data will speed up server
3257 at the possible expense of additional queries to resolve
3259 otherwise be provided in the additional section.
3262 For example, if a query asks for an MX record for host <code class="literal">foo.example.com</code>,
3263 and the record found is "<code class="literal">MX 10 mail.example.net</code>", normally the address
3264 records (A and AAAA) for <code class="literal">mail.example.net</code> will be provided as well,
3265 if known, even though they are not in the example.com zone.
3266 Setting these options to <span><strong class="command">no</strong></span>
3267 disables this behavior and makes
3268 the server only search for additional data in the zone it
3272 These options are intended for use in authoritative-only
3273 servers, or in authoritative-only views. Attempts to set
3274 them to <span><strong class="command">no</strong></span> without also
3276 <span><strong class="command">recursion no</strong></span> will cause the
3278 ignore the options and log a warning message.
3281 Specifying <span><strong class="command">additional-from-cache no</strong></span> actually
3282 disables the use of the cache not only for additional data
3284 but also when looking up the answer. This is usually the
3286 behavior in an authoritative-only server where the
3288 the cached data is an issue.
3291 When a name server is non-recursively queried for a name
3293 below the apex of any served zone, it normally answers with
3295 "upwards referral" to the root servers or the servers of
3297 known parent of the query name. Since the data in an
3299 comes from the cache, the server will not be able to provide
3301 referrals when <span><strong class="command">additional-from-cache no</strong></span>
3302 has been specified. Instead, it will respond to such
3304 with REFUSED. This should not cause any problems since
3305 upwards referrals are not required for the resolution
3309 <dt><span class="term"><span><strong class="command">match-mapped-addresses</strong></span></span></dt>
3312 If <strong class="userinput"><code>yes</code></strong>, then an
3313 IPv4-mapped IPv6 address will match any address match
3314 list entries that match the corresponding IPv4 address.
3317 This option was introduced to work around a kernel quirk
3318 in some operating systems that causes IPv4 TCP
3319 connections, such as zone transfers, to be accepted on an
3320 IPv6 socket using mapped addresses. This caused address
3321 match lists designed for IPv4 to fail to match. However,
3322 <span><strong class="command">named</strong></span> now solves this problem
3323 internally. The use of this option is discouraged.
3326 <dt><span class="term"><span><strong class="command">filter-aaaa-on-v4</strong></span></span></dt>
3329 This option is only available when
3330 <acronym class="acronym">BIND</acronym> 9 is compiled with the
3331 <strong class="userinput"><code>--enable-filter-aaaa</code></strong> option on the
3332 "configure" command line. It is intended to help the
3333 transition from IPv4 to IPv6 by not giving IPv6 addresses
3334 to DNS clients unless they have connections to the IPv6
3335 Internet. This is not recommended unless absolutely
3336 necessary. The default is <strong class="userinput"><code>no</code></strong>.
3337 The <span><strong class="command">filter-aaaa-on-v4</strong></span> option
3338 may also be specified in <span><strong class="command">view</strong></span> statements
3339 to override the global <span><strong class="command">filter-aaaa-on-v4</strong></span>
3343 If <strong class="userinput"><code>yes</code></strong>,
3344 the DNS client is at an IPv4 address, in <span><strong class="command">filter-aaaa</strong></span>,
3345 and if the response does not include DNSSEC signatures,
3346 then all AAAA records are deleted from the response.
3347 This filtering applies to all responses and not only
3348 authoritative responses.
3351 If <strong class="userinput"><code>break-dnssec</code></strong>,
3352 then AAAA records are deleted even when dnssec is enabled.
3353 As suggested by the name, this makes the response not verify,
3354 because the DNSSEC protocol is designed detect deletions.
3357 This mechanism can erroneously cause other servers to
3358 not give AAAA records to their clients.
3359 A recursing server with both IPv6 and IPv4 network connections
3360 that queries an authoritative server using this mechanism
3361 via IPv4 will be denied AAAA records even if its client is
3365 This mechanism is applied to authoritative as well as
3366 non-authoritative records.
3367 A client using IPv4 that is not allowed recursion can
3368 erroneously be given AAAA records because the server is not
3369 allowed to check for A records.
3372 Some AAAA records are given to IPv4 clients in glue records.
3373 IPv4 clients that are servers can then erroneously
3374 answer requests for AAAA records received via IPv4.
3377 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
3380 When <strong class="userinput"><code>yes</code></strong> and the server loads a new version of a master
3381 zone from its zone file or receives a new version of a slave
3382 file by a non-incremental zone transfer, it will compare
3383 the new version to the previous one and calculate a set
3384 of differences. The differences are then logged in the
3385 zone's journal file such that the changes can be transmitted
3386 to downstream slaves as an incremental zone transfer.
3389 By allowing incremental zone transfers to be used for
3390 non-dynamic zones, this option saves bandwidth at the
3391 expense of increased CPU and memory consumption at the
3393 In particular, if the new version of a zone is completely
3394 different from the previous one, the set of differences
3395 will be of a size comparable to the combined size of the
3396 old and new zone version, and the server will need to
3397 temporarily allocate memory to hold this complete
3400 <p><span><strong class="command">ixfr-from-differences</strong></span>
3401 also accepts <span><strong class="command">master</strong></span> and
3402 <span><strong class="command">slave</strong></span> at the view and options
3404 <span><strong class="command">ixfr-from-differences</strong></span> to be enabled for
3405 all <span><strong class="command">master</strong></span> or
3406 <span><strong class="command">slave</strong></span> zones respectively.
3407 It is off by default.
3410 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
3412 This should be set when you have multiple masters for a zone
3414 addresses refer to different machines. If <strong class="userinput"><code>yes</code></strong>, <span><strong class="command">named</strong></span> will
3416 when the serial number on the master is less than what <span><strong class="command">named</strong></span>
3418 has. The default is <strong class="userinput"><code>no</code></strong>.
3420 <dt><span class="term"><span><strong class="command">dnssec-enable</strong></span></span></dt>
3422 Enable DNSSEC support in <span><strong class="command">named</strong></span>. Unless set to <strong class="userinput"><code>yes</code></strong>,
3423 <span><strong class="command">named</strong></span> behaves as if it does not support DNSSEC.
3424 The default is <strong class="userinput"><code>yes</code></strong>.
3426 <dt><span class="term"><span><strong class="command">dnssec-validation</strong></span></span></dt>
3428 Enable DNSSEC validation in <span><strong class="command">named</strong></span>.
3429 Note <span><strong class="command">dnssec-enable</strong></span> also needs to be
3430 set to <strong class="userinput"><code>yes</code></strong> to be effective.
3431 If set to <strong class="userinput"><code>no</code></strong>, DNSSEC validation
3432 is disabled. If set to <strong class="userinput"><code>auto</code></strong>,
3433 DNSSEC validation is enabled, and a default
3434 trust-anchor for the DNS root zone is used. If set to
3435 <strong class="userinput"><code>yes</code></strong>, DNSSEC validation is enabled,
3436 but a trust anchor must be manually configured using
3437 a <span><strong class="command">trusted-keys</strong></span> or
3438 <span><strong class="command">managed-keys</strong></span> statement. The default
3439 is <strong class="userinput"><code>yes</code></strong>.
3441 <dt><span class="term"><span><strong class="command">dnssec-accept-expired</strong></span></span></dt>
3443 Accept expired signatures when verifying DNSSEC signatures.
3444 The default is <strong class="userinput"><code>no</code></strong>.
3445 Setting this option to <strong class="userinput"><code>yes</code></strong>
3446 leaves <span><strong class="command">named</strong></span> vulnerable to
3449 <dt><span class="term"><span><strong class="command">querylog</strong></span></span></dt>
3451 Specify whether query logging should be started when <span><strong class="command">named</strong></span>
3453 If <span><strong class="command">querylog</strong></span> is not specified,
3454 then the query logging
3455 is determined by the presence of the logging category <span><strong class="command">queries</strong></span>.
3457 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
3460 This option is used to restrict the character set and syntax
3462 certain domain names in master files and/or DNS responses
3464 from the network. The default varies according to usage
3466 <span><strong class="command">master</strong></span> zones the default is <span><strong class="command">fail</strong></span>.
3467 For <span><strong class="command">slave</strong></span> zones the default
3468 is <span><strong class="command">warn</strong></span>.
3469 For answers received from the network (<span><strong class="command">response</strong></span>)
3470 the default is <span><strong class="command">ignore</strong></span>.
3473 The rules for legal hostnames and mail domains are derived
3474 from RFC 952 and RFC 821 as modified by RFC 1123.
3476 <p><span><strong class="command">check-names</strong></span>
3477 applies to the owner names of A, AAAA and MX records.
3478 It also applies to the domain names in the RDATA of NS, SOA,
3479 MX, and SRV records.
3480 It also applies to the RDATA of PTR records where the owner
3481 name indicated that it is a reverse lookup of a hostname
3482 (the owner name ends in IN-ADDR.ARPA, IP6.ARPA, or IP6.INT).
3485 <dt><span class="term"><span><strong class="command">check-dup-records</strong></span></span></dt>
3487 Check master zones for records that are treated as different
3488 by DNSSEC but are semantically equal in plain DNS. The
3489 default is to <span><strong class="command">warn</strong></span>. Other possible
3490 values are <span><strong class="command">fail</strong></span> and
3491 <span><strong class="command">ignore</strong></span>.
3493 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
3495 Check whether the MX record appears to refer to a IP address.
3496 The default is to <span><strong class="command">warn</strong></span>. Other possible
3497 values are <span><strong class="command">fail</strong></span> and
3498 <span><strong class="command">ignore</strong></span>.
3500 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
3502 This option is used to check for non-terminal wildcards.
3503 The use of non-terminal wildcards is almost always as a
3505 to understand the wildcard matching algorithm (RFC 1034).
3507 affects master zones. The default (<span><strong class="command">yes</strong></span>) is to check
3508 for non-terminal wildcards and issue a warning.
3510 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
3512 Perform post load zone integrity checks on master
3513 zones. This checks that MX and SRV records refer
3514 to address (A or AAAA) records and that glue
3515 address records exist for delegated zones. For
3516 MX and SRV records only in-zone hostnames are
3517 checked (for out-of-zone hostnames use
3518 <span><strong class="command">named-checkzone</strong></span>).
3519 For NS records only names below top of zone are
3520 checked (for out-of-zone names and glue consistency
3521 checks use <span><strong class="command">named-checkzone</strong></span>).
3522 The default is <span><strong class="command">yes</strong></span>.
3524 <dt><span class="term"><span><strong class="command">check-mx-cname</strong></span></span></dt>
3526 If <span><strong class="command">check-integrity</strong></span> is set then
3527 fail, warn or ignore MX records that refer
3528 to CNAMES. The default is to <span><strong class="command">warn</strong></span>.
3530 <dt><span class="term"><span><strong class="command">check-srv-cname</strong></span></span></dt>
3532 If <span><strong class="command">check-integrity</strong></span> is set then
3533 fail, warn or ignore SRV records that refer
3534 to CNAMES. The default is to <span><strong class="command">warn</strong></span>.
3536 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
3538 When performing integrity checks, also check that
3539 sibling glue exists. The default is <span><strong class="command">yes</strong></span>.
3541 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
3543 When returning authoritative negative responses to
3544 SOA queries set the TTL of the SOA record returned in
3545 the authority section to zero.
3546 The default is <span><strong class="command">yes</strong></span>.
3548 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl-cache</strong></span></span></dt>
3550 When caching a negative response to a SOA query
3551 set the TTL to zero.
3552 The default is <span><strong class="command">no</strong></span>.
3554 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
3557 When set to the default value of <code class="literal">yes</code>,
3558 check the KSK bit in each key to determine how the key
3559 should be used when generating RRSIGs for a secure zone.
3562 Ordinarily, zone-signing keys (that is, keys without the
3563 KSK bit set) are used to sign the entire zone, while
3564 key-signing keys (keys with the KSK bit set) are only
3565 used to sign the DNSKEY RRset at the zone apex.
3566 However, if this option is set to <code class="literal">no</code>,
3567 then the KSK bit is ignored; KSKs are treated as if they
3568 were ZSKs and are used to sign the entire zone. This is
3569 similar to the <span><strong class="command">dnssec-signzone -z</strong></span>
3570 command line option.
3573 When this option is set to <code class="literal">yes</code>, there
3574 must be at least two active keys for every algorithm
3575 represented in the DNSKEY RRset: at least one KSK and one
3576 ZSK per algorithm. If there is any algorithm for which
3577 this requirement is not met, this option will be ignored
3581 <dt><span class="term"><span><strong class="command">dnssec-dnskey-kskonly</strong></span></span></dt>
3584 When this option and <span><strong class="command">update-check-ksk</strong></span>
3585 are both set to <code class="literal">yes</code>, only key-signing
3586 keys (that is, keys with the KSK bit set) will be used
3587 to sign the DNSKEY RRset at the zone apex. Zone-signing
3588 keys (keys without the KSK bit set) will be used to sign
3589 the remainder of the zone, but not the DNSKEY RRset.
3590 This is similar to the
3591 <span><strong class="command">dnssec-signzone -x</strong></span> command line option.
3594 The default is <span><strong class="command">no</strong></span>. If
3595 <span><strong class="command">update-check-ksk</strong></span> is set to
3596 <code class="literal">no</code>, this option is ignored.
3599 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
3601 Try to refresh the zone using TCP if UDP queries fail.
3602 For BIND 8 compatibility, the default is
3603 <span><strong class="command">yes</strong></span>.
3605 <dt><span class="term"><span><strong class="command">dnssec-secure-to-insecure</strong></span></span></dt>
3608 Allow a dynamic zone to transition from secure to
3609 insecure (i.e., signed to unsigned) by deleting all
3610 of the DNSKEY records. The default is <span><strong class="command">no</strong></span>.
3611 If set to <span><strong class="command">yes</strong></span>, and if the DNSKEY RRset
3612 at the zone apex is deleted, all RRSIG and NSEC records
3613 will be removed from the zone as well.
3616 If the zone uses NSEC3, then it is also necessary to
3617 delete the NSEC3PARAM RRset from the zone apex; this will
3618 cause the removal of all corresponding NSEC3 records.
3619 (It is expected that this requirement will be eliminated
3620 in a future release.)
3623 Note that if a zone has been configured with
3624 <span><strong class="command">auto-dnssec maintain</strong></span> and the
3625 private keys remain accessible in the key repository,
3626 then the zone will be automatically signed again the
3627 next time <span><strong class="command">named</strong></span> is started.
3632 <div class="sect3" lang="en">
3633 <div class="titlepage"><div><div><h4 class="title">
3634 <a name="id2583480"></a>Forwarding</h4></div></div></div>
3636 The forwarding facility can be used to create a large site-wide
3637 cache on a few servers, reducing traffic over links to external
3638 name servers. It can also be used to allow queries by servers that
3639 do not have direct access to the Internet, but wish to look up
3641 names anyway. Forwarding occurs only on those queries for which
3642 the server is not authoritative and does not have the answer in
3645 <div class="variablelist"><dl>
3646 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
3648 This option is only meaningful if the
3649 forwarders list is not empty. A value of <code class="varname">first</code>,
3650 the default, causes the server to query the forwarders
3652 if that doesn't answer the question, the server will then
3654 the answer itself. If <code class="varname">only</code> is
3656 server will only query the forwarders.
3658 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
3660 Specifies the IP addresses to be used
3661 for forwarding. The default is the empty list (no
3666 Forwarding can also be configured on a per-domain basis, allowing
3667 for the global forwarding options to be overridden in a variety
3668 of ways. You can set particular domains to use different
3670 or have a different <span><strong class="command">forward only/first</strong></span> behavior,
3671 or not forward at all, see <a href="Bv9ARM.ch06.html#zone_statement_grammar" title="zone
3672 Statement Grammar">the section called “<span><strong class="command">zone</strong></span>
3673 Statement Grammar”</a>.
3676 <div class="sect3" lang="en">
3677 <div class="titlepage"><div><div><h4 class="title">
3678 <a name="id2583607"></a>Dual-stack Servers</h4></div></div></div>
3680 Dual-stack servers are used as servers of last resort to work
3682 problems in reachability due the lack of support for either IPv4
3684 on the host machine.
3686 <div class="variablelist"><dl>
3687 <dt><span class="term"><span><strong class="command">dual-stack-servers</strong></span></span></dt>
3689 Specifies host names or addresses of machines with access to
3690 both IPv4 and IPv6 transports. If a hostname is used, the
3692 to resolve the name using only the transport it has. If the
3694 stacked, then the <span><strong class="command">dual-stack-servers</strong></span> have no effect unless
3695 access to a transport has been disabled on the command line
3696 (e.g. <span><strong class="command">named -4</strong></span>).
3700 <div class="sect3" lang="en">
3701 <div class="titlepage"><div><div><h4 class="title">
3702 <a name="access_control"></a>Access Control</h4></div></div></div>
3704 Access to the server can be restricted based on the IP address
3705 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
3706 details on how to specify IP address lists.
3708 <div class="variablelist"><dl>
3709 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
3711 Specifies which hosts are allowed to
3712 notify this server, a slave, of zone changes in addition
3713 to the zone masters.
3714 <span><strong class="command">allow-notify</strong></span> may also be
3716 <span><strong class="command">zone</strong></span> statement, in which case
3718 <span><strong class="command">options allow-notify</strong></span>
3719 statement. It is only meaningful
3720 for a slave zone. If not specified, the default is to
3721 process notify messages
3722 only from a zone's master.
3724 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
3727 Specifies which hosts are allowed to ask ordinary
3728 DNS questions. <span><strong class="command">allow-query</strong></span> may
3729 also be specified in the <span><strong class="command">zone</strong></span>
3730 statement, in which case it overrides the
3731 <span><strong class="command">options allow-query</strong></span> statement.
3732 If not specified, the default is to allow queries
3735 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3736 <h3 class="title">Note</h3>
3738 <span><strong class="command">allow-query-cache</strong></span> is now
3739 used to specify access to the cache.
3743 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
3746 Specifies which local addresses can accept ordinary
3747 DNS questions. This makes it possible, for instance,
3748 to allow queries on internal-facing interfaces but
3749 disallow them on external-facing ones, without
3750 necessarily knowing the internal network's addresses.
3753 <span><strong class="command">allow-query-on</strong></span> may
3754 also be specified in the <span><strong class="command">zone</strong></span>
3755 statement, in which case it overrides the
3756 <span><strong class="command">options allow-query-on</strong></span> statement.
3759 If not specified, the default is to allow queries
3762 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3763 <h3 class="title">Note</h3>
3765 <span><strong class="command">allow-query-cache</strong></span> is
3766 used to specify access to the cache.
3770 <dt><span class="term"><span><strong class="command">allow-query-cache</strong></span></span></dt>
3772 Specifies which hosts are allowed to get answers
3773 from the cache. If <span><strong class="command">allow-query-cache</strong></span>
3774 is not set then <span><strong class="command">allow-recursion</strong></span>
3775 is used if set, otherwise <span><strong class="command">allow-query</strong></span>
3776 is used if set unless <span><strong class="command">recursion no;</strong></span> is
3777 set in which case <span><strong class="command">none;</strong></span> is used,
3778 otherwise the default (<span><strong class="command">localnets;</strong></span>
3779 <span><strong class="command">localhost;</strong></span>) is used.
3781 <dt><span class="term"><span><strong class="command">allow-query-cache-on</strong></span></span></dt>
3783 Specifies which local addresses can give answers
3784 from the cache. If not specified, the default is
3785 to allow cache queries on any address,
3786 <span><strong class="command">localnets</strong></span> and
3787 <span><strong class="command">localhost</strong></span>.
3789 <dt><span class="term"><span><strong class="command">allow-recursion</strong></span></span></dt>
3791 Specifies which hosts are allowed to make recursive
3792 queries through this server. If
3793 <span><strong class="command">allow-recursion</strong></span> is not set
3794 then <span><strong class="command">allow-query-cache</strong></span> is
3795 used if set, otherwise <span><strong class="command">allow-query</strong></span>
3796 is used if set, otherwise the default
3797 (<span><strong class="command">localnets;</strong></span>
3798 <span><strong class="command">localhost;</strong></span>) is used.
3800 <dt><span class="term"><span><strong class="command">allow-recursion-on</strong></span></span></dt>
3802 Specifies which local addresses can accept recursive
3803 queries. If not specified, the default is to allow
3804 recursive queries on all addresses.
3806 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
3808 Specifies which hosts are allowed to
3809 submit Dynamic DNS updates for master zones. The default is
3811 updates from all hosts. Note that allowing updates based
3812 on the requestor's IP address is insecure; see
3813 <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called “Dynamic Update Security”</a> for details.
3815 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
3818 Specifies which hosts are allowed to
3819 submit Dynamic DNS updates to slave zones to be forwarded to
3821 master. The default is <strong class="userinput"><code>{ none; }</code></strong>,
3823 means that no update forwarding will be performed. To
3825 update forwarding, specify
3826 <strong class="userinput"><code>allow-update-forwarding { any; };</code></strong>.
3827 Specifying values other than <strong class="userinput"><code>{ none; }</code></strong> or
3828 <strong class="userinput"><code>{ any; }</code></strong> is usually
3829 counterproductive, since
3830 the responsibility for update access control should rest
3832 master server, not the slaves.
3835 Note that enabling the update forwarding feature on a slave
3837 may expose master servers relying on insecure IP address
3839 access control to attacks; see <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called “Dynamic Update Security”</a>
3843 <dt><span class="term"><span><strong class="command">allow-v6-synthesis</strong></span></span></dt>
3845 This option was introduced for the smooth transition from
3847 to A6 and from "nibble labels" to binary labels.
3848 However, since both A6 and binary labels were then
3850 this option was also deprecated.
3851 It is now ignored with some warning messages.
3853 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
3855 Specifies which hosts are allowed to
3856 receive zone transfers from the server. <span><strong class="command">allow-transfer</strong></span> may
3857 also be specified in the <span><strong class="command">zone</strong></span>
3859 case it overrides the <span><strong class="command">options allow-transfer</strong></span> statement.
3860 If not specified, the default is to allow transfers to all
3863 <dt><span class="term"><span><strong class="command">blackhole</strong></span></span></dt>
3865 Specifies a list of addresses that the
3866 server will not accept queries from or use to resolve a
3868 from these addresses will not be responded to. The default
3869 is <strong class="userinput"><code>none</code></strong>.
3871 <dt><span class="term"><span><strong class="command">filter-aaaa</strong></span></span></dt>
3873 Specifies a list of addresses to which
3874 <span><strong class="command">filter-aaaa-on-v4</strong></span>
3875 is applies. The default is <strong class="userinput"><code>any</code></strong>.
3877 <dt><span class="term"><span><strong class="command">resolver-query-timeout</strong></span></span></dt>
3879 The amount of time the resolver will spend attempting
3880 to resolve a recursive query before failing. The
3881 default is <code class="literal">10</code> and the maximum is
3882 <code class="literal">30</code>. Setting it to <code class="literal">0</code>
3883 will result in the default being used.
3887 <div class="sect3" lang="en">
3888 <div class="titlepage"><div><div><h4 class="title">
3889 <a name="id2584227"></a>Interfaces</h4></div></div></div>
3891 The interfaces and ports that the server will answer queries
3892 from may be specified using the <span><strong class="command">listen-on</strong></span> option. <span><strong class="command">listen-on</strong></span> takes
3893 an optional port and an <code class="varname">address_match_list</code>.
3894 The server will listen on all interfaces allowed by the address
3895 match list. If a port is not specified, port 53 will be used.
3898 Multiple <span><strong class="command">listen-on</strong></span> statements are
3902 <pre class="programlisting">listen-on { 5.6.7.8; };
3903 listen-on port 1234 { !1.2.3.4; 1.2/16; };
3906 will enable the name server on port 53 for the IP address
3907 5.6.7.8, and on port 1234 of an address on the machine in net
3908 1.2 that is not 1.2.3.4.
