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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#id2574283">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#id2574937"><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#id2575127"><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#id2575418"><span><strong class="command">include</strong></span> Statement Grammar</a></span></dt>
62 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575504"><span><strong class="command">include</strong></span> Statement Definition and
64 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575527"><span><strong class="command">key</strong></span> Statement Grammar</a></span></dt>
65 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575550"><span><strong class="command">key</strong></span> Statement Definition and Usage</a></span></dt>
66 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575709"><span><strong class="command">logging</strong></span> Statement Grammar</a></span></dt>
67 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575835"><span><strong class="command">logging</strong></span> Statement Definition and
69 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577834"><span><strong class="command">lwres</strong></span> Statement Grammar</a></span></dt>
70 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577908"><span><strong class="command">lwres</strong></span> Statement Definition and Usage</a></span></dt>
71 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578040"><span><strong class="command">masters</strong></span> Statement Grammar</a></span></dt>
72 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578084"><span><strong class="command">masters</strong></span> Statement Definition and
74 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578099"><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#id2589395"><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#id2589534"><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#id2589581"><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#id2590007"><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#id2591558"><span><strong class="command">zone</strong></span> Statement Definition and Usage</a></span></dt>
95 <dt><span class="sect1"><a href="Bv9ARM.ch06.html#id2595030">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#id2597260">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#id2597876">Inverse Mapping in IPv4</a></span></dt>
101 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2598003">Other Zone File Directives</a></span></dt>
102 <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2598276"><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="id2574050"></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="id2574077"></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="id2574283"></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="id2574298"></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="id2574328"></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="id2574937"></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="id2575127"></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="id2575418"></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="id2575504"></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="id2575527"></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="id2575550"></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="id2575709"></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="id2575835"></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="id2575888"></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="id2577315"></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="id2577834"></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="id2577908"></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="id2578040"></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="id2578084"></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="id2578099"></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 Normally, DNS64 won't apply to a domain name that
2741 owns one or more AAAA records; these records will
2742 simply be returned. The optional
2743 <span><strong class="command">exclude</strong></span> ACL allows specification
2744 of a list of IPv6 addresses that will be ignored
2745 if they appear in a domain name's AAAA records, and
2746 DNS64 will be applied to any A records the domain
2747 name owns. If not defined, <span><strong class="command">exclude</strong></span>
2751 A optional <span><strong class="command">suffix</strong></span> can also
2752 be defined to set the bits trailing the mapped
2753 IPv4 address bits. By default these bits are
2754 set to <strong class="userinput"><code>::</code></strong>. The bits
2755 matching the prefix and mapped IPv4 address
2759 If <span><strong class="command">recursive-only</strong></span> is set to
2760 <span><strong class="command">yes</strong></span> the DNS64 synthesis will
2761 only happen for recursive queries. The default
2762 is <span><strong class="command">no</strong></span>.
2765 If <span><strong class="command">break-dnssec</strong></span> is set to
2766 <span><strong class="command">yes</strong></span> the DNS64 synthesis will
2767 happen even if the result, if validated, would
2768 cause a DNSSEC validation failure. If this option
2769 is set to <span><strong class="command">no</strong></span> (the default), the DO
2770 is set on the incoming query, and there are RRSIGs on
2771 the applicable records, then synthesis will not happen.
2773 <pre class="programlisting">
2774 acl rfc1918 { 10/8; 192.168/16; 172.16/12; };
2776 dns64 64:FF9B::/96 {
2778 mapped { !rfc1918; any; };
2779 exclude { 64:FF9B::/96; ::ffff:0000:0000/96; };
2785 <div class="sect3" lang="en">
2786 <div class="titlepage"><div><div><h4 class="title">
2787 <a name="boolean_options"></a>Boolean Options</h4></div></div></div>
2788 <div class="variablelist"><dl>
2789 <dt><span class="term"><span><strong class="command">allow-new-zones</strong></span></span></dt>
2791 If <strong class="userinput"><code>yes</code></strong>, then zones can be
2792 added at runtime via <span><strong class="command">rndc addzone</strong></span>
2793 or deleted via <span><strong class="command">rndc delzone</strong></span>.
2794 The default is <strong class="userinput"><code>no</code></strong>.
2796 <dt><span class="term"><span><strong class="command">auth-nxdomain</strong></span></span></dt>
2798 If <strong class="userinput"><code>yes</code></strong>, then the <span><strong class="command">AA</strong></span> bit
2799 is always set on NXDOMAIN responses, even if the server is
2801 authoritative. The default is <strong class="userinput"><code>no</code></strong>;
2803 a change from <acronym class="acronym">BIND</acronym> 8. If you
2804 are using very old DNS software, you
2805 may need to set it to <strong class="userinput"><code>yes</code></strong>.
2807 <dt><span class="term"><span><strong class="command">deallocate-on-exit</strong></span></span></dt>
2809 This option was used in <acronym class="acronym">BIND</acronym>
2810 8 to enable checking
2811 for memory leaks on exit. <acronym class="acronym">BIND</acronym> 9 ignores the option and always performs
2814 <dt><span class="term"><span><strong class="command">memstatistics</strong></span></span></dt>
2816 Write memory statistics to the file specified by
2817 <span><strong class="command">memstatistics-file</strong></span> at exit.
2818 The default is <strong class="userinput"><code>no</code></strong> unless
2819 '-m record' is specified on the command line in
2820 which case it is <strong class="userinput"><code>yes</code></strong>.
2822 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
2825 If <strong class="userinput"><code>yes</code></strong>, then the
2826 server treats all zones as if they are doing zone transfers
2828 a dial-on-demand dialup link, which can be brought up by
2830 originating from this server. This has different effects
2832 to zone type and concentrates the zone maintenance so that
2834 happens in a short interval, once every <span><strong class="command">heartbeat-interval</strong></span> and
2835 hopefully during the one call. It also suppresses some of
2837 zone maintenance traffic. The default is <strong class="userinput"><code>no</code></strong>.
2840 The <span><strong class="command">dialup</strong></span> option
2841 may also be specified in the <span><strong class="command">view</strong></span> and
2842 <span><strong class="command">zone</strong></span> statements,
2843 in which case it overrides the global <span><strong class="command">dialup</strong></span>
2847 If the zone is a master zone, then the server will send out a
2849 request to all the slaves (default). This should trigger the
2851 number check in the slave (providing it supports NOTIFY)
2853 to verify the zone while the connection is active.
2854 The set of servers to which NOTIFY is sent can be controlled
2856 <span><strong class="command">notify</strong></span> and <span><strong class="command">also-notify</strong></span>.
2860 zone is a slave or stub zone, then the server will suppress
2862 "zone up to date" (refresh) queries and only perform them
2864 <span><strong class="command">heartbeat-interval</strong></span> expires in
2869 Finer control can be achieved by using
2870 <strong class="userinput"><code>notify</code></strong> which only sends NOTIFY
2872 <strong class="userinput"><code>notify-passive</code></strong> which sends NOTIFY
2874 suppresses the normal refresh queries, <strong class="userinput"><code>refresh</code></strong>
2875 which suppresses normal refresh processing and sends refresh
2877 when the <span><strong class="command">heartbeat-interval</strong></span>
2879 <strong class="userinput"><code>passive</code></strong> which just disables normal
2883 <div class="informaltable"><table border="1">
2915 <p><span><strong class="command">no</strong></span> (default)</p>
2935 <p><span><strong class="command">yes</strong></span></p>
2955 <p><span><strong class="command">notify</strong></span></p>
2975 <p><span><strong class="command">refresh</strong></span></p>
2995 <p><span><strong class="command">passive</strong></span></p>
3015 <p><span><strong class="command">notify-passive</strong></span></p>
3036 Note that normal NOTIFY processing is not affected by
3037 <span><strong class="command">dialup</strong></span>.
3040 <dt><span class="term"><span><strong class="command">fake-iquery</strong></span></span></dt>
3042 In <acronym class="acronym">BIND</acronym> 8, this option
3043 enabled simulating the obsolete DNS query type
3044 IQUERY. <acronym class="acronym">BIND</acronym> 9 never does
3047 <dt><span class="term"><span><strong class="command">fetch-glue</strong></span></span></dt>
3049 This option is obsolete.
3050 In BIND 8, <strong class="userinput"><code>fetch-glue yes</code></strong>
3051 caused the server to attempt to fetch glue resource records
3053 didn't have when constructing the additional
3054 data section of a response. This is now considered a bad
3056 and BIND 9 never does it.
3058 <dt><span class="term"><span><strong class="command">flush-zones-on-shutdown</strong></span></span></dt>
3060 When the nameserver exits due receiving SIGTERM,
3061 flush or do not flush any pending zone writes. The default
3063 <span><strong class="command">flush-zones-on-shutdown</strong></span> <strong class="userinput"><code>no</code></strong>.
3065 <dt><span class="term"><span><strong class="command">has-old-clients</strong></span></span></dt>
3067 This option was incorrectly implemented
3068 in <acronym class="acronym">BIND</acronym> 8, and is ignored by <acronym class="acronym">BIND</acronym> 9.
3069 To achieve the intended effect
3071 <span><strong class="command">has-old-clients</strong></span> <strong class="userinput"><code>yes</code></strong>, specify
3072 the two separate options <span><strong class="command">auth-nxdomain</strong></span> <strong class="userinput"><code>yes</code></strong>
3073 and <span><strong class="command">rfc2308-type1</strong></span> <strong class="userinput"><code>no</code></strong> instead.
3075 <dt><span class="term"><span><strong class="command">host-statistics</strong></span></span></dt>
3077 In BIND 8, this enables keeping of
3078 statistics for every host that the name server interacts
3080 Not implemented in BIND 9.
3082 <dt><span class="term"><span><strong class="command">maintain-ixfr-base</strong></span></span></dt>
3084 <span class="emphasis"><em>This option is obsolete</em></span>.
3085 It was used in <acronym class="acronym">BIND</acronym> 8 to
3086 determine whether a transaction log was
3087 kept for Incremental Zone Transfer. <acronym class="acronym">BIND</acronym> 9 maintains a transaction
3088 log whenever possible. If you need to disable outgoing
3090 transfers, use <span><strong class="command">provide-ixfr</strong></span> <strong class="userinput"><code>no</code></strong>.
3092 <dt><span class="term"><span><strong class="command">minimal-responses</strong></span></span></dt>
3094 If <strong class="userinput"><code>yes</code></strong>, then when generating
3095 responses the server will only add records to the authority
3096 and additional data sections when they are required (e.g.
3097 delegations, negative responses). This may improve the
3098 performance of the server.
3099 The default is <strong class="userinput"><code>no</code></strong>.
3101 <dt><span class="term"><span><strong class="command">multiple-cnames</strong></span></span></dt>
3103 This option was used in <acronym class="acronym">BIND</acronym> 8 to allow
3104 a domain name to have multiple CNAME records in violation of
3105 the DNS standards. <acronym class="acronym">BIND</acronym> 9.2 onwards
3106 always strictly enforces the CNAME rules both in master
3107 files and dynamic updates.
3109 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
3112 If <strong class="userinput"><code>yes</code></strong> (the default),
3113 DNS NOTIFY messages are sent when a zone the server is
3115 changes, see <a href="Bv9ARM.ch04.html#notify" title="Notify">the section called “Notify”</a>. The messages are
3117 servers listed in the zone's NS records (except the master
3119 in the SOA MNAME field), and to any servers listed in the
3120 <span><strong class="command">also-notify</strong></span> option.
3123 If <strong class="userinput"><code>master-only</code></strong>, notifies are only
3126 If <strong class="userinput"><code>explicit</code></strong>, notifies are sent only
3128 servers explicitly listed using <span><strong class="command">also-notify</strong></span>.
3129 If <strong class="userinput"><code>no</code></strong>, no notifies are sent.
3132 The <span><strong class="command">notify</strong></span> option may also be
3133 specified in the <span><strong class="command">zone</strong></span>
3135 in which case it overrides the <span><strong class="command">options notify</strong></span> statement.
3136 It would only be necessary to turn off this option if it
3141 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
3143 If <strong class="userinput"><code>yes</code></strong> do not check the nameservers
3144 in the NS RRset against the SOA MNAME. Normally a NOTIFY
3145 message is not sent to the SOA MNAME (SOA ORIGIN) as it is
3146 supposed to contain the name of the ultimate master.
3147 Sometimes, however, a slave is listed as the SOA MNAME in
3148 hidden master configurations and in that case you would
3149 want the ultimate master to still send NOTIFY messages to
3150 all the nameservers listed in the NS RRset.
3152 <dt><span class="term"><span><strong class="command">recursion</strong></span></span></dt>
3154 If <strong class="userinput"><code>yes</code></strong>, and a
3155 DNS query requests recursion, then the server will attempt
3157 all the work required to answer the query. If recursion is
3159 and the server does not already know the answer, it will
3161 referral response. The default is
3162 <strong class="userinput"><code>yes</code></strong>.
3163 Note that setting <span><strong class="command">recursion no</strong></span> does not prevent
3164 clients from getting data from the server's cache; it only
3165 prevents new data from being cached as an effect of client
3167 Caching may still occur as an effect the server's internal
3168 operation, such as NOTIFY address lookups.
3169 See also <span><strong class="command">fetch-glue</strong></span> above.
3171 <dt><span class="term"><span><strong class="command">rfc2308-type1</strong></span></span></dt>
3174 Setting this to <strong class="userinput"><code>yes</code></strong> will
3175 cause the server to send NS records along with the SOA
3177 answers. The default is <strong class="userinput"><code>no</code></strong>.
3179 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3180 <h3 class="title">Note</h3>
3182 Not yet implemented in <acronym class="acronym">BIND</acronym>
3187 <dt><span class="term"><span><strong class="command">use-id-pool</strong></span></span></dt>
3189 <span class="emphasis"><em>This option is obsolete</em></span>.
3190 <acronym class="acronym">BIND</acronym> 9 always allocates query
3193 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
3195 If <strong class="userinput"><code>yes</code></strong>, the server will collect
3196 statistical data on all zones (unless specifically turned
3198 on a per-zone basis by specifying <span><strong class="command">zone-statistics no</strong></span>
3199 in the <span><strong class="command">zone</strong></span> statement).
3200 The default is <strong class="userinput"><code>no</code></strong>.
3201 These statistics may be accessed
3202 using <span><strong class="command">rndc stats</strong></span>, which will
3203 dump them to the file listed
3204 in the <span><strong class="command">statistics-file</strong></span>. See
3205 also <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called “The Statistics File”</a>.
3207 <dt><span class="term"><span><strong class="command">use-ixfr</strong></span></span></dt>
3209 <span class="emphasis"><em>This option is obsolete</em></span>.
3210 If you need to disable IXFR to a particular server or
3212 the information on the <span><strong class="command">provide-ixfr</strong></span> option
3213 in <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 <a href="Bv9ARM.ch04.html#incremental_zone_transfers" title="Incremental Zone Transfers (IXFR)">the section called “Incremental Zone Transfers (IXFR)”</a>.
3219 <dt><span class="term"><span><strong class="command">provide-ixfr</strong></span></span></dt>
3221 See the description of
3222 <span><strong class="command">provide-ixfr</strong></span> in
3223 <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
3224 Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and
3227 <dt><span class="term"><span><strong class="command">request-ixfr</strong></span></span></dt>
3229 See the description of
3230 <span><strong class="command">request-ixfr</strong></span> in
3231 <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and
3232 Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and
3235 <dt><span class="term"><span><strong class="command">treat-cr-as-space</strong></span></span></dt>
3237 This option was used in <acronym class="acronym">BIND</acronym>
3239 the server treat carriage return ("<span><strong class="command">\r</strong></span>") characters the same way
3240 as a space or tab character,
3241 to facilitate loading of zone files on a UNIX system that
3243 on an NT or DOS machine. In <acronym class="acronym">BIND</acronym> 9, both UNIX "<span><strong class="command">\n</strong></span>"
3244 and NT/DOS "<span><strong class="command">\r\n</strong></span>" newlines
3245 are always accepted,
3246 and the option is ignored.
3249 <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>
3253 These options control the behavior of an authoritative
3255 answering queries which have additional data, or when
3260 When both of these options are set to <strong class="userinput"><code>yes</code></strong>
3262 query is being answered from authoritative data (a zone
3263 configured into the server), the additional data section of
3265 reply will be filled in using data from other authoritative
3267 and from the cache. In some situations this is undesirable,
3269 as when there is concern over the correctness of the cache,
3271 in servers where slave zones may be added and modified by
3272 untrusted third parties. Also, avoiding
3273 the search for this additional data will speed up server
3275 at the possible expense of additional queries to resolve
3277 otherwise be provided in the additional section.
3280 For example, if a query asks for an MX record for host <code class="literal">foo.example.com</code>,
3281 and the record found is "<code class="literal">MX 10 mail.example.net</code>", normally the address
3282 records (A and AAAA) for <code class="literal">mail.example.net</code> will be provided as well,
3283 if known, even though they are not in the example.com zone.
3284 Setting these options to <span><strong class="command">no</strong></span>
3285 disables this behavior and makes
3286 the server only search for additional data in the zone it
3290 These options are intended for use in authoritative-only
3291 servers, or in authoritative-only views. Attempts to set
3292 them to <span><strong class="command">no</strong></span> without also
3294 <span><strong class="command">recursion no</strong></span> will cause the
3296 ignore the options and log a warning message.
3299 Specifying <span><strong class="command">additional-from-cache no</strong></span> actually
3300 disables the use of the cache not only for additional data
3302 but also when looking up the answer. This is usually the
3304 behavior in an authoritative-only server where the
3306 the cached data is an issue.
3309 When a name server is non-recursively queried for a name
3311 below the apex of any served zone, it normally answers with
3313 "upwards referral" to the root servers or the servers of
3315 known parent of the query name. Since the data in an
3317 comes from the cache, the server will not be able to provide
3319 referrals when <span><strong class="command">additional-from-cache no</strong></span>
3320 has been specified. Instead, it will respond to such
3322 with REFUSED. This should not cause any problems since
3323 upwards referrals are not required for the resolution
3327 <dt><span class="term"><span><strong class="command">match-mapped-addresses</strong></span></span></dt>
3330 If <strong class="userinput"><code>yes</code></strong>, then an
3331 IPv4-mapped IPv6 address will match any address match
3332 list entries that match the corresponding IPv4 address.
3335 This option was introduced to work around a kernel quirk
3336 in some operating systems that causes IPv4 TCP
3337 connections, such as zone transfers, to be accepted on an
3338 IPv6 socket using mapped addresses. This caused address
3339 match lists designed for IPv4 to fail to match. However,
3340 <span><strong class="command">named</strong></span> now solves this problem
3341 internally. The use of this option is discouraged.
3344 <dt><span class="term"><span><strong class="command">filter-aaaa-on-v4</strong></span></span></dt>
3347 This option is only available when
3348 <acronym class="acronym">BIND</acronym> 9 is compiled with the
3349 <strong class="userinput"><code>--enable-filter-aaaa</code></strong> option on the
3350 "configure" command line. It is intended to help the
3351 transition from IPv4 to IPv6 by not giving IPv6 addresses
3352 to DNS clients unless they have connections to the IPv6
3353 Internet. This is not recommended unless absolutely
3354 necessary. The default is <strong class="userinput"><code>no</code></strong>.
3355 The <span><strong class="command">filter-aaaa-on-v4</strong></span> option
3356 may also be specified in <span><strong class="command">view</strong></span> statements
3357 to override the global <span><strong class="command">filter-aaaa-on-v4</strong></span>
3361 If <strong class="userinput"><code>yes</code></strong>,
3362 the DNS client is at an IPv4 address, in <span><strong class="command">filter-aaaa</strong></span>,
3363 and if the response does not include DNSSEC signatures,
3364 then all AAAA records are deleted from the response.
3365 This filtering applies to all responses and not only
3366 authoritative responses.
3369 If <strong class="userinput"><code>break-dnssec</code></strong>,
3370 then AAAA records are deleted even when dnssec is enabled.
3371 As suggested by the name, this makes the response not verify,
3372 because the DNSSEC protocol is designed detect deletions.
3375 This mechanism can erroneously cause other servers to
3376 not give AAAA records to their clients.
3377 A recursing server with both IPv6 and IPv4 network connections
3378 that queries an authoritative server using this mechanism
3379 via IPv4 will be denied AAAA records even if its client is
3383 This mechanism is applied to authoritative as well as
3384 non-authoritative records.
3385 A client using IPv4 that is not allowed recursion can
3386 erroneously be given AAAA records because the server is not
3387 allowed to check for A records.
3390 Some AAAA records are given to IPv4 clients in glue records.
3391 IPv4 clients that are servers can then erroneously
3392 answer requests for AAAA records received via IPv4.
3395 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
3398 When <strong class="userinput"><code>yes</code></strong> and the server loads a new version of a master
3399 zone from its zone file or receives a new version of a slave
3400 file by a non-incremental zone transfer, it will compare
3401 the new version to the previous one and calculate a set
3402 of differences. The differences are then logged in the
3403 zone's journal file such that the changes can be transmitted
3404 to downstream slaves as an incremental zone transfer.
3407 By allowing incremental zone transfers to be used for
3408 non-dynamic zones, this option saves bandwidth at the
3409 expense of increased CPU and memory consumption at the
3411 In particular, if the new version of a zone is completely
3412 different from the previous one, the set of differences
3413 will be of a size comparable to the combined size of the
3414 old and new zone version, and the server will need to
3415 temporarily allocate memory to hold this complete
3418 <p><span><strong class="command">ixfr-from-differences</strong></span>
3419 also accepts <span><strong class="command">master</strong></span> and
3420 <span><strong class="command">slave</strong></span> at the view and options
3422 <span><strong class="command">ixfr-from-differences</strong></span> to be enabled for
3423 all <span><strong class="command">master</strong></span> or
3424 <span><strong class="command">slave</strong></span> zones respectively.
3425 It is off by default.
3428 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
3430 This should be set when you have multiple masters for a zone
3432 addresses refer to different machines. If <strong class="userinput"><code>yes</code></strong>, <span><strong class="command">named</strong></span> will
3434 when the serial number on the master is less than what <span><strong class="command">named</strong></span>
3436 has. The default is <strong class="userinput"><code>no</code></strong>.
3438 <dt><span class="term"><span><strong class="command">dnssec-enable</strong></span></span></dt>
3440 Enable DNSSEC support in <span><strong class="command">named</strong></span>. Unless set to <strong class="userinput"><code>yes</code></strong>,
3441 <span><strong class="command">named</strong></span> behaves as if it does not support DNSSEC.
3442 The default is <strong class="userinput"><code>yes</code></strong>.
3444 <dt><span class="term"><span><strong class="command">dnssec-validation</strong></span></span></dt>
3446 Enable DNSSEC validation in <span><strong class="command">named</strong></span>.
3447 Note <span><strong class="command">dnssec-enable</strong></span> also needs to be
3448 set to <strong class="userinput"><code>yes</code></strong> to be effective.
3449 If set to <strong class="userinput"><code>no</code></strong>, DNSSEC validation
3450 is disabled. If set to <strong class="userinput"><code>auto</code></strong>,
3451 DNSSEC validation is enabled, and a default
3452 trust-anchor for the DNS root zone is used. If set to
3453 <strong class="userinput"><code>yes</code></strong>, DNSSEC validation is enabled,
3454 but a trust anchor must be manually configured using
3455 a <span><strong class="command">trusted-keys</strong></span> or
3456 <span><strong class="command">managed-keys</strong></span> statement. The default
3457 is <strong class="userinput"><code>yes</code></strong>.
3459 <dt><span class="term"><span><strong class="command">dnssec-accept-expired</strong></span></span></dt>
3461 Accept expired signatures when verifying DNSSEC signatures.
3462 The default is <strong class="userinput"><code>no</code></strong>.
3463 Setting this option to <strong class="userinput"><code>yes</code></strong>
3464 leaves <span><strong class="command">named</strong></span> vulnerable to
3467 <dt><span class="term"><span><strong class="command">querylog</strong></span></span></dt>
3469 Specify whether query logging should be started when <span><strong class="command">named</strong></span>
3471 If <span><strong class="command">querylog</strong></span> is not specified,
3472 then the query logging
3473 is determined by the presence of the logging category <span><strong class="command">queries</strong></span>.
3475 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
3478 This option is used to restrict the character set and syntax
3480 certain domain names in master files and/or DNS responses
3482 from the network. The default varies according to usage
3484 <span><strong class="command">master</strong></span> zones the default is <span><strong class="command">fail</strong></span>.
3485 For <span><strong class="command">slave</strong></span> zones the default
3486 is <span><strong class="command">warn</strong></span>.
3487 For answers received from the network (<span><strong class="command">response</strong></span>)
3488 the default is <span><strong class="command">ignore</strong></span>.
3491 The rules for legal hostnames and mail domains are derived
3492 from RFC 952 and RFC 821 as modified by RFC 1123.
3494 <p><span><strong class="command">check-names</strong></span>
3495 applies to the owner names of A, AAAA and MX records.
3496 It also applies to the domain names in the RDATA of NS, SOA,
3497 MX, and SRV records.
3498 It also applies to the RDATA of PTR records where the owner
3499 name indicated that it is a reverse lookup of a hostname
3500 (the owner name ends in IN-ADDR.ARPA, IP6.ARPA, or IP6.INT).