3911 If no <span><strong class="command">listen-on</strong></span> is specified, the
3912 server will listen on port 53 on all IPv4 interfaces.
3915 The <span><strong class="command">listen-on-v6</strong></span> option is used to
3916 specify the interfaces and the ports on which the server will
3918 for incoming queries sent using IPv6.
3922 <pre class="programlisting">{ any; }</pre>
3925 as the <code class="varname">address_match_list</code> for the
3926 <span><strong class="command">listen-on-v6</strong></span> option,
3927 the server does not bind a separate socket to each IPv6 interface
3928 address as it does for IPv4 if the operating system has enough API
3929 support for IPv6 (specifically if it conforms to RFC 3493 and RFC
3931 Instead, it listens on the IPv6 wildcard address.
3932 If the system only has incomplete API support for IPv6, however,
3933 the behavior is the same as that for IPv4.
3936 A list of particular IPv6 addresses can also be specified, in
3938 the server listens on a separate socket for each specified
3940 regardless of whether the desired API is supported by the system.
3943 Multiple <span><strong class="command">listen-on-v6</strong></span> options can
3947 <pre class="programlisting">listen-on-v6 { any; };
3948 listen-on-v6 port 1234 { !2001:db8::/32; any; };
3951 will enable the name server on port 53 for any IPv6 addresses
3952 (with a single wildcard socket),
3953 and on port 1234 of IPv6 addresses that is not in the prefix
3954 2001:db8::/32 (with separate sockets for each matched address.)
3957 To make the server not listen on any IPv6 address, use
3959 <pre class="programlisting">listen-on-v6 { none; };
3962 If no <span><strong class="command">listen-on-v6</strong></span> option is
3963 specified, the server will not listen on any IPv6 address
3964 unless <span><strong class="command">-6</strong></span> is specified when <span><strong class="command">named</strong></span> is
3965 invoked. If <span><strong class="command">-6</strong></span> is specified then
3966 <span><strong class="command">named</strong></span> will listen on port 53 on all IPv6 interfaces by default.
3969 <div class="sect3" lang="en">
3970 <div class="titlepage"><div><div><h4 class="title">
3971 <a name="query_address"></a>Query Address</h4></div></div></div>
3973 If the server doesn't know the answer to a question, it will
3974 query other name servers. <span><strong class="command">query-source</strong></span> specifies
3975 the address and port used for such queries. For queries sent over
3976 IPv6, there is a separate <span><strong class="command">query-source-v6</strong></span> option.
3977 If <span><strong class="command">address</strong></span> is <span><strong class="command">*</strong></span> (asterisk) or is omitted,
3978 a wildcard IP address (<span><strong class="command">INADDR_ANY</strong></span>)
3982 If <span><strong class="command">port</strong></span> is <span><strong class="command">*</strong></span> or is omitted,
3983 a random port number from a pre-configured
3984 range is picked up and will be used for each query.
3985 The port range(s) is that specified in
3986 the <span><strong class="command">use-v4-udp-ports</strong></span> (for IPv4)
3987 and <span><strong class="command">use-v6-udp-ports</strong></span> (for IPv6)
3988 options, excluding the ranges specified in
3989 the <span><strong class="command">avoid-v4-udp-ports</strong></span>
3990 and <span><strong class="command">avoid-v6-udp-ports</strong></span> options, respectively.
3993 The defaults of the <span><strong class="command">query-source</strong></span> and
3994 <span><strong class="command">query-source-v6</strong></span> options
3997 <pre class="programlisting">query-source address * port *;
3998 query-source-v6 address * port *;
4001 If <span><strong class="command">use-v4-udp-ports</strong></span> or
4002 <span><strong class="command">use-v6-udp-ports</strong></span> is unspecified,
4003 <span><strong class="command">named</strong></span> will check if the operating
4004 system provides a programming interface to retrieve the
4005 system's default range for ephemeral ports.
4006 If such an interface is available,
4007 <span><strong class="command">named</strong></span> will use the corresponding system
4008 default range; otherwise, it will use its own defaults:
4010 <pre class="programlisting">use-v4-udp-ports { range 1024 65535; };
4011 use-v6-udp-ports { range 1024 65535; };
4014 Note: make sure the ranges be sufficiently large for
4015 security. A desirable size depends on various parameters,
4016 but we generally recommend it contain at least 16384 ports
4017 (14 bits of entropy).
4018 Note also that the system's default range when used may be
4019 too small for this purpose, and that the range may even be
4020 changed while <span><strong class="command">named</strong></span> is running; the new
4021 range will automatically be applied when <span><strong class="command">named</strong></span>
4024 configure <span><strong class="command">use-v4-udp-ports</strong></span> and
4025 <span><strong class="command">use-v6-udp-ports</strong></span> explicitly so that the
4026 ranges are sufficiently large and are reasonably
4027 independent from the ranges used by other applications.
4030 Note: the operational configuration
4031 where <span><strong class="command">named</strong></span> runs may prohibit the use
4032 of some ports. For example, UNIX systems will not allow
4033 <span><strong class="command">named</strong></span> running without a root privilege
4034 to use ports less than 1024.
4035 If such ports are included in the specified (or detected)
4036 set of query ports, the corresponding query attempts will
4037 fail, resulting in resolution failures or delay.
4038 It is therefore important to configure the set of ports
4039 that can be safely used in the expected operational environment.
4042 The defaults of the <span><strong class="command">avoid-v4-udp-ports</strong></span> and
4043 <span><strong class="command">avoid-v6-udp-ports</strong></span> options
4046 <pre class="programlisting">avoid-v4-udp-ports {};
4047 avoid-v6-udp-ports {};
4050 Note: BIND 9.5.0 introduced
4051 the <span><strong class="command">use-queryport-pool</strong></span>
4052 option to support a pool of such random ports, but this
4053 option is now obsolete because reusing the same ports in
4054 the pool may not be sufficiently secure.
4055 For the same reason, it is generally strongly discouraged to
4056 specify a particular port for the
4057 <span><strong class="command">query-source</strong></span> or
4058 <span><strong class="command">query-source-v6</strong></span> options;
4059 it implicitly disables the use of randomized port numbers.
4061 <div class="variablelist"><dl>
4062 <dt><span class="term"><span><strong class="command">use-queryport-pool</strong></span></span></dt>
4064 This option is obsolete.
4066 <dt><span class="term"><span><strong class="command">queryport-pool-ports</strong></span></span></dt>
4068 This option is obsolete.
4070 <dt><span class="term"><span><strong class="command">queryport-pool-updateinterval</strong></span></span></dt>
4072 This option is obsolete.
4075 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4076 <h3 class="title">Note</h3>
4078 The address specified in the <span><strong class="command">query-source</strong></span> option
4079 is used for both UDP and TCP queries, but the port applies only
4080 to UDP queries. TCP queries always use a random
4084 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4085 <h3 class="title">Note</h3>
4087 Solaris 2.5.1 and earlier does not support setting the source
4088 address for TCP sockets.
4091 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4092 <h3 class="title">Note</h3>
4094 See also <span><strong class="command">transfer-source</strong></span> and
4095 <span><strong class="command">notify-source</strong></span>.
4099 <div class="sect3" lang="en">
4100 <div class="titlepage"><div><div><h4 class="title">
4101 <a name="zone_transfers"></a>Zone Transfers</h4></div></div></div>
4103 <acronym class="acronym">BIND</acronym> has mechanisms in place to
4104 facilitate zone transfers
4105 and set limits on the amount of load that transfers place on the
4106 system. The following options apply to zone transfers.
4108 <div class="variablelist"><dl>
4109 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
4111 Defines a global list of IP addresses of name servers
4112 that are also sent NOTIFY messages whenever a fresh copy of
4114 zone is loaded, in addition to the servers listed in the
4116 This helps to ensure that copies of the zones will
4117 quickly converge on stealth servers.
4118 Optionally, a port may be specified with each
4119 <span><strong class="command">also-notify</strong></span> address to send
4120 the notify messages to a port other than the
4122 If an <span><strong class="command">also-notify</strong></span> list
4123 is given in a <span><strong class="command">zone</strong></span> statement,
4125 the <span><strong class="command">options also-notify</strong></span>
4126 statement. When a <span><strong class="command">zone notify</strong></span>
4128 is set to <span><strong class="command">no</strong></span>, the IP
4129 addresses in the global <span><strong class="command">also-notify</strong></span> list will
4130 not be sent NOTIFY messages for that zone. The default is
4132 list (no global notification list).
4134 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
4136 Inbound zone transfers running longer than
4137 this many minutes will be terminated. The default is 120
4139 (2 hours). The maximum value is 28 days (40320 minutes).
4141 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
4143 Inbound zone transfers making no progress
4144 in this many minutes will be terminated. The default is 60
4146 (1 hour). The maximum value is 28 days (40320 minutes).
4148 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
4150 Outbound zone transfers running longer than
4151 this many minutes will be terminated. The default is 120
4153 (2 hours). The maximum value is 28 days (40320 minutes).
4155 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
4157 Outbound zone transfers making no progress
4158 in this many minutes will be terminated. The default is 60
4160 hour). The maximum value is 28 days (40320 minutes).
4162 <dt><span class="term"><span><strong class="command">serial-query-rate</strong></span></span></dt>
4164 Slave servers will periodically query master servers
4165 to find out if zone serial numbers have changed. Each such
4167 a minute amount of the slave server's network bandwidth. To
4169 amount of bandwidth used, BIND 9 limits the rate at which
4171 sent. The value of the <span><strong class="command">serial-query-rate</strong></span> option,
4172 an integer, is the maximum number of queries sent per
4176 <dt><span class="term"><span><strong class="command">serial-queries</strong></span></span></dt>
4178 In BIND 8, the <span><strong class="command">serial-queries</strong></span>
4180 set the maximum number of concurrent serial number queries
4181 allowed to be outstanding at any given time.
4182 BIND 9 does not limit the number of outstanding
4183 serial queries and ignores the <span><strong class="command">serial-queries</strong></span> option.
4184 Instead, it limits the rate at which the queries are sent
4185 as defined using the <span><strong class="command">serial-query-rate</strong></span> option.
4187 <dt><span class="term"><span><strong class="command">transfer-format</strong></span></span></dt>
4189 Zone transfers can be sent using two different formats,
4190 <span><strong class="command">one-answer</strong></span> and
4191 <span><strong class="command">many-answers</strong></span>.
4192 The <span><strong class="command">transfer-format</strong></span> option is used
4193 on the master server to determine which format it sends.
4194 <span><strong class="command">one-answer</strong></span> uses one DNS message per
4195 resource record transferred.
4196 <span><strong class="command">many-answers</strong></span> packs as many resource
4197 records as possible into a message.
4198 <span><strong class="command">many-answers</strong></span> is more efficient, but is
4199 only supported by relatively new slave servers,
4200 such as <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
4201 8.x and <acronym class="acronym">BIND</acronym> 4.9.5 onwards.
4202 The <span><strong class="command">many-answers</strong></span> format is also supported by
4203 recent Microsoft Windows nameservers.
4204 The default is <span><strong class="command">many-answers</strong></span>.
4205 <span><strong class="command">transfer-format</strong></span> may be overridden on a
4206 per-server basis by using the <span><strong class="command">server</strong></span>
4209 <dt><span class="term"><span><strong class="command">transfers-in</strong></span></span></dt>
4211 The maximum number of inbound zone transfers
4212 that can be running concurrently. The default value is <code class="literal">10</code>.
4213 Increasing <span><strong class="command">transfers-in</strong></span> may
4214 speed up the convergence
4215 of slave zones, but it also may increase the load on the
4218 <dt><span class="term"><span><strong class="command">transfers-out</strong></span></span></dt>
4220 The maximum number of outbound zone transfers
4221 that can be running concurrently. Zone transfer requests in
4223 of the limit will be refused. The default value is <code class="literal">10</code>.
4225 <dt><span class="term"><span><strong class="command">transfers-per-ns</strong></span></span></dt>
4227 The maximum number of inbound zone transfers
4228 that can be concurrently transferring from a given remote
4230 The default value is <code class="literal">2</code>.
4231 Increasing <span><strong class="command">transfers-per-ns</strong></span>
4233 speed up the convergence of slave zones, but it also may
4235 the load on the remote name server. <span><strong class="command">transfers-per-ns</strong></span> may
4236 be overridden on a per-server basis by using the <span><strong class="command">transfers</strong></span> phrase
4237 of the <span><strong class="command">server</strong></span> statement.
4239 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
4241 <p><span><strong class="command">transfer-source</strong></span>
4242 determines which local address will be bound to IPv4
4243 TCP connections used to fetch zones transferred
4244 inbound by the server. It also determines the
4245 source IPv4 address, and optionally the UDP port,
4246 used for the refresh queries and forwarded dynamic
4247 updates. If not set, it defaults to a system
4248 controlled value which will usually be the address
4249 of the interface "closest to" the remote end. This
4250 address must appear in the remote end's
4251 <span><strong class="command">allow-transfer</strong></span> option for the
4252 zone being transferred, if one is specified. This
4254 <span><strong class="command">transfer-source</strong></span> for all zones,
4255 but can be overridden on a per-view or per-zone
4256 basis by including a
4257 <span><strong class="command">transfer-source</strong></span> statement within
4258 the <span><strong class="command">view</strong></span> or
4259 <span><strong class="command">zone</strong></span> block in the configuration
4262 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4263 <h3 class="title">Note</h3>
4265 Solaris 2.5.1 and earlier does not support setting the
4266 source address for TCP sockets.
4270 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
4272 The same as <span><strong class="command">transfer-source</strong></span>,
4273 except zone transfers are performed using IPv6.
4275 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
4278 An alternate transfer source if the one listed in
4279 <span><strong class="command">transfer-source</strong></span> fails and
4280 <span><strong class="command">use-alt-transfer-source</strong></span> is
4283 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4284 <h3 class="title">Note</h3>
4285 If you do not wish the alternate transfer source
4286 to be used, you should set
4287 <span><strong class="command">use-alt-transfer-source</strong></span>
4288 appropriately and you should not depend upon
4289 getting an answer back to the first refresh
4293 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
4295 An alternate transfer source if the one listed in
4296 <span><strong class="command">transfer-source-v6</strong></span> fails and
4297 <span><strong class="command">use-alt-transfer-source</strong></span> is
4300 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
4302 Use the alternate transfer sources or not. If views are
4303 specified this defaults to <span><strong class="command">no</strong></span>
4304 otherwise it defaults to
4305 <span><strong class="command">yes</strong></span> (for BIND 8
4308 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
4310 <p><span><strong class="command">notify-source</strong></span>
4311 determines which local source address, and
4312 optionally UDP port, will be used to send NOTIFY
4313 messages. This address must appear in the slave
4314 server's <span><strong class="command">masters</strong></span> zone clause or
4315 in an <span><strong class="command">allow-notify</strong></span> clause. This
4316 statement sets the <span><strong class="command">notify-source</strong></span>
4317 for all zones, but can be overridden on a per-zone or
4318 per-view basis by including a
4319 <span><strong class="command">notify-source</strong></span> statement within
4320 the <span><strong class="command">zone</strong></span> or
4321 <span><strong class="command">view</strong></span> block in the configuration
4324 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4325 <h3 class="title">Note</h3>
4327 Solaris 2.5.1 and earlier does not support setting the
4328 source address for TCP sockets.
4332 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
4334 Like <span><strong class="command">notify-source</strong></span>,
4335 but applies to notify messages sent to IPv6 addresses.
4339 <div class="sect3" lang="en">
4340 <div class="titlepage"><div><div><h4 class="title">
4341 <a name="id2585362"></a>UDP Port Lists</h4></div></div></div>
4343 <span><strong class="command">use-v4-udp-ports</strong></span>,
4344 <span><strong class="command">avoid-v4-udp-ports</strong></span>,
4345 <span><strong class="command">use-v6-udp-ports</strong></span>, and
4346 <span><strong class="command">avoid-v6-udp-ports</strong></span>
4347 specify a list of IPv4 and IPv6 UDP ports that will be
4348 used or not used as source ports for UDP messages.
4349 See <a href="Bv9ARM.ch06.html#query_address" title="Query Address">the section called “Query Address”</a> about how the
4350 available ports are determined.
4351 For example, with the following configuration
4353 <pre class="programlisting">
4354 use-v6-udp-ports { range 32768 65535; };
4355 avoid-v6-udp-ports { 40000; range 50000 60000; };
4358 UDP ports of IPv6 messages sent
4359 from <span><strong class="command">named</strong></span> will be in one
4360 of the following ranges: 32768 to 39999, 40001 to 49999,
4364 <span><strong class="command">avoid-v4-udp-ports</strong></span> and
4365 <span><strong class="command">avoid-v6-udp-ports</strong></span> can be used
4366 to prevent <span><strong class="command">named</strong></span> from choosing as its random source port a
4367 port that is blocked by your firewall or a port that is
4368 used by other applications;
4369 if a query went out with a source port blocked by a
4371 answer would not get by the firewall and the name server would
4372 have to query again.
4373 Note: the desired range can also be represented only with
4374 <span><strong class="command">use-v4-udp-ports</strong></span> and
4375 <span><strong class="command">use-v6-udp-ports</strong></span>, and the
4376 <span><strong class="command">avoid-</strong></span> options are redundant in that
4377 sense; they are provided for backward compatibility and
4378 to possibly simplify the port specification.
4381 <div class="sect3" lang="en">
4382 <div class="titlepage"><div><div><h4 class="title">
4383 <a name="id2585421"></a>Operating System Resource Limits</h4></div></div></div>
4385 The server's usage of many system resources can be limited.
4386 Scaled values are allowed when specifying resource limits. For
4387 example, <span><strong class="command">1G</strong></span> can be used instead of
4388 <span><strong class="command">1073741824</strong></span> to specify a limit of
4390 gigabyte. <span><strong class="command">unlimited</strong></span> requests
4391 unlimited use, or the
4392 maximum available amount. <span><strong class="command">default</strong></span>
4394 that was in force when the server was started. See the description
4395 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>.
4398 The following options set operating system resource limits for
4399 the name server process. Some operating systems don't support
4401 any of the limits. On such systems, a warning will be issued if
4403 unsupported limit is used.
4405 <div class="variablelist"><dl>
4406 <dt><span class="term"><span><strong class="command">coresize</strong></span></span></dt>
4408 The maximum size of a core dump. The default
4409 is <code class="literal">default</code>.
4411 <dt><span class="term"><span><strong class="command">datasize</strong></span></span></dt>
4413 The maximum amount of data memory the server
4414 may use. The default is <code class="literal">default</code>.
4415 This is a hard limit on server memory usage.
4416 If the server attempts to allocate memory in excess of this
4417 limit, the allocation will fail, which may in turn leave
4418 the server unable to perform DNS service. Therefore,
4419 this option is rarely useful as a way of limiting the
4420 amount of memory used by the server, but it can be used
4421 to raise an operating system data size limit that is
4422 too small by default. If you wish to limit the amount
4423 of memory used by the server, use the
4424 <span><strong class="command">max-cache-size</strong></span> and
4425 <span><strong class="command">recursive-clients</strong></span>
4428 <dt><span class="term"><span><strong class="command">files</strong></span></span></dt>
4430 The maximum number of files the server
4431 may have open concurrently. The default is <code class="literal">unlimited</code>.
4433 <dt><span class="term"><span><strong class="command">stacksize</strong></span></span></dt>
4435 The maximum amount of stack memory the server
4436 may use. The default is <code class="literal">default</code>.
4440 <div class="sect3" lang="en">
4441 <div class="titlepage"><div><div><h4 class="title">
4442 <a name="server_resource_limits"></a>Server Resource Limits</h4></div></div></div>
4444 The following options set limits on the server's
4445 resource consumption that are enforced internally by the
4446 server rather than the operating system.
4448 <div class="variablelist"><dl>
4449 <dt><span class="term"><span><strong class="command">max-ixfr-log-size</strong></span></span></dt>
4451 This option is obsolete; it is accepted
4452 and ignored for BIND 8 compatibility. The option
4453 <span><strong class="command">max-journal-size</strong></span> performs a
4454 similar function in BIND 9.
4456 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
4458 Sets a maximum size for each journal file
4459 (see <a href="Bv9ARM.ch04.html#journal" title="The journal file">the section called “The journal file”</a>). When the journal file
4461 the specified size, some of the oldest transactions in the
4463 will be automatically removed. The default is
4464 <code class="literal">unlimited</code>.
4465 This may also be set on a per-zone basis.
4467 <dt><span class="term"><span><strong class="command">host-statistics-max</strong></span></span></dt>
4469 In BIND 8, specifies the maximum number of host statistics
4471 Not implemented in BIND 9.
4473 <dt><span class="term"><span><strong class="command">recursive-clients</strong></span></span></dt>
4475 The maximum number of simultaneous recursive lookups
4476 the server will perform on behalf of clients. The default
4478 <code class="literal">1000</code>. Because each recursing
4480 bit of memory, on the order of 20 kilobytes, the value of
4482 <span><strong class="command">recursive-clients</strong></span> option may
4483 have to be decreased
4484 on hosts with limited memory.
4486 <dt><span class="term"><span><strong class="command">tcp-clients</strong></span></span></dt>
4488 The maximum number of simultaneous client TCP
4489 connections that the server will accept.
4490 The default is <code class="literal">100</code>.
4492 <dt><span class="term"><span><strong class="command">reserved-sockets</strong></span></span></dt>
4495 The number of file descriptors reserved for TCP, stdio,
4496 etc. This needs to be big enough to cover the number of
4497 interfaces <span><strong class="command">named</strong></span> listens on, <span><strong class="command">tcp-clients</strong></span> as well as
4498 to provide room for outgoing TCP queries and incoming zone
4499 transfers. The default is <code class="literal">512</code>.
4500 The minimum value is <code class="literal">128</code> and the
4501 maximum value is <code class="literal">128</code> less than
4502 maxsockets (-S). This option may be removed in the future.
4505 This option has little effect on Windows.
4508 <dt><span class="term"><span><strong class="command">max-cache-size</strong></span></span></dt>
4510 The maximum amount of memory to use for the
4511 server's cache, in bytes.
4512 When the amount of data in the cache
4513 reaches this limit, the server will cause records to expire
4514 prematurely based on an LRU based strategy so that
4515 the limit is not exceeded.
4516 A value of 0 is special, meaning that
4517 records are purged from the cache only when their
4519 Another special keyword <strong class="userinput"><code>unlimited</code></strong>
4520 means the maximum value of 32-bit unsigned integers
4521 (0xffffffff), which may not have the same effect as
4522 0 on machines that support more than 32 bits of
4524 Any positive values less than 2MB will be ignored reset
4526 In a server with multiple views, the limit applies
4527 separately to the cache of each view.
4530 <dt><span class="term"><span><strong class="command">tcp-listen-queue</strong></span></span></dt>
4532 The listen queue depth. The default and minimum is 3.
4533 If the kernel supports the accept filter "dataready" this
4535 many TCP connections that will be queued in kernel space
4537 some data before being passed to accept. Values less than 3
4543 <div class="sect3" lang="en">
4544 <div class="titlepage"><div><div><h4 class="title">
4545 <a name="id2585912"></a>Periodic Task Intervals</h4></div></div></div>
4546 <div class="variablelist"><dl>
4547 <dt><span class="term"><span><strong class="command">cleaning-interval</strong></span></span></dt>
4549 This interval is effectively obsolete. Previously,
4550 the server would remove expired resource records
4551 from the cache every <span><strong class="command">cleaning-interval</strong></span> minutes.
4552 <acronym class="acronym">BIND</acronym> 9 now manages cache
4553 memory in a more sophisticated manner and does not
4554 rely on the periodic cleaning any more.