3503 <dt><span class="term"><span><strong class="command">check-dup-records</strong></span></span></dt>
3505 Check master zones for records that are treated as different
3506 by DNSSEC but are semantically equal in plain DNS. The
3507 default is to <span><strong class="command">warn</strong></span>. Other possible
3508 values are <span><strong class="command">fail</strong></span> and
3509 <span><strong class="command">ignore</strong></span>.
3511 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
3513 Check whether the MX record appears to refer to a IP address.
3514 The default is to <span><strong class="command">warn</strong></span>. Other possible
3515 values are <span><strong class="command">fail</strong></span> and
3516 <span><strong class="command">ignore</strong></span>.
3518 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
3520 This option is used to check for non-terminal wildcards.
3521 The use of non-terminal wildcards is almost always as a
3523 to understand the wildcard matching algorithm (RFC 1034).
3525 affects master zones. The default (<span><strong class="command">yes</strong></span>) is to check
3526 for non-terminal wildcards and issue a warning.
3528 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
3530 Perform post load zone integrity checks on master
3531 zones. This checks that MX and SRV records refer
3532 to address (A or AAAA) records and that glue
3533 address records exist for delegated zones. For
3534 MX and SRV records only in-zone hostnames are
3535 checked (for out-of-zone hostnames use
3536 <span><strong class="command">named-checkzone</strong></span>).
3537 For NS records only names below top of zone are
3538 checked (for out-of-zone names and glue consistency
3539 checks use <span><strong class="command">named-checkzone</strong></span>).
3540 The default is <span><strong class="command">yes</strong></span>.
3542 <dt><span class="term"><span><strong class="command">check-mx-cname</strong></span></span></dt>
3544 If <span><strong class="command">check-integrity</strong></span> is set then
3545 fail, warn or ignore MX records that refer
3546 to CNAMES. The default is to <span><strong class="command">warn</strong></span>.
3548 <dt><span class="term"><span><strong class="command">check-srv-cname</strong></span></span></dt>
3550 If <span><strong class="command">check-integrity</strong></span> is set then
3551 fail, warn or ignore SRV records that refer
3552 to CNAMES. The default is to <span><strong class="command">warn</strong></span>.
3554 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
3556 When performing integrity checks, also check that
3557 sibling glue exists. The default is <span><strong class="command">yes</strong></span>.
3559 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
3561 When returning authoritative negative responses to
3562 SOA queries set the TTL of the SOA record returned in
3563 the authority section to zero.
3564 The default is <span><strong class="command">yes</strong></span>.
3566 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl-cache</strong></span></span></dt>
3568 When caching a negative response to a SOA query
3569 set the TTL to zero.
3570 The default is <span><strong class="command">no</strong></span>.
3572 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
3575 When set to the default value of <code class="literal">yes</code>,
3576 check the KSK bit in each key to determine how the key
3577 should be used when generating RRSIGs for a secure zone.
3580 Ordinarily, zone-signing keys (that is, keys without the
3581 KSK bit set) are used to sign the entire zone, while
3582 key-signing keys (keys with the KSK bit set) are only
3583 used to sign the DNSKEY RRset at the zone apex.
3584 However, if this option is set to <code class="literal">no</code>,
3585 then the KSK bit is ignored; KSKs are treated as if they
3586 were ZSKs and are used to sign the entire zone. This is
3587 similar to the <span><strong class="command">dnssec-signzone -z</strong></span>
3588 command line option.
3591 When this option is set to <code class="literal">yes</code>, there
3592 must be at least two active keys for every algorithm
3593 represented in the DNSKEY RRset: at least one KSK and one
3594 ZSK per algorithm. If there is any algorithm for which
3595 this requirement is not met, this option will be ignored
3599 <dt><span class="term"><span><strong class="command">dnssec-dnskey-kskonly</strong></span></span></dt>
3602 When this option and <span><strong class="command">update-check-ksk</strong></span>
3603 are both set to <code class="literal">yes</code>, only key-signing
3604 keys (that is, keys with the KSK bit set) will be used
3605 to sign the DNSKEY RRset at the zone apex. Zone-signing
3606 keys (keys without the KSK bit set) will be used to sign
3607 the remainder of the zone, but not the DNSKEY RRset.
3608 This is similar to the
3609 <span><strong class="command">dnssec-signzone -x</strong></span> command line option.
3612 The default is <span><strong class="command">no</strong></span>. If
3613 <span><strong class="command">update-check-ksk</strong></span> is set to
3614 <code class="literal">no</code>, this option is ignored.
3617 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
3619 Try to refresh the zone using TCP if UDP queries fail.
3620 For BIND 8 compatibility, the default is
3621 <span><strong class="command">yes</strong></span>.
3623 <dt><span class="term"><span><strong class="command">dnssec-secure-to-insecure</strong></span></span></dt>
3626 Allow a dynamic zone to transition from secure to
3627 insecure (i.e., signed to unsigned) by deleting all
3628 of the DNSKEY records. The default is <span><strong class="command">no</strong></span>.
3629 If set to <span><strong class="command">yes</strong></span>, and if the DNSKEY RRset
3630 at the zone apex is deleted, all RRSIG and NSEC records
3631 will be removed from the zone as well.
3634 If the zone uses NSEC3, then it is also necessary to
3635 delete the NSEC3PARAM RRset from the zone apex; this will
3636 cause the removal of all corresponding NSEC3 records.
3637 (It is expected that this requirement will be eliminated
3638 in a future release.)
3641 Note that if a zone has been configured with
3642 <span><strong class="command">auto-dnssec maintain</strong></span> and the
3643 private keys remain accessible in the key repository,
3644 then the zone will be automatically signed again the
3645 next time <span><strong class="command">named</strong></span> is started.
3650 <div class="sect3" lang="en">
3651 <div class="titlepage"><div><div><h4 class="title">
3652 <a name="id2583636"></a>Forwarding</h4></div></div></div>
3654 The forwarding facility can be used to create a large site-wide
3655 cache on a few servers, reducing traffic over links to external
3656 name servers. It can also be used to allow queries by servers that
3657 do not have direct access to the Internet, but wish to look up
3659 names anyway. Forwarding occurs only on those queries for which
3660 the server is not authoritative and does not have the answer in
3663 <div class="variablelist"><dl>
3664 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
3666 This option is only meaningful if the
3667 forwarders list is not empty. A value of <code class="varname">first</code>,
3668 the default, causes the server to query the forwarders
3670 if that doesn't answer the question, the server will then
3672 the answer itself. If <code class="varname">only</code> is
3674 server will only query the forwarders.
3676 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
3678 Specifies the IP addresses to be used
3679 for forwarding. The default is the empty list (no
3684 Forwarding can also be configured on a per-domain basis, allowing
3685 for the global forwarding options to be overridden in a variety
3686 of ways. You can set particular domains to use different
3688 or have a different <span><strong class="command">forward only/first</strong></span> behavior,
3689 or not forward at all, see <a href="Bv9ARM.ch06.html#zone_statement_grammar" title="zone
3690 Statement Grammar">the section called “<span><strong class="command">zone</strong></span>
3691 Statement Grammar”</a>.
3694 <div class="sect3" lang="en">
3695 <div class="titlepage"><div><div><h4 class="title">
3696 <a name="id2583763"></a>Dual-stack Servers</h4></div></div></div>
3698 Dual-stack servers are used as servers of last resort to work
3700 problems in reachability due the lack of support for either IPv4
3702 on the host machine.
3704 <div class="variablelist"><dl>
3705 <dt><span class="term"><span><strong class="command">dual-stack-servers</strong></span></span></dt>
3707 Specifies host names or addresses of machines with access to
3708 both IPv4 and IPv6 transports. If a hostname is used, the
3710 to resolve the name using only the transport it has. If the
3712 stacked, then the <span><strong class="command">dual-stack-servers</strong></span> have no effect unless
3713 access to a transport has been disabled on the command line
3714 (e.g. <span><strong class="command">named -4</strong></span>).
3718 <div class="sect3" lang="en">
3719 <div class="titlepage"><div><div><h4 class="title">
3720 <a name="access_control"></a>Access Control</h4></div></div></div>
3722 Access to the server can be restricted based on the IP address
3723 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
3724 details on how to specify IP address lists.
3726 <div class="variablelist"><dl>
3727 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
3729 Specifies which hosts are allowed to
3730 notify this server, a slave, of zone changes in addition
3731 to the zone masters.
3732 <span><strong class="command">allow-notify</strong></span> may also be
3734 <span><strong class="command">zone</strong></span> statement, in which case
3736 <span><strong class="command">options allow-notify</strong></span>
3737 statement. It is only meaningful
3738 for a slave zone. If not specified, the default is to
3739 process notify messages
3740 only from a zone's master.
3742 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
3745 Specifies which hosts are allowed to ask ordinary
3746 DNS questions. <span><strong class="command">allow-query</strong></span> may
3747 also be specified in the <span><strong class="command">zone</strong></span>
3748 statement, in which case it overrides the
3749 <span><strong class="command">options allow-query</strong></span> statement.
3750 If not specified, the default is to allow queries
3753 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3754 <h3 class="title">Note</h3>
3756 <span><strong class="command">allow-query-cache</strong></span> is now
3757 used to specify access to the cache.
3761 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
3764 Specifies which local addresses can accept ordinary
3765 DNS questions. This makes it possible, for instance,
3766 to allow queries on internal-facing interfaces but
3767 disallow them on external-facing ones, without
3768 necessarily knowing the internal network's addresses.
3771 <span><strong class="command">allow-query-on</strong></span> may
3772 also be specified in the <span><strong class="command">zone</strong></span>
3773 statement, in which case it overrides the
3774 <span><strong class="command">options allow-query-on</strong></span> statement.
3777 If not specified, the default is to allow queries
3780 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
3781 <h3 class="title">Note</h3>
3783 <span><strong class="command">allow-query-cache</strong></span> is
3784 used to specify access to the cache.
3788 <dt><span class="term"><span><strong class="command">allow-query-cache</strong></span></span></dt>
3790 Specifies which hosts are allowed to get answers
3791 from the cache. If <span><strong class="command">allow-query-cache</strong></span>
3792 is not set then <span><strong class="command">allow-recursion</strong></span>
3793 is used if set, otherwise <span><strong class="command">allow-query</strong></span>
3794 is used if set unless <span><strong class="command">recursion no;</strong></span> is
3795 set in which case <span><strong class="command">none;</strong></span> is used,
3796 otherwise the default (<span><strong class="command">localnets;</strong></span>
3797 <span><strong class="command">localhost;</strong></span>) is used.
3799 <dt><span class="term"><span><strong class="command">allow-query-cache-on</strong></span></span></dt>
3801 Specifies which local addresses can give answers
3802 from the cache. If not specified, the default is
3803 to allow cache queries on any address,
3804 <span><strong class="command">localnets</strong></span> and
3805 <span><strong class="command">localhost</strong></span>.
3807 <dt><span class="term"><span><strong class="command">allow-recursion</strong></span></span></dt>
3809 Specifies which hosts are allowed to make recursive
3810 queries through this server. If
3811 <span><strong class="command">allow-recursion</strong></span> is not set
3812 then <span><strong class="command">allow-query-cache</strong></span> is
3813 used if set, otherwise <span><strong class="command">allow-query</strong></span>
3814 is used if set, otherwise the default
3815 (<span><strong class="command">localnets;</strong></span>
3816 <span><strong class="command">localhost;</strong></span>) is used.
3818 <dt><span class="term"><span><strong class="command">allow-recursion-on</strong></span></span></dt>
3820 Specifies which local addresses can accept recursive
3821 queries. If not specified, the default is to allow
3822 recursive queries on all addresses.
3824 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
3826 Specifies which hosts are allowed to
3827 submit Dynamic DNS updates for master zones. The default is
3829 updates from all hosts. Note that allowing updates based
3830 on the requestor's IP address is insecure; see
3831 <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called “Dynamic Update Security”</a> for details.
3833 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
3836 Specifies which hosts are allowed to
3837 submit Dynamic DNS updates to slave zones to be forwarded to
3839 master. The default is <strong class="userinput"><code>{ none; }</code></strong>,
3841 means that no update forwarding will be performed. To
3843 update forwarding, specify
3844 <strong class="userinput"><code>allow-update-forwarding { any; };</code></strong>.
3845 Specifying values other than <strong class="userinput"><code>{ none; }</code></strong> or
3846 <strong class="userinput"><code>{ any; }</code></strong> is usually
3847 counterproductive, since
3848 the responsibility for update access control should rest
3850 master server, not the slaves.
3853 Note that enabling the update forwarding feature on a slave
3855 may expose master servers relying on insecure IP address
3857 access control to attacks; see <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called “Dynamic Update Security”</a>
3861 <dt><span class="term"><span><strong class="command">allow-v6-synthesis</strong></span></span></dt>
3863 This option was introduced for the smooth transition from
3865 to A6 and from "nibble labels" to binary labels.
3866 However, since both A6 and binary labels were then
3868 this option was also deprecated.
3869 It is now ignored with some warning messages.
3871 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
3873 Specifies which hosts are allowed to
3874 receive zone transfers from the server. <span><strong class="command">allow-transfer</strong></span> may
3875 also be specified in the <span><strong class="command">zone</strong></span>
3877 case it overrides the <span><strong class="command">options allow-transfer</strong></span> statement.
3878 If not specified, the default is to allow transfers to all
3881 <dt><span class="term"><span><strong class="command">blackhole</strong></span></span></dt>
3883 Specifies a list of addresses that the
3884 server will not accept queries from or use to resolve a
3886 from these addresses will not be responded to. The default
3887 is <strong class="userinput"><code>none</code></strong>.
3889 <dt><span class="term"><span><strong class="command">filter-aaaa</strong></span></span></dt>
3891 Specifies a list of addresses to which
3892 <span><strong class="command">filter-aaaa-on-v4</strong></span>
3893 is applies. The default is <strong class="userinput"><code>any</code></strong>.
3895 <dt><span class="term"><span><strong class="command">resolver-query-timeout</strong></span></span></dt>
3897 The amount of time the resolver will spend attempting
3898 to resolve a recursive query before failing. The
3899 default is <code class="literal">10</code> and the maximum is
3900 <code class="literal">30</code>. Setting it to <code class="literal">0</code>
3901 will result in the default being used.
3905 <div class="sect3" lang="en">
3906 <div class="titlepage"><div><div><h4 class="title">
3907 <a name="id2584382"></a>Interfaces</h4></div></div></div>
3909 The interfaces and ports that the server will answer queries
3910 from may be specified using the <span><strong class="command">listen-on</strong></span> option. <span><strong class="command">listen-on</strong></span> takes
3911 an optional port and an <code class="varname">address_match_list</code>.
3912 The server will listen on all interfaces allowed by the address
3913 match list. If a port is not specified, port 53 will be used.
3916 Multiple <span><strong class="command">listen-on</strong></span> statements are
3920 <pre class="programlisting">listen-on { 5.6.7.8; };
3921 listen-on port 1234 { !1.2.3.4; 1.2/16; };
3924 will enable the name server on port 53 for the IP address
3925 5.6.7.8, and on port 1234 of an address on the machine in net
3926 1.2 that is not 1.2.3.4.
3929 If no <span><strong class="command">listen-on</strong></span> is specified, the
3930 server will listen on port 53 on all IPv4 interfaces.
3933 The <span><strong class="command">listen-on-v6</strong></span> option is used to
3934 specify the interfaces and the ports on which the server will
3936 for incoming queries sent using IPv6.
3940 <pre class="programlisting">{ any; }</pre>
3943 as the <code class="varname">address_match_list</code> for the
3944 <span><strong class="command">listen-on-v6</strong></span> option,
3945 the server does not bind a separate socket to each IPv6 interface
3946 address as it does for IPv4 if the operating system has enough API
3947 support for IPv6 (specifically if it conforms to RFC 3493 and RFC
3949 Instead, it listens on the IPv6 wildcard address.
3950 If the system only has incomplete API support for IPv6, however,
3951 the behavior is the same as that for IPv4.
3954 A list of particular IPv6 addresses can also be specified, in
3956 the server listens on a separate socket for each specified
3958 regardless of whether the desired API is supported by the system.
3961 Multiple <span><strong class="command">listen-on-v6</strong></span> options can
3965 <pre class="programlisting">listen-on-v6 { any; };
3966 listen-on-v6 port 1234 { !2001:db8::/32; any; };
3969 will enable the name server on port 53 for any IPv6 addresses
3970 (with a single wildcard socket),
3971 and on port 1234 of IPv6 addresses that is not in the prefix
3972 2001:db8::/32 (with separate sockets for each matched address.)
3975 To make the server not listen on any IPv6 address, use
3977 <pre class="programlisting">listen-on-v6 { none; };
3980 If no <span><strong class="command">listen-on-v6</strong></span> option is
3981 specified, the server will not listen on any IPv6 address
3982 unless <span><strong class="command">-6</strong></span> is specified when <span><strong class="command">named</strong></span> is
3983 invoked. If <span><strong class="command">-6</strong></span> is specified then
3984 <span><strong class="command">named</strong></span> will listen on port 53 on all IPv6 interfaces by default.
3987 <div class="sect3" lang="en">
3988 <div class="titlepage"><div><div><h4 class="title">
3989 <a name="query_address"></a>Query Address</h4></div></div></div>
3991 If the server doesn't know the answer to a question, it will
3992 query other name servers. <span><strong class="command">query-source</strong></span> specifies
3993 the address and port used for such queries. For queries sent over
3994 IPv6, there is a separate <span><strong class="command">query-source-v6</strong></span> option.
3995 If <span><strong class="command">address</strong></span> is <span><strong class="command">*</strong></span> (asterisk) or is omitted,
3996 a wildcard IP address (<span><strong class="command">INADDR_ANY</strong></span>)
4000 If <span><strong class="command">port</strong></span> is <span><strong class="command">*</strong></span> or is omitted,
4001 a random port number from a pre-configured
4002 range is picked up and will be used for each query.
4003 The port range(s) is that specified in
4004 the <span><strong class="command">use-v4-udp-ports</strong></span> (for IPv4)
4005 and <span><strong class="command">use-v6-udp-ports</strong></span> (for IPv6)
4006 options, excluding the ranges specified in
4007 the <span><strong class="command">avoid-v4-udp-ports</strong></span>
4008 and <span><strong class="command">avoid-v6-udp-ports</strong></span> options, respectively.
4011 The defaults of the <span><strong class="command">query-source</strong></span> and
4012 <span><strong class="command">query-source-v6</strong></span> options
4015 <pre class="programlisting">query-source address * port *;
4016 query-source-v6 address * port *;
4019 If <span><strong class="command">use-v4-udp-ports</strong></span> or
4020 <span><strong class="command">use-v6-udp-ports</strong></span> is unspecified,
4021 <span><strong class="command">named</strong></span> will check if the operating
4022 system provides a programming interface to retrieve the
4023 system's default range for ephemeral ports.
4024 If such an interface is available,
4025 <span><strong class="command">named</strong></span> will use the corresponding system
4026 default range; otherwise, it will use its own defaults:
4028 <pre class="programlisting">use-v4-udp-ports { range 1024 65535; };
4029 use-v6-udp-ports { range 1024 65535; };
4032 Note: make sure the ranges be sufficiently large for
4033 security. A desirable size depends on various parameters,
4034 but we generally recommend it contain at least 16384 ports
4035 (14 bits of entropy).
4036 Note also that the system's default range when used may be
4037 too small for this purpose, and that the range may even be
4038 changed while <span><strong class="command">named</strong></span> is running; the new
4039 range will automatically be applied when <span><strong class="command">named</strong></span>
4042 configure <span><strong class="command">use-v4-udp-ports</strong></span> and
4043 <span><strong class="command">use-v6-udp-ports</strong></span> explicitly so that the
4044 ranges are sufficiently large and are reasonably
4045 independent from the ranges used by other applications.
4048 Note: the operational configuration
4049 where <span><strong class="command">named</strong></span> runs may prohibit the use
4050 of some ports. For example, UNIX systems will not allow
4051 <span><strong class="command">named</strong></span> running without a root privilege
4052 to use ports less than 1024.
4053 If such ports are included in the specified (or detected)
4054 set of query ports, the corresponding query attempts will
4055 fail, resulting in resolution failures or delay.
4056 It is therefore important to configure the set of ports
4057 that can be safely used in the expected operational environment.
4060 The defaults of the <span><strong class="command">avoid-v4-udp-ports</strong></span> and
4061 <span><strong class="command">avoid-v6-udp-ports</strong></span> options
4064 <pre class="programlisting">avoid-v4-udp-ports {};
4065 avoid-v6-udp-ports {};
4068 Note: BIND 9.5.0 introduced
4069 the <span><strong class="command">use-queryport-pool</strong></span>
4070 option to support a pool of such random ports, but this
4071 option is now obsolete because reusing the same ports in
4072 the pool may not be sufficiently secure.
4073 For the same reason, it is generally strongly discouraged to
4074 specify a particular port for the
4075 <span><strong class="command">query-source</strong></span> or
4076 <span><strong class="command">query-source-v6</strong></span> options;
4077 it implicitly disables the use of randomized port numbers.
4079 <div class="variablelist"><dl>
4080 <dt><span class="term"><span><strong class="command">use-queryport-pool</strong></span></span></dt>
4082 This option is obsolete.
4084 <dt><span class="term"><span><strong class="command">queryport-pool-ports</strong></span></span></dt>
4086 This option is obsolete.
4088 <dt><span class="term"><span><strong class="command">queryport-pool-updateinterval</strong></span></span></dt>
4090 This option is obsolete.
4093 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4094 <h3 class="title">Note</h3>
4096 The address specified in the <span><strong class="command">query-source</strong></span> option
4097 is used for both UDP and TCP queries, but the port applies only
4098 to UDP queries. TCP queries always use a random
4102 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4103 <h3 class="title">Note</h3>
4105 Solaris 2.5.1 and earlier does not support setting the source
4106 address for TCP sockets.
4109 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4110 <h3 class="title">Note</h3>
4112 See also <span><strong class="command">transfer-source</strong></span> and
4113 <span><strong class="command">notify-source</strong></span>.
4117 <div class="sect3" lang="en">
4118 <div class="titlepage"><div><div><h4 class="title">
4119 <a name="zone_transfers"></a>Zone Transfers</h4></div></div></div>
4121 <acronym class="acronym">BIND</acronym> has mechanisms in place to
4122 facilitate zone transfers
4123 and set limits on the amount of load that transfers place on the
4124 system. The following options apply to zone transfers.
4126 <div class="variablelist"><dl>
4127 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
4129 Defines a global list of IP addresses of name servers
4130 that are also sent NOTIFY messages whenever a fresh copy of
4132 zone is loaded, in addition to the servers listed in the
4134 This helps to ensure that copies of the zones will
4135 quickly converge on stealth servers.
4136 Optionally, a port may be specified with each
4137 <span><strong class="command">also-notify</strong></span> address to send
4138 the notify messages to a port other than the
4140 If an <span><strong class="command">also-notify</strong></span> list
4141 is given in a <span><strong class="command">zone</strong></span> statement,
4143 the <span><strong class="command">options also-notify</strong></span>
4144 statement. When a <span><strong class="command">zone notify</strong></span>
4146 is set to <span><strong class="command">no</strong></span>, the IP
4147 addresses in the global <span><strong class="command">also-notify</strong></span> list will
4148 not be sent NOTIFY messages for that zone. The default is
4150 list (no global notification list).
4152 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
4154 Inbound zone transfers running longer than
4155 this many minutes will be terminated. The default is 120
4157 (2 hours). The maximum value is 28 days (40320 minutes).
4159 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
4161 Inbound zone transfers making no progress
4162 in this many minutes will be terminated. The default is 60
4164 (1 hour). The maximum value is 28 days (40320 minutes).
4166 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
4168 Outbound zone transfers running longer than
4169 this many minutes will be terminated. The default is 120
4171 (2 hours). The maximum value is 28 days (40320 minutes).
4173 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
4175 Outbound zone transfers making no progress
4176 in this many minutes will be terminated. The default is 60
4178 hour). The maximum value is 28 days (40320 minutes).
4180 <dt><span class="term"><span><strong class="command">serial-query-rate</strong></span></span></dt>
4183 Slave servers will periodically query master
4184 servers to find out if zone serial numbers have
4185 changed. Each such query uses a minute amount of
4186 the slave server's network bandwidth. To limit
4187 the amount of bandwidth used, BIND 9 limits the
4188 rate at which queries are sent. The value of the
4189 <span><strong class="command">serial-query-rate</strong></span> option, an
4190 integer, is the maximum number of queries sent
4191 per second. The default is 20.
4194 In addition to controlling the rate SOA refresh
4195 queries are issued at
4196 <span><strong class="command">serial-query-rate</strong></span> also controls
4197 the rate at which NOTIFY messages are sent from
4198 both master and slave zones.
4201 <dt><span class="term"><span><strong class="command">serial-queries</strong></span></span></dt>
4203 In BIND 8, the <span><strong class="command">serial-queries</strong></span>
4205 set the maximum number of concurrent serial number queries
4206 allowed to be outstanding at any given time.
4207 BIND 9 does not limit the number of outstanding
4208 serial queries and ignores the <span><strong class="command">serial-queries</strong></span> option.
4209 Instead, it limits the rate at which the queries are sent
4210 as defined using the <span><strong class="command">serial-query-rate</strong></span> option.
4212 <dt><span class="term"><span><strong class="command">transfer-format</strong></span></span></dt>
4214 Zone transfers can be sent using two different formats,
4215 <span><strong class="command">one-answer</strong></span> and
4216 <span><strong class="command">many-answers</strong></span>.