4555 Specifying this option therefore has no effect on
4556 the server's behavior.
4558 <dt><span class="term"><span><strong class="command">heartbeat-interval</strong></span></span></dt>
4560 The server will perform zone maintenance tasks
4561 for all zones marked as <span><strong class="command">dialup</strong></span> whenever this
4562 interval expires. The default is 60 minutes. Reasonable
4564 to 1 day (1440 minutes). The maximum value is 28 days
4566 If set to 0, no zone maintenance for these zones will occur.
4568 <dt><span class="term"><span><strong class="command">interface-interval</strong></span></span></dt>
4570 The server will scan the network interface list
4571 every <span><strong class="command">interface-interval</strong></span>
4572 minutes. The default
4573 is 60 minutes. The maximum value is 28 days (40320 minutes).
4574 If set to 0, interface scanning will only occur when
4575 the configuration file is loaded. After the scan, the
4577 begin listening for queries on any newly discovered
4578 interfaces (provided they are allowed by the
4579 <span><strong class="command">listen-on</strong></span> configuration), and
4581 stop listening on interfaces that have gone away.
4583 <dt><span class="term"><span><strong class="command">statistics-interval</strong></span></span></dt>
4586 Name server statistics will be logged
4587 every <span><strong class="command">statistics-interval</strong></span>
4588 minutes. The default is
4589 60. The maximum value is 28 days (40320 minutes).
4590 If set to 0, no statistics will be logged.
4592 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4593 <h3 class="title">Note</h3>
4595 Not yet implemented in
4596 <acronym class="acronym">BIND</acronym> 9.
4602 <div class="sect3" lang="en">
4603 <div class="titlepage"><div><div><h4 class="title">
4604 <a name="topology"></a>Topology</h4></div></div></div>
4606 All other things being equal, when the server chooses a name
4608 to query from a list of name servers, it prefers the one that is
4609 topologically closest to itself. The <span><strong class="command">topology</strong></span> statement
4610 takes an <span><strong class="command">address_match_list</strong></span> and
4612 in a special way. Each top-level list element is assigned a
4614 Non-negated elements get a distance based on their position in the
4615 list, where the closer the match is to the start of the list, the
4616 shorter the distance is between it and the server. A negated match
4617 will be assigned the maximum distance from the server. If there
4618 is no match, the address will get a distance which is further than
4619 any non-negated list element, and closer than any negated element.
4622 <pre class="programlisting">topology {
4628 will prefer servers on network 10 the most, followed by hosts
4629 on network 1.2.0.0 (netmask 255.255.0.0) and network 3, with the
4630 exception of hosts on network 1.2.3 (netmask 255.255.255.0), which
4631 is preferred least of all.
4634 The default topology is
4636 <pre class="programlisting"> topology { localhost; localnets; };
4638 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4639 <h3 class="title">Note</h3>
4641 The <span><strong class="command">topology</strong></span> option
4642 is not implemented in <acronym class="acronym">BIND</acronym> 9.
4646 <div class="sect3" lang="en">
4647 <div class="titlepage"><div><div><h4 class="title">
4648 <a name="the_sortlist_statement"></a>The <span><strong class="command">sortlist</strong></span> Statement</h4></div></div></div>
4650 The response to a DNS query may consist of multiple resource
4651 records (RRs) forming a resource records set (RRset).
4652 The name server will normally return the
4653 RRs within the RRset in an indeterminate order
4654 (but see the <span><strong class="command">rrset-order</strong></span>
4655 statement in <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called “RRset Ordering”</a>).
4656 The client resolver code should rearrange the RRs as appropriate,
4657 that is, using any addresses on the local net in preference to
4659 However, not all resolvers can do this or are correctly
4661 When a client is using a local server, the sorting can be performed
4662 in the server, based on the client's address. This only requires
4663 configuring the name servers, not all the clients.
4666 The <span><strong class="command">sortlist</strong></span> statement (see below)
4668 an <span><strong class="command">address_match_list</strong></span> and
4670 more specifically than the <span><strong class="command">topology</strong></span>
4672 does (<a href="Bv9ARM.ch06.html#topology" title="Topology">the section called “Topology”</a>).
4673 Each top level statement in the <span><strong class="command">sortlist</strong></span> must
4674 itself be an explicit <span><strong class="command">address_match_list</strong></span> with
4675 one or two elements. The first element (which may be an IP
4677 an IP prefix, an ACL name or a nested <span><strong class="command">address_match_list</strong></span>)
4678 of each top level list is checked against the source address of
4679 the query until a match is found.
4682 Once the source address of the query has been matched, if
4683 the top level statement contains only one element, the actual
4685 element that matched the source address is used to select the
4687 in the response to move to the beginning of the response. If the
4688 statement is a list of two elements, then the second element is
4689 treated the same as the <span><strong class="command">address_match_list</strong></span> in
4690 a <span><strong class="command">topology</strong></span> statement. Each top
4692 is assigned a distance and the address in the response with the
4694 distance is moved to the beginning of the response.
4697 In the following example, any queries received from any of
4698 the addresses of the host itself will get responses preferring
4700 on any of the locally connected networks. Next most preferred are
4702 on the 192.168.1/24 network, and after that either the
4705 192.168.3/24 network with no preference shown between these two
4706 networks. Queries received from a host on the 192.168.1/24 network
4707 will prefer other addresses on that network to the 192.168.2/24
4709 192.168.3/24 networks. Queries received from a host on the
4711 or the 192.168.5/24 network will only prefer other addresses on
4712 their directly connected networks.
4714 <pre class="programlisting">sortlist {
4715 // IF the local host
4716 // THEN first fit on the following nets
4720 { 192.168.2/24; 192.168.3/24; }; }; };
4721 // IF on class C 192.168.1 THEN use .1, or .2 or .3
4724 { 192.168.2/24; 192.168.3/24; }; }; };
4725 // IF on class C 192.168.2 THEN use .2, or .1 or .3
4728 { 192.168.1/24; 192.168.3/24; }; }; };
4729 // IF on class C 192.168.3 THEN use .3, or .1 or .2
4732 { 192.168.1/24; 192.168.2/24; }; }; };
4733 // IF .4 or .5 THEN prefer that net
4734 { { 192.168.4/24; 192.168.5/24; };
4738 The following example will give reasonable behavior for the
4739 local host and hosts on directly connected networks. It is similar
4740 to the behavior of the address sort in <acronym class="acronym">BIND</acronym> 4.9.x. Responses sent
4741 to queries from the local host will favor any of the directly
4743 networks. Responses sent to queries from any other hosts on a
4745 connected network will prefer addresses on that same network.
4747 to other queries will not be sorted.
4749 <pre class="programlisting">sortlist {
4750 { localhost; localnets; };
4755 <div class="sect3" lang="en">
4756 <div class="titlepage"><div><div><h4 class="title">
4757 <a name="rrset_ordering"></a>RRset Ordering</h4></div></div></div>
4759 When multiple records are returned in an answer it may be
4760 useful to configure the order of the records placed into the
4762 The <span><strong class="command">rrset-order</strong></span> statement permits
4764 of the ordering of the records in a multiple record response.
4765 See also the <span><strong class="command">sortlist</strong></span> statement,
4766 <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>.
4769 An <span><strong class="command">order_spec</strong></span> is defined as
4773 [<span class="optional">class <em class="replaceable"><code>class_name</code></em></span>]
4774 [<span class="optional">type <em class="replaceable"><code>type_name</code></em></span>]
4775 [<span class="optional">name <em class="replaceable"><code>"domain_name"</code></em></span>]
4776 order <em class="replaceable"><code>ordering</code></em>
4779 If no class is specified, the default is <span><strong class="command">ANY</strong></span>.
4780 If no type is specified, the default is <span><strong class="command">ANY</strong></span>.
4781 If no name is specified, the default is "<span><strong class="command">*</strong></span>" (asterisk).
4784 The legal values for <span><strong class="command">ordering</strong></span> are:
4786 <div class="informaltable"><table border="1">
4794 <p><span><strong class="command">fixed</strong></span></p>
4798 Records are returned in the order they
4799 are defined in the zone file.
4805 <p><span><strong class="command">random</strong></span></p>
4809 Records are returned in some random order.
4815 <p><span><strong class="command">cyclic</strong></span></p>
4819 Records are returned in a cyclic round-robin order.
4822 If <acronym class="acronym">BIND</acronym> is configured with the
4823 "--enable-fixed-rrset" option at compile time, then
4824 the initial ordering of the RRset will match the
4825 one specified in the zone file.
4834 <pre class="programlisting">rrset-order {
4835 class IN type A name "host.example.com" order random;
4840 will cause any responses for type A records in class IN that
4841 have "<code class="literal">host.example.com</code>" as a
4842 suffix, to always be returned
4843 in random order. All other records are returned in cyclic order.
4846 If multiple <span><strong class="command">rrset-order</strong></span> statements
4848 they are not combined — the last one applies.
4850 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4851 <h3 class="title">Note</h3>
4853 In this release of <acronym class="acronym">BIND</acronym> 9, the
4854 <span><strong class="command">rrset-order</strong></span> statement does not support
4855 "fixed" ordering by default. Fixed ordering can be enabled
4856 at compile time by specifying "--enable-fixed-rrset" on
4857 the "configure" command line.
4861 <div class="sect3" lang="en">
4862 <div class="titlepage"><div><div><h4 class="title">
4863 <a name="tuning"></a>Tuning</h4></div></div></div>
4864 <div class="variablelist"><dl>
4865 <dt><span class="term"><span><strong class="command">lame-ttl</strong></span></span></dt>
4868 Sets the number of seconds to cache a
4869 lame server indication. 0 disables caching. (This is
4870 <span class="bold"><strong>NOT</strong></span> recommended.)
4871 The default is <code class="literal">600</code> (10 minutes) and the
4873 <code class="literal">1800</code> (30 minutes).
4876 Lame-ttl also controls the amount of time DNSSEC
4877 validation failures are cached. There is a minimum
4878 of 30 seconds applied to bad cache entries if the
4879 lame-ttl is set to less than 30 seconds.
4882 <dt><span class="term"><span><strong class="command">max-ncache-ttl</strong></span></span></dt>
4884 To reduce network traffic and increase performance,
4885 the server stores negative answers. <span><strong class="command">max-ncache-ttl</strong></span> is
4886 used to set a maximum retention time for these answers in
4888 in seconds. The default
4889 <span><strong class="command">max-ncache-ttl</strong></span> is <code class="literal">10800</code> seconds (3 hours).
4890 <span><strong class="command">max-ncache-ttl</strong></span> cannot exceed
4892 be silently truncated to 7 days if set to a greater value.
4894 <dt><span class="term"><span><strong class="command">max-cache-ttl</strong></span></span></dt>
4896 Sets the maximum time for which the server will
4897 cache ordinary (positive) answers. The default is
4899 A value of zero may cause all queries to return
4900 SERVFAIL, because of lost caches of intermediate
4901 RRsets (such as NS and glue AAAA/A records) in the
4904 <dt><span class="term"><span><strong class="command">min-roots</strong></span></span></dt>
4907 The minimum number of root servers that
4908 is required for a request for the root servers to be
4909 accepted. The default
4910 is <strong class="userinput"><code>2</code></strong>.
4912 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4913 <h3 class="title">Note</h3>
4915 Not implemented in <acronym class="acronym">BIND</acronym> 9.
4919 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
4922 Specifies the number of days into the future when
4923 DNSSEC signatures automatically generated as a
4924 result of dynamic updates (<a href="Bv9ARM.ch04.html#dynamic_update" title="Dynamic Update">the section called “Dynamic Update”</a>) will expire. There
4925 is an optional second field which specifies how
4926 long before expiry that the signatures will be
4927 regenerated. If not specified, the signatures will
4928 be regenerated at 1/4 of base interval. The second
4929 field is specified in days if the base interval is
4930 greater than 7 days otherwise it is specified in hours.
4931 The default base interval is <code class="literal">30</code> days
4932 giving a re-signing interval of 7 1/2 days. The maximum
4933 values are 10 years (3660 days).
4936 The signature inception time is unconditionally
4937 set to one hour before the current time to allow
4938 for a limited amount of clock skew.
4941 The <span><strong class="command">sig-validity-interval</strong></span>
4942 should be, at least, several multiples of the SOA
4943 expire interval to allow for reasonable interaction
4944 between the various timer and expiry dates.
4947 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
4949 Specify the maximum number of nodes to be
4950 examined in each quantum when signing a zone with
4951 a new DNSKEY. The default is
4952 <code class="literal">100</code>.
4954 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
4956 Specify a threshold number of signatures that
4957 will terminate processing a quantum when signing
4958 a zone with a new DNSKEY. The default is
4959 <code class="literal">10</code>.
4961 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
4964 Specify a private RDATA type to be used when generating
4965 key signing records. The default is
4966 <code class="literal">65535</code>.
4969 It is expected that this parameter may be removed
4970 in a future version once there is a standard type.
4974 <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>
4978 These options control the server's behavior on refreshing a
4980 (querying for SOA changes) or retrying failed transfers.
4981 Usually the SOA values for the zone are used, but these
4983 are set by the master, giving slave server administrators
4985 control over their contents.
4988 These options allow the administrator to set a minimum and
4990 refresh and retry time either per-zone, per-view, or
4992 These options are valid for slave and stub zones,
4993 and clamp the SOA refresh and retry times to the specified
4997 The following defaults apply.
4998 <span><strong class="command">min-refresh-time</strong></span> 300 seconds,
4999 <span><strong class="command">max-refresh-time</strong></span> 2419200 seconds
5000 (4 weeks), <span><strong class="command">min-retry-time</strong></span> 500 seconds,
5001 and <span><strong class="command">max-retry-time</strong></span> 1209600 seconds
5005 <dt><span class="term"><span><strong class="command">edns-udp-size</strong></span></span></dt>
5008 Sets the advertised EDNS UDP buffer size in bytes
5009 to control the size of packets received.
5010 Valid values are 1024 to 4096 (values outside this range
5011 will be silently adjusted). The default value
5012 is 4096. The usual reason for setting
5013 <span><strong class="command">edns-udp-size</strong></span> to a non-default
5014 value is to get UDP answers to pass through broken
5015 firewalls that block fragmented packets and/or
5016 block UDP packets that are greater than 512 bytes.
5019 <span><strong class="command">named</strong></span> will fallback to using 512 bytes
5020 if it get a series of timeout at the initial value. 512
5021 bytes is not being offered to encourage sites to fix their
5022 firewalls. Small EDNS UDP sizes will result in the
5023 excessive use of TCP.
5026 <dt><span class="term"><span><strong class="command">max-udp-size</strong></span></span></dt>
5029 Sets the maximum EDNS UDP message size
5030 <span><strong class="command">named</strong></span> will send in bytes.
5031 Valid values are 512 to 4096 (values outside this
5032 range will be silently adjusted). The default
5033 value is 4096. The usual reason for setting
5034 <span><strong class="command">max-udp-size</strong></span> to a non-default
5035 value is to get UDP answers to pass through broken
5036 firewalls that block fragmented packets and/or
5037 block UDP packets that are greater than 512 bytes.
5038 This is independent of the advertised receive
5039 buffer (<span><strong class="command">edns-udp-size</strong></span>).
5042 Setting this to a low value will encourage additional
5043 TCP traffic to the nameserver.
5046 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
5048 the file format of zone files (see
5049 <a href="Bv9ARM.ch06.html#zonefile_format" title="Additional File Formats">the section called “Additional File Formats”</a>).
5050 The default value is <code class="constant">text</code>, which is the
5051 standard textual representation. Files in other formats
5052 than <code class="constant">text</code> are typically expected
5053 to be generated by the <span><strong class="command">named-compilezone</strong></span> tool.
5054 Note that when a zone file in a different format than
5055 <code class="constant">text</code> is loaded, <span><strong class="command">named</strong></span>
5056 may omit some of the checks which would be performed for a
5057 file in the <code class="constant">text</code> format. In particular,
5058 <span><strong class="command">check-names</strong></span> checks do not apply
5059 for the <code class="constant">raw</code> format. This means
5060 a zone file in the <code class="constant">raw</code> format
5061 must be generated with the same check level as that
5062 specified in the <span><strong class="command">named</strong></span> configuration
5063 file. This statement sets the
5064 <span><strong class="command">masterfile-format</strong></span> for all zones,
5065 but can be overridden on a per-zone or per-view basis
5066 by including a <span><strong class="command">masterfile-format</strong></span>
5067 statement within the <span><strong class="command">zone</strong></span> or
5068 <span><strong class="command">view</strong></span> block in the configuration
5072 <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>
5076 initial value (minimum) and maximum number of recursive
5077 simultaneous clients for any given query
5078 (<qname,qtype,qclass>) that the server will accept
5079 before dropping additional clients. <span><strong class="command">named</strong></span> will attempt to
5080 self tune this value and changes will be logged. The
5081 default values are 10 and 100.
5084 This value should reflect how many queries come in for
5085 a given name in the time it takes to resolve that name.
5086 If the number of queries exceed this value, <span><strong class="command">named</strong></span> will
5087 assume that it is dealing with a non-responsive zone
5088 and will drop additional queries. If it gets a response
5089 after dropping queries, it will raise the estimate. The
5090 estimate will then be lowered in 20 minutes if it has
5094 If <span><strong class="command">clients-per-query</strong></span> is set to zero,
5095 then there is no limit on the number of clients per query
5096 and no queries will be dropped.
5099 If <span><strong class="command">max-clients-per-query</strong></span> is set to zero,
5100 then there is no upper bound other than imposed by
5101 <span><strong class="command">recursive-clients</strong></span>.
5104 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
5106 The delay, in seconds, between sending sets of notify
5107 messages for a zone. The default is five (5) seconds.
5111 <div class="sect3" lang="en">
5112 <div class="titlepage"><div><div><h4 class="title">
5113 <a name="builtin"></a>Built-in server information zones</h4></div></div></div>
5115 The server provides some helpful diagnostic information
5116 through a number of built-in zones under the
5117 pseudo-top-level-domain <code class="literal">bind</code> in the
5118 <span><strong class="command">CHAOS</strong></span> class. These zones are part
5120 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
5122 <span><strong class="command">CHAOS</strong></span> which is separate from the
5124 class <span><strong class="command">IN</strong></span>; therefore, any global
5126 such as <span><strong class="command">allow-query</strong></span> do not apply
5128 If you feel the need to disable these zones, use the options
5129 below, or hide the built-in <span><strong class="command">CHAOS</strong></span>
5131 defining an explicit view of class <span><strong class="command">CHAOS</strong></span>
5132 that matches all clients.
5134 <div class="variablelist"><dl>
5135 <dt><span class="term"><span><strong class="command">version</strong></span></span></dt>
5137 The version the server should report
5138 via a query of the name <code class="literal">version.bind</code>
5139 with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
5140 The default is the real version number of this server.
5141 Specifying <span><strong class="command">version none</strong></span>
5142 disables processing of the queries.
5144 <dt><span class="term"><span><strong class="command">hostname</strong></span></span></dt>
5146 The hostname the server should report via a query of
5147 the name <code class="filename">hostname.bind</code>
5148 with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
5149 This defaults to the hostname of the machine hosting the
5151 found by the gethostname() function. The primary purpose of such queries
5153 identify which of a group of anycast servers is actually
5154 answering your queries. Specifying <span><strong class="command">hostname none;</strong></span>
5155 disables processing of the queries.
5157 <dt><span class="term"><span><strong class="command">server-id</strong></span></span></dt>
5159 The ID the server should report when receiving a Name
5160 Server Identifier (NSID) query, or a query of the name
5161 <code class="filename">ID.SERVER</code> with type
5162 <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
5163 The primary purpose of such queries is to
5164 identify which of a group of anycast servers is actually
5165 answering your queries. Specifying <span><strong class="command">server-id none;</strong></span>
5166 disables processing of the queries.
5167 Specifying <span><strong class="command">server-id hostname;</strong></span> will cause <span><strong class="command">named</strong></span> to
5168 use the hostname as found by the gethostname() function.
5169 The default <span><strong class="command">server-id</strong></span> is <span><strong class="command">none</strong></span>.
5173 <div class="sect3" lang="en">
5174 <div class="titlepage"><div><div><h4 class="title">
5175 <a name="empty"></a>Built-in Empty Zones</h4></div></div></div>
5177 Named has some built-in empty zones (SOA and NS records only).
5178 These are for zones that should normally be answered locally
5179 and which queries should not be sent to the Internet's root
5180 servers. The official servers which cover these namespaces
5181 return NXDOMAIN responses to these queries. In particular,
5182 these cover the reverse namespace for addresses from RFC 1918 and
5183 RFC 3330. They also include the reverse namespace for IPv6 local
5184 address (locally assigned), IPv6 link local addresses, the IPv6
5185 loopback address and the IPv6 unknown address.
5188 Named will attempt to determine if a built-in zone already exists
5189 or is active (covered by a forward-only forwarding declaration)
5190 and will not create an empty zone in that case.
5193 The current list of empty zones is:
5195 <div class="itemizedlist"><ul type="disc">
5196 <li>0.IN-ADDR.ARPA</li>
5197 <li>127.IN-ADDR.ARPA</li>
5198 <li>254.169.IN-ADDR.ARPA</li>
5199 <li>2.0.192.IN-ADDR.ARPA</li>
5200 <li>100.51.198.IN-ADDR.ARPA</li>
5201 <li>113.0.203.IN-ADDR.ARPA</li>
5202 <li>255.255.255.255.IN-ADDR.ARPA</li>
5203 <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>
5204 <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>
5205 <li>8.B.D.0.1.0.0.2.IP6.ARPA</li>
5206 <li>D.F.IP6.ARPA</li>
5207 <li>8.E.F.IP6.ARPA</li>
5208 <li>9.E.F.IP6.ARPA</li>
5209 <li>A.E.F.IP6.ARPA</li>
5210 <li>B.E.F.IP6.ARPA</li>
5215 Empty zones are settable at the view level and only apply to
5216 views of class IN. Disabled empty zones are only inherited
5217 from options if there are no disabled empty zones specified
5218 at the view level. To override the options list of disabled
5219 zones, you can disable the root zone at the view level, for example:
5221 <pre class="programlisting">
5222 disable-empty-zone ".";
5227 If you are using the address ranges covered here, you should
5228 already have reverse zones covering the addresses you use.
5229 In practice this appears to not be the case with many queries
5230 being made to the infrastructure servers for names in these
5231 spaces. So many in fact that sacrificial servers were needed
5232 to be deployed to channel the query load away from the
5233 infrastructure servers.
5235 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
5236 <h3 class="title">Note</h3>
5237 The real parent servers for these zones should disable all
5238 empty zone under the parent zone they serve. For the real
5239 root servers, this is all built-in empty zones. This will
5240 enable them to return referrals to deeper in the tree.
5242 <div class="variablelist"><dl>
5243 <dt><span class="term"><span><strong class="command">empty-server</strong></span></span></dt>
5245 Specify what server name will appear in the returned
5246 SOA record for empty zones. If none is specified, then
5247 the zone's name will be used.
5249 <dt><span class="term"><span><strong class="command">empty-contact</strong></span></span></dt>
5251 Specify what contact name will appear in the returned
5252 SOA record for empty zones. If none is specified, then
5255 <dt><span class="term"><span><strong class="command">empty-zones-enable</strong></span></span></dt>
5257 Enable or disable all empty zones. By default, they
5260 <dt><span class="term"><span><strong class="command">disable-empty-zone</strong></span></span></dt>
5262 Disable individual empty zones. By default, none are
5263 disabled. This option can be specified multiple times.
5267 <div class="sect3" lang="en">
5268 <div class="titlepage"><div><div><h4 class="title">
5269 <a name="acache"></a>Additional Section Caching</h4></div></div></div>
5271 The additional section cache, also called <span><strong class="command">acache</strong></span>,
5272 is an internal cache to improve the response performance of BIND 9.