4217 The <span><strong class="command">transfer-format</strong></span> option is used
4218 on the master server to determine which format it sends.
4219 <span><strong class="command">one-answer</strong></span> uses one DNS message per
4220 resource record transferred.
4221 <span><strong class="command">many-answers</strong></span> packs as many resource
4222 records as possible into a message.
4223 <span><strong class="command">many-answers</strong></span> is more efficient, but is
4224 only supported by relatively new slave servers,
4225 such as <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
4226 8.x and <acronym class="acronym">BIND</acronym> 4.9.5 onwards.
4227 The <span><strong class="command">many-answers</strong></span> format is also supported by
4228 recent Microsoft Windows nameservers.
4229 The default is <span><strong class="command">many-answers</strong></span>.
4230 <span><strong class="command">transfer-format</strong></span> may be overridden on a
4231 per-server basis by using the <span><strong class="command">server</strong></span>
4234 <dt><span class="term"><span><strong class="command">transfers-in</strong></span></span></dt>
4236 The maximum number of inbound zone transfers
4237 that can be running concurrently. The default value is <code class="literal">10</code>.
4238 Increasing <span><strong class="command">transfers-in</strong></span> may
4239 speed up the convergence
4240 of slave zones, but it also may increase the load on the
4243 <dt><span class="term"><span><strong class="command">transfers-out</strong></span></span></dt>
4245 The maximum number of outbound zone transfers
4246 that can be running concurrently. Zone transfer requests in
4248 of the limit will be refused. The default value is <code class="literal">10</code>.
4250 <dt><span class="term"><span><strong class="command">transfers-per-ns</strong></span></span></dt>
4252 The maximum number of inbound zone transfers
4253 that can be concurrently transferring from a given remote
4255 The default value is <code class="literal">2</code>.
4256 Increasing <span><strong class="command">transfers-per-ns</strong></span>
4258 speed up the convergence of slave zones, but it also may
4260 the load on the remote name server. <span><strong class="command">transfers-per-ns</strong></span> may
4261 be overridden on a per-server basis by using the <span><strong class="command">transfers</strong></span> phrase
4262 of the <span><strong class="command">server</strong></span> statement.
4264 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
4266 <p><span><strong class="command">transfer-source</strong></span>
4267 determines which local address will be bound to IPv4
4268 TCP connections used to fetch zones transferred
4269 inbound by the server. It also determines the
4270 source IPv4 address, and optionally the UDP port,
4271 used for the refresh queries and forwarded dynamic
4272 updates. If not set, it defaults to a system
4273 controlled value which will usually be the address
4274 of the interface "closest to" the remote end. This
4275 address must appear in the remote end's
4276 <span><strong class="command">allow-transfer</strong></span> option for the
4277 zone being transferred, if one is specified. This
4279 <span><strong class="command">transfer-source</strong></span> for all zones,
4280 but can be overridden on a per-view or per-zone
4281 basis by including a
4282 <span><strong class="command">transfer-source</strong></span> statement within
4283 the <span><strong class="command">view</strong></span> or
4284 <span><strong class="command">zone</strong></span> block in the configuration
4287 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4288 <h3 class="title">Note</h3>
4290 Solaris 2.5.1 and earlier does not support setting the
4291 source address for TCP sockets.
4295 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
4297 The same as <span><strong class="command">transfer-source</strong></span>,
4298 except zone transfers are performed using IPv6.
4300 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
4303 An alternate transfer source if the one listed in
4304 <span><strong class="command">transfer-source</strong></span> fails and
4305 <span><strong class="command">use-alt-transfer-source</strong></span> is
4308 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4309 <h3 class="title">Note</h3>
4310 If you do not wish the alternate transfer source
4311 to be used, you should set
4312 <span><strong class="command">use-alt-transfer-source</strong></span>
4313 appropriately and you should not depend upon
4314 getting an answer back to the first refresh
4318 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
4320 An alternate transfer source if the one listed in
4321 <span><strong class="command">transfer-source-v6</strong></span> fails and
4322 <span><strong class="command">use-alt-transfer-source</strong></span> is
4325 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
4327 Use the alternate transfer sources or not. If views are
4328 specified this defaults to <span><strong class="command">no</strong></span>
4329 otherwise it defaults to
4330 <span><strong class="command">yes</strong></span> (for BIND 8
4333 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
4335 <p><span><strong class="command">notify-source</strong></span>
4336 determines which local source address, and
4337 optionally UDP port, will be used to send NOTIFY
4338 messages. This address must appear in the slave
4339 server's <span><strong class="command">masters</strong></span> zone clause or
4340 in an <span><strong class="command">allow-notify</strong></span> clause. This
4341 statement sets the <span><strong class="command">notify-source</strong></span>
4342 for all zones, but can be overridden on a per-zone or
4343 per-view basis by including a
4344 <span><strong class="command">notify-source</strong></span> statement within
4345 the <span><strong class="command">zone</strong></span> or
4346 <span><strong class="command">view</strong></span> block in the configuration
4349 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4350 <h3 class="title">Note</h3>
4352 Solaris 2.5.1 and earlier does not support setting the
4353 source address for TCP sockets.
4357 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
4359 Like <span><strong class="command">notify-source</strong></span>,
4360 but applies to notify messages sent to IPv6 addresses.
4364 <div class="sect3" lang="en">
4365 <div class="titlepage"><div><div><h4 class="title">
4366 <a name="id2585456"></a>UDP Port Lists</h4></div></div></div>
4368 <span><strong class="command">use-v4-udp-ports</strong></span>,
4369 <span><strong class="command">avoid-v4-udp-ports</strong></span>,
4370 <span><strong class="command">use-v6-udp-ports</strong></span>, and
4371 <span><strong class="command">avoid-v6-udp-ports</strong></span>
4372 specify a list of IPv4 and IPv6 UDP ports that will be
4373 used or not used as source ports for UDP messages.
4374 See <a href="Bv9ARM.ch06.html#query_address" title="Query Address">the section called “Query Address”</a> about how the
4375 available ports are determined.
4376 For example, with the following configuration
4378 <pre class="programlisting">
4379 use-v6-udp-ports { range 32768 65535; };
4380 avoid-v6-udp-ports { 40000; range 50000 60000; };
4383 UDP ports of IPv6 messages sent
4384 from <span><strong class="command">named</strong></span> will be in one
4385 of the following ranges: 32768 to 39999, 40001 to 49999,
4389 <span><strong class="command">avoid-v4-udp-ports</strong></span> and
4390 <span><strong class="command">avoid-v6-udp-ports</strong></span> can be used
4391 to prevent <span><strong class="command">named</strong></span> from choosing as its random source port a
4392 port that is blocked by your firewall or a port that is
4393 used by other applications;
4394 if a query went out with a source port blocked by a
4396 answer would not get by the firewall and the name server would
4397 have to query again.
4398 Note: the desired range can also be represented only with
4399 <span><strong class="command">use-v4-udp-ports</strong></span> and
4400 <span><strong class="command">use-v6-udp-ports</strong></span>, and the
4401 <span><strong class="command">avoid-</strong></span> options are redundant in that
4402 sense; they are provided for backward compatibility and
4403 to possibly simplify the port specification.
4406 <div class="sect3" lang="en">
4407 <div class="titlepage"><div><div><h4 class="title">
4408 <a name="id2585584"></a>Operating System Resource Limits</h4></div></div></div>
4410 The server's usage of many system resources can be limited.
4411 Scaled values are allowed when specifying resource limits. For
4412 example, <span><strong class="command">1G</strong></span> can be used instead of
4413 <span><strong class="command">1073741824</strong></span> to specify a limit of
4415 gigabyte. <span><strong class="command">unlimited</strong></span> requests
4416 unlimited use, or the
4417 maximum available amount. <span><strong class="command">default</strong></span>
4419 that was in force when the server was started. See the description
4420 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>.
4423 The following options set operating system resource limits for
4424 the name server process. Some operating systems don't support
4426 any of the limits. On such systems, a warning will be issued if
4428 unsupported limit is used.
4430 <div class="variablelist"><dl>
4431 <dt><span class="term"><span><strong class="command">coresize</strong></span></span></dt>
4433 The maximum size of a core dump. The default
4434 is <code class="literal">default</code>.
4436 <dt><span class="term"><span><strong class="command">datasize</strong></span></span></dt>
4438 The maximum amount of data memory the server
4439 may use. The default is <code class="literal">default</code>.
4440 This is a hard limit on server memory usage.
4441 If the server attempts to allocate memory in excess of this
4442 limit, the allocation will fail, which may in turn leave
4443 the server unable to perform DNS service. Therefore,
4444 this option is rarely useful as a way of limiting the
4445 amount of memory used by the server, but it can be used
4446 to raise an operating system data size limit that is
4447 too small by default. If you wish to limit the amount
4448 of memory used by the server, use the
4449 <span><strong class="command">max-cache-size</strong></span> and
4450 <span><strong class="command">recursive-clients</strong></span>
4453 <dt><span class="term"><span><strong class="command">files</strong></span></span></dt>
4455 The maximum number of files the server
4456 may have open concurrently. The default is <code class="literal">unlimited</code>.
4458 <dt><span class="term"><span><strong class="command">stacksize</strong></span></span></dt>
4460 The maximum amount of stack memory the server
4461 may use. The default is <code class="literal">default</code>.
4465 <div class="sect3" lang="en">
4466 <div class="titlepage"><div><div><h4 class="title">
4467 <a name="server_resource_limits"></a>Server Resource Limits</h4></div></div></div>
4469 The following options set limits on the server's
4470 resource consumption that are enforced internally by the
4471 server rather than the operating system.
4473 <div class="variablelist"><dl>
4474 <dt><span class="term"><span><strong class="command">max-ixfr-log-size</strong></span></span></dt>
4476 This option is obsolete; it is accepted
4477 and ignored for BIND 8 compatibility. The option
4478 <span><strong class="command">max-journal-size</strong></span> performs a
4479 similar function in BIND 9.
4481 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
4483 Sets a maximum size for each journal file
4484 (see <a href="Bv9ARM.ch04.html#journal" title="The journal file">the section called “The journal file”</a>). When the journal file
4486 the specified size, some of the oldest transactions in the
4488 will be automatically removed. The default is
4489 <code class="literal">unlimited</code>.
4490 This may also be set on a per-zone basis.
4492 <dt><span class="term"><span><strong class="command">host-statistics-max</strong></span></span></dt>
4494 In BIND 8, specifies the maximum number of host statistics
4496 Not implemented in BIND 9.
4498 <dt><span class="term"><span><strong class="command">recursive-clients</strong></span></span></dt>
4500 The maximum number of simultaneous recursive lookups
4501 the server will perform on behalf of clients. The default
4503 <code class="literal">1000</code>. Because each recursing
4505 bit of memory, on the order of 20 kilobytes, the value of
4507 <span><strong class="command">recursive-clients</strong></span> option may
4508 have to be decreased
4509 on hosts with limited memory.
4511 <dt><span class="term"><span><strong class="command">tcp-clients</strong></span></span></dt>
4513 The maximum number of simultaneous client TCP
4514 connections that the server will accept.
4515 The default is <code class="literal">100</code>.
4517 <dt><span class="term"><span><strong class="command">reserved-sockets</strong></span></span></dt>
4520 The number of file descriptors reserved for TCP, stdio,
4521 etc. This needs to be big enough to cover the number of
4522 interfaces <span><strong class="command">named</strong></span> listens on, <span><strong class="command">tcp-clients</strong></span> as well as
4523 to provide room for outgoing TCP queries and incoming zone
4524 transfers. The default is <code class="literal">512</code>.
4525 The minimum value is <code class="literal">128</code> and the
4526 maximum value is <code class="literal">128</code> less than
4527 maxsockets (-S). This option may be removed in the future.
4530 This option has little effect on Windows.
4533 <dt><span class="term"><span><strong class="command">max-cache-size</strong></span></span></dt>
4535 The maximum amount of memory to use for the
4536 server's cache, in bytes.
4537 When the amount of data in the cache
4538 reaches this limit, the server will cause records to expire
4539 prematurely based on an LRU based strategy so that
4540 the limit is not exceeded.
4541 A value of 0 is special, meaning that
4542 records are purged from the cache only when their
4544 Another special keyword <strong class="userinput"><code>unlimited</code></strong>
4545 means the maximum value of 32-bit unsigned integers
4546 (0xffffffff), which may not have the same effect as
4547 0 on machines that support more than 32 bits of
4549 Any positive values less than 2MB will be ignored reset
4551 In a server with multiple views, the limit applies
4552 separately to the cache of each view.
4555 <dt><span class="term"><span><strong class="command">tcp-listen-queue</strong></span></span></dt>
4557 The listen queue depth. The default and minimum is 3.
4558 If the kernel supports the accept filter "dataready" this
4560 many TCP connections that will be queued in kernel space
4562 some data before being passed to accept. Values less than 3
4568 <div class="sect3" lang="en">
4569 <div class="titlepage"><div><div><h4 class="title">
4570 <a name="id2585869"></a>Periodic Task Intervals</h4></div></div></div>
4571 <div class="variablelist"><dl>
4572 <dt><span class="term"><span><strong class="command">cleaning-interval</strong></span></span></dt>
4574 This interval is effectively obsolete. Previously,
4575 the server would remove expired resource records
4576 from the cache every <span><strong class="command">cleaning-interval</strong></span> minutes.
4577 <acronym class="acronym">BIND</acronym> 9 now manages cache
4578 memory in a more sophisticated manner and does not
4579 rely on the periodic cleaning any more.
4580 Specifying this option therefore has no effect on
4581 the server's behavior.
4583 <dt><span class="term"><span><strong class="command">heartbeat-interval</strong></span></span></dt>
4585 The server will perform zone maintenance tasks
4586 for all zones marked as <span><strong class="command">dialup</strong></span> whenever this
4587 interval expires. The default is 60 minutes. Reasonable
4589 to 1 day (1440 minutes). The maximum value is 28 days
4591 If set to 0, no zone maintenance for these zones will occur.
4593 <dt><span class="term"><span><strong class="command">interface-interval</strong></span></span></dt>
4595 The server will scan the network interface list
4596 every <span><strong class="command">interface-interval</strong></span>
4597 minutes. The default
4598 is 60 minutes. The maximum value is 28 days (40320 minutes).
4599 If set to 0, interface scanning will only occur when
4600 the configuration file is loaded. After the scan, the
4602 begin listening for queries on any newly discovered
4603 interfaces (provided they are allowed by the
4604 <span><strong class="command">listen-on</strong></span> configuration), and
4606 stop listening on interfaces that have gone away.
4608 <dt><span class="term"><span><strong class="command">statistics-interval</strong></span></span></dt>
4611 Name server statistics will be logged
4612 every <span><strong class="command">statistics-interval</strong></span>
4613 minutes. The default is
4614 60. The maximum value is 28 days (40320 minutes).
4615 If set to 0, no statistics will be logged.
4617 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4618 <h3 class="title">Note</h3>
4620 Not yet implemented in
4621 <acronym class="acronym">BIND</acronym> 9.
4627 <div class="sect3" lang="en">
4628 <div class="titlepage"><div><div><h4 class="title">
4629 <a name="topology"></a>Topology</h4></div></div></div>
4631 All other things being equal, when the server chooses a name
4633 to query from a list of name servers, it prefers the one that is
4634 topologically closest to itself. The <span><strong class="command">topology</strong></span> statement
4635 takes an <span><strong class="command">address_match_list</strong></span> and
4637 in a special way. Each top-level list element is assigned a
4639 Non-negated elements get a distance based on their position in the
4640 list, where the closer the match is to the start of the list, the
4641 shorter the distance is between it and the server. A negated match
4642 will be assigned the maximum distance from the server. If there
4643 is no match, the address will get a distance which is further than
4644 any non-negated list element, and closer than any negated element.
4647 <pre class="programlisting">topology {
4653 will prefer servers on network 10 the most, followed by hosts
4654 on network 1.2.0.0 (netmask 255.255.0.0) and network 3, with the
4655 exception of hosts on network 1.2.3 (netmask 255.255.255.0), which
4656 is preferred least of all.
4659 The default topology is
4661 <pre class="programlisting"> topology { localhost; localnets; };
4663 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4664 <h3 class="title">Note</h3>
4666 The <span><strong class="command">topology</strong></span> option
4667 is not implemented in <acronym class="acronym">BIND</acronym> 9.
4671 <div class="sect3" lang="en">
4672 <div class="titlepage"><div><div><h4 class="title">
4673 <a name="the_sortlist_statement"></a>The <span><strong class="command">sortlist</strong></span> Statement</h4></div></div></div>
4675 The response to a DNS query may consist of multiple resource
4676 records (RRs) forming a resource records set (RRset).
4677 The name server will normally return the
4678 RRs within the RRset in an indeterminate order
4679 (but see the <span><strong class="command">rrset-order</strong></span>
4680 statement in <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called “RRset Ordering”</a>).
4681 The client resolver code should rearrange the RRs as appropriate,
4682 that is, using any addresses on the local net in preference to
4684 However, not all resolvers can do this or are correctly
4686 When a client is using a local server, the sorting can be performed
4687 in the server, based on the client's address. This only requires
4688 configuring the name servers, not all the clients.
4691 The <span><strong class="command">sortlist</strong></span> statement (see below)
4693 an <span><strong class="command">address_match_list</strong></span> and
4695 more specifically than the <span><strong class="command">topology</strong></span>
4697 does (<a href="Bv9ARM.ch06.html#topology" title="Topology">the section called “Topology”</a>).
4698 Each top level statement in the <span><strong class="command">sortlist</strong></span> must
4699 itself be an explicit <span><strong class="command">address_match_list</strong></span> with
4700 one or two elements. The first element (which may be an IP
4702 an IP prefix, an ACL name or a nested <span><strong class="command">address_match_list</strong></span>)
4703 of each top level list is checked against the source address of
4704 the query until a match is found.
4707 Once the source address of the query has been matched, if
4708 the top level statement contains only one element, the actual
4710 element that matched the source address is used to select the
4712 in the response to move to the beginning of the response. If the
4713 statement is a list of two elements, then the second element is
4714 treated the same as the <span><strong class="command">address_match_list</strong></span> in
4715 a <span><strong class="command">topology</strong></span> statement. Each top
4717 is assigned a distance and the address in the response with the
4719 distance is moved to the beginning of the response.
4722 In the following example, any queries received from any of
4723 the addresses of the host itself will get responses preferring
4725 on any of the locally connected networks. Next most preferred are
4727 on the 192.168.1/24 network, and after that either the
4730 192.168.3/24 network with no preference shown between these two
4731 networks. Queries received from a host on the 192.168.1/24 network
4732 will prefer other addresses on that network to the 192.168.2/24
4734 192.168.3/24 networks. Queries received from a host on the
4736 or the 192.168.5/24 network will only prefer other addresses on
4737 their directly connected networks.
4739 <pre class="programlisting">sortlist {
4740 // IF the local host
4741 // THEN first fit on the following nets
4745 { 192.168.2/24; 192.168.3/24; }; }; };
4746 // IF on class C 192.168.1 THEN use .1, or .2 or .3
4749 { 192.168.2/24; 192.168.3/24; }; }; };
4750 // IF on class C 192.168.2 THEN use .2, or .1 or .3
4753 { 192.168.1/24; 192.168.3/24; }; }; };
4754 // IF on class C 192.168.3 THEN use .3, or .1 or .2
4757 { 192.168.1/24; 192.168.2/24; }; }; };
4758 // IF .4 or .5 THEN prefer that net
4759 { { 192.168.4/24; 192.168.5/24; };
4763 The following example will give reasonable behavior for the
4764 local host and hosts on directly connected networks. It is similar
4765 to the behavior of the address sort in <acronym class="acronym">BIND</acronym> 4.9.x. Responses sent
4766 to queries from the local host will favor any of the directly
4768 networks. Responses sent to queries from any other hosts on a
4770 connected network will prefer addresses on that same network.
4772 to other queries will not be sorted.
4774 <pre class="programlisting">sortlist {
4775 { localhost; localnets; };
4780 <div class="sect3" lang="en">
4781 <div class="titlepage"><div><div><h4 class="title">
4782 <a name="rrset_ordering"></a>RRset Ordering</h4></div></div></div>
4784 When multiple records are returned in an answer it may be
4785 useful to configure the order of the records placed into the
4787 The <span><strong class="command">rrset-order</strong></span> statement permits
4789 of the ordering of the records in a multiple record response.
4790 See also the <span><strong class="command">sortlist</strong></span> statement,
4791 <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>.
4794 An <span><strong class="command">order_spec</strong></span> is defined as
4798 [<span class="optional">class <em class="replaceable"><code>class_name</code></em></span>]
4799 [<span class="optional">type <em class="replaceable"><code>type_name</code></em></span>]
4800 [<span class="optional">name <em class="replaceable"><code>"domain_name"</code></em></span>]
4801 order <em class="replaceable"><code>ordering</code></em>
4804 If no class is specified, the default is <span><strong class="command">ANY</strong></span>.
4805 If no type is specified, the default is <span><strong class="command">ANY</strong></span>.
4806 If no name is specified, the default is "<span><strong class="command">*</strong></span>" (asterisk).
4809 The legal values for <span><strong class="command">ordering</strong></span> are:
4811 <div class="informaltable"><table border="1">
4819 <p><span><strong class="command">fixed</strong></span></p>
4823 Records are returned in the order they
4824 are defined in the zone file.
4830 <p><span><strong class="command">random</strong></span></p>
4834 Records are returned in some random order.
4840 <p><span><strong class="command">cyclic</strong></span></p>
4844 Records are returned in a cyclic round-robin order.
4847 If <acronym class="acronym">BIND</acronym> is configured with the
4848 "--enable-fixed-rrset" option at compile time, then
4849 the initial ordering of the RRset will match the
4850 one specified in the zone file.
4859 <pre class="programlisting">rrset-order {
4860 class IN type A name "host.example.com" order random;
4865 will cause any responses for type A records in class IN that
4866 have "<code class="literal">host.example.com</code>" as a
4867 suffix, to always be returned
4868 in random order. All other records are returned in cyclic order.
4871 If multiple <span><strong class="command">rrset-order</strong></span> statements
4873 they are not combined — the last one applies.
4875 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4876 <h3 class="title">Note</h3>
4878 In this release of <acronym class="acronym">BIND</acronym> 9, the
4879 <span><strong class="command">rrset-order</strong></span> statement does not support
4880 "fixed" ordering by default. Fixed ordering can be enabled
4881 at compile time by specifying "--enable-fixed-rrset" on
4882 the "configure" command line.
4886 <div class="sect3" lang="en">
4887 <div class="titlepage"><div><div><h4 class="title">
4888 <a name="tuning"></a>Tuning</h4></div></div></div>
4889 <div class="variablelist"><dl>
4890 <dt><span class="term"><span><strong class="command">lame-ttl</strong></span></span></dt>
4893 Sets the number of seconds to cache a
4894 lame server indication. 0 disables caching. (This is
4895 <span class="bold"><strong>NOT</strong></span> recommended.)
4896 The default is <code class="literal">600</code> (10 minutes) and the
4898 <code class="literal">1800</code> (30 minutes).
4901 Lame-ttl also controls the amount of time DNSSEC
4902 validation failures are cached. There is a minimum
4903 of 30 seconds applied to bad cache entries if the
4904 lame-ttl is set to less than 30 seconds.
4907 <dt><span class="term"><span><strong class="command">max-ncache-ttl</strong></span></span></dt>
4909 To reduce network traffic and increase performance,
4910 the server stores negative answers. <span><strong class="command">max-ncache-ttl</strong></span> is
4911 used to set a maximum retention time for these answers in
4913 in seconds. The default
4914 <span><strong class="command">max-ncache-ttl</strong></span> is <code class="literal">10800</code> seconds (3 hours).
4915 <span><strong class="command">max-ncache-ttl</strong></span> cannot exceed
4917 be silently truncated to 7 days if set to a greater value.
4919 <dt><span class="term"><span><strong class="command">max-cache-ttl</strong></span></span></dt>
4921 Sets the maximum time for which the server will
4922 cache ordinary (positive) answers. The default is
4924 A value of zero may cause all queries to return
4925 SERVFAIL, because of lost caches of intermediate
4926 RRsets (such as NS and glue AAAA/A records) in the
4929 <dt><span class="term"><span><strong class="command">min-roots</strong></span></span></dt>
4932 The minimum number of root servers that
4933 is required for a request for the root servers to be
4934 accepted. The default
4935 is <strong class="userinput"><code>2</code></strong>.
4937 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
4938 <h3 class="title">Note</h3>
4940 Not implemented in <acronym class="acronym">BIND</acronym> 9.
4944 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
4947 Specifies the number of days into the future when
4948 DNSSEC signatures automatically generated as a
4949 result of dynamic updates (<a href="Bv9ARM.ch04.html#dynamic_update" title="Dynamic Update">the section called “Dynamic Update”</a>) will expire. There
4950 is an optional second field which specifies how
4951 long before expiry that the signatures will be
4952 regenerated. If not specified, the signatures will
4953 be regenerated at 1/4 of base interval. The second
4954 field is specified in days if the base interval is
4955 greater than 7 days otherwise it is specified in hours.
4956 The default base interval is <code class="literal">30</code> days
4957 giving a re-signing interval of 7 1/2 days. The maximum
4958 values are 10 years (3660 days).