5273 When additional section caching is enabled, BIND 9 will
5274 cache an internal short-cut to the additional section content for
5276 Note that <span><strong class="command">acache</strong></span> is an internal caching
5277 mechanism of BIND 9, and is not related to the DNS caching
5281 Additional section caching does not change the
5282 response content (except the RRsets ordering of the additional
5283 section, see below), but can improve the response performance
5285 It is particularly effective when BIND 9 acts as an authoritative
5286 server for a zone that has many delegations with many glue RRs.
5289 In order to obtain the maximum performance improvement
5290 from additional section caching, setting
5291 <span><strong class="command">additional-from-cache</strong></span>
5292 to <span><strong class="command">no</strong></span> is recommended, since the current
5293 implementation of <span><strong class="command">acache</strong></span>
5294 does not short-cut of additional section information from the
5298 One obvious disadvantage of <span><strong class="command">acache</strong></span> is
5299 that it requires much more
5300 memory for the internal cached data.
5301 Thus, if the response performance does not matter and memory
5302 consumption is much more critical, the
5303 <span><strong class="command">acache</strong></span> mechanism can be
5304 disabled by setting <span><strong class="command">acache-enable</strong></span> to
5305 <span><strong class="command">no</strong></span>.
5306 It is also possible to specify the upper limit of memory
5308 for acache by using <span><strong class="command">max-acache-size</strong></span>.
5311 Additional section caching also has a minor effect on the
5312 RRset ordering in the additional section.
5313 Without <span><strong class="command">acache</strong></span>,
5314 <span><strong class="command">cyclic</strong></span> order is effective for the additional
5315 section as well as the answer and authority sections.
5316 However, additional section caching fixes the ordering when it
5317 first caches an RRset for the additional section, and the same
5318 ordering will be kept in succeeding responses, regardless of the
5319 setting of <span><strong class="command">rrset-order</strong></span>.
5320 The effect of this should be minor, however, since an
5321 RRset in the additional section
5322 typically only contains a small number of RRs (and in many cases
5323 it only contains a single RR), in which case the
5324 ordering does not matter much.
5327 The following is a summary of options related to
5328 <span><strong class="command">acache</strong></span>.
5330 <div class="variablelist"><dl>
5331 <dt><span class="term"><span><strong class="command">acache-enable</strong></span></span></dt>
5333 If <span><strong class="command">yes</strong></span>, additional section caching is
5334 enabled. The default value is <span><strong class="command">no</strong></span>.
5336 <dt><span class="term"><span><strong class="command">acache-cleaning-interval</strong></span></span></dt>
5338 The server will remove stale cache entries, based on an LRU
5340 algorithm, every <span><strong class="command">acache-cleaning-interval</strong></span> minutes.
5341 The default is 60 minutes.
5342 If set to 0, no periodic cleaning will occur.
5344 <dt><span class="term"><span><strong class="command">max-acache-size</strong></span></span></dt>
5346 The maximum amount of memory in bytes to use for the server's acache.
5347 When the amount of data in the acache reaches this limit,
5349 will clean more aggressively so that the limit is not
5351 In a server with multiple views, the limit applies
5353 acache of each view.
5354 The default is <code class="literal">16M</code>.
5358 <div class="sect3" lang="en">
5359 <div class="titlepage"><div><div><h4 class="title">
5360 <a name="id2588025"></a>Content Filtering</h4></div></div></div>
5362 <acronym class="acronym">BIND</acronym> 9 provides the ability to filter
5363 out DNS responses from external DNS servers containing
5364 certain types of data in the answer section.
5365 Specifically, it can reject address (A or AAAA) records if
5366 the corresponding IPv4 or IPv6 addresses match the given
5367 <code class="varname">address_match_list</code> of the
5368 <span><strong class="command">deny-answer-addresses</strong></span> option.
5369 It can also reject CNAME or DNAME records if the "alias"
5370 name (i.e., the CNAME alias or the substituted query name
5371 due to DNAME) matches the
5372 given <code class="varname">namelist</code> of the
5373 <span><strong class="command">deny-answer-aliases</strong></span> option, where
5374 "match" means the alias name is a subdomain of one of
5375 the <code class="varname">name_list</code> elements.
5376 If the optional <code class="varname">namelist</code> is specified
5377 with <span><strong class="command">except-from</strong></span>, records whose query name
5378 matches the list will be accepted regardless of the filter
5380 Likewise, if the alias name is a subdomain of the
5381 corresponding zone, the <span><strong class="command">deny-answer-aliases</strong></span>
5382 filter will not apply;
5383 for example, even if "example.com" is specified for
5384 <span><strong class="command">deny-answer-aliases</strong></span>,
5386 <pre class="programlisting">www.example.com. CNAME xxx.example.com.</pre>
5388 returned by an "example.com" server will be accepted.
5391 In the <code class="varname">address_match_list</code> of the
5392 <span><strong class="command">deny-answer-addresses</strong></span> option, only
5393 <code class="varname">ip_addr</code>
5394 and <code class="varname">ip_prefix</code>
5396 any <code class="varname">key_id</code> will be silently ignored.
5399 If a response message is rejected due to the filtering,
5400 the entire message is discarded without being cached, and
5401 a SERVFAIL error will be returned to the client.
5404 This filtering is intended to prevent "DNS rebinding attacks," in
5405 which an attacker, in response to a query for a domain name the
5406 attacker controls, returns an IP address within your own network or
5407 an alias name within your own domain.
5408 A naive web browser or script could then serve as an
5409 unintended proxy, allowing the attacker
5410 to get access to an internal node of your local network
5411 that couldn't be externally accessed otherwise.
5412 See the paper available at
5413 <a href="" target="_top">
5414 http://portal.acm.org/citation.cfm?id=1315245.1315298
5416 for more details about the attacks.
5419 For example, if you own a domain named "example.net" and
5420 your internal network uses an IPv4 prefix 192.0.2.0/24,
5421 you might specify the following rules:
5423 <pre class="programlisting">deny-answer-addresses { 192.0.2.0/24; } except-from { "example.net"; };
5424 deny-answer-aliases { "example.net"; };
5427 If an external attacker lets a web browser in your local
5428 network look up an IPv4 address of "attacker.example.com",
5429 the attacker's DNS server would return a response like this:
5431 <pre class="programlisting">attacker.example.com. A 192.0.2.1</pre>
5433 in the answer section.
5434 Since the rdata of this record (the IPv4 address) matches
5435 the specified prefix 192.0.2.0/24, this response will be
5439 On the other hand, if the browser looks up a legitimate
5440 internal web server "www.example.net" and the
5441 following response is returned to
5442 the <acronym class="acronym">BIND</acronym> 9 server
5444 <pre class="programlisting">www.example.net. A 192.0.2.2</pre>
5446 it will be accepted since the owner name "www.example.net"
5447 matches the <span><strong class="command">except-from</strong></span> element,
5451 Note that this is not really an attack on the DNS per se.
5452 In fact, there is nothing wrong for an "external" name to
5453 be mapped to your "internal" IP address or domain name
5454 from the DNS point of view.
5455 It might actually be provided for a legitimate purpose,
5456 such as for debugging.
5457 As long as the mapping is provided by the correct owner,
5458 it is not possible or does not make sense to detect
5459 whether the intent of the mapping is legitimate or not
5461 The "rebinding" attack must primarily be protected at the
5462 application that uses the DNS.
5463 For a large site, however, it may be difficult to protect
5464 all possible applications at once.
5465 This filtering feature is provided only to help such an
5466 operational environment;
5467 it is generally discouraged to turn it on unless you are
5468 very sure you have no other choice and the attack is a
5469 real threat for your applications.
5472 Care should be particularly taken if you want to use this
5473 option for addresses within 127.0.0.0/8.
5474 These addresses are obviously "internal", but many
5475 applications conventionally rely on a DNS mapping from
5476 some name to such an address.
5477 Filtering out DNS records containing this address
5478 spuriously can break such applications.
5481 <div class="sect3" lang="en">
5482 <div class="titlepage"><div><div><h4 class="title">
5483 <a name="id2588148"></a>Response Policy Zone (RPZ) Rewriting</h4></div></div></div>
5485 <acronym class="acronym">BIND</acronym> 9 includes an intentionally limited
5486 mechanism to modify DNS responses for recursive requests
5487 similar to email anti-spam DNS blacklists.
5488 All response policy zones are named in the
5489 <span><strong class="command">response-policy</strong></span> option for the view or among the
5490 global options if there is no response-policy option for the view.
5493 The rules encoded in a response policy zone (RPZ) are applied
5494 only to responses to queries that ask for recursion (RD=1).
5495 RPZs are normal DNS zones containing RRsets
5496 that can be queried normally if allowed.
5497 It is usually best to restrict those queries with something like
5498 <span><strong class="command">allow-query {none; };</strong></span> or
5499 <span><strong class="command">allow-query { 127.0.0.1; };</strong></span>.
5502 There are four kinds of RPZ rewrite rules. QNAME rules are
5503 applied to query names in requests and to targets of CNAME
5504 records resolved in the process of generating the response.
5505 The owner name of a QNAME rule is the query name relativized
5507 The records in a rewrite rule are usually A, AAAA, or special
5508 CNAMEs, but can be any type except DNAME.
5511 IP rules are triggered by addresses in A and AAAA records.
5512 All IP addresses in A or AAAA RRsets are tested and the rule
5513 longest prefix is applied. Ties between rules with equal prefixes
5514 are broken in favor of the first RPZ mentioned in the
5515 response-policy option.
5516 The rule matching the smallest IP address is chosen among equal
5517 prefix rules from a single RPZ.
5518 IP rules are expressed in RRsets with owner names that are
5519 subdomains of rpz-ip and encoding an IP address block, reversed
5521 prefix.B.B.B.B with prefix between 1 and 32 and B between 1 and 255
5522 encodes an IPv4 address.
5523 IPv6 addresses are encoded by with prefix.W.W.W.W.W.W.W.W or
5524 prefix.WORDS.zz.WORDS. The words in the standard IPv6 text
5525 representation are reversed, "::" is replaced with ".zz.",
5526 and ":" becomes ".".
5529 NSDNAME rules match names in NS RRsets for the response or a
5530 parent. They are encoded as subdomains of rpz-nsdomain relativized
5531 to the RPZ origin name.
5534 NSIP rules match IP addresses in A and AAAA RRsets for names of
5535 responsible servers or the names that can be matched by NSDNAME
5536 rules. The are encoded like IP rules except as subdomains of
5540 Authority verification issues and variations in authority data in
5541 the current version of <acronym class="acronym">BIND</acronym> 9 can cause
5542 inconsistent results from NSIP and NSDNAME. So they are available
5543 only when <acronym class="acronym">BIND</acronym> is built with the
5544 <strong class="userinput"><code>--enable-rpz-nsip</code></strong> or
5545 <strong class="userinput"><code>--enable-rpz-nsdname</code></strong> options
5546 on the "configure" command line.
5549 Four policies can be expressed.
5550 The <span><strong class="command">NXDOMAIN</strong></span> policy causes a NXDOMAIN response
5551 and is expressed with an RRset consisting of a single CNAME
5552 whose target is the root domain (.).
5553 <span><strong class="command">NODATA</strong></span> generates NODATA or ANCOUNT=1 regardless
5555 It is expressed with a CNAME whose target is the wildcard
5556 top-level domain (*.).
5557 The <span><strong class="command">NO-OP</strong></span> policy does not change the response
5558 and is used to "poke holes" in policies for larger CIDR blocks or in
5559 zones named later in the <span><strong class="command">response-policy</strong></span> option.
5560 The NO-OP policy is expressed by a CNAME with a target consisting
5561 of the variable part of the owner name, such as "example.com." for
5562 a QNAME rule or "128.1.0.0.127." for an IP rule.
5563 The <span><strong class="command">CNAME</strong></span> policy is used to replace the RRsets
5565 A and AAAA RRsets are most common and useful to capture
5566 an evil domain in a walled garden, but any valid set of RRsets
5570 All of the policies in an RPZ can be overridden with a
5571 <span><strong class="command">policy</strong></span> clause.
5572 <span><strong class="command">given</strong></span> says "do not override."
5573 <span><strong class="command">no-op</strong></span> says "do nothing" regardless of the policy
5575 <span><strong class="command">nxdomain</strong></span> causes all RPZ rules to generate
5577 <span><strong class="command">nodata</strong></span> gives nodata.
5578 <span><strong class="command">cname domain</strong></span> causes all RPZ rules to act as if
5579 the consisted of a "cname domain" record.
5582 For example, you might use this option statement
5584 <pre class="programlisting">response-policy { zone "bl"; };</pre>
5586 and this zone statement
5588 <pre class="programlisting">zone "bl" {type master; file "example/bl"; allow-query {none;}; };</pre>
5592 <pre class="programlisting">$TTL 1H
5593 @ SOA LOCALHOST. named-mgr.example.com (1 1h 15m 30d 2h)
5596 nxdomain.domain.com CNAME .
5597 nodata.domain.com CNAME *.
5598 bad.domain.com A 10.0.0.1
5600 ok.domain.com CNAME ok.domain.com.
5601 *.badzone.domain.com CNAME garden.example.com.
5603 ; IP rules rewriting all answers for 127/8 except 127.0.0.1
5604 8.0.0.0.127.ip CNAME .
5605 32.1.0.0.127.ip CNAME 32.1.0.0.127.
5607 ; NSDNAME and NSIP rules
5608 ns.domain.com.rpz-nsdname CNAME .
5609 48.zz.2.2001.rpz-nsip CNAME .
5613 <div class="sect2" lang="en">
5614 <div class="titlepage"><div><div><h3 class="title">
5615 <a name="server_statement_grammar"></a><span><strong class="command">server</strong></span> Statement Grammar</h3></div></div></div>
5616 <pre class="programlisting"><span><strong class="command">server</strong></span> <em class="replaceable"><code>ip_addr[/prefixlen]</code></em> {
5617 [<span class="optional"> bogus <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5618 [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5619 [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5620 [<span class="optional"> edns <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5621 [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
5622 [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
5623 [<span class="optional"> transfers <em class="replaceable"><code>number</code></em> ; </span>]
5624 [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em> ; ]</span>]
5625 [<span class="optional"> keys <em class="replaceable"><code>{ string ; [<span class="optional"> string ; [<span class="optional">...</span>]</span>] }</code></em> ; </span>]
5626 [<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>]
5627 [<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>]
5628 [<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>]
5629 [<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>]
5630 [<span class="optional"> query-source [<span class="optional"> address ( <em class="replaceable"><code>ip_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
5631 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>]
5632 [<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>]
5633 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>]
5634 [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5635 [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>]
5636 [<span class="optional"> queryport-pool-updateinterval <em class="replaceable"><code>number</code></em>; </span>]
5640 <div class="sect2" lang="en">
5641 <div class="titlepage"><div><div><h3 class="title">
5642 <a name="server_statement_definition_and_usage"></a><span><strong class="command">server</strong></span> Statement Definition and
5643 Usage</h3></div></div></div>
5645 The <span><strong class="command">server</strong></span> statement defines
5647 to be associated with a remote name server. If a prefix length is
5648 specified, then a range of servers is covered. Only the most
5650 server clause applies regardless of the order in
5651 <code class="filename">named.conf</code>.
5654 The <span><strong class="command">server</strong></span> statement can occur at
5655 the top level of the
5656 configuration file or inside a <span><strong class="command">view</strong></span>
5658 If a <span><strong class="command">view</strong></span> statement contains
5659 one or more <span><strong class="command">server</strong></span> statements, only
5661 apply to the view and any top-level ones are ignored.
5662 If a view contains no <span><strong class="command">server</strong></span>
5664 any top-level <span><strong class="command">server</strong></span> statements are
5669 If you discover that a remote server is giving out bad data,
5670 marking it as bogus will prevent further queries to it. The
5672 value of <span><strong class="command">bogus</strong></span> is <span><strong class="command">no</strong></span>.
5675 The <span><strong class="command">provide-ixfr</strong></span> clause determines
5677 the local server, acting as master, will respond with an
5679 zone transfer when the given remote server, a slave, requests it.
5680 If set to <span><strong class="command">yes</strong></span>, incremental transfer
5682 whenever possible. If set to <span><strong class="command">no</strong></span>,
5684 to the remote server will be non-incremental. If not set, the
5686 of the <span><strong class="command">provide-ixfr</strong></span> option in the
5688 global options block is used as a default.
5691 The <span><strong class="command">request-ixfr</strong></span> clause determines
5693 the local server, acting as a slave, will request incremental zone
5694 transfers from the given remote server, a master. If not set, the
5695 value of the <span><strong class="command">request-ixfr</strong></span> option in
5697 global options block is used as a default.
5700 IXFR requests to servers that do not support IXFR will
5702 fall back to AXFR. Therefore, there is no need to manually list
5703 which servers support IXFR and which ones do not; the global
5705 of <span><strong class="command">yes</strong></span> should always work.
5706 The purpose of the <span><strong class="command">provide-ixfr</strong></span> and
5707 <span><strong class="command">request-ixfr</strong></span> clauses is
5708 to make it possible to disable the use of IXFR even when both
5710 and slave claim to support it, for example if one of the servers
5711 is buggy and crashes or corrupts data when IXFR is used.
5714 The <span><strong class="command">edns</strong></span> clause determines whether
5715 the local server will attempt to use EDNS when communicating
5716 with the remote server. The default is <span><strong class="command">yes</strong></span>.
5719 The <span><strong class="command">edns-udp-size</strong></span> option sets the EDNS UDP size
5720 that is advertised by <span><strong class="command">named</strong></span> when querying the remote server.
5721 Valid values are 512 to 4096 bytes (values outside this range will be
5722 silently adjusted). This option is useful when you wish to
5723 advertises a different value to this server than the value you
5724 advertise globally, for example, when there is a firewall at the
5725 remote site that is blocking large replies.
5728 The <span><strong class="command">max-udp-size</strong></span> option sets the
5729 maximum EDNS UDP message size <span><strong class="command">named</strong></span> will send. Valid
5730 values are 512 to 4096 bytes (values outside this range will
5731 be silently adjusted). This option is useful when you
5732 know that there is a firewall that is blocking large
5733 replies from <span><strong class="command">named</strong></span>.
5736 The server supports two zone transfer methods. The first, <span><strong class="command">one-answer</strong></span>,
5737 uses one DNS message per resource record transferred. <span><strong class="command">many-answers</strong></span> packs
5738 as many resource records as possible into a message. <span><strong class="command">many-answers</strong></span> is
5739 more efficient, but is only known to be understood by <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
5740 8.x, and patched versions of <acronym class="acronym">BIND</acronym>
5741 4.9.5. You can specify which method
5742 to use for a server with the <span><strong class="command">transfer-format</strong></span> option.
5743 If <span><strong class="command">transfer-format</strong></span> is not
5744 specified, the <span><strong class="command">transfer-format</strong></span>
5746 by the <span><strong class="command">options</strong></span> statement will be
5749 <p><span><strong class="command">transfers</strong></span>
5750 is used to limit the number of concurrent inbound zone
5751 transfers from the specified server. If no
5752 <span><strong class="command">transfers</strong></span> clause is specified, the
5753 limit is set according to the
5754 <span><strong class="command">transfers-per-ns</strong></span> option.
5757 The <span><strong class="command">keys</strong></span> clause identifies a
5758 <span><strong class="command">key_id</strong></span> defined by the <span><strong class="command">key</strong></span> statement,
5759 to be used for transaction security (TSIG, <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called “TSIG”</a>)
5760 when talking to the remote server.
5761 When a request is sent to the remote server, a request signature
5762 will be generated using the key specified here and appended to the
5763 message. A request originating from the remote server is not
5765 to be signed by this key.
5768 Although the grammar of the <span><strong class="command">keys</strong></span>
5770 allows for multiple keys, only a single key per server is
5775 The <span><strong class="command">transfer-source</strong></span> and
5776 <span><strong class="command">transfer-source-v6</strong></span> clauses specify
5777 the IPv4 and IPv6 source
5778 address to be used for zone transfer with the remote server,
5780 For an IPv4 remote server, only <span><strong class="command">transfer-source</strong></span> can
5782 Similarly, for an IPv6 remote server, only
5783 <span><strong class="command">transfer-source-v6</strong></span> can be
5785 For more details, see the description of
5786 <span><strong class="command">transfer-source</strong></span> and
5787 <span><strong class="command">transfer-source-v6</strong></span> in
5788 <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5791 The <span><strong class="command">notify-source</strong></span> and
5792 <span><strong class="command">notify-source-v6</strong></span> clauses specify the
5793 IPv4 and IPv6 source address to be used for notify
5794 messages sent to remote servers, respectively. For an
5795 IPv4 remote server, only <span><strong class="command">notify-source</strong></span>
5796 can be specified. Similarly, for an IPv6 remote server,
5797 only <span><strong class="command">notify-source-v6</strong></span> can be specified.
5800 The <span><strong class="command">query-source</strong></span> and
5801 <span><strong class="command">query-source-v6</strong></span> clauses specify the
5802 IPv4 and IPv6 source address to be used for queries
5803 sent to remote servers, respectively. For an IPv4
5804 remote server, only <span><strong class="command">query-source</strong></span> can
5805 be specified. Similarly, for an IPv6 remote server,
5806 only <span><strong class="command">query-source-v6</strong></span> can be specified.
5809 <div class="sect2" lang="en">
5810 <div class="titlepage"><div><div><h3 class="title">
5811 <a name="statschannels"></a><span><strong class="command">statistics-channels</strong></span> Statement Grammar</h3></div></div></div>
5812 <pre class="programlisting"><span><strong class="command">statistics-channels</strong></span> {
5813 [ inet ( ip_addr | * ) [ port ip_port ]
5814 [ allow { <em class="replaceable"><code> address_match_list </code></em> } ]; ]
5819 <div class="sect2" lang="en">
5820 <div class="titlepage"><div><div><h3 class="title">
5821 <a name="id2589239"></a><span><strong class="command">statistics-channels</strong></span> Statement Definition and
5822 Usage</h3></div></div></div>
5824 The <span><strong class="command">statistics-channels</strong></span> statement
5825 declares communication channels to be used by system
5826 administrators to get access to statistics information of
5830 This statement intends to be flexible to support multiple
5831 communication protocols in the future, but currently only
5832 HTTP access is supported.
5833 It requires that BIND 9 be compiled with libxml2;
5834 the <span><strong class="command">statistics-channels</strong></span> statement is
5835 still accepted even if it is built without the library,
5836 but any HTTP access will fail with an error.
5839 An <span><strong class="command">inet</strong></span> control channel is a TCP socket
5840 listening at the specified <span><strong class="command">ip_port</strong></span> on the
5841 specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6
5842 address. An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is
5843 interpreted as the IPv4 wildcard address; connections will be
5844 accepted on any of the system's IPv4 addresses.
5845 To listen on the IPv6 wildcard address,
5846 use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>.
5849 If no port is specified, port 80 is used for HTTP channels.
5850 The asterisk "<code class="literal">*</code>" cannot be used for
5851 <span><strong class="command">ip_port</strong></span>.
5854 The attempt of opening a statistics channel is
5855 restricted by the optional <span><strong class="command">allow</strong></span> clause.
5856 Connections to the statistics channel are permitted based on the
5857 <span><strong class="command">address_match_list</strong></span>.
5858 If no <span><strong class="command">allow</strong></span> clause is present,
5859 <span><strong class="command">named</strong></span> accepts connection
5860 attempts from any address; since the statistics may
5861 contain sensitive internal information, it is highly
5862 recommended to restrict the source of connection requests
5866 If no <span><strong class="command">statistics-channels</strong></span> statement is present,
5867 <span><strong class="command">named</strong></span> will not open any communication channels.