4961 The signature inception time is unconditionally
4962 set to one hour before the current time to allow
4963 for a limited amount of clock skew.
4966 The <span><strong class="command">sig-validity-interval</strong></span>
4967 should be, at least, several multiples of the SOA
4968 expire interval to allow for reasonable interaction
4969 between the various timer and expiry dates.
4972 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
4974 Specify the maximum number of nodes to be
4975 examined in each quantum when signing a zone with
4976 a new DNSKEY. The default is
4977 <code class="literal">100</code>.
4979 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
4981 Specify a threshold number of signatures that
4982 will terminate processing a quantum when signing
4983 a zone with a new DNSKEY. The default is
4984 <code class="literal">10</code>.
4986 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
4989 Specify a private RDATA type to be used when generating
4990 key signing records. The default is
4991 <code class="literal">65535</code>.
4994 It is expected that this parameter may be removed
4995 in a future version once there is a standard type.
4999 <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>
5003 These options control the server's behavior on refreshing a
5005 (querying for SOA changes) or retrying failed transfers.
5006 Usually the SOA values for the zone are used, but these
5008 are set by the master, giving slave server administrators
5010 control over their contents.
5013 These options allow the administrator to set a minimum and
5015 refresh and retry time either per-zone, per-view, or
5017 These options are valid for slave and stub zones,
5018 and clamp the SOA refresh and retry times to the specified
5022 The following defaults apply.
5023 <span><strong class="command">min-refresh-time</strong></span> 300 seconds,
5024 <span><strong class="command">max-refresh-time</strong></span> 2419200 seconds
5025 (4 weeks), <span><strong class="command">min-retry-time</strong></span> 500 seconds,
5026 and <span><strong class="command">max-retry-time</strong></span> 1209600 seconds
5030 <dt><span class="term"><span><strong class="command">edns-udp-size</strong></span></span></dt>
5033 Sets the advertised EDNS UDP buffer size in bytes
5034 to control the size of packets received.
5035 Valid values are 512 to 4096 (values outside this range
5036 will be silently adjusted). The default value
5037 is 4096. The usual reason for setting
5038 <span><strong class="command">edns-udp-size</strong></span> to a non-default
5039 value is to get UDP answers to pass through broken
5040 firewalls that block fragmented packets and/or
5041 block UDP packets that are greater than 512 bytes.
5044 <span><strong class="command">named</strong></span> will fallback to using 512 bytes
5045 if it get a series of timeout at the initial value. 512
5046 bytes is not being offered to encourage sites to fix their
5047 firewalls. Small EDNS UDP sizes will result in the
5048 excessive use of TCP.
5051 <dt><span class="term"><span><strong class="command">max-udp-size</strong></span></span></dt>
5054 Sets the maximum EDNS UDP message size
5055 <span><strong class="command">named</strong></span> will send in bytes.
5056 Valid values are 512 to 4096 (values outside this
5057 range will be silently adjusted). The default
5058 value is 4096. The usual reason for setting
5059 <span><strong class="command">max-udp-size</strong></span> to a non-default
5060 value is to get UDP answers to pass through broken
5061 firewalls that block fragmented packets and/or
5062 block UDP packets that are greater than 512 bytes.
5063 This is independent of the advertised receive
5064 buffer (<span><strong class="command">edns-udp-size</strong></span>).
5067 Setting this to a low value will encourage additional
5068 TCP traffic to the nameserver.
5071 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
5073 the file format of zone files (see
5074 <a href="Bv9ARM.ch06.html#zonefile_format" title="Additional File Formats">the section called “Additional File Formats”</a>).
5075 The default value is <code class="constant">text</code>, which is the
5076 standard textual representation. Files in other formats
5077 than <code class="constant">text</code> are typically expected
5078 to be generated by the <span><strong class="command">named-compilezone</strong></span> tool.
5079 Note that when a zone file in a different format than
5080 <code class="constant">text</code> is loaded, <span><strong class="command">named</strong></span>
5081 may omit some of the checks which would be performed for a
5082 file in the <code class="constant">text</code> format. In particular,
5083 <span><strong class="command">check-names</strong></span> checks do not apply
5084 for the <code class="constant">raw</code> format. This means
5085 a zone file in the <code class="constant">raw</code> format
5086 must be generated with the same check level as that
5087 specified in the <span><strong class="command">named</strong></span> configuration
5088 file. This statement sets the
5089 <span><strong class="command">masterfile-format</strong></span> for all zones,
5090 but can be overridden on a per-zone or per-view basis
5091 by including a <span><strong class="command">masterfile-format</strong></span>
5092 statement within the <span><strong class="command">zone</strong></span> or
5093 <span><strong class="command">view</strong></span> block in the configuration
5097 <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>
5101 initial value (minimum) and maximum number of recursive
5102 simultaneous clients for any given query
5103 (<qname,qtype,qclass>) that the server will accept
5104 before dropping additional clients. <span><strong class="command">named</strong></span> will attempt to
5105 self tune this value and changes will be logged. The
5106 default values are 10 and 100.
5109 This value should reflect how many queries come in for
5110 a given name in the time it takes to resolve that name.
5111 If the number of queries exceed this value, <span><strong class="command">named</strong></span> will
5112 assume that it is dealing with a non-responsive zone
5113 and will drop additional queries. If it gets a response
5114 after dropping queries, it will raise the estimate. The
5115 estimate will then be lowered in 20 minutes if it has
5119 If <span><strong class="command">clients-per-query</strong></span> is set to zero,
5120 then there is no limit on the number of clients per query
5121 and no queries will be dropped.
5124 If <span><strong class="command">max-clients-per-query</strong></span> is set to zero,
5125 then there is no upper bound other than imposed by
5126 <span><strong class="command">recursive-clients</strong></span>.
5129 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
5132 The delay, in seconds, between sending sets of notify
5133 messages for a zone. The default is five (5) seconds.
5136 The overall rate that NOTIFY messages are sent for all
5137 zones is controlled by <span><strong class="command">serial-query-rate</strong></span>.
5142 <div class="sect3" lang="en">
5143 <div class="titlepage"><div><div><h4 class="title">
5144 <a name="builtin"></a>Built-in server information zones</h4></div></div></div>
5146 The server provides some helpful diagnostic information
5147 through a number of built-in zones under the
5148 pseudo-top-level-domain <code class="literal">bind</code> in the
5149 <span><strong class="command">CHAOS</strong></span> class. These zones are part
5151 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
5153 <span><strong class="command">CHAOS</strong></span> which is separate from the
5155 class <span><strong class="command">IN</strong></span>; therefore, any global
5157 such as <span><strong class="command">allow-query</strong></span> do not apply
5159 If you feel the need to disable these zones, use the options
5160 below, or hide the built-in <span><strong class="command">CHAOS</strong></span>
5162 defining an explicit view of class <span><strong class="command">CHAOS</strong></span>
5163 that matches all clients.
5165 <div class="variablelist"><dl>
5166 <dt><span class="term"><span><strong class="command">version</strong></span></span></dt>
5168 The version the server should report
5169 via a query of the name <code class="literal">version.bind</code>
5170 with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
5171 The default is the real version number of this server.
5172 Specifying <span><strong class="command">version none</strong></span>
5173 disables processing of the queries.
5175 <dt><span class="term"><span><strong class="command">hostname</strong></span></span></dt>
5177 The hostname the server should report via a query of
5178 the name <code class="filename">hostname.bind</code>
5179 with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
5180 This defaults to the hostname of the machine hosting the
5182 found by the gethostname() function. The primary purpose of such queries
5184 identify which of a group of anycast servers is actually
5185 answering your queries. Specifying <span><strong class="command">hostname none;</strong></span>
5186 disables processing of the queries.
5188 <dt><span class="term"><span><strong class="command">server-id</strong></span></span></dt>
5190 The ID the server should report when receiving a Name
5191 Server Identifier (NSID) query, or a query of the name
5192 <code class="filename">ID.SERVER</code> with type
5193 <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>.
5194 The primary purpose of such queries is to
5195 identify which of a group of anycast servers is actually
5196 answering your queries. Specifying <span><strong class="command">server-id none;</strong></span>
5197 disables processing of the queries.
5198 Specifying <span><strong class="command">server-id hostname;</strong></span> will cause <span><strong class="command">named</strong></span> to
5199 use the hostname as found by the gethostname() function.
5200 The default <span><strong class="command">server-id</strong></span> is <span><strong class="command">none</strong></span>.
5204 <div class="sect3" lang="en">
5205 <div class="titlepage"><div><div><h4 class="title">
5206 <a name="empty"></a>Built-in Empty Zones</h4></div></div></div>
5208 Named has some built-in empty zones (SOA and NS records only).
5209 These are for zones that should normally be answered locally
5210 and which queries should not be sent to the Internet's root
5211 servers. The official servers which cover these namespaces
5212 return NXDOMAIN responses to these queries. In particular,
5213 these cover the reverse namespace for addresses from RFC 1918 and
5214 RFC 3330. They also include the reverse namespace for IPv6 local
5215 address (locally assigned), IPv6 link local addresses, the IPv6
5216 loopback address and the IPv6 unknown address.
5219 Named will attempt to determine if a built-in zone already exists
5220 or is active (covered by a forward-only forwarding declaration)
5221 and will not create an empty zone in that case.
5224 The current list of empty zones is:
5226 <div class="itemizedlist"><ul type="disc">
5227 <li>10.IN-ADDR.ARPA</li>
5228 <li>16.172.IN-ADDR.ARPA</li>
5229 <li>17.172.IN-ADDR.ARPA</li>
5230 <li>18.172.IN-ADDR.ARPA</li>
5231 <li>19.172.IN-ADDR.ARPA</li>
5232 <li>20.172.IN-ADDR.ARPA</li>
5233 <li>21.172.IN-ADDR.ARPA</li>
5234 <li>22.172.IN-ADDR.ARPA</li>
5235 <li>23.172.IN-ADDR.ARPA</li>
5236 <li>24.172.IN-ADDR.ARPA</li>
5237 <li>25.172.IN-ADDR.ARPA</li>
5238 <li>26.172.IN-ADDR.ARPA</li>
5239 <li>27.172.IN-ADDR.ARPA</li>
5240 <li>28.172.IN-ADDR.ARPA</li>
5241 <li>29.172.IN-ADDR.ARPA</li>
5242 <li>30.172.IN-ADDR.ARPA</li>
5243 <li>31.172.IN-ADDR.ARPA</li>
5244 <li>168.192.IN-ADDR.ARPA</li>
5245 <li>0.IN-ADDR.ARPA</li>
5246 <li>127.IN-ADDR.ARPA</li>
5247 <li>254.169.IN-ADDR.ARPA</li>
5248 <li>2.0.192.IN-ADDR.ARPA</li>
5249 <li>100.51.198.IN-ADDR.ARPA</li>
5250 <li>113.0.203.IN-ADDR.ARPA</li>
5251 <li>255.255.255.255.IN-ADDR.ARPA</li>
5252 <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>
5253 <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>
5254 <li>8.B.D.0.1.0.0.2.IP6.ARPA</li>
5255 <li>D.F.IP6.ARPA</li>
5256 <li>8.E.F.IP6.ARPA</li>
5257 <li>9.E.F.IP6.ARPA</li>
5258 <li>A.E.F.IP6.ARPA</li>
5259 <li>B.E.F.IP6.ARPA</li>
5264 Empty zones are settable at the view level and only apply to
5265 views of class IN. Disabled empty zones are only inherited
5266 from options if there are no disabled empty zones specified
5267 at the view level. To override the options list of disabled
5268 zones, you can disable the root zone at the view level, for example:
5270 <pre class="programlisting">
5271 disable-empty-zone ".";
5276 If you are using the address ranges covered here, you should
5277 already have reverse zones covering the addresses you use.
5278 In practice this appears to not be the case with many queries
5279 being made to the infrastructure servers for names in these
5280 spaces. So many in fact that sacrificial servers were needed
5281 to be deployed to channel the query load away from the
5282 infrastructure servers.
5284 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
5285 <h3 class="title">Note</h3>
5286 The real parent servers for these zones should disable all
5287 empty zone under the parent zone they serve. For the real
5288 root servers, this is all built-in empty zones. This will
5289 enable them to return referrals to deeper in the tree.
5291 <div class="variablelist"><dl>
5292 <dt><span class="term"><span><strong class="command">empty-server</strong></span></span></dt>
5294 Specify what server name will appear in the returned
5295 SOA record for empty zones. If none is specified, then
5296 the zone's name will be used.
5298 <dt><span class="term"><span><strong class="command">empty-contact</strong></span></span></dt>
5300 Specify what contact name will appear in the returned
5301 SOA record for empty zones. If none is specified, then
5304 <dt><span class="term"><span><strong class="command">empty-zones-enable</strong></span></span></dt>
5306 Enable or disable all empty zones. By default, they
5309 <dt><span class="term"><span><strong class="command">disable-empty-zone</strong></span></span></dt>
5311 Disable individual empty zones. By default, none are
5312 disabled. This option can be specified multiple times.
5316 <div class="sect3" lang="en">
5317 <div class="titlepage"><div><div><h4 class="title">
5318 <a name="acache"></a>Additional Section Caching</h4></div></div></div>
5320 The additional section cache, also called <span><strong class="command">acache</strong></span>,
5321 is an internal cache to improve the response performance of BIND 9.
5322 When additional section caching is enabled, BIND 9 will
5323 cache an internal short-cut to the additional section content for
5325 Note that <span><strong class="command">acache</strong></span> is an internal caching
5326 mechanism of BIND 9, and is not related to the DNS caching
5330 Additional section caching does not change the
5331 response content (except the RRsets ordering of the additional
5332 section, see below), but can improve the response performance
5334 It is particularly effective when BIND 9 acts as an authoritative
5335 server for a zone that has many delegations with many glue RRs.
5338 In order to obtain the maximum performance improvement
5339 from additional section caching, setting
5340 <span><strong class="command">additional-from-cache</strong></span>
5341 to <span><strong class="command">no</strong></span> is recommended, since the current
5342 implementation of <span><strong class="command">acache</strong></span>
5343 does not short-cut of additional section information from the
5347 One obvious disadvantage of <span><strong class="command">acache</strong></span> is
5348 that it requires much more
5349 memory for the internal cached data.
5350 Thus, if the response performance does not matter and memory
5351 consumption is much more critical, the
5352 <span><strong class="command">acache</strong></span> mechanism can be
5353 disabled by setting <span><strong class="command">acache-enable</strong></span> to
5354 <span><strong class="command">no</strong></span>.
5355 It is also possible to specify the upper limit of memory
5357 for acache by using <span><strong class="command">max-acache-size</strong></span>.
5360 Additional section caching also has a minor effect on the
5361 RRset ordering in the additional section.
5362 Without <span><strong class="command">acache</strong></span>,
5363 <span><strong class="command">cyclic</strong></span> order is effective for the additional
5364 section as well as the answer and authority sections.
5365 However, additional section caching fixes the ordering when it
5366 first caches an RRset for the additional section, and the same
5367 ordering will be kept in succeeding responses, regardless of the
5368 setting of <span><strong class="command">rrset-order</strong></span>.
5369 The effect of this should be minor, however, since an
5370 RRset in the additional section
5371 typically only contains a small number of RRs (and in many cases
5372 it only contains a single RR), in which case the
5373 ordering does not matter much.
5376 The following is a summary of options related to
5377 <span><strong class="command">acache</strong></span>.
5379 <div class="variablelist"><dl>
5380 <dt><span class="term"><span><strong class="command">acache-enable</strong></span></span></dt>
5382 If <span><strong class="command">yes</strong></span>, additional section caching is
5383 enabled. The default value is <span><strong class="command">no</strong></span>.
5385 <dt><span class="term"><span><strong class="command">acache-cleaning-interval</strong></span></span></dt>
5387 The server will remove stale cache entries, based on an LRU
5389 algorithm, every <span><strong class="command">acache-cleaning-interval</strong></span> minutes.
5390 The default is 60 minutes.
5391 If set to 0, no periodic cleaning will occur.
5393 <dt><span class="term"><span><strong class="command">max-acache-size</strong></span></span></dt>
5395 The maximum amount of memory in bytes to use for the server's acache.
5396 When the amount of data in the acache reaches this limit,
5398 will clean more aggressively so that the limit is not
5400 In a server with multiple views, the limit applies
5402 acache of each view.
5403 The default is <code class="literal">16M</code>.
5407 <div class="sect3" lang="en">
5408 <div class="titlepage"><div><div><h4 class="title">
5409 <a name="id2588113"></a>Content Filtering</h4></div></div></div>
5411 <acronym class="acronym">BIND</acronym> 9 provides the ability to filter
5412 out DNS responses from external DNS servers containing
5413 certain types of data in the answer section.
5414 Specifically, it can reject address (A or AAAA) records if
5415 the corresponding IPv4 or IPv6 addresses match the given
5416 <code class="varname">address_match_list</code> of the
5417 <span><strong class="command">deny-answer-addresses</strong></span> option.
5418 It can also reject CNAME or DNAME records if the "alias"
5419 name (i.e., the CNAME alias or the substituted query name
5420 due to DNAME) matches the
5421 given <code class="varname">namelist</code> of the
5422 <span><strong class="command">deny-answer-aliases</strong></span> option, where
5423 "match" means the alias name is a subdomain of one of
5424 the <code class="varname">name_list</code> elements.
5425 If the optional <code class="varname">namelist</code> is specified
5426 with <span><strong class="command">except-from</strong></span>, records whose query name
5427 matches the list will be accepted regardless of the filter
5429 Likewise, if the alias name is a subdomain of the
5430 corresponding zone, the <span><strong class="command">deny-answer-aliases</strong></span>
5431 filter will not apply;
5432 for example, even if "example.com" is specified for
5433 <span><strong class="command">deny-answer-aliases</strong></span>,
5435 <pre class="programlisting">www.example.com. CNAME xxx.example.com.</pre>
5437 returned by an "example.com" server will be accepted.
5440 In the <code class="varname">address_match_list</code> of the
5441 <span><strong class="command">deny-answer-addresses</strong></span> option, only
5442 <code class="varname">ip_addr</code>
5443 and <code class="varname">ip_prefix</code>
5445 any <code class="varname">key_id</code> will be silently ignored.
5448 If a response message is rejected due to the filtering,
5449 the entire message is discarded without being cached, and
5450 a SERVFAIL error will be returned to the client.
5453 This filtering is intended to prevent "DNS rebinding attacks," in
5454 which an attacker, in response to a query for a domain name the
5455 attacker controls, returns an IP address within your own network or
5456 an alias name within your own domain.
5457 A naive web browser or script could then serve as an
5458 unintended proxy, allowing the attacker
5459 to get access to an internal node of your local network
5460 that couldn't be externally accessed otherwise.
5461 See the paper available at
5462 <a href="" target="_top">
5463 http://portal.acm.org/citation.cfm?id=1315245.1315298
5465 for more details about the attacks.
5468 For example, if you own a domain named "example.net" and
5469 your internal network uses an IPv4 prefix 192.0.2.0/24,
5470 you might specify the following rules:
5472 <pre class="programlisting">deny-answer-addresses { 192.0.2.0/24; } except-from { "example.net"; };
5473 deny-answer-aliases { "example.net"; };
5476 If an external attacker lets a web browser in your local
5477 network look up an IPv4 address of "attacker.example.com",
5478 the attacker's DNS server would return a response like this:
5480 <pre class="programlisting">attacker.example.com. A 192.0.2.1</pre>
5482 in the answer section.
5483 Since the rdata of this record (the IPv4 address) matches
5484 the specified prefix 192.0.2.0/24, this response will be
5488 On the other hand, if the browser looks up a legitimate
5489 internal web server "www.example.net" and the
5490 following response is returned to
5491 the <acronym class="acronym">BIND</acronym> 9 server
5493 <pre class="programlisting">www.example.net. A 192.0.2.2</pre>
5495 it will be accepted since the owner name "www.example.net"
5496 matches the <span><strong class="command">except-from</strong></span> element,
5500 Note that this is not really an attack on the DNS per se.
5501 In fact, there is nothing wrong for an "external" name to
5502 be mapped to your "internal" IP address or domain name
5503 from the DNS point of view.
5504 It might actually be provided for a legitimate purpose,
5505 such as for debugging.
5506 As long as the mapping is provided by the correct owner,
5507 it is not possible or does not make sense to detect
5508 whether the intent of the mapping is legitimate or not
5510 The "rebinding" attack must primarily be protected at the
5511 application that uses the DNS.
5512 For a large site, however, it may be difficult to protect
5513 all possible applications at once.
5514 This filtering feature is provided only to help such an
5515 operational environment;
5516 it is generally discouraged to turn it on unless you are
5517 very sure you have no other choice and the attack is a
5518 real threat for your applications.
5521 Care should be particularly taken if you want to use this
5522 option for addresses within 127.0.0.0/8.
5523 These addresses are obviously "internal", but many
5524 applications conventionally rely on a DNS mapping from
5525 some name to such an address.
5526 Filtering out DNS records containing this address
5527 spuriously can break such applications.
5530 <div class="sect3" lang="en">
5531 <div class="titlepage"><div><div><h4 class="title">
5532 <a name="id2588372"></a>Response Policy Zone (RPZ) Rewriting</h4></div></div></div>
5534 <acronym class="acronym">BIND</acronym> 9 includes an intentionally limited
5535 mechanism to modify DNS responses for recursive requests
5536 similar to email anti-spam DNS blacklists.
5537 All response policy zones are named in the
5538 <span><strong class="command">response-policy</strong></span> option for the view or among the
5539 global options if there is no response-policy option for the view.
5542 The rules encoded in a response policy zone (RPZ) are applied
5543 only to responses to queries that ask for recursion (RD=1).
5544 RPZs are normal DNS zones containing RRsets
5545 that can be queried normally if allowed.
5546 It is usually best to restrict those queries with something like
5547 <span><strong class="command">allow-query {none; };</strong></span> or
5548 <span><strong class="command">allow-query { 127.0.0.1; };</strong></span>.
5551 There are four kinds of RPZ rewrite rules. QNAME rules are
5552 applied to query names in requests and to targets of CNAME
5553 records resolved in the process of generating the response.
5554 The owner name of a QNAME rule is the query name relativized
5556 The records in a rewrite rule are usually A, AAAA, or special
5557 CNAMEs, but can be any type except DNAME.
5560 IP rules are triggered by addresses in A and AAAA records.
5561 All IP addresses in A or AAAA RRsets are tested and the rule
5562 longest prefix is applied. Ties between rules with equal prefixes
5563 are broken in favor of the first RPZ mentioned in the
5564 response-policy option.
5565 The rule matching the smallest IP address is chosen among equal
5566 prefix rules from a single RPZ.
5567 IP rules are expressed in RRsets with owner names that are
5568 subdomains of rpz-ip and encoding an IP address block, reversed
5570 prefix.B.B.B.B with prefix between 1 and 32 and B between 1 and 255
5571 encodes an IPv4 address.
5572 IPv6 addresses are encoded by with prefix.W.W.W.W.W.W.W.W or
5573 prefix.WORDS.zz.WORDS. The words in the standard IPv6 text
5574 representation are reversed, "::" is replaced with ".zz.",
5575 and ":" becomes ".".
5578 NSDNAME rules match names in NS RRsets for the response or a
5579 parent. They are encoded as subdomains of rpz-nsdomain relativized
5580 to the RPZ origin name.
5583 NSIP rules match IP addresses in A and AAAA RRsets for names of
5584 responsible servers or the names that can be matched by NSDNAME
5585 rules. The are encoded like IP rules except as subdomains of
5589 Authority verification issues and variations in authority data in
5590 the current version of <acronym class="acronym">BIND</acronym> 9 can cause
5591 inconsistent results from NSIP and NSDNAME. So they are available
5592 only when <acronym class="acronym">BIND</acronym> is built with the
5593 <strong class="userinput"><code>--enable-rpz-nsip</code></strong> or
5594 <strong class="userinput"><code>--enable-rpz-nsdname</code></strong> options
5595 on the "configure" command line.
5598 Four policies can be expressed.
5599 The <span><strong class="command">NXDOMAIN</strong></span> policy causes a NXDOMAIN response
5600 and is expressed with an RRset consisting of a single CNAME
5601 whose target is the root domain (.).
5602 <span><strong class="command">NODATA</strong></span> generates NODATA or ANCOUNT=1 regardless
5604 It is expressed with a CNAME whose target is the wildcard
5605 top-level domain (*.).
5606 The <span><strong class="command">NO-OP</strong></span> policy does not change the response
5607 and is used to "poke holes" in policies for larger CIDR blocks or in
5608 zones named later in the <span><strong class="command">response-policy</strong></span> option.
5609 The NO-OP policy is expressed by a CNAME with a target consisting
5610 of the variable part of the owner name, such as "example.com." for
5611 a QNAME rule or "128.1.0.0.127." for an IP rule.
5612 The <span><strong class="command">CNAME</strong></span> policy is used to replace the RRsets
5614 A and AAAA RRsets are most common and useful to capture
5615 an evil domain in a walled garden, but any valid set of RRsets
5619 All of the policies in an RPZ can be overridden with a
5620 <span><strong class="command">policy</strong></span> clause.
5621 <span><strong class="command">given</strong></span> says "do not override."
5622 <span><strong class="command">no-op</strong></span> says "do nothing" regardless of the policy
5624 <span><strong class="command">nxdomain</strong></span> causes all RPZ rules to generate
5626 <span><strong class="command">nodata</strong></span> gives nodata.