5870 <div class="sect2" lang="en">
5871 <div class="titlepage"><div><div><h3 class="title">
5872 <a name="trusted-keys"></a><span><strong class="command">trusted-keys</strong></span> Statement Grammar</h3></div></div></div>
5873 <pre class="programlisting"><span><strong class="command">trusted-keys</strong></span> {
5874 <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> ;
5875 [<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>]
5879 <div class="sect2" lang="en">
5880 <div class="titlepage"><div><div><h3 class="title">
5881 <a name="id2589379"></a><span><strong class="command">trusted-keys</strong></span> Statement Definition
5882 and Usage</h3></div></div></div>
5884 The <span><strong class="command">trusted-keys</strong></span> statement defines
5885 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
5886 public key for a non-authoritative zone is known, but
5887 cannot be securely obtained through DNS, either because
5888 it is the DNS root zone or because its parent zone is
5889 unsigned. Once a key has been configured as a trusted
5890 key, it is treated as if it had been validated and
5891 proven secure. The resolver attempts DNSSEC validation
5892 on all DNS data in subdomains of a security root.
5895 All keys (and corresponding zones) listed in
5896 <span><strong class="command">trusted-keys</strong></span> are deemed to exist regardless
5897 of what parent zones say. Similarly for all keys listed in
5898 <span><strong class="command">trusted-keys</strong></span> only those keys are
5899 used to validate the DNSKEY RRset. The parent's DS RRset
5903 The <span><strong class="command">trusted-keys</strong></span> statement can contain
5904 multiple key entries, each consisting of the key's
5905 domain name, flags, protocol, algorithm, and the Base-64
5906 representation of the key data.
5907 Spaces, tabs, newlines and carriage returns are ignored
5908 in the key data, so the configuration may be split up into
5912 <span><strong class="command">trusted-keys</strong></span> may be set at the top level
5913 of <code class="filename">named.conf</code> or within a view. If it is
5914 set in both places, they are additive: keys defined at the top
5915 level are inherited by all views, but keys defined in a view
5916 are only used within that view.
5919 <div class="sect2" lang="en">
5920 <div class="titlepage"><div><div><h3 class="title">
5921 <a name="id2589494"></a><span><strong class="command">managed-keys</strong></span> Statement Grammar</h3></div></div></div>
5922 <pre class="programlisting"><span><strong class="command">managed-keys</strong></span> {
5923 <em class="replaceable"><code>string</code></em> initial-key <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> ;
5924 [<span class="optional"> <em class="replaceable"><code>string</code></em> initial-key <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>]
5928 <div class="sect2" lang="en">
5929 <div class="titlepage"><div><div><h3 class="title">
5930 <a name="managed-keys"></a><span><strong class="command">managed-keys</strong></span> Statement Definition
5931 and Usage</h3></div></div></div>
5933 The <span><strong class="command">managed-keys</strong></span> statement, like
5934 <span><strong class="command">trusted-keys</strong></span>, defines DNSSEC
5935 security roots. The difference is that
5936 <span><strong class="command">managed-keys</strong></span> can be kept up to date
5937 automatically, without intervention from the resolver
5941 Suppose, for example, that a zone's key-signing
5942 key was compromised, and the zone owner had to revoke and
5943 replace the key. A resolver which had the old key in a
5944 <span><strong class="command">trusted-keys</strong></span> statement would be
5945 unable to validate this zone any longer; it would
5946 reply with a SERVFAIL response code. This would
5947 continue until the resolver operator had updated the
5948 <span><strong class="command">trusted-keys</strong></span> statement with the new key.
5951 If, however, the zone were listed in a
5952 <span><strong class="command">managed-keys</strong></span> statement instead, then the
5953 zone owner could add a "stand-by" key to the zone in advance.
5954 <span><strong class="command">named</strong></span> would store the stand-by key, and
5955 when the original key was revoked, <span><strong class="command">named</strong></span>
5956 would be able to transition smoothly to the new key. It would
5957 also recognize that the old key had been revoked, and cease
5958 using that key to validate answers, minimizing the damage that
5959 the compromised key could do.
5962 A <span><strong class="command">managed-keys</strong></span> statement contains a list of
5963 the keys to be managed, along with information about how the
5964 keys are to be initialized for the first time. The only
5965 initialization method currently supported (as of
5966 <acronym class="acronym">BIND</acronym> 9.7.0) is <code class="literal">initial-key</code>.
5967 This means the <span><strong class="command">managed-keys</strong></span> statement must
5968 contain a copy of the initializing key. (Future releases may
5969 allow keys to be initialized by other methods, eliminating this
5973 Consequently, a <span><strong class="command">managed-keys</strong></span> statement
5974 appears similar to a <span><strong class="command">trusted-keys</strong></span>, differing
5975 in the presence of the second field, containing the keyword
5976 <code class="literal">initial-key</code>. The difference is, whereas the
5977 keys listed in a <span><strong class="command">trusted-keys</strong></span> continue to be
5978 trusted until they are removed from
5979 <code class="filename">named.conf</code>, an initializing key listed
5980 in a <span><strong class="command">managed-keys</strong></span> statement is only trusted
5981 <span class="emphasis"><em>once</em></span>: for as long as it takes to load the
5982 managed key database and start the RFC 5011 key maintenance
5986 The first time <span><strong class="command">named</strong></span> runs with a managed key
5987 configured in <code class="filename">named.conf</code>, it fetches the
5988 DNSKEY RRset directly from the zone apex, and validates it
5989 using the key specified in the <span><strong class="command">managed-keys</strong></span>
5990 statement. If the DNSKEY RRset is validly signed, then it is
5991 used as the basis for a new managed keys database.
5994 From that point on, whenever <span><strong class="command">named</strong></span> runs, it
5995 sees the <span><strong class="command">managed-keys</strong></span> statement, checks to
5996 make sure RFC 5011 key maintenance has already been initialized
5997 for the specified domain, and if so, it simply moves on. The
5998 key specified in the <span><strong class="command">managed-keys</strong></span> is not
5999 used to validate answers; it has been superseded by the key or
6000 keys stored in the managed keys database.
6003 The next time <span><strong class="command">named</strong></span> runs after a name
6004 has been <span class="emphasis"><em>removed</em></span> from the
6005 <span><strong class="command">managed-keys</strong></span> statement, the corresponding
6006 zone will be removed from the managed keys database,
6007 and RFC 5011 key maintenance will no longer be used for that
6011 <span><strong class="command">named</strong></span> only maintains a single managed keys
6012 database; consequently, unlike <span><strong class="command">trusted-keys</strong></span>,
6013 <span><strong class="command">managed-keys</strong></span> may only be set at the top
6014 level of <code class="filename">named.conf</code>, not within a view.
6017 In the current implementation, the managed keys database is
6018 stored as a master-format zone file called
6019 <code class="filename">managed-keys.bind</code>. When the key database
6020 is changed, the zone is updated. As with any other dynamic
6021 zone, changes will be written into a journal file,
6022 <code class="filename">managed-keys.bind.jnl</code>. They are committed
6023 to the master file as soon as possible afterward; in the case
6024 of the managed key database, this will usually occur within 30
6025 seconds. So, whenever <span><strong class="command">named</strong></span> is using
6026 automatic key maintenance, those two files can be expected to
6027 exist in the working directory. (For this reason among others,
6028 the working directory should be always be writable by
6029 <span><strong class="command">named</strong></span>.)
6032 If the <span><strong class="command">dnssec-lookaside</strong></span> option is
6033 set to <strong class="userinput"><code>auto</code></strong>, <span><strong class="command">named</strong></span>
6034 will automatically initialize a managed key for the
6035 zone <code class="literal">dlv.isc.org</code>. The key that is
6036 used to initialize the key maintenance process is built
6037 into <span><strong class="command">named</strong></span>, and can be overridden
6038 from <span><strong class="command">bindkeys-file</strong></span>.
6041 <div class="sect2" lang="en">
6042 <div class="titlepage"><div><div><h3 class="title">
6043 <a name="view_statement_grammar"></a><span><strong class="command">view</strong></span> Statement Grammar</h3></div></div></div>
6044 <pre class="programlisting"><span><strong class="command">view</strong></span> <em class="replaceable"><code>view_name</code></em>
6045 [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6046 match-clients { <em class="replaceable"><code>address_match_list</code></em> };
6047 match-destinations { <em class="replaceable"><code>address_match_list</code></em> };
6048 match-recursive-only <em class="replaceable"><code>yes_or_no</code></em> ;
6049 [<span class="optional"> <em class="replaceable"><code>view_option</code></em>; ...</span>]
6050 [<span class="optional"> <em class="replaceable"><code>zone_statement</code></em>; ...</span>]
6054 <div class="sect2" lang="en">
6055 <div class="titlepage"><div><div><h3 class="title">
6056 <a name="id2589851"></a><span><strong class="command">view</strong></span> Statement Definition and Usage</h3></div></div></div>
6058 The <span><strong class="command">view</strong></span> statement is a powerful
6060 of <acronym class="acronym">BIND</acronym> 9 that lets a name server
6061 answer a DNS query differently
6062 depending on who is asking. It is particularly useful for
6064 split DNS setups without having to run multiple servers.
6067 Each <span><strong class="command">view</strong></span> statement defines a view
6069 DNS namespace that will be seen by a subset of clients. A client
6071 a view if its source IP address matches the
6072 <code class="varname">address_match_list</code> of the view's
6073 <span><strong class="command">match-clients</strong></span> clause and its
6074 destination IP address matches
6075 the <code class="varname">address_match_list</code> of the
6077 <span><strong class="command">match-destinations</strong></span> clause. If not
6079 <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
6080 default to matching all addresses. In addition to checking IP
6082 <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
6083 can also take <span><strong class="command">keys</strong></span> which provide an
6085 client to select the view. A view can also be specified
6086 as <span><strong class="command">match-recursive-only</strong></span>, which
6087 means that only recursive
6088 requests from matching clients will match that view.
6089 The order of the <span><strong class="command">view</strong></span> statements is
6091 a client request will be resolved in the context of the first
6092 <span><strong class="command">view</strong></span> that it matches.
6095 Zones defined within a <span><strong class="command">view</strong></span>
6097 only be accessible to clients that match the <span><strong class="command">view</strong></span>.
6098 By defining a zone of the same name in multiple views, different
6099 zone data can be given to different clients, for example,
6101 and "external" clients in a split DNS setup.
6104 Many of the options given in the <span><strong class="command">options</strong></span> statement
6105 can also be used within a <span><strong class="command">view</strong></span>
6107 apply only when resolving queries with that view. When no
6109 value is given, the value in the <span><strong class="command">options</strong></span> statement
6110 is used as a default. Also, zone options can have default values
6112 in the <span><strong class="command">view</strong></span> statement; these
6113 view-specific defaults
6114 take precedence over those in the <span><strong class="command">options</strong></span> statement.
6117 Views are class specific. If no class is given, class IN
6118 is assumed. Note that all non-IN views must contain a hint zone,
6119 since only the IN class has compiled-in default hints.
6122 If there are no <span><strong class="command">view</strong></span> statements in
6124 file, a default view that matches any client is automatically
6126 in class IN. Any <span><strong class="command">zone</strong></span> statements
6128 the top level of the configuration file are considered to be part
6130 this default view, and the <span><strong class="command">options</strong></span>
6132 apply to the default view. If any explicit <span><strong class="command">view</strong></span>
6133 statements are present, all <span><strong class="command">zone</strong></span>
6135 occur inside <span><strong class="command">view</strong></span> statements.
6138 Here is an example of a typical split DNS setup implemented
6139 using <span><strong class="command">view</strong></span> statements:
6141 <pre class="programlisting">view "internal" {
6142 // This should match our internal networks.
6143 match-clients { 10.0.0.0/8; };
6145 // Provide recursive service to internal
6149 // Provide a complete view of the example.com
6150 // zone including addresses of internal hosts.
6151 zone "example.com" {
6153 file "example-internal.db";
6158 // Match all clients not matched by the
6160 match-clients { any; };
6162 // Refuse recursive service to external clients.
6165 // Provide a restricted view of the example.com
6166 // zone containing only publicly accessible hosts.
6167 zone "example.com" {
6169 file "example-external.db";
6174 <div class="sect2" lang="en">
6175 <div class="titlepage"><div><div><h3 class="title">
6176 <a name="zone_statement_grammar"></a><span><strong class="command">zone</strong></span>
6177 Statement Grammar</h3></div></div></div>
6178 <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>] {
6180 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6181 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6182 [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6183 [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6184 [<span class="optional"> update-policy <em class="replaceable"><code>local</code></em> | { <em class="replaceable"><code>update_policy_rule</code></em> [<span class="optional">...</span>] }; </span>]
6185 [<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>] ;
6186 [<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>]
6187 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6188 [<span class="optional"> check-mx (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6189 [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6190 [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6191 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
6192 [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
6193 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
6194 [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>]
6195 [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
6196 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
6197 [<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>]
6198 [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>]
6199 [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6200 [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>]
6201 [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6202 [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
6203 [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
6204 [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
6205 [<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>]
6206 [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
6207 [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6208 [<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>]
6209 [<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>]
6210 [<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>]
6211 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6212 [<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>]
6213 [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>]
6214 [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>]
6215 [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>]
6216 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
6217 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6218 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6219 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6220 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6221 [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>]
6222 [<span class="optional"> auto-dnssec <code class="constant">allow</code>|<code class="constant">maintain</code>|<code class="constant">create</code>|<code class="constant">off</code>; </span>]
6223 [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6226 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6228 [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6229 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6230 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6231 [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6232 [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6233 [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6234 [<span class="optional"> dnssec-dnskey-kskonly <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6235 [<span class="optional"> dnssec-secure-to-insecure <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6236 [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6237 [<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>] ;
6238 [<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>]
6239 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6240 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
6241 [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
6242 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
6243 [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>]
6244 [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
6245 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
6246 [<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>]
6247 [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>]
6248 [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6249 [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>]
6250 [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6251 [<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>
6252 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>]
6253 [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] }; </span>]
6254 [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
6255 [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
6256 [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
6257 [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
6258 [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
6259 [<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>]
6260 [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
6261 [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6262 [<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>]
6263 [<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>]
6264 [<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>]
6265 [<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>]
6266 [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>)
6267 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6268 [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6269 [<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>]
6270 [<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>]
6271 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6272 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
6273 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6274 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6275 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6276 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6277 [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6278 [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6281 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6283 file <em class="replaceable"><code>string</code></em> ;
6284 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6285 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>] // Not Implemented.
6288 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6290 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6291 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6292 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6293 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
6294 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6295 [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
6296 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
6297 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
6298 [<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>]
6299 [<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>
6300 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>]
6301 [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] }; </span>]
6302 [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
6303 [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
6304 [<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>]
6305 [<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>]
6306 [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>)
6307 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6308 [<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>]
6309 [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>)
6310 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6311 [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6312 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6313 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
6314 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6315 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6316 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6317 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6318 [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6321 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6323 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6324 [<span class="optional"> server-addresses { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> ; ... </span>] }; </span>]
6325 [<span class="optional"> server-names { [<span class="optional"> <em class="replaceable"><code>namelist</code></em> </span>] }; </span>]
6326 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6329 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6331 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
6332 [<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>]
6333 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6336 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6337 type delegation-only;
6342 <div class="sect2" lang="en">
6343 <div class="titlepage"><div><div><h3 class="title">
6344 <a name="id2591396"></a><span><strong class="command">zone</strong></span> Statement Definition and Usage</h3></div></div></div>
6345 <div class="sect3" lang="en">
6346 <div class="titlepage"><div><div><h4 class="title">
6347 <a name="id2591403"></a>Zone Types</h4></div></div></div>
6348 <div class="informaltable"><table border="1">
6357 <code class="varname">master</code>
6362 The server has a master copy of the data
6363 for the zone and will be able to provide authoritative
6372 <code class="varname">slave</code>
6377 A slave zone is a replica of a master
6378 zone. The <span><strong class="command">masters</strong></span> list
6379 specifies one or more IP addresses
6380 of master servers that the slave contacts to update
6381 its copy of the zone.
6382 Masters list elements can also be names of other
6384 By default, transfers are made from port 53 on the
6386 be changed for all servers by specifying a port number
6388 list of IP addresses, or on a per-server basis after
6390 Authentication to the master can also be done with
6391 per-server TSIG keys.
6392 If a file is specified, then the
6393 replica will be written to this file whenever the zone
6395 and reloaded from this file on a server restart. Use
6397 recommended, since it often speeds server startup and
6399 a needless waste of bandwidth. Note that for large
6401 tens or hundreds of thousands) of zones per server, it
6403 use a two-level naming scheme for zone filenames. For
6405 a slave server for the zone <code class="literal">example.com</code> might place
6406 the zone contents into a file called
6407 <code class="filename">ex/example.com</code> where <code class="filename">ex/</code> is
6408 just the first two letters of the zone name. (Most
6410 behave very slowly if you put 100000 files into
6411 a single directory.)
6418 <code class="varname">stub</code>
6423 A stub zone is similar to a slave zone,
6424 except that it replicates only the NS records of a
6426 of the entire zone. Stub zones are not a standard part
6428 they are a feature specific to the <acronym class="acronym">BIND</acronym> implementation.
6432 Stub zones can be used to eliminate the need for glue
6434 in a parent zone at the expense of maintaining a stub
6436 a set of name server addresses in <code class="filename">named.conf</code>.
6437 This usage is not recommended for new configurations,
6439 supports it only in a limited way.
6440 In <acronym class="acronym">BIND</acronym> 4/8, zone
6441 transfers of a parent zone
6442 included the NS records from stub children of that
6444 that, in some cases, users could get away with
6445 configuring child stubs
6446 only in the master server for the parent zone. <acronym class="acronym">BIND</acronym>
6447 9 never mixes together zone data from different zones
6449 way. Therefore, if a <acronym class="acronym">BIND</acronym> 9 master serving a parent
6450 zone has child stub zones configured, all the slave
6452 parent zone also need to have the same child stub
6458 Stub zones can also be used as a way of forcing the
6460 of a given domain to use a particular set of
6461 authoritative servers.
6462 For example, the caching name servers on a private
6464 RFC1918 addressing may be configured with stub zones
6466 <code class="literal">10.in-addr.arpa</code>
6467 to use a set of internal name servers as the
6469 servers for that domain.
6476 <code class="varname">static-stub</code>
6481 A static-stub zone is similar to a stub zone
6482 with the following exceptions:
6483 the zone data is statically configured, rather
6484 than transferred from a master server;
6485 when recursion is necessary for a query that
6486 matches a static-stub zone, the locally
6487 configured data (nameserver names and glue addresses)
6488 is always used even if different authoritative
6489 information is cached.
6492 Zone data is configured via the
6493 <span><strong class="command">server-addresses</strong></span> and
6494 <span><strong class="command">server-names</strong></span> zone options.
6497 The zone data is maintained in the form of NS
6498 and (if necessary) glue A or AAAA RRs
6499 internally, which can be seen by dumping zone
6500 databases by <span><strong class="command">rndc dumpdb -all</strong></span>.
6501 The configured RRs are considered local configuration
6502 parameters rather than public data.
6503 Non recursive queries (i.e., those with the RD
6504 bit off) to a static-stub zone are therefore
6505 prohibited and will be responded with REFUSED.
6508 Since the data is statically configured, no
6509 zone maintenance action takes place for a static-stub
6511 For example, there is no periodic refresh
6512 attempt, and an incoming notify message
6513 will be rejected with an rcode of NOTAUTH.
6516 Each static-stub zone is configured with
6517 internally generated NS and (if necessary)
6525 <code class="varname">forward</code>
6530 A "forward zone" is a way to configure
6531 forwarding on a per-domain basis. A <span><strong class="command">zone</strong></span> statement
6532 of type <span><strong class="command">forward</strong></span> can
6533 contain a <span><strong class="command">forward</strong></span>
6534 and/or <span><strong class="command">forwarders</strong></span>
6536 which will apply to queries within the domain given by
6538 name. If no <span><strong class="command">forwarders</strong></span>
6539 statement is present or
6540 an empty list for <span><strong class="command">forwarders</strong></span> is given, then no
6541 forwarding will be done for the domain, canceling the
6543 any forwarders in the <span><strong class="command">options</strong></span> statement. Thus
6544 if you want to use this type of zone to change the
6546 global <span><strong class="command">forward</strong></span> option
6547 (that is, "forward first"
6548 to, then "forward only", or vice versa, but want to
6550 servers as set globally) you need to re-specify the
6558 <code class="varname">hint</code>
6563 The initial set of root name servers is
6564 specified using a "hint zone". When the server starts
6566 the root hints to find a root name server and get the
6568 list of root name servers. If no hint zone is
6570 IN, the server uses a compiled-in default set of root
6572 Classes other than IN have no built-in defaults hints.
6579 <code class="varname">delegation-only</code>
6584 This is used to enforce the delegation-only
6585 status of infrastructure zones (e.g. COM,
6586 NET, ORG). Any answer that is received
6587 without an explicit or implicit delegation
6588 in the authority section will be treated
6589 as NXDOMAIN. This does not apply to the
6590 zone apex. This should not be applied to
6594 <code class="varname">delegation-only</code> has no
6595 effect on answers received from forwarders.
6598 See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>.
6605 <div class="sect3" lang="en">
6606 <div class="titlepage"><div><div><h4 class="title">
6607 <a name="id2592085"></a>Class</h4></div></div></div>
6609 The zone's name may optionally be followed by a class. If
6610 a class is not specified, class <code class="literal">IN</code> (for <code class="varname">Internet</code>),
6611 is assumed. This is correct for the vast majority of cases.
6614 The <code class="literal">hesiod</code> class is
6615 named for an information service from MIT's Project Athena. It
6617 used to share information about various systems databases, such
6618 as users, groups, printers and so on. The keyword
6619 <code class="literal">HS</code> is
6620 a synonym for hesiod.
6623 Another MIT development is Chaosnet, a LAN protocol created
6624 in the mid-1970s. Zone data for it can be specified with the <code class="literal">CHAOS</code> class.
6627 <div class="sect3" lang="en">
6628 <div class="titlepage"><div><div><h4 class="title">
6629 <a name="id2592118"></a>Zone Options</h4></div></div></div>
6630 <div class="variablelist"><dl>
6631 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
6633 See the description of
6634 <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>.
6636 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
6638 See the description of
6639 <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>.
6641 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
6643 See the description of
6644 <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>.
6646 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
6648 See the description of <span><strong class="command">allow-transfer</strong></span>
6649 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
6651 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
6653 See the description of <span><strong class="command">allow-update</strong></span>
6654 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
6656 <dt><span class="term"><span><strong class="command">update-policy</strong></span></span></dt>
6658 Specifies a "Simple Secure Update" policy. See
6659 <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called “Dynamic Update Policies”</a>.
6661 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
6663 See the description of <span><strong class="command">allow-update-forwarding</strong></span>
6664 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
6666 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
6668 Only meaningful if <span><strong class="command">notify</strong></span>
6670 active for this zone. The set of machines that will
6672 <code class="literal">DNS NOTIFY</code> message
6673 for this zone is made up of all the listed name servers
6675 the primary master) for the zone plus any IP addresses
6677 with <span><strong class="command">also-notify</strong></span>. A port
6679 with each <span><strong class="command">also-notify</strong></span>
6680 address to send the notify
6681 messages to a port other than the default of 53.
6682 <span><strong class="command">also-notify</strong></span> is not
6683 meaningful for stub zones.
6684 The default is the empty list.
6686 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
6688 This option is used to restrict the character set and
6690 certain domain names in master files and/or DNS responses
6692 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>
6693 zones the default is <span><strong class="command">warn</strong></span>.
6694 It is not implemented for <span><strong class="command">hint</strong></span> zones.
6696 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
6698 See the description of
6699 <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>.
6701 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
6703 See the description of
6704 <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>.
6706 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
6708 See the description of
6709 <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>.
6711 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
6713 See the description of
6714 <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>.
6716 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
6718 See the description of
6719 <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>.
6721 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
6723 See the description of
6724 <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>.
6726 <dt><span class="term"><span><strong class="command">dnssec-dnskey-kskonly</strong></span></span></dt>
6728 See the description of
6729 <span><strong class="command">dnssec-dnskey-kskonly</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
6731 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
6733 See the description of
6734 <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>.
6736 <dt><span class="term"><span><strong class="command">database</strong></span></span></dt>
6739 Specify the type of database to be used for storing the
6740 zone data. The string following the <span><strong class="command">database</strong></span> keyword
6741 is interpreted as a list of whitespace-delimited words.
6743 identifies the database type, and any subsequent words are
6745 as arguments to the database to be interpreted in a way
6747 to the database type.
6750 The default is <strong class="userinput"><code>"rbt"</code></strong>, BIND 9's
6752 red-black-tree database. This database does not take
6756 Other values are possible if additional database drivers
6757 have been linked into the server. Some sample drivers are
6759 with the distribution but none are linked in by default.
6762 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
6764 See the description of
6765 <span><strong class="command">dialup</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
6767 <dt><span class="term"><span><strong class="command">delegation-only</strong></span></span></dt>
6770 The flag only applies to hint and stub zones. If set
6771 to <strong class="userinput"><code>yes</code></strong>, then the zone will also be
6772 treated as if it is also a delegation-only type zone.
6775 See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>.
6778 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
6780 Only meaningful if the zone has a forwarders
6781 list. The <span><strong class="command">only</strong></span> value causes
6783 after trying the forwarders and getting no answer, while <span><strong class="command">first</strong></span> would
6784 allow a normal lookup to be tried.
6786 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
6788 Used to override the list of global forwarders.
6789 If it is not specified in a zone of type <span><strong class="command">forward</strong></span>,
6790 no forwarding is done for the zone and the global options are
6793 <dt><span class="term"><span><strong class="command">ixfr-base</strong></span></span></dt>
6795 Was used in <acronym class="acronym">BIND</acronym> 8 to
6797 of the transaction log (journal) file for dynamic update
6799 <acronym class="acronym">BIND</acronym> 9 ignores the option
6800 and constructs the name of the journal
6801 file by appending "<code class="filename">.jnl</code>"
6805 <dt><span class="term"><span><strong class="command">ixfr-tmp-file</strong></span></span></dt>
6807 Was an undocumented option in <acronym class="acronym">BIND</acronym> 8.
6808 Ignored in <acronym class="acronym">BIND</acronym> 9.
6810 <dt><span class="term"><span><strong class="command">journal</strong></span></span></dt>
6812 Allow the default journal's filename to be overridden.
6813 The default is the zone's filename with "<code class="filename">.jnl</code>" appended.
6814 This is applicable to <span><strong class="command">master</strong></span> and <span><strong class="command">slave</strong></span> zones.
6816 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
6818 See the description of
6819 <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>.
6821 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
6823 See the description of
6824 <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>.
6826 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
6828 See the description of
6829 <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>.
6831 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
6833 See the description of
6834 <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>.
6836 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
6838 See the description of
6839 <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>.
6841 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
6843 See the description of
6844 <span><strong class="command">notify</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
6846 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
6848 See the description of
6849 <span><strong class="command">notify-delay</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
6851 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
6853 See the description of
6854 <span><strong class="command">notify-to-soa</strong></span> in
6855 <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
6857 <dt><span class="term"><span><strong class="command">pubkey</strong></span></span></dt>
6859 In <acronym class="acronym">BIND</acronym> 8, this option was
6860 intended for specifying
6861 a public zone key for verification of signatures in DNSSEC
6863 zones when they are loaded from disk. <acronym class="acronym">BIND</acronym> 9 does not verify signatures
6864 on load and ignores the option.
6866 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
6868 If <strong class="userinput"><code>yes</code></strong>, the server will keep
6870 information for this zone, which can be dumped to the
6871 <span><strong class="command">statistics-file</strong></span> defined in
6874 <dt><span class="term"><span><strong class="command">server-addresses</strong></span></span></dt>
6877 Only meaningful for static-stub zones.
6878 This is a list of IP addresses to which queries
6879 should be sent in recursive resolution for the
6881 A non empty list for this option will internally
6882 configure the apex NS RR with associated glue A or
6886 For example, if "example.com" is configured as a
6887 static-stub zone with 192.0.2.1 and 2001:db8::1234
6888 in a <span><strong class="command">server-addresses</strong></span> option,
6889 the following RRs will be internally configured.
6891 <pre class="programlisting">example.com. NS example.com.
6892 example.com. A 192.0.2.1
6893 example.com. AAAA 2001:db8::1234</pre>
6895 These records are internally used to resolve
6896 names under the static-stub zone.
6897 For instance, if the server receives a query for
6898 "www.example.com" with the RD bit on, the server
6899 will initiate recursive resolution and send
6900 queries to 192.0.2.1 and/or 2001:db8::1234.
6903 <dt><span class="term"><span><strong class="command">server-names</strong></span></span></dt>
6906 Only meaningful for static-stub zones.
6907 This is a list of domain names of nameservers that
6908 act as authoritative servers of the static-stub
6910 These names will be resolved to IP addresses when
6911 <span><strong class="command">named</strong></span> needs to send queries to
6913 To make this supplemental resolution successful,
6914 these names must not be a subdomain of the origin
6915 name of static-stub zone.
6916 That is, when "example.net" is the origin of a
6917 static-stub zone, "ns.example" and
6918 "master.example.com" can be specified in the
6919 <span><strong class="command">server-names</strong></span> option, but
6920 "ns.example.net" cannot, and will be rejected by
6921 the configuration parser.
6924 A non empty list for this option will internally
6925 configure the apex NS RR with the specified names.
6926 For example, if "example.com" is configured as a
6927 static-stub zone with "ns1.example.net" and
6929 in a <span><strong class="command">server-names</strong></span> option,
6930 the following RRs will be internally configured.
6932 <pre class="programlisting">example.com. NS ns1.example.net.
6933 example.com. NS ns2.example.net.
6936 These records are internally used to resolve
6937 names under the static-stub zone.
6938 For instance, if the server receives a query for
6939 "www.example.com" with the RD bit on, the server
6940 initiate recursive resolution,
6941 resolve "ns1.example.net" and/or
6942 "ns2.example.net" to IP addresses, and then send
6943 queries to (one or more of) these addresses.
6946 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
6948 See the description of
6949 <span><strong class="command">sig-validity-interval</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
6951 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
6953 See the description of
6954 <span><strong class="command">sig-signing-nodes</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
6956 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
6958 See the description of
6959 <span><strong class="command">sig-signing-signatures</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
6961 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
6963 See the description of
6964 <span><strong class="command">sig-signing-type</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
6966 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
6968 See the description of
6969 <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>.
6971 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
6973 See the description of
6974 <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>.
6976 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
6978 See the description of
6979 <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>.
6981 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
6983 See the description of
6984 <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>.
6986 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
6988 See the description of
6989 <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>.
6991 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
6993 See the description of
6994 <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>.
6996 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
6998 See the description of
6999 <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>.
7002 <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>
7005 See the description in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
7007 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
7009 See the description of
7010 <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>.
7011 (Note that the <span><strong class="command">ixfr-from-differences</strong></span>
7012 <strong class="userinput"><code>master</code></strong> and
7013 <strong class="userinput"><code>slave</code></strong> choices are not
7014 available at the zone level.)
7016 <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt>
7018 See the description of
7019 <span><strong class="command">key-directory</strong></span> in <a href="Bv9ARM.ch06.html#options" title="options Statement Definition and
7020 Usage">the section called “<span><strong class="command">options</strong></span> Statement Definition and
7023 <dt><span class="term"><span><strong class="command">auto-dnssec</strong></span></span></dt>
7026 Zones configured for dynamic DNS may also use this
7027 option to allow varying levels of automatic DNSSEC key
7028 management. There are four possible settings:
7031 <span><strong class="command">auto-dnssec allow;</strong></span> permits
7032 keys to be updated and the zone fully re-signed
7033 whenever the user issues the command <span><strong class="command">rndc sign
7034 <em class="replaceable"><code>zonename</code></em></strong></span>.
7037 <span><strong class="command">auto-dnssec maintain;</strong></span> includes the
7038 above, but also automatically adjusts the zone's DNSSEC
7039 keys on schedule, according to the keys' timing metadata
7040 (see <a href="man.dnssec-keygen.html" title="dnssec-keygen"><span class="refentrytitle"><span class="application">dnssec-keygen</span></span>(8)</a> and
7041 <a href="man.dnssec-settime.html" title="dnssec-settime"><span class="refentrytitle"><span class="application">dnssec-settime</span></span>(8)</a>). The command
7042 <span><strong class="command">rndc sign
7043 <em class="replaceable"><code>zonename</code></em></strong></span> causes
7044 <span><strong class="command">named</strong></span> to load keys from the key
7045 repository and sign the zone with all keys that are
7047 <span><strong class="command">rndc loadkeys
7048 <em class="replaceable"><code>zonename</code></em></strong></span> causes
7049 <span><strong class="command">named</strong></span> to load keys from the key
7050 repository and schedule key maintenance events to occur
7051 in the future, but it does not sign the full zone
7055 <span><strong class="command">auto-dnssec create;</strong></span> includes the
7056 above, but also allows <span><strong class="command">named</strong></span>
7057 to create new keys in the key repository when needed.
7058 (NOTE: This option is not yet implemented; the syntax is
7059 being reserved for future use.)
7062 The default setting is <span><strong class="command">auto-dnssec off</strong></span>.
7065 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
7067 See the description of <span><strong class="command">multi-master</strong></span> in
7068 <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
7070 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
7072 See the description of <span><strong class="command">masterfile-format</strong></span>
7073 in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
7075 <dt><span class="term"><span><strong class="command">dnssec-secure-to-insecure</strong></span></span></dt>
7077 See the description of
7078 <span><strong class="command">dnssec-secure-to-insecure</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
7082 <div class="sect3" lang="en">
7083 <div class="titlepage"><div><div><h4 class="title">
7084 <a name="dynamic_update_policies"></a>Dynamic Update Policies</h4></div></div></div>
7085 <p><acronym class="acronym">BIND</acronym> 9 supports two alternative
7086 methods of granting clients the right to perform
7087 dynamic updates to a zone, configured by the
7088 <span><strong class="command">allow-update</strong></span> and
7089 <span><strong class="command">update-policy</strong></span> option, respectively.
7092 The <span><strong class="command">allow-update</strong></span> clause works the
7093 same way as in previous versions of <acronym class="acronym">BIND</acronym>.
7094 It grants given clients the permission to update any
7095 record of any name in the zone.
7098 The <span><strong class="command">update-policy</strong></span> clause
7099 allows more fine-grained control over what updates are
7100 allowed. A set of rules is specified, where each rule
7101 either grants or denies permissions for one or more
7102 names to be updated by one or more identities. If
7103 the dynamic update request message is signed (that is,
7104 it includes either a TSIG or SIG(0) record), the
7105 identity of the signer can be determined.
7108 Rules are specified in the <span><strong class="command">update-policy</strong></span>
7109 zone option, and are only meaningful for master zones.
7110 When the <span><strong class="command">update-policy</strong></span> statement
7111 is present, it is a configuration error for the
7112 <span><strong class="command">allow-update</strong></span> statement to be
7113 present. The <span><strong class="command">update-policy</strong></span> statement
7114 only examines the signer of a message; the source
7115 address is not relevant.
7118 There is a pre-defined <span><strong class="command">update-policy</strong></span>
7119 rule which can be switched on with the command
7120 <span><strong class="command">update-policy local;</strong></span>.
7121 Switching on this rule in a zone causes
7122 <span><strong class="command">named</strong></span> to generate a TSIG session
7123 key and place it in a file, and to allow that key
7124 to update the zone. (By default, the file is
7125 <code class="filename">/var/run/named/session.key</code>, the key
7126 name is "local-ddns" and the key algorithm is HMAC-SHA256,
7127 but these values are configurable with the
7128 <span><strong class="command">session-keyfile</strong></span>,
7129 <span><strong class="command">session-keyname</strong></span> and
7130 <span><strong class="command">session-keyalg</strong></span> options, respectively).
7133 A client running on the local system, and with appropriate
7134 permissions, may read that file and use the key to sign update
7135 requests. The zone's update policy will be set to allow that
7136 key to change any record within the zone. Assuming the
7137 key name is "local-ddns", this policy is equivalent to:
7139 <pre class="programlisting">update-policy { grant local-ddns zonesub any; };
7142 The command <span><strong class="command">nsupdate -l</strong></span> sends update
7143 requests to localhost, and signs them using the session key.
7146 Other rule definitions look like this:
7148 <pre class="programlisting">
7149 ( <span><strong class="command">grant</strong></span> | <span><strong class="command">deny</strong></span> ) <em class="replaceable"><code>identity</code></em> <em class="replaceable"><code>nametype</code></em> [<span class="optional"> <em class="replaceable"><code>name</code></em> </span>] [<span class="optional"> <em class="replaceable"><code>types</code></em> </span>]
7152 Each rule grants or denies privileges. Once a message has
7153 successfully matched a rule, the operation is immediately
7154 granted or denied and no further rules are examined. A rule
7155 is matched when the signer matches the identity field, the
7156 name matches the name field in accordance with the nametype
7157 field, and the type matches the types specified in the type
7161 No signer is required for <em class="replaceable"><code>tcp-self</code></em>
7162 or <em class="replaceable"><code>6to4-self</code></em> however the standard
7163 reverse mapping / prefix conversion must match the identity
7167 The identity field specifies a name or a wildcard
7168 name. Normally, this is the name of the TSIG or
7169 SIG(0) key used to sign the update request. When a
7170 TKEY exchange has been used to create a shared secret,
7171 the identity of the shared secret is the same as the
7172 identity of the key used to authenticate the TKEY
7173 exchange. TKEY is also the negotiation method used
7174 by GSS-TSIG, which establishes an identity that is
7175 the Kerberos principal of the client, such as
7176 <strong class="userinput"><code>"user@host.domain"</code></strong>. When the
7177 <em class="replaceable"><code>identity</code></em> field specifies
7178 a wildcard name, it is subject to DNS wildcard
7179 expansion, so the rule will apply to multiple identities.
7180 The <em class="replaceable"><code>identity</code></em> field must
7181 contain a fully-qualified domain name.
7184 The <em class="replaceable"><code>nametype</code></em> field has 13
7186 <code class="varname">name</code>, <code class="varname">subdomain</code>,
7187 <code class="varname">wildcard</code>, <code class="varname">self</code>,
7188 <code class="varname">selfsub</code>, <code class="varname">selfwild</code>,
7189 <code class="varname">krb5-self</code>, <code class="varname">ms-self</code>,
7190 <code class="varname">krb5-subdomain</code>,
7191 <code class="varname">ms-subdomain</code>,
7192 <code class="varname">tcp-self</code>, <code class="varname">6to4-self</code>,
7193 <code class="varname">zonesub</code>, and <code class="varname">external</code>.
7195 <div class="informaltable"><table border="1">
7204 <code class="varname">name</code>
7209 Exact-match semantics. This rule matches
7210 when the name being updated is identical
7211 to the contents of the
7212 <em class="replaceable"><code>name</code></em> field.
7219 <code class="varname">subdomain</code>
7224 This rule matches when the name being updated
7225 is a subdomain of, or identical to, the
7226 contents of the <em class="replaceable"><code>name</code></em>
7234 <code class="varname">zonesub</code>
7239 This rule is similar to subdomain, except that
7240 it matches when the name being updated is a
7241 subdomain of the zone in which the
7242 <span><strong class="command">update-policy</strong></span> statement
7243 appears. This obviates the need to type the zone
7244 name twice, and enables the use of a standard
7245 <span><strong class="command">update-policy</strong></span> statement in
7246 multiple zones without modification.
7249 When this rule is used, the
7250 <em class="replaceable"><code>name</code></em> field is omitted.
7257 <code class="varname">wildcard</code>
7262 The <em class="replaceable"><code>name</code></em> field
7263 is subject to DNS wildcard expansion, and
7264 this rule matches when the name being updated
7265 name is a valid expansion of the wildcard.
7272 <code class="varname">self</code>
7277 This rule matches when the name being updated
7278 matches the contents of the
7279 <em class="replaceable"><code>identity</code></em> field.
7280 The <em class="replaceable"><code>name</code></em> field
7281 is ignored, but should be the same as the
7282 <em class="replaceable"><code>identity</code></em> field.
7283 The <code class="varname">self</code> nametype is
7284 most useful when allowing using one key per
7285 name to update, where the key has the same
7286 name as the name to be updated. The
7287 <em class="replaceable"><code>identity</code></em> would
7288 be specified as <code class="constant">*</code> (an asterisk) in
7296 <code class="varname">selfsub</code>
7301 This rule is similar to <code class="varname">self</code>
7302 except that subdomains of <code class="varname">self</code>
7303 can also be updated.
7310 <code class="varname">selfwild</code>
7315 This rule is similar to <code class="varname">self</code>
7316 except that only subdomains of
7317 <code class="varname">self</code> can be updated.
7324 <code class="varname">tcp-self</code>
7329 Allow updates that have been sent via TCP and
7330 for which the standard mapping from the initiating
7331 IP address into the IN-ADDR.ARPA and IP6.ARPA
7332 namespaces match the name to be updated.
7334 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7335 <h3 class="title">Note</h3>
7336 It is theoretically possible to spoof these TCP
7344 <code class="varname">6to4-self</code>
7349 Allow the 6to4 prefix to be update by any TCP
7350 connection from the 6to4 network or from the
7351 corresponding IPv4 address. This is intended
7352 to allow NS or DNAME RRsets to be added to the
7355 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7356 <h3 class="title">Note</h3>
7357 It is theoretically possible to spoof these TCP
7365 <code class="varname">external</code>
7370 This rule allows <span><strong class="command">named</strong></span>
7371 to defer the decision of whether to allow a
7372 given update to an external daemon.
7375 The method of communicating with the daemon is
7376 specified in the <em class="replaceable"><code>identity</code></em>
7377 field, the format of which is
7378 "<code class="constant">local:</code><em class="replaceable"><code>path</code></em>",
7379 where <em class="replaceable"><code>path</code></em> is the location
7380 of a UNIX-domain socket. (Currently, "local" is the
7381 only supported mechanism.)
7384 Requests to the external daemon are sent over the
7385 UNIX-domain socket as datagrams with the following
7388 <pre class="programlisting">
7389 Protocol version number (4 bytes, network byte order, currently 1)
7390 Request length (4 bytes, network byte order)
7391 Signer (null-terminated string)
7392 Name (null-terminated string)
7393 TCP source address (null-terminated string)
7394 Rdata type (null-terminated string)
7395 Key (null-terminated string)
7396 TKEY token length (4 bytes, network byte order)
7397 TKEY token (remainder of packet)</pre>
7399 The daemon replies with a four-byte value in
7400 network byte order, containing either 0 or 1; 0
7401 indicates that the specified update is not
7402 permitted, and 1 indicates that it is.
7409 In all cases, the <em class="replaceable"><code>name</code></em>
7410 field must specify a fully-qualified domain name.
7413 If no types are explicitly specified, this rule matches
7414 all types except RRSIG, NS, SOA, NSEC and NSEC3. Types
7415 may be specified by name, including "ANY" (ANY matches
7416 all types except NSEC and NSEC3, which can never be
7417 updated). Note that when an attempt is made to delete
7418 all records associated with a name, the rules are
7419 checked for each existing record type.
7424 <div class="sect1" lang="en">
7425 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
7426 <a name="id2594660"></a>Zone File</h2></div></div></div>
7427 <div class="sect2" lang="en">
7428 <div class="titlepage"><div><div><h3 class="title">
7429 <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>
7431 This section, largely borrowed from RFC 1034, describes the
7432 concept of a Resource Record (RR) and explains when each is used.
7433 Since the publication of RFC 1034, several new RRs have been
7435 and implemented in the DNS. These are also included.
7437 <div class="sect3" lang="en">
7438 <div class="titlepage"><div><div><h4 class="title">
7439 <a name="id2594678"></a>Resource Records</h4></div></div></div>
7441 A domain name identifies a node. Each node has a set of
7442 resource information, which may be empty. The set of resource
7443 information associated with a particular name is composed of
7444 separate RRs. The order of RRs in a set is not significant and
7445 need not be preserved by name servers, resolvers, or other
7446 parts of the DNS. However, sorting of multiple RRs is
7447 permitted for optimization purposes, for example, to specify
7448 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>.
7451 The components of a Resource Record are:
7453 <div class="informaltable"><table border="1">
7467 The domain name where the RR is found.
7479 An encoded 16-bit value that specifies
7480 the type of the resource record.
7492 The time-to-live of the RR. This field
7493 is a 32-bit integer in units of seconds, and is
7495 resolvers when they cache RRs. The TTL describes how
7497 be cached before it should be discarded.
7509 An encoded 16-bit value that identifies
7510 a protocol family or instance of a protocol.
7522 The resource data. The format of the
7523 data is type (and sometimes class) specific.
7530 The following are <span class="emphasis"><em>types</em></span> of valid RRs:
7532 <div class="informaltable"><table border="1">
7546 A host address. In the IN class, this is a
7547 32-bit IP address. Described in RFC 1035.
7559 IPv6 address. Described in RFC 1886.
7571 IPv6 address. This can be a partial
7572 address (a suffix) and an indirection to the name
7573 where the rest of the
7574 address (the prefix) can be found. Experimental.
7575 Described in RFC 2874.
7587 Location of AFS database servers.
7588 Experimental. Described in RFC 1183.
7600 Address prefix list. Experimental.
7601 Described in RFC 3123.
7613 Holds a digital certificate.
7614 Described in RFC 2538.
7626 Identifies the canonical name of an alias.
7627 Described in RFC 1035.
7639 Is used for identifying which DHCP client is
7640 associated with this name. Described in RFC 4701.
7652 Replaces the domain name specified with
7653 another name to be looked up, effectively aliasing an
7655 subtree of the domain name space rather than a single
7657 as in the case of the CNAME RR.
7658 Described in RFC 2672.
7670 Stores a public key associated with a signed
7671 DNS zone. Described in RFC 4034.
7683 Stores the hash of a public key associated with a
7684 signed DNS zone. Described in RFC 4034.
7696 Specifies the global position. Superseded by LOC.
7708 Identifies the CPU and OS used by a host.
7709 Described in RFC 1035.
7721 Provides a method for storing IPsec keying material in
7722 DNS. Described in RFC 4025.
7734 Representation of ISDN addresses.
7735 Experimental. Described in RFC 1183.
7747 Stores a public key associated with a
7748 DNS name. Used in original DNSSEC; replaced
7749 by DNSKEY in DNSSECbis, but still used with
7750 SIG(0). Described in RFCs 2535 and 2931.
7762 Identifies a key exchanger for this
7763 DNS name. Described in RFC 2230.
7775 For storing GPS info. Described in RFC 1876.
7788 Identifies a mail exchange for the domain with
7789 a 16-bit preference value (lower is better)
7790 followed by the host name of the mail exchange.
7791 Described in RFC 974, RFC 1035.
7803 Name authority pointer. Described in RFC 2915.
7815 A network service access point.
7816 Described in RFC 1706.
7828 The authoritative name server for the
7829 domain. Described in RFC 1035.
7841 Used in DNSSECbis to securely indicate that
7842 RRs with an owner name in a certain name interval do
7844 a zone and indicate what RR types are present for an
7846 Described in RFC 4034.
7858 Used in DNSSECbis to securely indicate that
7859 RRs with an owner name in a certain name
7860 interval do not exist in a zone and indicate
7861 what RR types are present for an existing
7862 name. NSEC3 differs from NSEC in that it
7863 prevents zone enumeration but is more
7864 computationally expensive on both the server
7865 and the client than NSEC. Described in RFC
7878 Used in DNSSECbis to tell the authoritative
7879 server which NSEC3 chains are available to use.