5627 <span><strong class="command">cname domain</strong></span> causes all RPZ rules to act as if
5628 the consisted of a "cname domain" record.
5631 For example, you might use this option statement
5633 <pre class="programlisting">response-policy { zone "bl"; };</pre>
5635 and this zone statement
5637 <pre class="programlisting">zone "bl" {type master; file "example/bl"; allow-query {none;}; };</pre>
5641 <pre class="programlisting">$TTL 1H
5642 @ SOA LOCALHOST. named-mgr.example.com (1 1h 15m 30d 2h)
5645 nxdomain.domain.com CNAME .
5646 nodata.domain.com CNAME *.
5647 bad.domain.com A 10.0.0.1
5649 ok.domain.com CNAME ok.domain.com.
5650 *.badzone.domain.com CNAME garden.example.com.
5652 ; IP rules rewriting all answers for 127/8 except 127.0.0.1
5653 8.0.0.0.127.ip CNAME .
5654 32.1.0.0.127.ip CNAME 32.1.0.0.127.
5656 ; NSDNAME and NSIP rules
5657 ns.domain.com.rpz-nsdname CNAME .
5658 48.zz.2.2001.rpz-nsip CNAME .
5662 <div class="sect2" lang="en">
5663 <div class="titlepage"><div><div><h3 class="title">
5664 <a name="server_statement_grammar"></a><span><strong class="command">server</strong></span> Statement Grammar</h3></div></div></div>
5665 <pre class="programlisting"><span><strong class="command">server</strong></span> <em class="replaceable"><code>ip_addr[/prefixlen]</code></em> {
5666 [<span class="optional"> bogus <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5667 [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5668 [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5669 [<span class="optional"> edns <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
5670 [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
5671 [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em> ; </span>]
5672 [<span class="optional"> transfers <em class="replaceable"><code>number</code></em> ; </span>]
5673 [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em> ; ]</span>]
5674 [<span class="optional"> keys <em class="replaceable"><code>{ string ; [<span class="optional"> string ; [<span class="optional">...</span>]</span>] }</code></em> ; </span>]
5675 [<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>]
5676 [<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>]
5677 [<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>]
5678 [<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>]
5679 [<span class="optional"> query-source [<span class="optional"> address ( <em class="replaceable"><code>ip_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]
5680 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>]
5681 [<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>]
5682 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>]
5683 [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>]
5684 [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>]
5685 [<span class="optional"> queryport-pool-updateinterval <em class="replaceable"><code>number</code></em>; </span>]
5689 <div class="sect2" lang="en">
5690 <div class="titlepage"><div><div><h3 class="title">
5691 <a name="server_statement_definition_and_usage"></a><span><strong class="command">server</strong></span> Statement Definition and
5692 Usage</h3></div></div></div>
5694 The <span><strong class="command">server</strong></span> statement defines
5696 to be associated with a remote name server. If a prefix length is
5697 specified, then a range of servers is covered. Only the most
5699 server clause applies regardless of the order in
5700 <code class="filename">named.conf</code>.
5703 The <span><strong class="command">server</strong></span> statement can occur at
5704 the top level of the
5705 configuration file or inside a <span><strong class="command">view</strong></span>
5707 If a <span><strong class="command">view</strong></span> statement contains
5708 one or more <span><strong class="command">server</strong></span> statements, only
5710 apply to the view and any top-level ones are ignored.
5711 If a view contains no <span><strong class="command">server</strong></span>
5713 any top-level <span><strong class="command">server</strong></span> statements are
5718 If you discover that a remote server is giving out bad data,
5719 marking it as bogus will prevent further queries to it. The
5721 value of <span><strong class="command">bogus</strong></span> is <span><strong class="command">no</strong></span>.
5724 The <span><strong class="command">provide-ixfr</strong></span> clause determines
5726 the local server, acting as master, will respond with an
5728 zone transfer when the given remote server, a slave, requests it.
5729 If set to <span><strong class="command">yes</strong></span>, incremental transfer
5731 whenever possible. If set to <span><strong class="command">no</strong></span>,
5733 to the remote server will be non-incremental. If not set, the
5735 of the <span><strong class="command">provide-ixfr</strong></span> option in the
5737 global options block is used as a default.
5740 The <span><strong class="command">request-ixfr</strong></span> clause determines
5742 the local server, acting as a slave, will request incremental zone
5743 transfers from the given remote server, a master. If not set, the
5744 value of the <span><strong class="command">request-ixfr</strong></span> option in
5746 global options block is used as a default.
5749 IXFR requests to servers that do not support IXFR will
5751 fall back to AXFR. Therefore, there is no need to manually list
5752 which servers support IXFR and which ones do not; the global
5754 of <span><strong class="command">yes</strong></span> should always work.
5755 The purpose of the <span><strong class="command">provide-ixfr</strong></span> and
5756 <span><strong class="command">request-ixfr</strong></span> clauses is
5757 to make it possible to disable the use of IXFR even when both
5759 and slave claim to support it, for example if one of the servers
5760 is buggy and crashes or corrupts data when IXFR is used.
5763 The <span><strong class="command">edns</strong></span> clause determines whether
5764 the local server will attempt to use EDNS when communicating
5765 with the remote server. The default is <span><strong class="command">yes</strong></span>.
5768 The <span><strong class="command">edns-udp-size</strong></span> option sets the EDNS UDP size
5769 that is advertised by <span><strong class="command">named</strong></span> when querying the remote server.
5770 Valid values are 512 to 4096 bytes (values outside this range will be
5771 silently adjusted). This option is useful when you wish to
5772 advertises a different value to this server than the value you
5773 advertise globally, for example, when there is a firewall at the
5774 remote site that is blocking large replies.
5777 The <span><strong class="command">max-udp-size</strong></span> option sets the
5778 maximum EDNS UDP message size <span><strong class="command">named</strong></span> will send. Valid
5779 values are 512 to 4096 bytes (values outside this range will
5780 be silently adjusted). This option is useful when you
5781 know that there is a firewall that is blocking large
5782 replies from <span><strong class="command">named</strong></span>.
5785 The server supports two zone transfer methods. The first, <span><strong class="command">one-answer</strong></span>,
5786 uses one DNS message per resource record transferred. <span><strong class="command">many-answers</strong></span> packs
5787 as many resource records as possible into a message. <span><strong class="command">many-answers</strong></span> is
5788 more efficient, but is only known to be understood by <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
5789 8.x, and patched versions of <acronym class="acronym">BIND</acronym>
5790 4.9.5. You can specify which method
5791 to use for a server with the <span><strong class="command">transfer-format</strong></span> option.
5792 If <span><strong class="command">transfer-format</strong></span> is not
5793 specified, the <span><strong class="command">transfer-format</strong></span>
5795 by the <span><strong class="command">options</strong></span> statement will be
5798 <p><span><strong class="command">transfers</strong></span>
5799 is used to limit the number of concurrent inbound zone
5800 transfers from the specified server. If no
5801 <span><strong class="command">transfers</strong></span> clause is specified, the
5802 limit is set according to the
5803 <span><strong class="command">transfers-per-ns</strong></span> option.
5806 The <span><strong class="command">keys</strong></span> clause identifies a
5807 <span><strong class="command">key_id</strong></span> defined by the <span><strong class="command">key</strong></span> statement,
5808 to be used for transaction security (TSIG, <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called “TSIG”</a>)
5809 when talking to the remote server.
5810 When a request is sent to the remote server, a request signature
5811 will be generated using the key specified here and appended to the
5812 message. A request originating from the remote server is not
5814 to be signed by this key.
5817 Although the grammar of the <span><strong class="command">keys</strong></span>
5819 allows for multiple keys, only a single key per server is
5824 The <span><strong class="command">transfer-source</strong></span> and
5825 <span><strong class="command">transfer-source-v6</strong></span> clauses specify
5826 the IPv4 and IPv6 source
5827 address to be used for zone transfer with the remote server,
5829 For an IPv4 remote server, only <span><strong class="command">transfer-source</strong></span> can
5831 Similarly, for an IPv6 remote server, only
5832 <span><strong class="command">transfer-source-v6</strong></span> can be
5834 For more details, see the description of
5835 <span><strong class="command">transfer-source</strong></span> and
5836 <span><strong class="command">transfer-source-v6</strong></span> in
5837 <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.
5840 The <span><strong class="command">notify-source</strong></span> and
5841 <span><strong class="command">notify-source-v6</strong></span> clauses specify the
5842 IPv4 and IPv6 source address to be used for notify
5843 messages sent to remote servers, respectively. For an
5844 IPv4 remote server, only <span><strong class="command">notify-source</strong></span>
5845 can be specified. Similarly, for an IPv6 remote server,
5846 only <span><strong class="command">notify-source-v6</strong></span> can be specified.
5849 The <span><strong class="command">query-source</strong></span> and
5850 <span><strong class="command">query-source-v6</strong></span> clauses specify the
5851 IPv4 and IPv6 source address to be used for queries
5852 sent to remote servers, respectively. For an IPv4
5853 remote server, only <span><strong class="command">query-source</strong></span> can
5854 be specified. Similarly, for an IPv6 remote server,
5855 only <span><strong class="command">query-source-v6</strong></span> can be specified.
5858 <div class="sect2" lang="en">
5859 <div class="titlepage"><div><div><h3 class="title">
5860 <a name="statschannels"></a><span><strong class="command">statistics-channels</strong></span> Statement Grammar</h3></div></div></div>
5861 <pre class="programlisting"><span><strong class="command">statistics-channels</strong></span> {
5862 [ inet ( ip_addr | * ) [ port ip_port ]
5863 [ allow { <em class="replaceable"><code> address_match_list </code></em> } ]; ]
5868 <div class="sect2" lang="en">
5869 <div class="titlepage"><div><div><h3 class="title">
5870 <a name="id2589395"></a><span><strong class="command">statistics-channels</strong></span> Statement Definition and
5871 Usage</h3></div></div></div>
5873 The <span><strong class="command">statistics-channels</strong></span> statement
5874 declares communication channels to be used by system
5875 administrators to get access to statistics information of
5879 This statement intends to be flexible to support multiple
5880 communication protocols in the future, but currently only
5881 HTTP access is supported.
5882 It requires that BIND 9 be compiled with libxml2;
5883 the <span><strong class="command">statistics-channels</strong></span> statement is
5884 still accepted even if it is built without the library,
5885 but any HTTP access will fail with an error.
5888 An <span><strong class="command">inet</strong></span> control channel is a TCP socket
5889 listening at the specified <span><strong class="command">ip_port</strong></span> on the
5890 specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6
5891 address. An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is
5892 interpreted as the IPv4 wildcard address; connections will be
5893 accepted on any of the system's IPv4 addresses.
5894 To listen on the IPv6 wildcard address,
5895 use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>.
5898 If no port is specified, port 80 is used for HTTP channels.
5899 The asterisk "<code class="literal">*</code>" cannot be used for
5900 <span><strong class="command">ip_port</strong></span>.
5903 The attempt of opening a statistics channel is
5904 restricted by the optional <span><strong class="command">allow</strong></span> clause.
5905 Connections to the statistics channel are permitted based on the
5906 <span><strong class="command">address_match_list</strong></span>.
5907 If no <span><strong class="command">allow</strong></span> clause is present,
5908 <span><strong class="command">named</strong></span> accepts connection
5909 attempts from any address; since the statistics may
5910 contain sensitive internal information, it is highly
5911 recommended to restrict the source of connection requests
5915 If no <span><strong class="command">statistics-channels</strong></span> statement is present,
5916 <span><strong class="command">named</strong></span> will not open any communication channels.
5919 <div class="sect2" lang="en">
5920 <div class="titlepage"><div><div><h3 class="title">
5921 <a name="trusted-keys"></a><span><strong class="command">trusted-keys</strong></span> Statement Grammar</h3></div></div></div>
5922 <pre class="programlisting"><span><strong class="command">trusted-keys</strong></span> {
5923 <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> ;
5924 [<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>]
5928 <div class="sect2" lang="en">
5929 <div class="titlepage"><div><div><h3 class="title">
5930 <a name="id2589534"></a><span><strong class="command">trusted-keys</strong></span> Statement Definition
5931 and Usage</h3></div></div></div>
5933 The <span><strong class="command">trusted-keys</strong></span> statement defines
5934 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
5935 public key for a non-authoritative zone is known, but
5936 cannot be securely obtained through DNS, either because
5937 it is the DNS root zone or because its parent zone is
5938 unsigned. Once a key has been configured as a trusted
5939 key, it is treated as if it had been validated and
5940 proven secure. The resolver attempts DNSSEC validation
5941 on all DNS data in subdomains of a security root.
5944 All keys (and corresponding zones) listed in
5945 <span><strong class="command">trusted-keys</strong></span> are deemed to exist regardless
5946 of what parent zones say. Similarly for all keys listed in
5947 <span><strong class="command">trusted-keys</strong></span> only those keys are
5948 used to validate the DNSKEY RRset. The parent's DS RRset
5952 The <span><strong class="command">trusted-keys</strong></span> statement can contain
5953 multiple key entries, each consisting of the key's
5954 domain name, flags, protocol, algorithm, and the Base-64
5955 representation of the key data.
5956 Spaces, tabs, newlines and carriage returns are ignored
5957 in the key data, so the configuration may be split up into
5961 <span><strong class="command">trusted-keys</strong></span> may be set at the top level
5962 of <code class="filename">named.conf</code> or within a view. If it is
5963 set in both places, they are additive: keys defined at the top
5964 level are inherited by all views, but keys defined in a view
5965 are only used within that view.
5968 <div class="sect2" lang="en">
5969 <div class="titlepage"><div><div><h3 class="title">
5970 <a name="id2589581"></a><span><strong class="command">managed-keys</strong></span> Statement Grammar</h3></div></div></div>
5971 <pre class="programlisting"><span><strong class="command">managed-keys</strong></span> {
5972 <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> ;
5973 [<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>]
5977 <div class="sect2" lang="en">
5978 <div class="titlepage"><div><div><h3 class="title">
5979 <a name="managed-keys"></a><span><strong class="command">managed-keys</strong></span> Statement Definition
5980 and Usage</h3></div></div></div>
5982 The <span><strong class="command">managed-keys</strong></span> statement, like
5983 <span><strong class="command">trusted-keys</strong></span>, defines DNSSEC
5984 security roots. The difference is that
5985 <span><strong class="command">managed-keys</strong></span> can be kept up to date
5986 automatically, without intervention from the resolver
5990 Suppose, for example, that a zone's key-signing
5991 key was compromised, and the zone owner had to revoke and
5992 replace the key. A resolver which had the old key in a
5993 <span><strong class="command">trusted-keys</strong></span> statement would be
5994 unable to validate this zone any longer; it would
5995 reply with a SERVFAIL response code. This would
5996 continue until the resolver operator had updated the
5997 <span><strong class="command">trusted-keys</strong></span> statement with the new key.
6000 If, however, the zone were listed in a
6001 <span><strong class="command">managed-keys</strong></span> statement instead, then the
6002 zone owner could add a "stand-by" key to the zone in advance.
6003 <span><strong class="command">named</strong></span> would store the stand-by key, and
6004 when the original key was revoked, <span><strong class="command">named</strong></span>
6005 would be able to transition smoothly to the new key. It would
6006 also recognize that the old key had been revoked, and cease
6007 using that key to validate answers, minimizing the damage that
6008 the compromised key could do.
6011 A <span><strong class="command">managed-keys</strong></span> statement contains a list of
6012 the keys to be managed, along with information about how the
6013 keys are to be initialized for the first time. The only
6014 initialization method currently supported (as of
6015 <acronym class="acronym">BIND</acronym> 9.7.0) is <code class="literal">initial-key</code>.
6016 This means the <span><strong class="command">managed-keys</strong></span> statement must
6017 contain a copy of the initializing key. (Future releases may
6018 allow keys to be initialized by other methods, eliminating this
6022 Consequently, a <span><strong class="command">managed-keys</strong></span> statement
6023 appears similar to a <span><strong class="command">trusted-keys</strong></span>, differing
6024 in the presence of the second field, containing the keyword
6025 <code class="literal">initial-key</code>. The difference is, whereas the
6026 keys listed in a <span><strong class="command">trusted-keys</strong></span> continue to be
6027 trusted until they are removed from
6028 <code class="filename">named.conf</code>, an initializing key listed
6029 in a <span><strong class="command">managed-keys</strong></span> statement is only trusted
6030 <span class="emphasis"><em>once</em></span>: for as long as it takes to load the
6031 managed key database and start the RFC 5011 key maintenance
6035 The first time <span><strong class="command">named</strong></span> runs with a managed key
6036 configured in <code class="filename">named.conf</code>, it fetches the
6037 DNSKEY RRset directly from the zone apex, and validates it
6038 using the key specified in the <span><strong class="command">managed-keys</strong></span>
6039 statement. If the DNSKEY RRset is validly signed, then it is
6040 used as the basis for a new managed keys database.
6043 From that point on, whenever <span><strong class="command">named</strong></span> runs, it
6044 sees the <span><strong class="command">managed-keys</strong></span> statement, checks to
6045 make sure RFC 5011 key maintenance has already been initialized
6046 for the specified domain, and if so, it simply moves on. The
6047 key specified in the <span><strong class="command">managed-keys</strong></span> is not
6048 used to validate answers; it has been superseded by the key or
6049 keys stored in the managed keys database.
6052 The next time <span><strong class="command">named</strong></span> runs after a name
6053 has been <span class="emphasis"><em>removed</em></span> from the
6054 <span><strong class="command">managed-keys</strong></span> statement, the corresponding
6055 zone will be removed from the managed keys database,
6056 and RFC 5011 key maintenance will no longer be used for that
6060 <span><strong class="command">named</strong></span> only maintains a single managed keys
6061 database; consequently, unlike <span><strong class="command">trusted-keys</strong></span>,
6062 <span><strong class="command">managed-keys</strong></span> may only be set at the top
6063 level of <code class="filename">named.conf</code>, not within a view.
6066 In the current implementation, the managed keys database is
6067 stored as a master-format zone file called
6068 <code class="filename">managed-keys.bind</code>. When the key database
6069 is changed, the zone is updated. As with any other dynamic
6070 zone, changes will be written into a journal file,
6071 <code class="filename">managed-keys.bind.jnl</code>. They are committed
6072 to the master file as soon as possible afterward; in the case
6073 of the managed key database, this will usually occur within 30
6074 seconds. So, whenever <span><strong class="command">named</strong></span> is using
6075 automatic key maintenance, those two files can be expected to
6076 exist in the working directory. (For this reason among others,
6077 the working directory should be always be writable by
6078 <span><strong class="command">named</strong></span>.)
6081 If the <span><strong class="command">dnssec-lookaside</strong></span> option is
6082 set to <strong class="userinput"><code>auto</code></strong>, <span><strong class="command">named</strong></span>
6083 will automatically initialize a managed key for the
6084 zone <code class="literal">dlv.isc.org</code>. The key that is
6085 used to initialize the key maintenance process is built
6086 into <span><strong class="command">named</strong></span>, and can be overridden
6087 from <span><strong class="command">bindkeys-file</strong></span>.
6090 <div class="sect2" lang="en">
6091 <div class="titlepage"><div><div><h3 class="title">
6092 <a name="view_statement_grammar"></a><span><strong class="command">view</strong></span> Statement Grammar</h3></div></div></div>
6093 <pre class="programlisting"><span><strong class="command">view</strong></span> <em class="replaceable"><code>view_name</code></em>
6094 [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6095 match-clients { <em class="replaceable"><code>address_match_list</code></em> };
6096 match-destinations { <em class="replaceable"><code>address_match_list</code></em> };
6097 match-recursive-only <em class="replaceable"><code>yes_or_no</code></em> ;
6098 [<span class="optional"> <em class="replaceable"><code>view_option</code></em>; ...</span>]
6099 [<span class="optional"> <em class="replaceable"><code>zone_statement</code></em>; ...</span>]
6103 <div class="sect2" lang="en">
6104 <div class="titlepage"><div><div><h3 class="title">
6105 <a name="id2590007"></a><span><strong class="command">view</strong></span> Statement Definition and Usage</h3></div></div></div>
6107 The <span><strong class="command">view</strong></span> statement is a powerful
6109 of <acronym class="acronym">BIND</acronym> 9 that lets a name server
6110 answer a DNS query differently
6111 depending on who is asking. It is particularly useful for
6113 split DNS setups without having to run multiple servers.
6116 Each <span><strong class="command">view</strong></span> statement defines a view
6118 DNS namespace that will be seen by a subset of clients. A client
6120 a view if its source IP address matches the
6121 <code class="varname">address_match_list</code> of the view's
6122 <span><strong class="command">match-clients</strong></span> clause and its
6123 destination IP address matches
6124 the <code class="varname">address_match_list</code> of the
6126 <span><strong class="command">match-destinations</strong></span> clause. If not
6128 <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
6129 default to matching all addresses. In addition to checking IP
6131 <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span>
6132 can also take <span><strong class="command">keys</strong></span> which provide an
6134 client to select the view. A view can also be specified
6135 as <span><strong class="command">match-recursive-only</strong></span>, which
6136 means that only recursive
6137 requests from matching clients will match that view.
6138 The order of the <span><strong class="command">view</strong></span> statements is
6140 a client request will be resolved in the context of the first
6141 <span><strong class="command">view</strong></span> that it matches.
6144 Zones defined within a <span><strong class="command">view</strong></span>
6146 only be accessible to clients that match the <span><strong class="command">view</strong></span>.
6147 By defining a zone of the same name in multiple views, different
6148 zone data can be given to different clients, for example,
6150 and "external" clients in a split DNS setup.
6153 Many of the options given in the <span><strong class="command">options</strong></span> statement
6154 can also be used within a <span><strong class="command">view</strong></span>
6156 apply only when resolving queries with that view. When no
6158 value is given, the value in the <span><strong class="command">options</strong></span> statement
6159 is used as a default. Also, zone options can have default values
6161 in the <span><strong class="command">view</strong></span> statement; these
6162 view-specific defaults
6163 take precedence over those in the <span><strong class="command">options</strong></span> statement.
6166 Views are class specific. If no class is given, class IN
6167 is assumed. Note that all non-IN views must contain a hint zone,
6168 since only the IN class has compiled-in default hints.
6171 If there are no <span><strong class="command">view</strong></span> statements in
6173 file, a default view that matches any client is automatically
6175 in class IN. Any <span><strong class="command">zone</strong></span> statements
6177 the top level of the configuration file are considered to be part
6179 this default view, and the <span><strong class="command">options</strong></span>
6181 apply to the default view. If any explicit <span><strong class="command">view</strong></span>
6182 statements are present, all <span><strong class="command">zone</strong></span>
6184 occur inside <span><strong class="command">view</strong></span> statements.
6187 Here is an example of a typical split DNS setup implemented
6188 using <span><strong class="command">view</strong></span> statements:
6190 <pre class="programlisting">view "internal" {
6191 // This should match our internal networks.
6192 match-clients { 10.0.0.0/8; };
6194 // Provide recursive service to internal
6198 // Provide a complete view of the example.com
6199 // zone including addresses of internal hosts.
6200 zone "example.com" {
6202 file "example-internal.db";
6207 // Match all clients not matched by the
6209 match-clients { any; };
6211 // Refuse recursive service to external clients.
6214 // Provide a restricted view of the example.com
6215 // zone containing only publicly accessible hosts.
6216 zone "example.com" {
6218 file "example-external.db";
6223 <div class="sect2" lang="en">
6224 <div class="titlepage"><div><div><h3 class="title">
6225 <a name="zone_statement_grammar"></a><span><strong class="command">zone</strong></span>
6226 Statement Grammar</h3></div></div></div>
6227 <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>] {
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 { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6233 [<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>]
6234 [<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>] ;
6235 [<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>]
6236 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6237 [<span class="optional"> check-mx (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6238 [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6239 [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em> ; </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"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
6252 [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
6253 [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
6254 [<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>]
6255 [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
6256 [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6257 [<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>]
6258 [<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>]
6259 [<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>]
6260 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6261 [<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>]
6262 [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>]
6263 [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>]
6264 [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>]
6265 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
6266 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6267 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6268 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6269 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6270 [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>]
6271 [<span class="optional"> auto-dnssec <code class="constant">allow</code>|<code class="constant">maintain</code>|<code class="constant">off</code>; </span>]
6272 [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6275 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6277 [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6278 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6279 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6280 [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6281 [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6282 [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6283 [<span class="optional"> dnssec-update-mode ( <em class="replaceable"><code>maintain</code></em> | <em class="replaceable"><code>no-resign</code></em> ); </span>]
6284 [<span class="optional"> dnssec-dnskey-kskonly <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6285 [<span class="optional"> dnssec-secure-to-insecure <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6286 [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6287 [<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>] ;
6288 [<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>]
6289 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6290 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
6291 [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
6292 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
6293 [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>]
6294 [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>]
6295 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
6296 [<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>]
6297 [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>]
6298 [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6299 [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>]
6300 [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6301 [<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>
6302 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>]
6303 [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] }; </span>]
6304 [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>]
6305 [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
6306 [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>]
6307 [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
6308 [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>]
6309 [<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>]
6310 [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>]
6311 [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6312 [<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>]
6313 [<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>]
6314 [<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>]
6315 [<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>]
6316 [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>)
6317 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6318 [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6319 [<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>]
6320 [<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>]
6321 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6322 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
6323 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6324 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6325 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6326 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6327 [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6328 [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6331 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6333 file <em class="replaceable"><code>string</code></em> ;
6334 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6335 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>] // Not Implemented.