7880 Described in RFC 5155.
7892 Used in DNSSEC to securely indicate that
7893 RRs with an owner name in a certain name interval do
7895 a zone and indicate what RR types are present for an
7897 Used in original DNSSEC; replaced by NSEC in
7899 Described in RFC 2535.
7911 A pointer to another part of the domain
7912 name space. Described in RFC 1035.
7924 Provides mappings between RFC 822 and X.400
7925 addresses. Described in RFC 2163.
7937 Information on persons responsible
7938 for the domain. Experimental. Described in RFC 1183.
7950 Contains DNSSECbis signature data. Described
7963 Route-through binding for hosts that
7964 do not have their own direct wide area network
7966 Experimental. Described in RFC 1183.
7978 Contains DNSSEC signature data. Used in
7979 original DNSSEC; replaced by RRSIG in
7980 DNSSECbis, but still used for SIG(0).
7981 Described in RFCs 2535 and 2931.
7993 Identifies the start of a zone of authority.
7994 Described in RFC 1035.
8006 Contains the Sender Policy Framework information
8007 for a given email domain. Described in RFC 4408.
8019 Information about well known network
8020 services (replaces WKS). Described in RFC 2782.
8032 Provides a way to securely publish a secure shell key's
8033 fingerprint. Described in RFC 4255.
8045 Text records. Described in RFC 1035.
8057 Information about which well known
8058 network services, such as SMTP, that a domain
8059 supports. Historical.
8071 Representation of X.25 network addresses.
8072 Experimental. Described in RFC 1183.
8079 The following <span class="emphasis"><em>classes</em></span> of resource records
8080 are currently valid in the DNS:
8082 <div class="informaltable"><table border="1">
8108 Chaosnet, a LAN protocol created at MIT in the
8110 Rarely used for its historical purpose, but reused for
8112 built-in server information zones, e.g.,
8113 <code class="literal">version.bind</code>.
8125 Hesiod, an information service
8126 developed by MIT's Project Athena. It is used to share
8128 about various systems databases, such as users,
8137 The owner name is often implicit, rather than forming an
8139 part of the RR. For example, many name servers internally form
8141 or hash structures for the name space, and chain RRs off nodes.
8142 The remaining RR parts are the fixed header (type, class, TTL)
8143 which is consistent for all RRs, and a variable part (RDATA)
8145 fits the needs of the resource being described.
8148 The meaning of the TTL field is a time limit on how long an
8149 RR can be kept in a cache. This limit does not apply to
8151 data in zones; it is also timed out, but by the refreshing
8153 for the zone. The TTL is assigned by the administrator for the
8154 zone where the data originates. While short TTLs can be used to
8155 minimize caching, and a zero TTL prohibits caching, the
8157 of Internet performance suggest that these times should be on
8159 order of days for the typical host. If a change can be
8161 the TTL can be reduced prior to the change to minimize
8163 during the change, and then increased back to its former value
8168 The data in the RDATA section of RRs is carried as a combination
8169 of binary strings and domain names. The domain names are
8171 used as "pointers" to other data in the DNS.
8174 <div class="sect3" lang="en">
8175 <div class="titlepage"><div><div><h4 class="title">
8176 <a name="id2596301"></a>Textual expression of RRs</h4></div></div></div>
8178 RRs are represented in binary form in the packets of the DNS
8179 protocol, and are usually represented in highly encoded form
8181 stored in a name server or resolver. In the examples provided
8183 RFC 1034, a style similar to that used in master files was
8185 in order to show the contents of RRs. In this format, most RRs
8186 are shown on a single line, although continuation lines are
8191 The start of the line gives the owner of the RR. If a line
8192 begins with a blank, then the owner is assumed to be the same as
8193 that of the previous RR. Blank lines are often included for
8197 Following the owner, we list the TTL, type, and class of the
8198 RR. Class and type use the mnemonics defined above, and TTL is
8199 an integer before the type field. In order to avoid ambiguity
8201 parsing, type and class mnemonics are disjoint, TTLs are
8203 and the type mnemonic is always last. The IN class and TTL
8205 are often omitted from examples in the interests of clarity.
8208 The resource data or RDATA section of the RR are given using
8209 knowledge of the typical representation for the data.
8212 For example, we might show the RRs carried in a message as:
8214 <div class="informaltable"><table border="1">
8224 <code class="literal">ISI.EDU.</code>
8229 <code class="literal">MX</code>
8234 <code class="literal">10 VENERA.ISI.EDU.</code>
8244 <code class="literal">MX</code>
8249 <code class="literal">10 VAXA.ISI.EDU</code>
8256 <code class="literal">VENERA.ISI.EDU</code>
8261 <code class="literal">A</code>
8266 <code class="literal">128.9.0.32</code>
8276 <code class="literal">A</code>
8281 <code class="literal">10.1.0.52</code>
8288 <code class="literal">VAXA.ISI.EDU</code>
8293 <code class="literal">A</code>
8298 <code class="literal">10.2.0.27</code>
8308 <code class="literal">A</code>
8313 <code class="literal">128.9.0.33</code>
8320 The MX RRs have an RDATA section which consists of a 16-bit
8321 number followed by a domain name. The address RRs use a
8323 IP address format to contain a 32-bit internet address.
8326 The above example shows six RRs, with two RRs at each of three
8330 Similarly we might see:
8332 <div class="informaltable"><table border="1">
8342 <code class="literal">XX.LCS.MIT.EDU.</code>
8347 <code class="literal">IN A</code>
8352 <code class="literal">10.0.0.44</code>
8360 <code class="literal">CH A</code>
8365 <code class="literal">MIT.EDU. 2420</code>
8372 This example shows two addresses for
8373 <code class="literal">XX.LCS.MIT.EDU</code>, each of a different class.
8377 <div class="sect2" lang="en">
8378 <div class="titlepage"><div><div><h3 class="title">
8379 <a name="id2596822"></a>Discussion of MX Records</h3></div></div></div>
8381 As described above, domain servers store information as a
8382 series of resource records, each of which contains a particular
8383 piece of information about a given domain name (which is usually,
8384 but not always, a host). The simplest way to think of a RR is as
8385 a typed pair of data, a domain name matched with a relevant datum,
8386 and stored with some additional type information to help systems
8387 determine when the RR is relevant.
8390 MX records are used to control delivery of email. The data
8391 specified in the record is a priority and a domain name. The
8393 controls the order in which email delivery is attempted, with the
8394 lowest number first. If two priorities are the same, a server is
8395 chosen randomly. If no servers at a given priority are responding,
8396 the mail transport agent will fall back to the next largest
8398 Priority numbers do not have any absolute meaning — they are
8400 only respective to other MX records for that domain name. The
8402 name given is the machine to which the mail will be delivered.
8403 It <span class="emphasis"><em>must</em></span> have an associated address record
8404 (A or AAAA) — CNAME is not sufficient.
8407 For a given domain, if there is both a CNAME record and an
8408 MX record, the MX record is in error, and will be ignored.
8410 the mail will be delivered to the server specified in the MX
8412 pointed to by the CNAME.
8415 <div class="informaltable"><table border="1">
8427 <code class="literal">example.com.</code>
8432 <code class="literal">IN</code>
8437 <code class="literal">MX</code>
8442 <code class="literal">10</code>
8447 <code class="literal">mail.example.com.</code>
8457 <code class="literal">IN</code>
8462 <code class="literal">MX</code>
8467 <code class="literal">10</code>
8472 <code class="literal">mail2.example.com.</code>
8482 <code class="literal">IN</code>
8487 <code class="literal">MX</code>
8492 <code class="literal">20</code>
8497 <code class="literal">mail.backup.org.</code>
8504 <code class="literal">mail.example.com.</code>
8509 <code class="literal">IN</code>
8514 <code class="literal">A</code>
8519 <code class="literal">10.0.0.1</code>
8529 <code class="literal">mail2.example.com.</code>
8534 <code class="literal">IN</code>
8539 <code class="literal">A</code>
8544 <code class="literal">10.0.0.2</code>
8554 Mail delivery will be attempted to <code class="literal">mail.example.com</code> and
8555 <code class="literal">mail2.example.com</code> (in
8556 any order), and if neither of those succeed, delivery to <code class="literal">mail.backup.org</code> will
8560 <div class="sect2" lang="en">
8561 <div class="titlepage"><div><div><h3 class="title">
8562 <a name="Setting_TTLs"></a>Setting TTLs</h3></div></div></div>
8564 The time-to-live of the RR field is a 32-bit integer represented
8565 in units of seconds, and is primarily used by resolvers when they
8566 cache RRs. The TTL describes how long a RR can be cached before it
8567 should be discarded. The following three types of TTL are
8569 used in a zone file.
8571 <div class="informaltable"><table border="1">
8585 The last field in the SOA is the negative
8586 caching TTL. This controls how long other servers will
8587 cache no-such-domain
8588 (NXDOMAIN) responses from you.
8591 The maximum time for
8592 negative caching is 3 hours (3h).
8604 The $TTL directive at the top of the
8605 zone file (before the SOA) gives a default TTL for every
8619 Each RR can have a TTL as the second
8620 field in the RR, which will control how long other
8629 All of these TTLs default to units of seconds, though units
8630 can be explicitly specified, for example, <code class="literal">1h30m</code>.
8633 <div class="sect2" lang="en">
8634 <div class="titlepage"><div><div><h3 class="title">
8635 <a name="id2597574"></a>Inverse Mapping in IPv4</h3></div></div></div>
8637 Reverse name resolution (that is, translation from IP address
8638 to name) is achieved by means of the <span class="emphasis"><em>in-addr.arpa</em></span> domain
8639 and PTR records. Entries in the in-addr.arpa domain are made in
8640 least-to-most significant order, read left to right. This is the
8641 opposite order to the way IP addresses are usually written. Thus,
8642 a machine with an IP address of 10.1.2.3 would have a
8644 in-addr.arpa name of
8645 3.2.1.10.in-addr.arpa. This name should have a PTR resource record
8646 whose data field is the name of the machine or, optionally,
8648 PTR records if the machine has more than one name. For example,
8649 in the [<span class="optional">example.com</span>] domain:
8651 <div class="informaltable"><table border="1">
8660 <code class="literal">$ORIGIN</code>
8665 <code class="literal">2.1.10.in-addr.arpa</code>
8672 <code class="literal">3</code>
8677 <code class="literal">IN PTR foo.example.com.</code>
8683 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
8684 <h3 class="title">Note</h3>
8686 The <span><strong class="command">$ORIGIN</strong></span> lines in the examples
8687 are for providing context to the examples only — they do not
8689 appear in the actual usage. They are only used here to indicate
8690 that the example is relative to the listed origin.
8694 <div class="sect2" lang="en">
8695 <div class="titlepage"><div><div><h3 class="title">
8696 <a name="id2597701"></a>Other Zone File Directives</h3></div></div></div>
8698 The Master File Format was initially defined in RFC 1035 and
8699 has subsequently been extended. While the Master File Format
8701 is class independent all records in a Master File must be of the
8706 Master File Directives include <span><strong class="command">$ORIGIN</strong></span>, <span><strong class="command">$INCLUDE</strong></span>,
8707 and <span><strong class="command">$TTL.</strong></span>
8709 <div class="sect3" lang="en">
8710 <div class="titlepage"><div><div><h4 class="title">
8711 <a name="id2597723"></a>The <span><strong class="command">@</strong></span> (at-sign)</h4></div></div></div>
8713 When used in the label (or name) field, the asperand or
8714 at-sign (@) symbol represents the current origin.
8715 At the start of the zone file, it is the
8716 <<code class="varname">zone_name</code>> (followed by
8720 <div class="sect3" lang="en">
8721 <div class="titlepage"><div><div><h4 class="title">
8722 <a name="id2597739"></a>The <span><strong class="command">$ORIGIN</strong></span> Directive</h4></div></div></div>
8724 Syntax: <span><strong class="command">$ORIGIN</strong></span>
8725 <em class="replaceable"><code>domain-name</code></em>
8726 [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
8728 <p><span><strong class="command">$ORIGIN</strong></span>
8729 sets the domain name that will be appended to any
8730 unqualified records. When a zone is first read in there
8731 is an implicit <span><strong class="command">$ORIGIN</strong></span>
8732 <<code class="varname">zone_name</code>><span><strong class="command">.</strong></span>
8733 (followed by trailing dot).
8734 The current <span><strong class="command">$ORIGIN</strong></span> is appended to
8735 the domain specified in the <span><strong class="command">$ORIGIN</strong></span>
8736 argument if it is not absolute.
8738 <pre class="programlisting">
8739 $ORIGIN example.com.
8740 WWW CNAME MAIN-SERVER
8745 <pre class="programlisting">
8746 WWW.EXAMPLE.COM. CNAME MAIN-SERVER.EXAMPLE.COM.
8749 <div class="sect3" lang="en">
8750 <div class="titlepage"><div><div><h4 class="title">
8751 <a name="id2597868"></a>The <span><strong class="command">$INCLUDE</strong></span> Directive</h4></div></div></div>
8753 Syntax: <span><strong class="command">$INCLUDE</strong></span>
8754 <em class="replaceable"><code>filename</code></em>
8755 [<span class="optional">
8756 <em class="replaceable"><code>origin</code></em> </span>]
8757 [<span class="optional"> <em class="replaceable"><code>comment</code></em> </span>]
8760 Read and process the file <code class="filename">filename</code> as
8761 if it were included into the file at this point. If <span><strong class="command">origin</strong></span> is
8762 specified the file is processed with <span><strong class="command">$ORIGIN</strong></span> set
8763 to that value, otherwise the current <span><strong class="command">$ORIGIN</strong></span> is
8767 The origin and the current domain name
8768 revert to the values they had prior to the <span><strong class="command">$INCLUDE</strong></span> once
8769 the file has been read.
8771 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
8772 <h3 class="title">Note</h3>
8774 RFC 1035 specifies that the current origin should be restored
8776 an <span><strong class="command">$INCLUDE</strong></span>, but it is silent
8777 on whether the current
8778 domain name should also be restored. BIND 9 restores both of
8780 This could be construed as a deviation from RFC 1035, a
8785 <div class="sect3" lang="en">
8786 <div class="titlepage"><div><div><h4 class="title">
8787 <a name="id2597938"></a>The <span><strong class="command">$TTL</strong></span> Directive</h4></div></div></div>
8789 Syntax: <span><strong class="command">$TTL</strong></span>
8790 <em class="replaceable"><code>default-ttl</code></em>
8791 [<span class="optional">
8792 <em class="replaceable"><code>comment</code></em> </span>]
8795 Set the default Time To Live (TTL) for subsequent records
8796 with undefined TTLs. Valid TTLs are of the range 0-2147483647
8799 <p><span><strong class="command">$TTL</strong></span>
8800 is defined in RFC 2308.
8804 <div class="sect2" lang="en">
8805 <div class="titlepage"><div><div><h3 class="title">
8806 <a name="id2597974"></a><acronym class="acronym">BIND</acronym> Master File Extension: the <span><strong class="command">$GENERATE</strong></span> Directive</h3></div></div></div>
8808 Syntax: <span><strong class="command">$GENERATE</strong></span>
8809 <em class="replaceable"><code>range</code></em>
8810 <em class="replaceable"><code>lhs</code></em>
8811 [<span class="optional"><em class="replaceable"><code>ttl</code></em></span>]
8812 [<span class="optional"><em class="replaceable"><code>class</code></em></span>]
8813 <em class="replaceable"><code>type</code></em>
8814 <em class="replaceable"><code>rhs</code></em>
8815 [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
8817 <p><span><strong class="command">$GENERATE</strong></span>
8818 is used to create a series of resource records that only
8819 differ from each other by an
8820 iterator. <span><strong class="command">$GENERATE</strong></span> can be used to
8821 easily generate the sets of records required to support
8822 sub /24 reverse delegations described in RFC 2317:
8823 Classless IN-ADDR.ARPA delegation.
8825 <pre class="programlisting">$ORIGIN 0.0.192.IN-ADDR.ARPA.
8826 $GENERATE 1-2 @ NS SERVER$.EXAMPLE.
8827 $GENERATE 1-127 $ CNAME $.0</pre>
8831 <pre class="programlisting">0.0.0.192.IN-ADDR.ARPA. NS SERVER1.EXAMPLE.
8832 0.0.0.192.IN-ADDR.ARPA. NS SERVER2.EXAMPLE.
8833 1.0.0.192.IN-ADDR.ARPA. CNAME 1.0.0.0.192.IN-ADDR.ARPA.
8834 2.0.0.192.IN-ADDR.ARPA. CNAME 2.0.0.0.192.IN-ADDR.ARPA.
8836 127.0.0.192.IN-ADDR.ARPA. CNAME 127.0.0.0.192.IN-ADDR.ARPA.
8839 Generate a set of A and MX records. Note the MX's right hand
8840 side is a quoted string. The quotes will be stripped when the
8841 right hand side is processed.
8843 <pre class="programlisting">
8845 $GENERATE 1-127 HOST-$ A 1.2.3.$
8846 $GENERATE 1-127 HOST-$ MX "0 ."</pre>
8850 <pre class="programlisting">HOST-1.EXAMPLE. A 1.2.3.1
8851 HOST-1.EXAMPLE. MX 0 .
8852 HOST-2.EXAMPLE. A 1.2.3.2
8853 HOST-2.EXAMPLE. MX 0 .
8854 HOST-3.EXAMPLE. A 1.2.3.3
8855 HOST-3.EXAMPLE. MX 0 .
8857 HOST-127.EXAMPLE. A 1.2.3.127
8858 HOST-127.EXAMPLE. MX 0 .
8860 <div class="informaltable"><table border="1">
8868 <p><span><strong class="command">range</strong></span></p>
8872 This can be one of two forms: start-stop
8873 or start-stop/step. If the first form is used, then step
8875 1. All of start, stop and step must be positive.
8881 <p><span><strong class="command">lhs</strong></span></p>
8885 describes the owner name of the resource records
8886 to be created. Any single <span><strong class="command">$</strong></span>
8888 symbols within the <span><strong class="command">lhs</strong></span> string
8889 are replaced by the iterator value.
8891 To get a $ in the output, you need to escape the
8892 <span><strong class="command">$</strong></span> using a backslash
8893 <span><strong class="command">\</strong></span>,
8894 e.g. <span><strong class="command">\$</strong></span>. The
8895 <span><strong class="command">$</strong></span> may optionally be followed
8896 by modifiers which change the offset from the
8897 iterator, field width and base.
8899 Modifiers are introduced by a
8900 <span><strong class="command">{</strong></span> (left brace) immediately following the
8901 <span><strong class="command">$</strong></span> as
8902 <span><strong class="command">${offset[,width[,base]]}</strong></span>.
8903 For example, <span><strong class="command">${-20,3,d}</strong></span>
8904 subtracts 20 from the current value, prints the
8905 result as a decimal in a zero-padded field of
8908 Available output forms are decimal
8909 (<span><strong class="command">d</strong></span>), octal
8910 (<span><strong class="command">o</strong></span>), hexadecimal
8911 (<span><strong class="command">x</strong></span> or <span><strong class="command">X</strong></span>
8912 for uppercase) and nibble
8913 (<span><strong class="command">n</strong></span> or <span><strong class="command">N</strong></span>\
8914 for uppercase). The default modifier is
8915 <span><strong class="command">${0,0,d}</strong></span>. If the
8916 <span><strong class="command">lhs</strong></span> is not absolute, the
8917 current <span><strong class="command">$ORIGIN</strong></span> is appended
8921 In nibble mode the value will be treated as
8922 if it was a reversed hexadecimal string
8923 with each hexadecimal digit as a separate
8924 label. The width field includes the label
8928 For compatibility with earlier versions,
8929 <span><strong class="command">$$</strong></span> is still recognized as
8930 indicating a literal $ in the output.
8936 <p><span><strong class="command">ttl</strong></span></p>
8940 Specifies the time-to-live of the generated records. If
8941 not specified this will be inherited using the
8942 normal TTL inheritance rules.
8944 <p><span><strong class="command">class</strong></span>
8945 and <span><strong class="command">ttl</strong></span> can be
8946 entered in either order.
8952 <p><span><strong class="command">class</strong></span></p>
8956 Specifies the class of the generated records.
8957 This must match the zone class if it is
8960 <p><span><strong class="command">class</strong></span>
8961 and <span><strong class="command">ttl</strong></span> can be
8962 entered in either order.
8968 <p><span><strong class="command">type</strong></span></p>
8978 <p><span><strong class="command">rhs</strong></span></p>
8982 <span><strong class="command">rhs</strong></span>, optionally, quoted string.
8989 The <span><strong class="command">$GENERATE</strong></span> directive is a <acronym class="acronym">BIND</acronym> extension
8990 and not part of the standard zone file format.
8993 BIND 8 does not support the optional TTL and CLASS fields.
8996 <div class="sect2" lang="en">
8997 <div class="titlepage"><div><div><h3 class="title">
8998 <a name="zonefile_format"></a>Additional File Formats</h3></div></div></div>
9000 In addition to the standard textual format, BIND 9
9001 supports the ability to read or dump to zone files in
9002 other formats. The <code class="constant">raw</code> format is
9003 currently available as an additional format. It is a
9004 binary format representing BIND 9's internal data
9005 structure directly, thereby remarkably improving the
9009 For a primary server, a zone file in the
9010 <code class="constant">raw</code> format is expected to be
9011 generated from a textual zone file by the
9012 <span><strong class="command">named-compilezone</strong></span> command. For a
9013 secondary server or for a dynamic zone, it is automatically
9014 generated (if this format is specified by the
9015 <span><strong class="command">masterfile-format</strong></span> option) when
9016 <span><strong class="command">named</strong></span> dumps the zone contents after
9017 zone transfer or when applying prior updates.
9020 If a zone file in a binary format needs manual modification,
9021 it first must be converted to a textual form by the
9022 <span><strong class="command">named-compilezone</strong></span> command. All
9023 necessary modification should go to the text file, which
9024 should then be converted to the binary form by the
9025 <span><strong class="command">named-compilezone</strong></span> command again.
9028 Although the <code class="constant">raw</code> format uses the
9029 network byte order and avoids architecture-dependent
9030 data alignment so that it is as much portable as
9031 possible, it is primarily expected to be used inside
9032 the same single system. In order to export a zone
9033 file in the <code class="constant">raw</code> format or make a
9034 portable backup of the file, it is recommended to
9035 convert the file to the standard textual representation.
9039 <div class="sect1" lang="en">
9040 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
9041 <a name="statistics"></a>BIND9 Statistics</h2></div></div></div>
9043 <acronym class="acronym">BIND</acronym> 9 maintains lots of statistics
9044 information and provides several interfaces for users to
9045 get access to the statistics.
9046 The available statistics include all statistics counters
9047 that were available in <acronym class="acronym">BIND</acronym> 8 and
9048 are meaningful in <acronym class="acronym">BIND</acronym> 9,
9049 and other information that is considered useful.
9052 The statistics information is categorized into the following
9055 <div class="informaltable"><table border="1">
9063 <p>Incoming Requests</p>
9067 The number of incoming DNS requests for each OPCODE.
9073 <p>Incoming Queries</p>
9077 The number of incoming queries for each RR type.
9083 <p>Outgoing Queries</p>
9087 The number of outgoing queries for each RR
9088 type sent from the internal resolver.
9089 Maintained per view.
9095 <p>Name Server Statistics</p>
9099 Statistics counters about incoming request processing.
9105 <p>Zone Maintenance Statistics</p>
9109 Statistics counters regarding zone maintenance
9110 operations such as zone transfers.
9116 <p>Resolver Statistics</p>
9120 Statistics counters about name resolution
9121 performed in the internal resolver.