6338 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6340 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6341 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6342 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>]
6343 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>]
6344 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6345 [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>]
6346 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>]
6347 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
6348 [<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>]
6349 [<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>
6350 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>]
6351 [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] }; </span>]
6352 [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>]
6353 [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>]
6354 [<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>]
6355 [<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>]
6356 [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>)
6357 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6358 [<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>]
6359 [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>)
6360 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>]
6361 [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>]
6362 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6363 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>]
6364 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6365 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>]
6366 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6367 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>]
6368 [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6371 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6373 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>]
6374 [<span class="optional"> server-addresses { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> ; ... </span>] }; </span>]
6375 [<span class="optional"> server-names { [<span class="optional"> <em class="replaceable"><code>namelist</code></em> </span>] }; </span>]
6376 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6379 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6381 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>]
6382 [<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>]
6383 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>]
6386 zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] {
6387 type delegation-only;
6392 <div class="sect2" lang="en">
6393 <div class="titlepage"><div><div><h3 class="title">
6394 <a name="id2591558"></a><span><strong class="command">zone</strong></span> Statement Definition and Usage</h3></div></div></div>
6395 <div class="sect3" lang="en">
6396 <div class="titlepage"><div><div><h4 class="title">
6397 <a name="id2591565"></a>Zone Types</h4></div></div></div>
6398 <div class="informaltable"><table border="1">
6407 <code class="varname">master</code>
6412 The server has a master copy of the data
6413 for the zone and will be able to provide authoritative
6422 <code class="varname">slave</code>
6427 A slave zone is a replica of a master
6428 zone. The <span><strong class="command">masters</strong></span> list
6429 specifies one or more IP addresses
6430 of master servers that the slave contacts to update
6431 its copy of the zone.
6432 Masters list elements can also be names of other
6434 By default, transfers are made from port 53 on the
6436 be changed for all servers by specifying a port number
6438 list of IP addresses, or on a per-server basis after
6440 Authentication to the master can also be done with
6441 per-server TSIG keys.
6442 If a file is specified, then the
6443 replica will be written to this file whenever the zone
6445 and reloaded from this file on a server restart. Use
6447 recommended, since it often speeds server startup and
6449 a needless waste of bandwidth. Note that for large
6451 tens or hundreds of thousands) of zones per server, it
6453 use a two-level naming scheme for zone filenames. For
6455 a slave server for the zone <code class="literal">example.com</code> might place
6456 the zone contents into a file called
6457 <code class="filename">ex/example.com</code> where <code class="filename">ex/</code> is
6458 just the first two letters of the zone name. (Most
6460 behave very slowly if you put 100000 files into
6461 a single directory.)
6468 <code class="varname">stub</code>
6473 A stub zone is similar to a slave zone,
6474 except that it replicates only the NS records of a
6476 of the entire zone. Stub zones are not a standard part
6478 they are a feature specific to the <acronym class="acronym">BIND</acronym> implementation.
6482 Stub zones can be used to eliminate the need for glue
6484 in a parent zone at the expense of maintaining a stub
6486 a set of name server addresses in <code class="filename">named.conf</code>.
6487 This usage is not recommended for new configurations,
6489 supports it only in a limited way.
6490 In <acronym class="acronym">BIND</acronym> 4/8, zone
6491 transfers of a parent zone
6492 included the NS records from stub children of that
6494 that, in some cases, users could get away with
6495 configuring child stubs
6496 only in the master server for the parent zone. <acronym class="acronym">BIND</acronym>
6497 9 never mixes together zone data from different zones
6499 way. Therefore, if a <acronym class="acronym">BIND</acronym> 9 master serving a parent
6500 zone has child stub zones configured, all the slave
6502 parent zone also need to have the same child stub
6508 Stub zones can also be used as a way of forcing the
6510 of a given domain to use a particular set of
6511 authoritative servers.
6512 For example, the caching name servers on a private
6514 RFC1918 addressing may be configured with stub zones
6516 <code class="literal">10.in-addr.arpa</code>
6517 to use a set of internal name servers as the
6519 servers for that domain.
6526 <code class="varname">static-stub</code>
6531 A static-stub zone is similar to a stub zone
6532 with the following exceptions:
6533 the zone data is statically configured, rather
6534 than transferred from a master server;
6535 when recursion is necessary for a query that
6536 matches a static-stub zone, the locally
6537 configured data (nameserver names and glue addresses)
6538 is always used even if different authoritative
6539 information is cached.
6542 Zone data is configured via the
6543 <span><strong class="command">server-addresses</strong></span> and
6544 <span><strong class="command">server-names</strong></span> zone options.
6547 The zone data is maintained in the form of NS
6548 and (if necessary) glue A or AAAA RRs
6549 internally, which can be seen by dumping zone
6550 databases by <span><strong class="command">rndc dumpdb -all</strong></span>.
6551 The configured RRs are considered local configuration
6552 parameters rather than public data.
6553 Non recursive queries (i.e., those with the RD
6554 bit off) to a static-stub zone are therefore
6555 prohibited and will be responded with REFUSED.
6558 Since the data is statically configured, no
6559 zone maintenance action takes place for a static-stub
6561 For example, there is no periodic refresh
6562 attempt, and an incoming notify message
6563 will be rejected with an rcode of NOTAUTH.
6566 Each static-stub zone is configured with
6567 internally generated NS and (if necessary)
6575 <code class="varname">forward</code>
6580 A "forward zone" is a way to configure
6581 forwarding on a per-domain basis. A <span><strong class="command">zone</strong></span> statement
6582 of type <span><strong class="command">forward</strong></span> can
6583 contain a <span><strong class="command">forward</strong></span>
6584 and/or <span><strong class="command">forwarders</strong></span>
6586 which will apply to queries within the domain given by
6588 name. If no <span><strong class="command">forwarders</strong></span>
6589 statement is present or
6590 an empty list for <span><strong class="command">forwarders</strong></span> is given, then no
6591 forwarding will be done for the domain, canceling the
6593 any forwarders in the <span><strong class="command">options</strong></span> statement. Thus
6594 if you want to use this type of zone to change the
6596 global <span><strong class="command">forward</strong></span> option
6597 (that is, "forward first"
6598 to, then "forward only", or vice versa, but want to
6600 servers as set globally) you need to re-specify the
6608 <code class="varname">hint</code>
6613 The initial set of root name servers is
6614 specified using a "hint zone". When the server starts
6616 the root hints to find a root name server and get the
6618 list of root name servers. If no hint zone is
6620 IN, the server uses a compiled-in default set of root
6622 Classes other than IN have no built-in defaults hints.
6629 <code class="varname">delegation-only</code>
6634 This is used to enforce the delegation-only
6635 status of infrastructure zones (e.g. COM,
6636 NET, ORG). Any answer that is received
6637 without an explicit or implicit delegation
6638 in the authority section will be treated
6639 as NXDOMAIN. This does not apply to the
6640 zone apex. This should not be applied to
6644 <code class="varname">delegation-only</code> has no
6645 effect on answers received from forwarders.
6648 See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>.
6655 <div class="sect3" lang="en">
6656 <div class="titlepage"><div><div><h4 class="title">
6657 <a name="id2592179"></a>Class</h4></div></div></div>
6659 The zone's name may optionally be followed by a class. If
6660 a class is not specified, class <code class="literal">IN</code> (for <code class="varname">Internet</code>),
6661 is assumed. This is correct for the vast majority of cases.
6664 The <code class="literal">hesiod</code> class is
6665 named for an information service from MIT's Project Athena. It
6667 used to share information about various systems databases, such
6668 as users, groups, printers and so on. The keyword
6669 <code class="literal">HS</code> is
6670 a synonym for hesiod.
6673 Another MIT development is Chaosnet, a LAN protocol created
6674 in the mid-1970s. Zone data for it can be specified with the <code class="literal">CHAOS</code> class.
6677 <div class="sect3" lang="en">
6678 <div class="titlepage"><div><div><h4 class="title">
6679 <a name="id2592212"></a>Zone Options</h4></div></div></div>
6680 <div class="variablelist"><dl>
6681 <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt>
6683 See the description of
6684 <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>.
6686 <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt>
6688 See the description of
6689 <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>.
6691 <dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt>
6693 See the description of
6694 <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>.
6696 <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt>
6698 See the description of <span><strong class="command">allow-transfer</strong></span>
6699 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
6701 <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt>
6703 See the description of <span><strong class="command">allow-update</strong></span>
6704 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
6706 <dt><span class="term"><span><strong class="command">update-policy</strong></span></span></dt>
6708 Specifies a "Simple Secure Update" policy. See
6709 <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called “Dynamic Update Policies”</a>.
6711 <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt>
6713 See the description of <span><strong class="command">allow-update-forwarding</strong></span>
6714 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.
6716 <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt>
6718 Only meaningful if <span><strong class="command">notify</strong></span>
6720 active for this zone. The set of machines that will
6722 <code class="literal">DNS NOTIFY</code> message
6723 for this zone is made up of all the listed name servers
6725 the primary master) for the zone plus any IP addresses
6727 with <span><strong class="command">also-notify</strong></span>. A port
6729 with each <span><strong class="command">also-notify</strong></span>
6730 address to send the notify
6731 messages to a port other than the default of 53.
6732 <span><strong class="command">also-notify</strong></span> is not
6733 meaningful for stub zones.
6734 The default is the empty list.
6736 <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt>
6738 This option is used to restrict the character set and
6740 certain domain names in master files and/or DNS responses
6742 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>
6743 zones the default is <span><strong class="command">warn</strong></span>.
6744 It is not implemented for <span><strong class="command">hint</strong></span> zones.
6746 <dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt>
6748 See the description of
6749 <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>.
6751 <dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt>
6753 See the description of
6754 <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>.
6756 <dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt>
6758 See the description of
6759 <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>.
6761 <dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt>
6763 See the description of
6764 <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>.
6766 <dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt>
6768 See the description of
6769 <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>.
6771 <dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt>
6773 See the description of
6774 <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>.
6776 <dt><span class="term"><span><strong class="command">dnssec-dnskey-kskonly</strong></span></span></dt>
6778 See the description of
6779 <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>.
6781 <dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt>
6783 See the description of
6784 <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>.
6786 <dt><span class="term"><span><strong class="command">database</strong></span></span></dt>
6789 Specify the type of database to be used for storing the
6790 zone data. The string following the <span><strong class="command">database</strong></span> keyword
6791 is interpreted as a list of whitespace-delimited words.
6793 identifies the database type, and any subsequent words are
6795 as arguments to the database to be interpreted in a way
6797 to the database type.
6800 The default is <strong class="userinput"><code>"rbt"</code></strong>, BIND 9's
6802 red-black-tree database. This database does not take
6806 Other values are possible if additional database drivers
6807 have been linked into the server. Some sample drivers are
6809 with the distribution but none are linked in by default.
6812 <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt>
6814 See the description of
6815 <span><strong class="command">dialup</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
6817 <dt><span class="term"><span><strong class="command">delegation-only</strong></span></span></dt>
6820 The flag only applies to hint and stub zones. If set
6821 to <strong class="userinput"><code>yes</code></strong>, then the zone will also be
6822 treated as if it is also a delegation-only type zone.
6825 See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>.
6828 <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt>
6830 Only meaningful if the zone has a forwarders
6831 list. The <span><strong class="command">only</strong></span> value causes
6833 after trying the forwarders and getting no answer, while <span><strong class="command">first</strong></span> would
6834 allow a normal lookup to be tried.
6836 <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt>
6838 Used to override the list of global forwarders.
6839 If it is not specified in a zone of type <span><strong class="command">forward</strong></span>,
6840 no forwarding is done for the zone and the global options are
6843 <dt><span class="term"><span><strong class="command">ixfr-base</strong></span></span></dt>
6845 Was used in <acronym class="acronym">BIND</acronym> 8 to
6847 of the transaction log (journal) file for dynamic update
6849 <acronym class="acronym">BIND</acronym> 9 ignores the option
6850 and constructs the name of the journal
6851 file by appending "<code class="filename">.jnl</code>"
6855 <dt><span class="term"><span><strong class="command">ixfr-tmp-file</strong></span></span></dt>
6857 Was an undocumented option in <acronym class="acronym">BIND</acronym> 8.
6858 Ignored in <acronym class="acronym">BIND</acronym> 9.
6860 <dt><span class="term"><span><strong class="command">journal</strong></span></span></dt>
6862 Allow the default journal's filename to be overridden.
6863 The default is the zone's filename with "<code class="filename">.jnl</code>" appended.
6864 This is applicable to <span><strong class="command">master</strong></span> and <span><strong class="command">slave</strong></span> zones.
6866 <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt>
6868 See the description of
6869 <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>.
6871 <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt>
6873 See the description of
6874 <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>.
6876 <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt>
6878 See the description of
6879 <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>.
6881 <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt>
6883 See the description of
6884 <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>.
6886 <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt>
6888 See the description of
6889 <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>.
6891 <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt>
6893 See the description of
6894 <span><strong class="command">notify</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
6896 <dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt>
6898 See the description of
6899 <span><strong class="command">notify-delay</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
6901 <dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt>
6903 See the description of
6904 <span><strong class="command">notify-to-soa</strong></span> in
6905 <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
6907 <dt><span class="term"><span><strong class="command">pubkey</strong></span></span></dt>
6909 In <acronym class="acronym">BIND</acronym> 8, this option was
6910 intended for specifying
6911 a public zone key for verification of signatures in DNSSEC
6913 zones when they are loaded from disk. <acronym class="acronym">BIND</acronym> 9 does not verify signatures
6914 on load and ignores the option.
6916 <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt>
6918 If <strong class="userinput"><code>yes</code></strong>, the server will keep
6920 information for this zone, which can be dumped to the
6921 <span><strong class="command">statistics-file</strong></span> defined in
6924 <dt><span class="term"><span><strong class="command">server-addresses</strong></span></span></dt>
6927 Only meaningful for static-stub zones.
6928 This is a list of IP addresses to which queries
6929 should be sent in recursive resolution for the
6931 A non empty list for this option will internally
6932 configure the apex NS RR with associated glue A or
6936 For example, if "example.com" is configured as a
6937 static-stub zone with 192.0.2.1 and 2001:db8::1234
6938 in a <span><strong class="command">server-addresses</strong></span> option,
6939 the following RRs will be internally configured.
6941 <pre class="programlisting">example.com. NS example.com.
6942 example.com. A 192.0.2.1
6943 example.com. AAAA 2001:db8::1234</pre>
6945 These records are internally used to resolve
6946 names under the static-stub zone.
6947 For instance, if the server receives a query for
6948 "www.example.com" with the RD bit on, the server
6949 will initiate recursive resolution and send
6950 queries to 192.0.2.1 and/or 2001:db8::1234.
6953 <dt><span class="term"><span><strong class="command">server-names</strong></span></span></dt>
6956 Only meaningful for static-stub zones.
6957 This is a list of domain names of nameservers that
6958 act as authoritative servers of the static-stub
6960 These names will be resolved to IP addresses when
6961 <span><strong class="command">named</strong></span> needs to send queries to
6963 To make this supplemental resolution successful,
6964 these names must not be a subdomain of the origin
6965 name of static-stub zone.
6966 That is, when "example.net" is the origin of a
6967 static-stub zone, "ns.example" and
6968 "master.example.com" can be specified in the
6969 <span><strong class="command">server-names</strong></span> option, but
6970 "ns.example.net" cannot, and will be rejected by
6971 the configuration parser.
6974 A non empty list for this option will internally
6975 configure the apex NS RR with the specified names.
6976 For example, if "example.com" is configured as a
6977 static-stub zone with "ns1.example.net" and
6979 in a <span><strong class="command">server-names</strong></span> option,
6980 the following RRs will be internally configured.
6982 <pre class="programlisting">example.com. NS ns1.example.net.
6983 example.com. NS ns2.example.net.
6986 These records are internally used to resolve
6987 names under the static-stub zone.
6988 For instance, if the server receives a query for
6989 "www.example.com" with the RD bit on, the server
6990 initiate recursive resolution,
6991 resolve "ns1.example.net" and/or
6992 "ns2.example.net" to IP addresses, and then send
6993 queries to (one or more of) these addresses.
6996 <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt>
6998 See the description of
6999 <span><strong class="command">sig-validity-interval</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
7001 <dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt>
7003 See the description of
7004 <span><strong class="command">sig-signing-nodes</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
7006 <dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt>
7008 See the description of
7009 <span><strong class="command">sig-signing-signatures</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
7011 <dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt>
7013 See the description of
7014 <span><strong class="command">sig-signing-type</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
7016 <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt>
7018 See the description of
7019 <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>.
7021 <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt>
7023 See the description of
7024 <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>.
7026 <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt>
7028 See the description of
7029 <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>.
7031 <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt>
7033 See the description of
7034 <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>.
7036 <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt>
7038 See the description of
7039 <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>.
7041 <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt>
7043 See the description of
7044 <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>.
7046 <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt>
7048 See the description of
7049 <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>.
7052 <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>
7055 See the description in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
7057 <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt>
7059 See the description of
7060 <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>.
7061 (Note that the <span><strong class="command">ixfr-from-differences</strong></span>
7062 <strong class="userinput"><code>master</code></strong> and
7063 <strong class="userinput"><code>slave</code></strong> choices are not
7064 available at the zone level.)
7066 <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt>
7068 See the description of
7069 <span><strong class="command">key-directory</strong></span> in <a href="Bv9ARM.ch06.html#options" title="options Statement Definition and
7070 Usage">the section called “<span><strong class="command">options</strong></span> Statement Definition and
7073 <dt><span class="term"><span><strong class="command">auto-dnssec</strong></span></span></dt>
7076 Zones configured for dynamic DNS may also use this
7077 option to allow varying levels of automatic DNSSEC key
7078 management. There are three possible settings:
7081 <span><strong class="command">auto-dnssec allow;</strong></span> permits
7082 keys to be updated and the zone fully re-signed
7083 whenever the user issues the command <span><strong class="command">rndc sign
7084 <em class="replaceable"><code>zonename</code></em></strong></span>.
7087 <span><strong class="command">auto-dnssec maintain;</strong></span> includes the
7088 above, but also automatically adjusts the zone's DNSSEC
7089 keys on schedule, according to the keys' timing metadata
7090 (see <a href="man.dnssec-keygen.html" title="dnssec-keygen"><span class="refentrytitle"><span class="application">dnssec-keygen</span></span>(8)</a> and
7091 <a href="man.dnssec-settime.html" title="dnssec-settime"><span class="refentrytitle"><span class="application">dnssec-settime</span></span>(8)</a>). The command
7092 <span><strong class="command">rndc sign
7093 <em class="replaceable"><code>zonename</code></em></strong></span> causes
7094 <span><strong class="command">named</strong></span> to load keys from the key
7095 repository and sign the zone with all keys that are
7097 <span><strong class="command">rndc loadkeys
7098 <em class="replaceable"><code>zonename</code></em></strong></span> causes
7099 <span><strong class="command">named</strong></span> to load keys from the key
7100 repository and schedule key maintenance events to occur
7101 in the future, but it does not sign the full zone
7102 immediately. Note: once keys have been loaded for a
7103 zone the first time, the repository will be searched
7104 for changes periodically, regardless of whether
7105 <span><strong class="command">rndc loadkeys</strong></span> is used. The recheck
7106 interval is hard-coded to
7110 <span><strong class="command">auto-dnssec create;</strong></span> includes the
7111 above, but also allows <span><strong class="command">named</strong></span>
7112 to create new keys in the key repository when needed.
7113 (NOTE: This option is not yet implemented; the syntax is
7114 being reserved for future use.)
7117 The default setting is <span><strong class="command">auto-dnssec off</strong></span>.
7120 <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt>
7122 See the description of <span><strong class="command">multi-master</strong></span> in
7123 <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.
7125 <dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt>
7127 See the description of <span><strong class="command">masterfile-format</strong></span>
7128 in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.
7130 <dt><span class="term"><span><strong class="command">dnssec-secure-to-insecure</strong></span></span></dt>
7132 See the description of
7133 <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>.
7137 <div class="sect3" lang="en">
7138 <div class="titlepage"><div><div><h4 class="title">
7139 <a name="dynamic_update_policies"></a>Dynamic Update Policies</h4></div></div></div>
7140 <p><acronym class="acronym">BIND</acronym> 9 supports two alternative
7141 methods of granting clients the right to perform
7142 dynamic updates to a zone, configured by the
7143 <span><strong class="command">allow-update</strong></span> and
7144 <span><strong class="command">update-policy</strong></span> option, respectively.
7147 The <span><strong class="command">allow-update</strong></span> clause works the
7148 same way as in previous versions of <acronym class="acronym">BIND</acronym>.
7149 It grants given clients the permission to update any
7150 record of any name in the zone.
7153 The <span><strong class="command">update-policy</strong></span> clause
7154 allows more fine-grained control over what updates are
7155 allowed. A set of rules is specified, where each rule
7156 either grants or denies permissions for one or more
7157 names to be updated by one or more identities. If
7158 the dynamic update request message is signed (that is,
7159 it includes either a TSIG or SIG(0) record), the
7160 identity of the signer can be determined.
7163 Rules are specified in the <span><strong class="command">update-policy</strong></span>
7164 zone option, and are only meaningful for master zones.
7165 When the <span><strong class="command">update-policy</strong></span> statement
7166 is present, it is a configuration error for the
7167 <span><strong class="command">allow-update</strong></span> statement to be
7168 present. The <span><strong class="command">update-policy</strong></span> statement
7169 only examines the signer of a message; the source
7170 address is not relevant.
7173 There is a pre-defined <span><strong class="command">update-policy</strong></span>
7174 rule which can be switched on with the command
7175 <span><strong class="command">update-policy local;</strong></span>.
7176 Switching on this rule in a zone causes
7177 <span><strong class="command">named</strong></span> to generate a TSIG session
7178 key and place it in a file, and to allow that key
7179 to update the zone. (By default, the file is
7180 <code class="filename">/var/run/named/session.key</code>, the key
7181 name is "local-ddns" and the key algorithm is HMAC-SHA256,
7182 but these values are configurable with the
7183 <span><strong class="command">session-keyfile</strong></span>,
7184 <span><strong class="command">session-keyname</strong></span> and
7185 <span><strong class="command">session-keyalg</strong></span> options, respectively).
7188 A client running on the local system, and with appropriate
7189 permissions, may read that file and use the key to sign update
7190 requests. The zone's update policy will be set to allow that
7191 key to change any record within the zone. Assuming the
7192 key name is "local-ddns", this policy is equivalent to:
7194 <pre class="programlisting">update-policy { grant local-ddns zonesub any; };
7197 The command <span><strong class="command">nsupdate -l</strong></span> sends update
7198 requests to localhost, and signs them using the session key.
7201 Other rule definitions look like this:
7203 <pre class="programlisting">
7204 ( <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>]
7207 Each rule grants or denies privileges. Once a message has
7208 successfully matched a rule, the operation is immediately
7209 granted or denied and no further rules are examined. A rule
7210 is matched when the signer matches the identity field, the
7211 name matches the name field in accordance with the nametype
7212 field, and the type matches the types specified in the type
7216 No signer is required for <em class="replaceable"><code>tcp-self</code></em>
7217 or <em class="replaceable"><code>6to4-self</code></em> however the standard
7218 reverse mapping / prefix conversion must match the identity
7222 The identity field specifies a name or a wildcard
7223 name. Normally, this is the name of the TSIG or
7224 SIG(0) key used to sign the update request. When a
7225 TKEY exchange has been used to create a shared secret,
7226 the identity of the shared secret is the same as the
7227 identity of the key used to authenticate the TKEY
7228 exchange. TKEY is also the negotiation method used
7229 by GSS-TSIG, which establishes an identity that is
7230 the Kerberos principal of the client, such as
7231 <strong class="userinput"><code>"user@host.domain"</code></strong>. When the
7232 <em class="replaceable"><code>identity</code></em> field specifies
7233 a wildcard name, it is subject to DNS wildcard
7234 expansion, so the rule will apply to multiple identities.
7235 The <em class="replaceable"><code>identity</code></em> field must
7236 contain a fully-qualified domain name.
7239 For nametypes <code class="varname">krb5-self</code>,
7240 <code class="varname">ms-self</code>, <code class="varname">krb5-subdomain</code>,
7241 and <code class="varname">ms-subdomain</code> the
7242 <em class="replaceable"><code>identity</code></em> field specifies
7243 the Windows or Kerberos realm of the machine belongs to.
7246 The <em class="replaceable"><code>nametype</code></em> field has 13
7248 <code class="varname">name</code>, <code class="varname">subdomain</code>,
7249 <code class="varname">wildcard</code>, <code class="varname">self</code>,
7250 <code class="varname">selfsub</code>, <code class="varname">selfwild</code>,
7251 <code class="varname">krb5-self</code>, <code class="varname">ms-self</code>,
7252 <code class="varname">krb5-subdomain</code>,
7253 <code class="varname">ms-subdomain</code>,
7254 <code class="varname">tcp-self</code>, <code class="varname">6to4-self</code>,
7255 <code class="varname">zonesub</code>, and <code class="varname">external</code>.
7257 <div class="informaltable"><table border="1">
7266 <code class="varname">name</code>
7271 Exact-match semantics. This rule matches
7272 when the name being updated is identical
7273 to the contents of the
7274 <em class="replaceable"><code>name</code></em> field.