9122 Maintained per view.
9128 <p>Cache DB RRsets</p>
9132 The number of RRsets per RR type and nonexistent
9133 names stored in the cache database.
9134 If the exclamation mark (!) is printed for a RR
9135 type, it means that particular type of RRset is
9136 known to be nonexistent (this is also known as
9138 Maintained per view.
9144 <p>Socket I/O Statistics</p>
9148 Statistics counters about network related events.
9155 A subset of Name Server Statistics is collected and shown
9156 per zone for which the server has the authority when
9157 <span><strong class="command">zone-statistics</strong></span> is set to
9158 <strong class="userinput"><code>yes</code></strong>.
9159 These statistics counters are shown with their zone and view
9161 In some cases the view names are omitted for the default view.
9164 There are currently two user interfaces to get access to the
9166 One is in the plain text format dumped to the file specified
9167 by the <span><strong class="command">statistics-file</strong></span> configuration option.
9168 The other is remotely accessible via a statistics channel
9169 when the <span><strong class="command">statistics-channels</strong></span> statement
9170 is specified in the configuration file
9171 (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>.)
9173 <div class="sect3" lang="en">
9174 <div class="titlepage"><div><div><h4 class="title">
9175 <a name="statsfile"></a>The Statistics File</h4></div></div></div>
9177 The text format statistics dump begins with a line, like:
9180 <span><strong class="command">+++ Statistics Dump +++ (973798949)</strong></span>
9183 The number in parentheses is a standard
9184 Unix-style timestamp, measured as seconds since January 1, 1970.
9187 that line is a set of statistics information, which is categorized
9189 Each section begins with a line, like:
9192 <span><strong class="command">++ Name Server Statistics ++</strong></span>
9195 Each section consists of lines, each containing the statistics
9196 counter value followed by its textual description.
9197 See below for available counters.
9198 For brevity, counters that have a value of 0 are not shown
9199 in the statistics file.
9202 The statistics dump ends with the line where the
9203 number is identical to the number in the beginning line; for example:
9206 <span><strong class="command">--- Statistics Dump --- (973798949)</strong></span>
9209 <div class="sect2" lang="en">
9210 <div class="titlepage"><div><div><h3 class="title">
9211 <a name="statistics_counters"></a>Statistics Counters</h3></div></div></div>
9213 The following tables summarize statistics counters that
9214 <acronym class="acronym">BIND</acronym> 9 provides.
9215 For each row of the tables, the leftmost column is the
9216 abbreviated symbol name of that counter.
9217 These symbols are shown in the statistics information
9218 accessed via an HTTP statistics channel.
9219 The rightmost column gives the description of the counter,
9220 which is also shown in the statistics file
9221 (but, in this document, possibly with slight modification
9222 for better readability).
9223 Additional notes may also be provided in this column.
9224 When a middle column exists between these two columns,
9225 it gives the corresponding counter name of the
9226 <acronym class="acronym">BIND</acronym> 8 statistics, if applicable.
9228 <div class="sect3" lang="en">
9229 <div class="titlepage"><div><div><h4 class="title">
9230 <a name="id2598928"></a>Name Server Statistics Counters</h4></div></div></div>
9231 <div class="informaltable"><table border="1">
9241 <span class="emphasis"><em>Symbol</em></span>
9246 <span class="emphasis"><em>BIND8 Symbol</em></span>
9251 <span class="emphasis"><em>Description</em></span>
9257 <p><span><strong class="command">Requestv4</strong></span></p>
9260 <p><span><strong class="command">RQ</strong></span></p>
9264 IPv4 requests received.
9265 Note: this also counts non query requests.
9271 <p><span><strong class="command">Requestv6</strong></span></p>
9274 <p><span><strong class="command">RQ</strong></span></p>
9278 IPv6 requests received.
9279 Note: this also counts non query requests.
9285 <p><span><strong class="command">ReqEdns0</strong></span></p>
9288 <p><span><strong class="command"></strong></span></p>
9292 Requests with EDNS(0) received.
9298 <p><span><strong class="command">ReqBadEDNSVer</strong></span></p>
9301 <p><span><strong class="command"></strong></span></p>
9305 Requests with unsupported EDNS version received.
9311 <p><span><strong class="command">ReqTSIG</strong></span></p>
9314 <p><span><strong class="command"></strong></span></p>
9318 Requests with TSIG received.
9324 <p><span><strong class="command">ReqSIG0</strong></span></p>
9327 <p><span><strong class="command"></strong></span></p>
9331 Requests with SIG(0) received.
9337 <p><span><strong class="command">ReqBadSIG</strong></span></p>
9340 <p><span><strong class="command"></strong></span></p>
9344 Requests with invalid (TSIG or SIG(0)) signature.
9350 <p><span><strong class="command">ReqTCP</strong></span></p>
9353 <p><span><strong class="command">RTCP</strong></span></p>
9357 TCP requests received.
9363 <p><span><strong class="command">AuthQryRej</strong></span></p>
9366 <p><span><strong class="command">RUQ</strong></span></p>
9370 Authoritative (non recursive) queries rejected.
9376 <p><span><strong class="command">RecQryRej</strong></span></p>
9379 <p><span><strong class="command">RURQ</strong></span></p>
9383 Recursive queries rejected.
9389 <p><span><strong class="command">XfrRej</strong></span></p>
9392 <p><span><strong class="command">RUXFR</strong></span></p>
9396 Zone transfer requests rejected.
9402 <p><span><strong class="command">UpdateRej</strong></span></p>
9405 <p><span><strong class="command">RUUpd</strong></span></p>
9409 Dynamic update requests rejected.
9415 <p><span><strong class="command">Response</strong></span></p>
9418 <p><span><strong class="command">SAns</strong></span></p>
9428 <p><span><strong class="command">RespTruncated</strong></span></p>
9431 <p><span><strong class="command"></strong></span></p>
9435 Truncated responses sent.
9441 <p><span><strong class="command">RespEDNS0</strong></span></p>
9444 <p><span><strong class="command"></strong></span></p>
9448 Responses with EDNS(0) sent.
9454 <p><span><strong class="command">RespTSIG</strong></span></p>
9457 <p><span><strong class="command"></strong></span></p>
9461 Responses with TSIG sent.
9467 <p><span><strong class="command">RespSIG0</strong></span></p>
9470 <p><span><strong class="command"></strong></span></p>
9474 Responses with SIG(0) sent.
9480 <p><span><strong class="command">QrySuccess</strong></span></p>
9483 <p><span><strong class="command"></strong></span></p>
9487 Queries resulted in a successful answer.
9488 This means the query which returns a NOERROR response
9489 with at least one answer RR.
9490 This corresponds to the
9491 <span><strong class="command">success</strong></span> counter
9492 of previous versions of
9493 <acronym class="acronym">BIND</acronym> 9.
9499 <p><span><strong class="command">QryAuthAns</strong></span></p>
9502 <p><span><strong class="command"></strong></span></p>
9506 Queries resulted in authoritative answer.
9512 <p><span><strong class="command">QryNoauthAns</strong></span></p>
9515 <p><span><strong class="command">SNaAns</strong></span></p>
9519 Queries resulted in non authoritative answer.
9525 <p><span><strong class="command">QryReferral</strong></span></p>
9528 <p><span><strong class="command"></strong></span></p>
9532 Queries resulted in referral answer.
9533 This corresponds to the
9534 <span><strong class="command">referral</strong></span> counter
9535 of previous versions of
9536 <acronym class="acronym">BIND</acronym> 9.
9542 <p><span><strong class="command">QryNxrrset</strong></span></p>
9545 <p><span><strong class="command"></strong></span></p>
9549 Queries resulted in NOERROR responses with no data.
9550 This corresponds to the
9551 <span><strong class="command">nxrrset</strong></span> counter
9552 of previous versions of
9553 <acronym class="acronym">BIND</acronym> 9.
9559 <p><span><strong class="command">QrySERVFAIL</strong></span></p>
9562 <p><span><strong class="command">SFail</strong></span></p>
9566 Queries resulted in SERVFAIL.
9572 <p><span><strong class="command">QryFORMERR</strong></span></p>
9575 <p><span><strong class="command">SFErr</strong></span></p>
9579 Queries resulted in FORMERR.
9585 <p><span><strong class="command">QryNXDOMAIN</strong></span></p>
9588 <p><span><strong class="command">SNXD</strong></span></p>
9592 Queries resulted in NXDOMAIN.
9593 This corresponds to the
9594 <span><strong class="command">nxdomain</strong></span> counter
9595 of previous versions of
9596 <acronym class="acronym">BIND</acronym> 9.
9602 <p><span><strong class="command">QryRecursion</strong></span></p>
9605 <p><span><strong class="command">RFwdQ</strong></span></p>
9609 Queries which caused the server
9610 to perform recursion in order to find the final answer.
9611 This corresponds to the
9612 <span><strong class="command">recursion</strong></span> counter
9613 of previous versions of
9614 <acronym class="acronym">BIND</acronym> 9.
9620 <p><span><strong class="command">QryDuplicate</strong></span></p>
9623 <p><span><strong class="command">RDupQ</strong></span></p>
9627 Queries which the server attempted to
9628 recurse but discovered an existing query with the same
9629 IP address, port, query ID, name, type and class
9630 already being processed.
9631 This corresponds to the
9632 <span><strong class="command">duplicate</strong></span> counter
9633 of previous versions of
9634 <acronym class="acronym">BIND</acronym> 9.
9640 <p><span><strong class="command">QryDropped</strong></span></p>
9643 <p><span><strong class="command"></strong></span></p>
9647 Recursive queries for which the server
9648 discovered an excessive number of existing
9649 recursive queries for the same name, type and
9650 class and were subsequently dropped.
9651 This is the number of dropped queries due to
9652 the reason explained with the
9653 <span><strong class="command">clients-per-query</strong></span>
9655 <span><strong class="command">max-clients-per-query</strong></span>
9657 (see the description about
9658 <a href="Bv9ARM.ch06.html#clients-per-query"><span><strong class="command">clients-per-query</strong></span></a>.)
9659 This corresponds to the
9660 <span><strong class="command">dropped</strong></span> counter
9661 of previous versions of
9662 <acronym class="acronym">BIND</acronym> 9.
9668 <p><span><strong class="command">QryFailure</strong></span></p>
9671 <p><span><strong class="command"></strong></span></p>
9675 Other query failures.
9676 This corresponds to the
9677 <span><strong class="command">failure</strong></span> counter
9678 of previous versions of
9679 <acronym class="acronym">BIND</acronym> 9.
9680 Note: this counter is provided mainly for
9681 backward compatibility with the previous versions.
9682 Normally a more fine-grained counters such as
9683 <span><strong class="command">AuthQryRej</strong></span> and
9684 <span><strong class="command">RecQryRej</strong></span>
9685 that would also fall into this counter are provided,
9686 and so this counter would not be of much
9687 interest in practice.
9693 <p><span><strong class="command">XfrReqDone</strong></span></p>
9696 <p><span><strong class="command"></strong></span></p>
9700 Requested zone transfers completed.
9706 <p><span><strong class="command">UpdateReqFwd</strong></span></p>
9709 <p><span><strong class="command"></strong></span></p>
9713 Update requests forwarded.
9719 <p><span><strong class="command">UpdateRespFwd</strong></span></p>
9722 <p><span><strong class="command"></strong></span></p>
9726 Update responses forwarded.
9732 <p><span><strong class="command">UpdateFwdFail</strong></span></p>
9735 <p><span><strong class="command"></strong></span></p>
9739 Dynamic update forward failed.
9745 <p><span><strong class="command">UpdateDone</strong></span></p>
9748 <p><span><strong class="command"></strong></span></p>
9752 Dynamic updates completed.
9758 <p><span><strong class="command">UpdateFail</strong></span></p>
9761 <p><span><strong class="command"></strong></span></p>
9765 Dynamic updates failed.
9771 <p><span><strong class="command">UpdateBadPrereq</strong></span></p>
9774 <p><span><strong class="command"></strong></span></p>
9778 Dynamic updates rejected due to prerequisite failure.
9785 <div class="sect3" lang="en">
9786 <div class="titlepage"><div><div><h4 class="title">
9787 <a name="id2600401"></a>Zone Maintenance Statistics Counters</h4></div></div></div>
9788 <div class="informaltable"><table border="1">
9797 <span class="emphasis"><em>Symbol</em></span>
9802 <span class="emphasis"><em>Description</em></span>
9808 <p><span><strong class="command">NotifyOutv4</strong></span></p>
9818 <p><span><strong class="command">NotifyOutv6</strong></span></p>
9828 <p><span><strong class="command">NotifyInv4</strong></span></p>
9832 IPv4 notifies received.
9838 <p><span><strong class="command">NotifyInv6</strong></span></p>
9842 IPv6 notifies received.
9848 <p><span><strong class="command">NotifyRej</strong></span></p>
9852 Incoming notifies rejected.
9858 <p><span><strong class="command">SOAOutv4</strong></span></p>
9862 IPv4 SOA queries sent.
9868 <p><span><strong class="command">SOAOutv6</strong></span></p>
9872 IPv6 SOA queries sent.
9878 <p><span><strong class="command">AXFRReqv4</strong></span></p>
9882 IPv4 AXFR requested.
9888 <p><span><strong class="command">AXFRReqv6</strong></span></p>
9892 IPv6 AXFR requested.
9898 <p><span><strong class="command">IXFRReqv4</strong></span></p>
9902 IPv4 IXFR requested.
9908 <p><span><strong class="command">IXFRReqv6</strong></span></p>
9912 IPv6 IXFR requested.
9918 <p><span><strong class="command">XfrSuccess</strong></span></p>
9922 Zone transfer requests succeeded.
9928 <p><span><strong class="command">XfrFail</strong></span></p>
9932 Zone transfer requests failed.
9939 <div class="sect3" lang="en">
9940 <div class="titlepage"><div><div><h4 class="title">
9941 <a name="id2600852"></a>Resolver Statistics Counters</h4></div></div></div>
9942 <div class="informaltable"><table border="1">
9952 <span class="emphasis"><em>Symbol</em></span>
9957 <span class="emphasis"><em>BIND8 Symbol</em></span>
9962 <span class="emphasis"><em>Description</em></span>
9968 <p><span><strong class="command">Queryv4</strong></span></p>
9971 <p><span><strong class="command">SFwdQ</strong></span></p>
9981 <p><span><strong class="command">Queryv6</strong></span></p>
9984 <p><span><strong class="command">SFwdQ</strong></span></p>
9994 <p><span><strong class="command">Responsev4</strong></span></p>
9997 <p><span><strong class="command">RR</strong></span></p>
10001 IPv4 responses received.
10007 <p><span><strong class="command">Responsev6</strong></span></p>
10010 <p><span><strong class="command">RR</strong></span></p>
10014 IPv6 responses received.
10020 <p><span><strong class="command">NXDOMAIN</strong></span></p>
10023 <p><span><strong class="command">RNXD</strong></span></p>
10033 <p><span><strong class="command">SERVFAIL</strong></span></p>
10036 <p><span><strong class="command">RFail</strong></span></p>
10046 <p><span><strong class="command">FORMERR</strong></span></p>
10049 <p><span><strong class="command">RFErr</strong></span></p>
10059 <p><span><strong class="command">OtherError</strong></span></p>
10062 <p><span><strong class="command">RErr</strong></span></p>
10066 Other errors received.
10072 <p><span><strong class="command">EDNS0Fail</strong></span></p>
10075 <p><span><strong class="command"></strong></span></p>
10079 EDNS(0) query failures.
10085 <p><span><strong class="command">Mismatch</strong></span></p>
10088 <p><span><strong class="command">RDupR</strong></span></p>
10092 Mismatch responses received.
10093 The DNS ID, response's source address,
10094 and/or the response's source port does not
10095 match what was expected.
10096 (The port must be 53 or as defined by
10097 the <span><strong class="command">port</strong></span> option.)
10098 This may be an indication of a cache
10105 <p><span><strong class="command">Truncated</strong></span></p>
10108 <p><span><strong class="command"></strong></span></p>
10112 Truncated responses received.
10118 <p><span><strong class="command">Lame</strong></span></p>
10121 <p><span><strong class="command">RLame</strong></span></p>
10125 Lame delegations received.
10131 <p><span><strong class="command">Retry</strong></span></p>
10134 <p><span><strong class="command">SDupQ</strong></span></p>
10138 Query retries performed.
10144 <p><span><strong class="command">QueryAbort</strong></span></p>
10147 <p><span><strong class="command"></strong></span></p>
10151 Queries aborted due to quota control.
10157 <p><span><strong class="command">QuerySockFail</strong></span></p>
10160 <p><span><strong class="command"></strong></span></p>
10164 Failures in opening query sockets.
10165 One common reason for such failures is a
10166 failure of opening a new socket due to a
10167 limitation on file descriptors.
10173 <p><span><strong class="command">QueryTimeout</strong></span></p>
10176 <p><span><strong class="command"></strong></span></p>
10186 <p><span><strong class="command">GlueFetchv4</strong></span></p>
10189 <p><span><strong class="command">SSysQ</strong></span></p>
10193 IPv4 NS address fetches invoked.
10199 <p><span><strong class="command">GlueFetchv6</strong></span></p>
10202 <p><span><strong class="command">SSysQ</strong></span></p>
10206 IPv6 NS address fetches invoked.
10212 <p><span><strong class="command">GlueFetchv4Fail</strong></span></p>
10215 <p><span><strong class="command"></strong></span></p>
10219 IPv4 NS address fetch failed.
10225 <p><span><strong class="command">GlueFetchv6Fail</strong></span></p>
10228 <p><span><strong class="command"></strong></span></p>
10232 IPv6 NS address fetch failed.
10238 <p><span><strong class="command">ValAttempt</strong></span></p>
10241 <p><span><strong class="command"></strong></span></p>
10245 DNSSEC validation attempted.
10251 <p><span><strong class="command">ValOk</strong></span></p>
10254 <p><span><strong class="command"></strong></span></p>
10258 DNSSEC validation succeeded.
10264 <p><span><strong class="command">ValNegOk</strong></span></p>
10267 <p><span><strong class="command"></strong></span></p>
10271 DNSSEC validation on negative information succeeded.
10277 <p><span><strong class="command">ValFail</strong></span></p>
10280 <p><span><strong class="command"></strong></span></p>
10284 DNSSEC validation failed.
10290 <p><span><strong class="command">QryRTTnn</strong></span></p>
10293 <p><span><strong class="command"></strong></span></p>
10297 Frequency table on round trip times (RTTs) of
10299 Each <span><strong class="command">nn</strong></span> specifies the corresponding
10302 <span><strong class="command">nn_1</strong></span>,
10303 <span><strong class="command">nn_2</strong></span>,
10305 <span><strong class="command">nn_m</strong></span>,
10306 the value of <span><strong class="command">nn_i</strong></span> is the
10307 number of queries whose RTTs are between
10308 <span><strong class="command">nn_(i-1)</strong></span> (inclusive) and
10309 <span><strong class="command">nn_i</strong></span> (exclusive) milliseconds.
10310 For the sake of convenience we define
10311 <span><strong class="command">nn_0</strong></span> to be 0.
10312 The last entry should be represented as
10313 <span><strong class="command">nn_m+</strong></span>, which means the
10314 number of queries whose RTTs are equal to or over
10315 <span><strong class="command">nn_m</strong></span> milliseconds.
10322 <div class="sect3" lang="en">
10323 <div class="titlepage"><div><div><h4 class="title">
10324 <a name="id2601942"></a>Socket I/O Statistics Counters</h4></div></div></div>
10326 Socket I/O statistics counters are defined per socket
10328 <span><strong class="command">UDP4</strong></span> (UDP/IPv4),
10329 <span><strong class="command">UDP6</strong></span> (UDP/IPv6),
10330 <span><strong class="command">TCP4</strong></span> (TCP/IPv4),
10331 <span><strong class="command">TCP6</strong></span> (TCP/IPv6),
10332 <span><strong class="command">Unix</strong></span> (Unix Domain), and
10333 <span><strong class="command">FDwatch</strong></span> (sockets opened outside the
10335 In the following table <span><strong class="command"><TYPE></strong></span>
10336 represents a socket type.
10337 Not all counters are available for all socket types;
10338 exceptions are noted in the description field.
10340 <div class="informaltable"><table border="1">
10349 <span class="emphasis"><em>Symbol</em></span>
10354 <span class="emphasis"><em>Description</em></span>
10360 <p><span><strong class="command"><TYPE>Open</strong></span></p>
10364 Sockets opened successfully.
10365 This counter is not applicable to the
10366 <span><strong class="command">FDwatch</strong></span> type.
10372 <p><span><strong class="command"><TYPE>OpenFail</strong></span></p>
10376 Failures of opening sockets.
10377 This counter is not applicable to the
10378 <span><strong class="command">FDwatch</strong></span> type.
10384 <p><span><strong class="command"><TYPE>Close</strong></span></p>
10394 <p><span><strong class="command"><TYPE>BindFail</strong></span></p>
10398 Failures of binding sockets.
10404 <p><span><strong class="command"><TYPE>ConnFail</strong></span></p>
10408 Failures of connecting sockets.
10414 <p><span><strong class="command"><TYPE>Conn</strong></span></p>
10418 Connections established successfully.
10424 <p><span><strong class="command"><TYPE>AcceptFail</strong></span></p>
10428 Failures of accepting incoming connection requests.
10429 This counter is not applicable to the
10430 <span><strong class="command">UDP</strong></span> and
10431 <span><strong class="command">FDwatch</strong></span> types.
10437 <p><span><strong class="command"><TYPE>Accept</strong></span></p>
10441 Incoming connections successfully accepted.
10442 This counter is not applicable to the
10443 <span><strong class="command">UDP</strong></span> and
10444 <span><strong class="command">FDwatch</strong></span> types.
10450 <p><span><strong class="command"><TYPE>SendErr</strong></span></p>
10454 Errors in socket send operations.
10455 This counter corresponds
10456 to <span><strong class="command">SErr</strong></span> counter of
10457 <span><strong class="command">BIND</strong></span> 8.
10463 <p><span><strong class="command"><TYPE>RecvErr</strong></span></p>
10467 Errors in socket receive operations.
10468 This includes errors of send operations on a
10469 connected UDP socket notified by an ICMP error
10477 <div class="sect3" lang="en">
10478 <div class="titlepage"><div><div><h4 class="title">
10479 <a name="id2602384"></a>Compatibility with <span class="emphasis"><em>BIND</em></span> 8 Counters</h4></div></div></div>
10481 Most statistics counters that were available
10482 in <span><strong class="command">BIND</strong></span> 8 are also supported in
10483 <span><strong class="command">BIND</strong></span> 9 as shown in the above tables.
10484 Here are notes about other counters that do not appear
10487 <div class="variablelist"><dl>
10488 <dt><span class="term"><span><strong class="command">RFwdR,SFwdR</strong></span></span></dt>
10490 These counters are not supported
10491 because <span><strong class="command">BIND</strong></span> 9 does not adopt
10492 the notion of <span class="emphasis"><em>forwarding</em></span>
10493 as <span><strong class="command">BIND</strong></span> 8 did.
10495 <dt><span class="term"><span><strong class="command">RAXFR</strong></span></span></dt>
10497 This counter is accessible in the Incoming Queries section.
10499 <dt><span class="term"><span><strong class="command">RIQ</strong></span></span></dt>
10501 This counter is accessible in the Incoming Requests section.
10503 <dt><span class="term"><span><strong class="command">ROpts</strong></span></span></dt>
10505 This counter is not supported
10506 because <span><strong class="command">BIND</strong></span> 9 does not care
10507 about IP options in the first place.
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10527 <td width="40%" align="right" valign="top"> Chapter 7. <acronym class="acronym">BIND</acronym> 9 Security Considerations</td>