7281 <code class="varname">subdomain</code>
7286 This rule matches when the name being updated
7287 is a subdomain of, or identical to, the
7288 contents of the <em class="replaceable"><code>name</code></em>
7296 <code class="varname">zonesub</code>
7301 This rule is similar to subdomain, except that
7302 it matches when the name being updated is a
7303 subdomain of the zone in which the
7304 <span><strong class="command">update-policy</strong></span> statement
7305 appears. This obviates the need to type the zone
7306 name twice, and enables the use of a standard
7307 <span><strong class="command">update-policy</strong></span> statement in
7308 multiple zones without modification.
7311 When this rule is used, the
7312 <em class="replaceable"><code>name</code></em> field is omitted.
7319 <code class="varname">wildcard</code>
7324 The <em class="replaceable"><code>name</code></em> field
7325 is subject to DNS wildcard expansion, and
7326 this rule matches when the name being updated
7327 name is a valid expansion of the wildcard.
7334 <code class="varname">self</code>
7339 This rule matches when the name being updated
7340 matches the contents of the
7341 <em class="replaceable"><code>identity</code></em> field.
7342 The <em class="replaceable"><code>name</code></em> field
7343 is ignored, but should be the same as the
7344 <em class="replaceable"><code>identity</code></em> field.
7345 The <code class="varname">self</code> nametype is
7346 most useful when allowing using one key per
7347 name to update, where the key has the same
7348 name as the name to be updated. The
7349 <em class="replaceable"><code>identity</code></em> would
7350 be specified as <code class="constant">*</code> (an asterisk) in
7358 <code class="varname">selfsub</code>
7363 This rule is similar to <code class="varname">self</code>
7364 except that subdomains of <code class="varname">self</code>
7365 can also be updated.
7372 <code class="varname">selfwild</code>
7377 This rule is similar to <code class="varname">self</code>
7378 except that only subdomains of
7379 <code class="varname">self</code> can be updated.
7386 <code class="varname">ms-self</code>
7391 This rule takes a Windows machine principal
7392 (machine$@REALM) for machine in REALM and
7393 and converts it machine.realm allowing the machine
7394 to update machine.realm. The REALM to be matched
7395 is specified in the <font color="red"><replacable>identity</replacable></font>
7403 <code class="varname">ms-subdomain</code>
7408 This rule takes a Windows machine principal
7409 (machine$@REALM) for machine in REALM and
7410 converts it to machine.realm allowing the machine
7411 to update subdomains of machine.realm. The REALM
7412 to be matched is specified in the
7413 <font color="red"><replacable>identity</replacable></font> field.
7420 <code class="varname">krb5-self</code>
7425 This rule takes a Kerberos machine principal
7426 (host/machine@REALM) for machine in REALM and
7427 and converts it machine.realm allowing the machine
7428 to update machine.realm. The REALM to be matched
7429 is specified in the <font color="red"><replacable>identity</replacable></font>
7437 <code class="varname">krb5-subdomain</code>
7442 This rule takes a Kerberos machine principal
7443 (host/machine@REALM) for machine in REALM and
7444 converts it to machine.realm allowing the machine
7445 to update subdomains of machine.realm. The REALM
7446 to be matched is specified in the
7447 <font color="red"><replacable>identity</replacable></font> field.
7454 <code class="varname">tcp-self</code>
7459 Allow updates that have been sent via TCP and
7460 for which the standard mapping from the initiating
7461 IP address into the IN-ADDR.ARPA and IP6.ARPA
7462 namespaces match the name to be updated.
7464 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7465 <h3 class="title">Note</h3>
7466 It is theoretically possible to spoof these TCP
7474 <code class="varname">6to4-self</code>
7479 Allow the 6to4 prefix to be update by any TCP
7480 connection from the 6to4 network or from the
7481 corresponding IPv4 address. This is intended
7482 to allow NS or DNAME RRsets to be added to the
7485 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
7486 <h3 class="title">Note</h3>
7487 It is theoretically possible to spoof these TCP
7495 <code class="varname">external</code>
7500 This rule allows <span><strong class="command">named</strong></span>
7501 to defer the decision of whether to allow a
7502 given update to an external daemon.
7505 The method of communicating with the daemon is
7506 specified in the <em class="replaceable"><code>identity</code></em>
7507 field, the format of which is
7508 "<code class="constant">local:</code><em class="replaceable"><code>path</code></em>",
7509 where <em class="replaceable"><code>path</code></em> is the location
7510 of a UNIX-domain socket. (Currently, "local" is the
7511 only supported mechanism.)
7514 Requests to the external daemon are sent over the
7515 UNIX-domain socket as datagrams with the following
7518 <pre class="programlisting">
7519 Protocol version number (4 bytes, network byte order, currently 1)
7520 Request length (4 bytes, network byte order)
7521 Signer (null-terminated string)
7522 Name (null-terminated string)
7523 TCP source address (null-terminated string)
7524 Rdata type (null-terminated string)
7525 Key (null-terminated string)
7526 TKEY token length (4 bytes, network byte order)
7527 TKEY token (remainder of packet)</pre>
7529 The daemon replies with a four-byte value in
7530 network byte order, containing either 0 or 1; 0
7531 indicates that the specified update is not
7532 permitted, and 1 indicates that it is.
7539 In all cases, the <em class="replaceable"><code>name</code></em>
7540 field must specify a fully-qualified domain name.
7543 If no types are explicitly specified, this rule matches
7544 all types except RRSIG, NS, SOA, NSEC and NSEC3. Types
7545 may be specified by name, including "ANY" (ANY matches
7546 all types except NSEC and NSEC3, which can never be
7547 updated). Note that when an attempt is made to delete
7548 all records associated with a name, the rules are
7549 checked for each existing record type.
7554 <div class="sect1" lang="en">
7555 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
7556 <a name="id2595030"></a>Zone File</h2></div></div></div>
7557 <div class="sect2" lang="en">
7558 <div class="titlepage"><div><div><h3 class="title">
7559 <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>
7561 This section, largely borrowed from RFC 1034, describes the
7562 concept of a Resource Record (RR) and explains when each is used.
7563 Since the publication of RFC 1034, several new RRs have been
7565 and implemented in the DNS. These are also included.
7567 <div class="sect3" lang="en">
7568 <div class="titlepage"><div><div><h4 class="title">
7569 <a name="id2595048"></a>Resource Records</h4></div></div></div>
7571 A domain name identifies a node. Each node has a set of
7572 resource information, which may be empty. The set of resource
7573 information associated with a particular name is composed of
7574 separate RRs. The order of RRs in a set is not significant and
7575 need not be preserved by name servers, resolvers, or other
7576 parts of the DNS. However, sorting of multiple RRs is
7577 permitted for optimization purposes, for example, to specify
7578 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>.
7581 The components of a Resource Record are:
7583 <div class="informaltable"><table border="1">
7597 The domain name where the RR is found.
7609 An encoded 16-bit value that specifies
7610 the type of the resource record.
7622 The time-to-live of the RR. This field
7623 is a 32-bit integer in units of seconds, and is
7625 resolvers when they cache RRs. The TTL describes how
7627 be cached before it should be discarded.
7639 An encoded 16-bit value that identifies
7640 a protocol family or instance of a protocol.
7652 The resource data. The format of the
7653 data is type (and sometimes class) specific.
7660 The following are <span class="emphasis"><em>types</em></span> of valid RRs:
7662 <div class="informaltable"><table border="1">
7676 A host address. In the IN class, this is a
7677 32-bit IP address. Described in RFC 1035.
7689 IPv6 address. Described in RFC 1886.
7701 IPv6 address. This can be a partial
7702 address (a suffix) and an indirection to the name
7703 where the rest of the
7704 address (the prefix) can be found. Experimental.
7705 Described in RFC 2874.
7717 Location of AFS database servers.
7718 Experimental. Described in RFC 1183.
7730 Address prefix list. Experimental.
7731 Described in RFC 3123.
7743 Holds a digital certificate.
7744 Described in RFC 2538.
7756 Identifies the canonical name of an alias.
7757 Described in RFC 1035.
7769 Is used for identifying which DHCP client is
7770 associated with this name. Described in RFC 4701.
7782 Replaces the domain name specified with
7783 another name to be looked up, effectively aliasing an
7785 subtree of the domain name space rather than a single
7787 as in the case of the CNAME RR.
7788 Described in RFC 2672.
7800 Stores a public key associated with a signed
7801 DNS zone. Described in RFC 4034.
7813 Stores the hash of a public key associated with a
7814 signed DNS zone. Described in RFC 4034.
7826 Specifies the global position. Superseded by LOC.
7838 Identifies the CPU and OS used by a host.
7839 Described in RFC 1035.
7851 Provides a method for storing IPsec keying material in
7852 DNS. Described in RFC 4025.
7864 Representation of ISDN addresses.
7865 Experimental. Described in RFC 1183.
7877 Stores a public key associated with a
7878 DNS name. Used in original DNSSEC; replaced
7879 by DNSKEY in DNSSECbis, but still used with
7880 SIG(0). Described in RFCs 2535 and 2931.
7892 Identifies a key exchanger for this
7893 DNS name. Described in RFC 2230.
7905 For storing GPS info. Described in RFC 1876.
7918 Identifies a mail exchange for the domain with
7919 a 16-bit preference value (lower is better)
7920 followed by the host name of the mail exchange.
7921 Described in RFC 974, RFC 1035.
7933 Name authority pointer. Described in RFC 2915.
7945 A network service access point.
7946 Described in RFC 1706.
7958 The authoritative name server for the
7959 domain. Described in RFC 1035.
7971 Used in DNSSECbis to securely indicate that
7972 RRs with an owner name in a certain name interval do
7974 a zone and indicate what RR types are present for an
7976 Described in RFC 4034.
7988 Used in DNSSECbis to securely indicate that
7989 RRs with an owner name in a certain name
7990 interval do not exist in a zone and indicate
7991 what RR types are present for an existing
7992 name. NSEC3 differs from NSEC in that it
7993 prevents zone enumeration but is more
7994 computationally expensive on both the server
7995 and the client than NSEC. Described in RFC
8008 Used in DNSSECbis to tell the authoritative
8009 server which NSEC3 chains are available to use.
8010 Described in RFC 5155.
8022 Used in DNSSEC to securely indicate that
8023 RRs with an owner name in a certain name interval do
8025 a zone and indicate what RR types are present for an
8027 Used in original DNSSEC; replaced by NSEC in
8029 Described in RFC 2535.
8041 A pointer to another part of the domain
8042 name space. Described in RFC 1035.
8054 Provides mappings between RFC 822 and X.400
8055 addresses. Described in RFC 2163.
8067 Information on persons responsible
8068 for the domain. Experimental. Described in RFC 1183.
8080 Contains DNSSECbis signature data. Described
8093 Route-through binding for hosts that
8094 do not have their own direct wide area network
8096 Experimental. Described in RFC 1183.
8108 Contains DNSSEC signature data. Used in
8109 original DNSSEC; replaced by RRSIG in
8110 DNSSECbis, but still used for SIG(0).
8111 Described in RFCs 2535 and 2931.
8123 Identifies the start of a zone of authority.
8124 Described in RFC 1035.
8136 Contains the Sender Policy Framework information
8137 for a given email domain. Described in RFC 4408.
8149 Information about well known network
8150 services (replaces WKS). Described in RFC 2782.
8162 Provides a way to securely publish a secure shell key's
8163 fingerprint. Described in RFC 4255.
8175 Text records. Described in RFC 1035.
8187 Information about which well known
8188 network services, such as SMTP, that a domain
8189 supports. Historical.
8201 Representation of X.25 network addresses.
8202 Experimental. Described in RFC 1183.
8209 The following <span class="emphasis"><em>classes</em></span> of resource records
8210 are currently valid in the DNS:
8212 <div class="informaltable"><table border="1">
8238 Chaosnet, a LAN protocol created at MIT in the
8240 Rarely used for its historical purpose, but reused for
8242 built-in server information zones, e.g.,
8243 <code class="literal">version.bind</code>.
8255 Hesiod, an information service
8256 developed by MIT's Project Athena. It is used to share
8258 about various systems databases, such as users,
8267 The owner name is often implicit, rather than forming an
8269 part of the RR. For example, many name servers internally form
8271 or hash structures for the name space, and chain RRs off nodes.
8272 The remaining RR parts are the fixed header (type, class, TTL)
8273 which is consistent for all RRs, and a variable part (RDATA)
8275 fits the needs of the resource being described.
8278 The meaning of the TTL field is a time limit on how long an
8279 RR can be kept in a cache. This limit does not apply to
8281 data in zones; it is also timed out, but by the refreshing
8283 for the zone. The TTL is assigned by the administrator for the
8284 zone where the data originates. While short TTLs can be used to
8285 minimize caching, and a zero TTL prohibits caching, the
8287 of Internet performance suggest that these times should be on
8289 order of days for the typical host. If a change can be
8291 the TTL can be reduced prior to the change to minimize
8293 during the change, and then increased back to its former value
8298 The data in the RDATA section of RRs is carried as a combination
8299 of binary strings and domain names. The domain names are
8301 used as "pointers" to other data in the DNS.
8304 <div class="sect3" lang="en">
8305 <div class="titlepage"><div><div><h4 class="title">
8306 <a name="id2596603"></a>Textual expression of RRs</h4></div></div></div>
8308 RRs are represented in binary form in the packets of the DNS
8309 protocol, and are usually represented in highly encoded form
8311 stored in a name server or resolver. In the examples provided
8313 RFC 1034, a style similar to that used in master files was
8315 in order to show the contents of RRs. In this format, most RRs
8316 are shown on a single line, although continuation lines are
8321 The start of the line gives the owner of the RR. If a line
8322 begins with a blank, then the owner is assumed to be the same as
8323 that of the previous RR. Blank lines are often included for
8327 Following the owner, we list the TTL, type, and class of the
8328 RR. Class and type use the mnemonics defined above, and TTL is
8329 an integer before the type field. In order to avoid ambiguity
8331 parsing, type and class mnemonics are disjoint, TTLs are
8333 and the type mnemonic is always last. The IN class and TTL
8335 are often omitted from examples in the interests of clarity.
8338 The resource data or RDATA section of the RR are given using
8339 knowledge of the typical representation for the data.
8342 For example, we might show the RRs carried in a message as:
8344 <div class="informaltable"><table border="1">
8354 <code class="literal">ISI.EDU.</code>
8359 <code class="literal">MX</code>
8364 <code class="literal">10 VENERA.ISI.EDU.</code>
8374 <code class="literal">MX</code>
8379 <code class="literal">10 VAXA.ISI.EDU</code>
8386 <code class="literal">VENERA.ISI.EDU</code>
8391 <code class="literal">A</code>
8396 <code class="literal">128.9.0.32</code>
8406 <code class="literal">A</code>
8411 <code class="literal">10.1.0.52</code>
8418 <code class="literal">VAXA.ISI.EDU</code>
8423 <code class="literal">A</code>
8428 <code class="literal">10.2.0.27</code>
8438 <code class="literal">A</code>
8443 <code class="literal">128.9.0.33</code>
8450 The MX RRs have an RDATA section which consists of a 16-bit
8451 number followed by a domain name. The address RRs use a
8453 IP address format to contain a 32-bit internet address.
8456 The above example shows six RRs, with two RRs at each of three
8460 Similarly we might see:
8462 <div class="informaltable"><table border="1">
8472 <code class="literal">XX.LCS.MIT.EDU.</code>
8477 <code class="literal">IN A</code>
8482 <code class="literal">10.0.0.44</code>
8490 <code class="literal">CH A</code>
8495 <code class="literal">MIT.EDU. 2420</code>
8502 This example shows two addresses for
8503 <code class="literal">XX.LCS.MIT.EDU</code>, each of a different class.
8507 <div class="sect2" lang="en">
8508 <div class="titlepage"><div><div><h3 class="title">
8509 <a name="id2597260"></a>Discussion of MX Records</h3></div></div></div>
8511 As described above, domain servers store information as a
8512 series of resource records, each of which contains a particular
8513 piece of information about a given domain name (which is usually,
8514 but not always, a host). The simplest way to think of a RR is as
8515 a typed pair of data, a domain name matched with a relevant datum,
8516 and stored with some additional type information to help systems
8517 determine when the RR is relevant.
8520 MX records are used to control delivery of email. The data
8521 specified in the record is a priority and a domain name. The
8523 controls the order in which email delivery is attempted, with the
8524 lowest number first. If two priorities are the same, a server is
8525 chosen randomly. If no servers at a given priority are responding,
8526 the mail transport agent will fall back to the next largest
8528 Priority numbers do not have any absolute meaning — they are
8530 only respective to other MX records for that domain name. The
8532 name given is the machine to which the mail will be delivered.
8533 It <span class="emphasis"><em>must</em></span> have an associated address record
8534 (A or AAAA) — CNAME is not sufficient.
8537 For a given domain, if there is both a CNAME record and an
8538 MX record, the MX record is in error, and will be ignored.
8540 the mail will be delivered to the server specified in the MX
8542 pointed to by the CNAME.
8545 <div class="informaltable"><table border="1">
8557 <code class="literal">example.com.</code>
8562 <code class="literal">IN</code>
8567 <code class="literal">MX</code>
8572 <code class="literal">10</code>
8577 <code class="literal">mail.example.com.</code>
8587 <code class="literal">IN</code>
8592 <code class="literal">MX</code>
8597 <code class="literal">10</code>
8602 <code class="literal">mail2.example.com.</code>
8612 <code class="literal">IN</code>
8617 <code class="literal">MX</code>
8622 <code class="literal">20</code>
8627 <code class="literal">mail.backup.org.</code>
8634 <code class="literal">mail.example.com.</code>
8639 <code class="literal">IN</code>
8644 <code class="literal">A</code>
8649 <code class="literal">10.0.0.1</code>
8659 <code class="literal">mail2.example.com.</code>
8664 <code class="literal">IN</code>
8669 <code class="literal">A</code>
8674 <code class="literal">10.0.0.2</code>
8684 Mail delivery will be attempted to <code class="literal">mail.example.com</code> and
8685 <code class="literal">mail2.example.com</code> (in
8686 any order), and if neither of those succeed, delivery to <code class="literal">mail.backup.org</code> will
8690 <div class="sect2" lang="en">
8691 <div class="titlepage"><div><div><h3 class="title">
8692 <a name="Setting_TTLs"></a>Setting TTLs</h3></div></div></div>
8694 The time-to-live of the RR field is a 32-bit integer represented
8695 in units of seconds, and is primarily used by resolvers when they
8696 cache RRs. The TTL describes how long a RR can be cached before it
8697 should be discarded. The following three types of TTL are
8699 used in a zone file.
8701 <div class="informaltable"><table border="1">
8715 The last field in the SOA is the negative
8716 caching TTL. This controls how long other servers will
8717 cache no-such-domain
8718 (NXDOMAIN) responses from you.
8721 The maximum time for
8722 negative caching is 3 hours (3h).
8734 The $TTL directive at the top of the
8735 zone file (before the SOA) gives a default TTL for every
8749 Each RR can have a TTL as the second
8750 field in the RR, which will control how long other
8759 All of these TTLs default to units of seconds, though units
8760 can be explicitly specified, for example, <code class="literal">1h30m</code>.
8763 <div class="sect2" lang="en">
8764 <div class="titlepage"><div><div><h3 class="title">
8765 <a name="id2597876"></a>Inverse Mapping in IPv4</h3></div></div></div>
8767 Reverse name resolution (that is, translation from IP address
8768 to name) is achieved by means of the <span class="emphasis"><em>in-addr.arpa</em></span> domain
8769 and PTR records. Entries in the in-addr.arpa domain are made in
8770 least-to-most significant order, read left to right. This is the
8771 opposite order to the way IP addresses are usually written. Thus,
8772 a machine with an IP address of 10.1.2.3 would have a
8774 in-addr.arpa name of
8775 3.2.1.10.in-addr.arpa. This name should have a PTR resource record
8776 whose data field is the name of the machine or, optionally,
8778 PTR records if the machine has more than one name. For example,
8779 in the [<span class="optional">example.com</span>] domain:
8781 <div class="informaltable"><table border="1">
8790 <code class="literal">$ORIGIN</code>
8795 <code class="literal">2.1.10.in-addr.arpa</code>
8802 <code class="literal">3</code>
8807 <code class="literal">IN PTR foo.example.com.</code>
8813 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
8814 <h3 class="title">Note</h3>
8816 The <span><strong class="command">$ORIGIN</strong></span> lines in the examples
8817 are for providing context to the examples only — they do not
8819 appear in the actual usage. They are only used here to indicate
8820 that the example is relative to the listed origin.
8824 <div class="sect2" lang="en">
8825 <div class="titlepage"><div><div><h3 class="title">
8826 <a name="id2598003"></a>Other Zone File Directives</h3></div></div></div>
8828 The Master File Format was initially defined in RFC 1035 and
8829 has subsequently been extended. While the Master File Format
8831 is class independent all records in a Master File must be of the
8836 Master File Directives include <span><strong class="command">$ORIGIN</strong></span>, <span><strong class="command">$INCLUDE</strong></span>,
8837 and <span><strong class="command">$TTL.</strong></span>
8839 <div class="sect3" lang="en">
8840 <div class="titlepage"><div><div><h4 class="title">
8841 <a name="id2598093"></a>The <span><strong class="command">@</strong></span> (at-sign)</h4></div></div></div>
8843 When used in the label (or name) field, the asperand or
8844 at-sign (@) symbol represents the current origin.
8845 At the start of the zone file, it is the
8846 <<code class="varname">zone_name</code>> (followed by
8850 <div class="sect3" lang="en">
8851 <div class="titlepage"><div><div><h4 class="title">
8852 <a name="id2598109"></a>The <span><strong class="command">$ORIGIN</strong></span> Directive</h4></div></div></div>
8854 Syntax: <span><strong class="command">$ORIGIN</strong></span>
8855 <em class="replaceable"><code>domain-name</code></em>
8856 [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
8858 <p><span><strong class="command">$ORIGIN</strong></span>
8859 sets the domain name that will be appended to any
8860 unqualified records. When a zone is first read in there
8861 is an implicit <span><strong class="command">$ORIGIN</strong></span>
8862 <<code class="varname">zone_name</code>><span><strong class="command">.</strong></span>
8863 (followed by trailing dot).
8864 The current <span><strong class="command">$ORIGIN</strong></span> is appended to
8865 the domain specified in the <span><strong class="command">$ORIGIN</strong></span>
8866 argument if it is not absolute.
8868 <pre class="programlisting">
8869 $ORIGIN example.com.
8870 WWW CNAME MAIN-SERVER
8875 <pre class="programlisting">
8876 WWW.EXAMPLE.COM. CNAME MAIN-SERVER.EXAMPLE.COM.
8879 <div class="sect3" lang="en">
8880 <div class="titlepage"><div><div><h4 class="title">
8881 <a name="id2598170"></a>The <span><strong class="command">$INCLUDE</strong></span> Directive</h4></div></div></div>
8883 Syntax: <span><strong class="command">$INCLUDE</strong></span>
8884 <em class="replaceable"><code>filename</code></em>
8885 [<span class="optional">
8886 <em class="replaceable"><code>origin</code></em> </span>]
8887 [<span class="optional"> <em class="replaceable"><code>comment</code></em> </span>]
8890 Read and process the file <code class="filename">filename</code> as
8891 if it were included into the file at this point. If <span><strong class="command">origin</strong></span> is
8892 specified the file is processed with <span><strong class="command">$ORIGIN</strong></span> set
8893 to that value, otherwise the current <span><strong class="command">$ORIGIN</strong></span> is
8897 The origin and the current domain name
8898 revert to the values they had prior to the <span><strong class="command">$INCLUDE</strong></span> once
8899 the file has been read.
8901 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
8902 <h3 class="title">Note</h3>
8904 RFC 1035 specifies that the current origin should be restored
8906 an <span><strong class="command">$INCLUDE</strong></span>, but it is silent
8907 on whether the current
8908 domain name should also be restored. BIND 9 restores both of
8910 This could be construed as a deviation from RFC 1035, a
8915 <div class="sect3" lang="en">
8916 <div class="titlepage"><div><div><h4 class="title">
8917 <a name="id2598240"></a>The <span><strong class="command">$TTL</strong></span> Directive</h4></div></div></div>
8919 Syntax: <span><strong class="command">$TTL</strong></span>
8920 <em class="replaceable"><code>default-ttl</code></em>
8921 [<span class="optional">
8922 <em class="replaceable"><code>comment</code></em> </span>]
8925 Set the default Time To Live (TTL) for subsequent records
8926 with undefined TTLs. Valid TTLs are of the range 0-2147483647
8929 <p><span><strong class="command">$TTL</strong></span>
8930 is defined in RFC 2308.
8934 <div class="sect2" lang="en">
8935 <div class="titlepage"><div><div><h3 class="title">
8936 <a name="id2598276"></a><acronym class="acronym">BIND</acronym> Master File Extension: the <span><strong class="command">$GENERATE</strong></span> Directive</h3></div></div></div>
8938 Syntax: <span><strong class="command">$GENERATE</strong></span>
8939 <em class="replaceable"><code>range</code></em>
8940 <em class="replaceable"><code>lhs</code></em>
8941 [<span class="optional"><em class="replaceable"><code>ttl</code></em></span>]
8942 [<span class="optional"><em class="replaceable"><code>class</code></em></span>]
8943 <em class="replaceable"><code>type</code></em>
8944 <em class="replaceable"><code>rhs</code></em>
8945 [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
8947 <p><span><strong class="command">$GENERATE</strong></span>
8948 is used to create a series of resource records that only
8949 differ from each other by an
8950 iterator. <span><strong class="command">$GENERATE</strong></span> can be used to
8951 easily generate the sets of records required to support
8952 sub /24 reverse delegations described in RFC 2317:
8953 Classless IN-ADDR.ARPA delegation.
8955 <pre class="programlisting">$ORIGIN 0.0.192.IN-ADDR.ARPA.
8956 $GENERATE 1-2 @ NS SERVER$.EXAMPLE.
8957 $GENERATE 1-127 $ CNAME $.0</pre>
8961 <pre class="programlisting">0.0.0.192.IN-ADDR.ARPA. NS SERVER1.EXAMPLE.
8962 0.0.0.192.IN-ADDR.ARPA. NS SERVER2.EXAMPLE.
8963 1.0.0.192.IN-ADDR.ARPA. CNAME 1.0.0.0.192.IN-ADDR.ARPA.
8964 2.0.0.192.IN-ADDR.ARPA. CNAME 2.0.0.0.192.IN-ADDR.ARPA.
8966 127.0.0.192.IN-ADDR.ARPA. CNAME 127.0.0.0.192.IN-ADDR.ARPA.
8969 Generate a set of A and MX records. Note the MX's right hand
8970 side is a quoted string. The quotes will be stripped when the
8971 right hand side is processed.
8973 <pre class="programlisting">
8975 $GENERATE 1-127 HOST-$ A 1.2.3.$
8976 $GENERATE 1-127 HOST-$ MX "0 ."</pre>
8980 <pre class="programlisting">HOST-1.EXAMPLE. A 1.2.3.1
8981 HOST-1.EXAMPLE. MX 0 .
8982 HOST-2.EXAMPLE. A 1.2.3.2
8983 HOST-2.EXAMPLE. MX 0 .
8984 HOST-3.EXAMPLE. A 1.2.3.3
8985 HOST-3.EXAMPLE. MX 0 .
8987 HOST-127.EXAMPLE. A 1.2.3.127
8988 HOST-127.EXAMPLE. MX 0 .
8990 <div class="informaltable"><table border="1">
8998 <p><span><strong class="command">range</strong></span></p>
9002 This can be one of two forms: start-stop
9003 or start-stop/step. If the first form is used, then step
9005 1. All of start, stop and step must be positive.
9011 <p><span><strong class="command">lhs</strong></span></p>
9015 describes the owner name of the resource records
9016 to be created. Any single <span><strong class="command">$</strong></span>
9018 symbols within the <span><strong class="command">lhs</strong></span> string
9019 are replaced by the iterator value.
9021 To get a $ in the output, you need to escape the
9022 <span><strong class="command">$</strong></span> using a backslash
9023 <span><strong class="command">\</strong></span>,
9024 e.g. <span><strong class="command">\$</strong></span>. The
9025 <span><strong class="command">$</strong></span> may optionally be followed
9026 by modifiers which change the offset from the
9027 iterator, field width and base.
9029 Modifiers are introduced by a
9030 <span><strong class="command">{</strong></span> (left brace) immediately following the
9031 <span><strong class="command">$</strong></span> as
9032 <span><strong class="command">${offset[,width[,base]]}</strong></span>.
9033 For example, <span><strong class="command">${-20,3,d}</strong></span>
9034 subtracts 20 from the current value, prints the
9035 result as a decimal in a zero-padded field of
9038 Available output forms are decimal
9039 (<span><strong class="command">d</strong></span>), octal
9040 (<span><strong class="command">o</strong></span>), hexadecimal
9041 (<span><strong class="command">x</strong></span> or <span><strong class="command">X</strong></span>
9042 for uppercase) and nibble
9043 (<span><strong class="command">n</strong></span> or <span><strong class="command">N</strong></span>\
9044 for uppercase). The default modifier is
9045 <span><strong class="command">${0,0,d}</strong></span>. If the
9046 <span><strong class="command">lhs</strong></span> is not absolute, the
9047 current <span><strong class="command">$ORIGIN</strong></span> is appended
9051 In nibble mode the value will be treated as
9052 if it was a reversed hexadecimal string
9053 with each hexadecimal digit as a separate
9054 label. The width field includes the label
9058 For compatibility with earlier versions,
9059 <span><strong class="command">$$</strong></span> is still recognized as
9060 indicating a literal $ in the output.
9066 <p><span><strong class="command">ttl</strong></span></p>
9070 Specifies the time-to-live of the generated records. If
9071 not specified this will be inherited using the
9072 normal TTL inheritance rules.
9074 <p><span><strong class="command">class</strong></span>
9075 and <span><strong class="command">ttl</strong></span> can be
9076 entered in either order.
9082 <p><span><strong class="command">class</strong></span></p>
9086 Specifies the class of the generated records.
9087 This must match the zone class if it is
9090 <p><span><strong class="command">class</strong></span>
9091 and <span><strong class="command">ttl</strong></span> can be
9092 entered in either order.
9098 <p><span><strong class="command">type</strong></span></p>
9108 <p><span><strong class="command">rhs</strong></span></p>
9112 <span><strong class="command">rhs</strong></span>, optionally, quoted string.
9119 The <span><strong class="command">$GENERATE</strong></span> directive is a <acronym class="acronym">BIND</acronym> extension
9120 and not part of the standard zone file format.
9123 BIND 8 does not support the optional TTL and CLASS fields.
9126 <div class="sect2" lang="en">
9127 <div class="titlepage"><div><div><h3 class="title">
9128 <a name="zonefile_format"></a>Additional File Formats</h3></div></div></div>
9130 In addition to the standard textual format, BIND 9
9131 supports the ability to read or dump to zone files in
9132 other formats. The <code class="constant">raw</code> format is
9133 currently available as an additional format. It is a
9134 binary format representing BIND 9's internal data
9135 structure directly, thereby remarkably improving the
9139 For a primary server, a zone file in the
9140 <code class="constant">raw</code> format is expected to be
9141 generated from a textual zone file by the
9142 <span><strong class="command">named-compilezone</strong></span> command. For a
9143 secondary server or for a dynamic zone, it is automatically
9144 generated (if this format is specified by the
9145 <span><strong class="command">masterfile-format</strong></span> option) when
9146 <span><strong class="command">named</strong></span> dumps the zone contents after
9147 zone transfer or when applying prior updates.
9150 If a zone file in a binary format needs manual modification,
9151 it first must be converted to a textual form by the
9152 <span><strong class="command">named-compilezone</strong></span> command. All
9153 necessary modification should go to the text file, which
9154 should then be converted to the binary form by the
9155 <span><strong class="command">named-compilezone</strong></span> command again.
9158 Although the <code class="constant">raw</code> format uses the
9159 network byte order and avoids architecture-dependent
9160 data alignment so that it is as much portable as
9161 possible, it is primarily expected to be used inside
9162 the same single system. In order to export a zone
9163 file in the <code class="constant">raw</code> format or make a
9164 portable backup of the file, it is recommended to
9165 convert the file to the standard textual representation.
9169 <div class="sect1" lang="en">
9170 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
9171 <a name="statistics"></a>BIND9 Statistics</h2></div></div></div>
9173 <acronym class="acronym">BIND</acronym> 9 maintains lots of statistics
9174 information and provides several interfaces for users to
9175 get access to the statistics.
9176 The available statistics include all statistics counters
9177 that were available in <acronym class="acronym">BIND</acronym> 8 and
9178 are meaningful in <acronym class="acronym">BIND</acronym> 9,
9179 and other information that is considered useful.
9182 The statistics information is categorized into the following
9185 <div class="informaltable"><table border="1">
9193 <p>Incoming Requests</p>
9197 The number of incoming DNS requests for each OPCODE.
9203 <p>Incoming Queries</p>
9207 The number of incoming queries for each RR type.
9213 <p>Outgoing Queries</p>
9217 The number of outgoing queries for each RR
9218 type sent from the internal resolver.
9219 Maintained per view.
9225 <p>Name Server Statistics</p>
9229 Statistics counters about incoming request processing.
9235 <p>Zone Maintenance Statistics</p>
9239 Statistics counters regarding zone maintenance
9240 operations such as zone transfers.
9246 <p>Resolver Statistics</p>
9250 Statistics counters about name resolution
9251 performed in the internal resolver.
9252 Maintained per view.
9258 <p>Cache DB RRsets</p>
9262 The number of RRsets per RR type and nonexistent
9263 names stored in the cache database.
9264 If the exclamation mark (!) is printed for a RR
9265 type, it means that particular type of RRset is
9266 known to be nonexistent (this is also known as
9268 Maintained per view.
9274 <p>Socket I/O Statistics</p>
9278 Statistics counters about network related events.
9285 A subset of Name Server Statistics is collected and shown
9286 per zone for which the server has the authority when
9287 <span><strong class="command">zone-statistics</strong></span> is set to
9288 <strong class="userinput"><code>yes</code></strong>.
9289 These statistics counters are shown with their zone and view
9291 In some cases the view names are omitted for the default view.
9294 There are currently two user interfaces to get access to the
9296 One is in the plain text format dumped to the file specified
9297 by the <span><strong class="command">statistics-file</strong></span> configuration option.
9298 The other is remotely accessible via a statistics channel
9299 when the <span><strong class="command">statistics-channels</strong></span> statement
9300 is specified in the configuration file
9301 (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>.)
9303 <div class="sect3" lang="en">
9304 <div class="titlepage"><div><div><h4 class="title">
9305 <a name="statsfile"></a>The Statistics File</h4></div></div></div>
9307 The text format statistics dump begins with a line, like:
9310 <span><strong class="command">+++ Statistics Dump +++ (973798949)</strong></span>
9313 The number in parentheses is a standard
9314 Unix-style timestamp, measured as seconds since January 1, 1970.
9317 that line is a set of statistics information, which is categorized
9319 Each section begins with a line, like:
9322 <span><strong class="command">++ Name Server Statistics ++</strong></span>
9325 Each section consists of lines, each containing the statistics
9326 counter value followed by its textual description.
9327 See below for available counters.
9328 For brevity, counters that have a value of 0 are not shown
9329 in the statistics file.
9332 The statistics dump ends with the line where the
9333 number is identical to the number in the beginning line; for example:
9336 <span><strong class="command">--- Statistics Dump --- (973798949)</strong></span>
9339 <div class="sect2" lang="en">
9340 <div class="titlepage"><div><div><h3 class="title">
9341 <a name="statistics_counters"></a>Statistics Counters</h3></div></div></div>
9343 The following tables summarize statistics counters that
9344 <acronym class="acronym">BIND</acronym> 9 provides.
9345 For each row of the tables, the leftmost column is the
9346 abbreviated symbol name of that counter.
9347 These symbols are shown in the statistics information
9348 accessed via an HTTP statistics channel.
9349 The rightmost column gives the description of the counter,
9350 which is also shown in the statistics file
9351 (but, in this document, possibly with slight modification
9352 for better readability).
9353 Additional notes may also be provided in this column.
9354 When a middle column exists between these two columns,
9355 it gives the corresponding counter name of the
9356 <acronym class="acronym">BIND</acronym> 8 statistics, if applicable.
9358 <div class="sect3" lang="en">
9359 <div class="titlepage"><div><div><h4 class="title">
9360 <a name="id2599229"></a>Name Server Statistics Counters</h4></div></div></div>
9361 <div class="informaltable"><table border="1">
9371 <span class="emphasis"><em>Symbol</em></span>
9376 <span class="emphasis"><em>BIND8 Symbol</em></span>
9381 <span class="emphasis"><em>Description</em></span>
9387 <p><span><strong class="command">Requestv4</strong></span></p>
9390 <p><span><strong class="command">RQ</strong></span></p>
9394 IPv4 requests received.
9395 Note: this also counts non query requests.
9401 <p><span><strong class="command">Requestv6</strong></span></p>
9404 <p><span><strong class="command">RQ</strong></span></p>
9408 IPv6 requests received.
9409 Note: this also counts non query requests.
9415 <p><span><strong class="command">ReqEdns0</strong></span></p>
9418 <p><span><strong class="command"></strong></span></p>
9422 Requests with EDNS(0) received.
9428 <p><span><strong class="command">ReqBadEDNSVer</strong></span></p>
9431 <p><span><strong class="command"></strong></span></p>
9435 Requests with unsupported EDNS version received.
9441 <p><span><strong class="command">ReqTSIG</strong></span></p>
9444 <p><span><strong class="command"></strong></span></p>
9448 Requests with TSIG received.
9454 <p><span><strong class="command">ReqSIG0</strong></span></p>
9457 <p><span><strong class="command"></strong></span></p>
9461 Requests with SIG(0) received.
9467 <p><span><strong class="command">ReqBadSIG</strong></span></p>
9470 <p><span><strong class="command"></strong></span></p>
9474 Requests with invalid (TSIG or SIG(0)) signature.
9480 <p><span><strong class="command">ReqTCP</strong></span></p>
9483 <p><span><strong class="command">RTCP</strong></span></p>
9487 TCP requests received.
9493 <p><span><strong class="command">AuthQryRej</strong></span></p>
9496 <p><span><strong class="command">RUQ</strong></span></p>
9500 Authoritative (non recursive) queries rejected.
9506 <p><span><strong class="command">RecQryRej</strong></span></p>
9509 <p><span><strong class="command">RURQ</strong></span></p>
9513 Recursive queries rejected.
9519 <p><span><strong class="command">XfrRej</strong></span></p>
9522 <p><span><strong class="command">RUXFR</strong></span></p>
9526 Zone transfer requests rejected.
9532 <p><span><strong class="command">UpdateRej</strong></span></p>
9535 <p><span><strong class="command">RUUpd</strong></span></p>
9539 Dynamic update requests rejected.
9545 <p><span><strong class="command">Response</strong></span></p>
9548 <p><span><strong class="command">SAns</strong></span></p>
9558 <p><span><strong class="command">RespTruncated</strong></span></p>
9561 <p><span><strong class="command"></strong></span></p>
9565 Truncated responses sent.
9571 <p><span><strong class="command">RespEDNS0</strong></span></p>
9574 <p><span><strong class="command"></strong></span></p>
9578 Responses with EDNS(0) sent.
9584 <p><span><strong class="command">RespTSIG</strong></span></p>
9587 <p><span><strong class="command"></strong></span></p>
9591 Responses with TSIG sent.
9597 <p><span><strong class="command">RespSIG0</strong></span></p>
9600 <p><span><strong class="command"></strong></span></p>
9604 Responses with SIG(0) sent.
9610 <p><span><strong class="command">QrySuccess</strong></span></p>
9613 <p><span><strong class="command"></strong></span></p>
9617 Queries resulted in a successful answer.
9618 This means the query which returns a NOERROR response
9619 with at least one answer RR.
9620 This corresponds to the
9621 <span><strong class="command">success</strong></span> counter
9622 of previous versions of
9623 <acronym class="acronym">BIND</acronym> 9.
9629 <p><span><strong class="command">QryAuthAns</strong></span></p>
9632 <p><span><strong class="command"></strong></span></p>
9636 Queries resulted in authoritative answer.
9642 <p><span><strong class="command">QryNoauthAns</strong></span></p>
9645 <p><span><strong class="command">SNaAns</strong></span></p>
9649 Queries resulted in non authoritative answer.
9655 <p><span><strong class="command">QryReferral</strong></span></p>
9658 <p><span><strong class="command"></strong></span></p>
9662 Queries resulted in referral answer.
9663 This corresponds to the
9664 <span><strong class="command">referral</strong></span> counter
9665 of previous versions of
9666 <acronym class="acronym">BIND</acronym> 9.
9672 <p><span><strong class="command">QryNxrrset</strong></span></p>
9675 <p><span><strong class="command"></strong></span></p>
9679 Queries resulted in NOERROR responses with no data.
9680 This corresponds to the
9681 <span><strong class="command">nxrrset</strong></span> counter
9682 of previous versions of
9683 <acronym class="acronym">BIND</acronym> 9.
9689 <p><span><strong class="command">QrySERVFAIL</strong></span></p>
9692 <p><span><strong class="command">SFail</strong></span></p>
9696 Queries resulted in SERVFAIL.
9702 <p><span><strong class="command">QryFORMERR</strong></span></p>
9705 <p><span><strong class="command">SFErr</strong></span></p>
9709 Queries resulted in FORMERR.
9715 <p><span><strong class="command">QryNXDOMAIN</strong></span></p>
9718 <p><span><strong class="command">SNXD</strong></span></p>
9722 Queries resulted in NXDOMAIN.
9723 This corresponds to the
9724 <span><strong class="command">nxdomain</strong></span> counter
9725 of previous versions of
9726 <acronym class="acronym">BIND</acronym> 9.
9732 <p><span><strong class="command">QryRecursion</strong></span></p>
9735 <p><span><strong class="command">RFwdQ</strong></span></p>
9739 Queries which caused the server
9740 to perform recursion in order to find the final answer.
9741 This corresponds to the
9742 <span><strong class="command">recursion</strong></span> counter
9743 of previous versions of
9744 <acronym class="acronym">BIND</acronym> 9.
9750 <p><span><strong class="command">QryDuplicate</strong></span></p>
9753 <p><span><strong class="command">RDupQ</strong></span></p>
9757 Queries which the server attempted to
9758 recurse but discovered an existing query with the same
9759 IP address, port, query ID, name, type and class
9760 already being processed.
9761 This corresponds to the
9762 <span><strong class="command">duplicate</strong></span> counter
9763 of previous versions of
9764 <acronym class="acronym">BIND</acronym> 9.
9770 <p><span><strong class="command">QryDropped</strong></span></p>
9773 <p><span><strong class="command"></strong></span></p>
9777 Recursive queries for which the server
9778 discovered an excessive number of existing
9779 recursive queries for the same name, type and
9780 class and were subsequently dropped.
9781 This is the number of dropped queries due to
9782 the reason explained with the
9783 <span><strong class="command">clients-per-query</strong></span>
9785 <span><strong class="command">max-clients-per-query</strong></span>
9787 (see the description about
9788 <a href="Bv9ARM.ch06.html#clients-per-query"><span><strong class="command">clients-per-query</strong></span></a>.)
9789 This corresponds to the
9790 <span><strong class="command">dropped</strong></span> counter
9791 of previous versions of
9792 <acronym class="acronym">BIND</acronym> 9.
9798 <p><span><strong class="command">QryFailure</strong></span></p>
9801 <p><span><strong class="command"></strong></span></p>
9805 Other query failures.
9806 This corresponds to the
9807 <span><strong class="command">failure</strong></span> counter
9808 of previous versions of
9809 <acronym class="acronym">BIND</acronym> 9.
9810 Note: this counter is provided mainly for
9811 backward compatibility with the previous versions.
9812 Normally a more fine-grained counters such as
9813 <span><strong class="command">AuthQryRej</strong></span> and
9814 <span><strong class="command">RecQryRej</strong></span>
9815 that would also fall into this counter are provided,
9816 and so this counter would not be of much
9817 interest in practice.
9823 <p><span><strong class="command">XfrReqDone</strong></span></p>
9826 <p><span><strong class="command"></strong></span></p>
9830 Requested zone transfers completed.
9836 <p><span><strong class="command">UpdateReqFwd</strong></span></p>
9839 <p><span><strong class="command"></strong></span></p>
9843 Update requests forwarded.
9849 <p><span><strong class="command">UpdateRespFwd</strong></span></p>
9852 <p><span><strong class="command"></strong></span></p>
9856 Update responses forwarded.
9862 <p><span><strong class="command">UpdateFwdFail</strong></span></p>
9865 <p><span><strong class="command"></strong></span></p>
9869 Dynamic update forward failed.
9875 <p><span><strong class="command">UpdateDone</strong></span></p>
9878 <p><span><strong class="command"></strong></span></p>
9882 Dynamic updates completed.
9888 <p><span><strong class="command">UpdateFail</strong></span></p>
9891 <p><span><strong class="command"></strong></span></p>
9895 Dynamic updates failed.
9901 <p><span><strong class="command">UpdateBadPrereq</strong></span></p>
9904 <p><span><strong class="command"></strong></span></p>
9908 Dynamic updates rejected due to prerequisite failure.
9915 <div class="sect3" lang="en">
9916 <div class="titlepage"><div><div><h4 class="title">
9917 <a name="id2600702"></a>Zone Maintenance Statistics Counters</h4></div></div></div>
9918 <div class="informaltable"><table border="1">
9927 <span class="emphasis"><em>Symbol</em></span>
9932 <span class="emphasis"><em>Description</em></span>
9938 <p><span><strong class="command">NotifyOutv4</strong></span></p>
9948 <p><span><strong class="command">NotifyOutv6</strong></span></p>
9958 <p><span><strong class="command">NotifyInv4</strong></span></p>
9962 IPv4 notifies received.
9968 <p><span><strong class="command">NotifyInv6</strong></span></p>
9972 IPv6 notifies received.
9978 <p><span><strong class="command">NotifyRej</strong></span></p>
9982 Incoming notifies rejected.
9988 <p><span><strong class="command">SOAOutv4</strong></span></p>
9992 IPv4 SOA queries sent.
9998 <p><span><strong class="command">SOAOutv6</strong></span></p>
10002 IPv6 SOA queries sent.
10008 <p><span><strong class="command">AXFRReqv4</strong></span></p>
10012 IPv4 AXFR requested.
10018 <p><span><strong class="command">AXFRReqv6</strong></span></p>
10022 IPv6 AXFR requested.
10028 <p><span><strong class="command">IXFRReqv4</strong></span></p>
10032 IPv4 IXFR requested.
10038 <p><span><strong class="command">IXFRReqv6</strong></span></p>
10042 IPv6 IXFR requested.
10048 <p><span><strong class="command">XfrSuccess</strong></span></p>
10052 Zone transfer requests succeeded.
10058 <p><span><strong class="command">XfrFail</strong></span></p>
10062 Zone transfer requests failed.
10069 <div class="sect3" lang="en">
10070 <div class="titlepage"><div><div><h4 class="title">
10071 <a name="id2601154"></a>Resolver Statistics Counters</h4></div></div></div>
10072 <div class="informaltable"><table border="1">
10082 <span class="emphasis"><em>Symbol</em></span>
10087 <span class="emphasis"><em>BIND8 Symbol</em></span>
10092 <span class="emphasis"><em>Description</em></span>
10098 <p><span><strong class="command">Queryv4</strong></span></p>
10101 <p><span><strong class="command">SFwdQ</strong></span></p>
10111 <p><span><strong class="command">Queryv6</strong></span></p>
10114 <p><span><strong class="command">SFwdQ</strong></span></p>
10124 <p><span><strong class="command">Responsev4</strong></span></p>
10127 <p><span><strong class="command">RR</strong></span></p>
10131 IPv4 responses received.
10137 <p><span><strong class="command">Responsev6</strong></span></p>
10140 <p><span><strong class="command">RR</strong></span></p>
10144 IPv6 responses received.
10150 <p><span><strong class="command">NXDOMAIN</strong></span></p>
10153 <p><span><strong class="command">RNXD</strong></span></p>
10163 <p><span><strong class="command">SERVFAIL</strong></span></p>
10166 <p><span><strong class="command">RFail</strong></span></p>
10176 <p><span><strong class="command">FORMERR</strong></span></p>
10179 <p><span><strong class="command">RFErr</strong></span></p>
10189 <p><span><strong class="command">OtherError</strong></span></p>
10192 <p><span><strong class="command">RErr</strong></span></p>
10196 Other errors received.
10202 <p><span><strong class="command">EDNS0Fail</strong></span></p>
10205 <p><span><strong class="command"></strong></span></p>
10209 EDNS(0) query failures.
10215 <p><span><strong class="command">Mismatch</strong></span></p>
10218 <p><span><strong class="command">RDupR</strong></span></p>
10222 Mismatch responses received.
10223 The DNS ID, response's source address,
10224 and/or the response's source port does not
10225 match what was expected.
10226 (The port must be 53 or as defined by
10227 the <span><strong class="command">port</strong></span> option.)
10228 This may be an indication of a cache
10235 <p><span><strong class="command">Truncated</strong></span></p>
10238 <p><span><strong class="command"></strong></span></p>
10242 Truncated responses received.
10248 <p><span><strong class="command">Lame</strong></span></p>
10251 <p><span><strong class="command">RLame</strong></span></p>
10255 Lame delegations received.
10261 <p><span><strong class="command">Retry</strong></span></p>
10264 <p><span><strong class="command">SDupQ</strong></span></p>
10268 Query retries performed.
10274 <p><span><strong class="command">QueryAbort</strong></span></p>
10277 <p><span><strong class="command"></strong></span></p>
10281 Queries aborted due to quota control.
10287 <p><span><strong class="command">QuerySockFail</strong></span></p>
10290 <p><span><strong class="command"></strong></span></p>
10294 Failures in opening query sockets.
10295 One common reason for such failures is a
10296 failure of opening a new socket due to a
10297 limitation on file descriptors.
10303 <p><span><strong class="command">QueryTimeout</strong></span></p>
10306 <p><span><strong class="command"></strong></span></p>
10316 <p><span><strong class="command">GlueFetchv4</strong></span></p>
10319 <p><span><strong class="command">SSysQ</strong></span></p>
10323 IPv4 NS address fetches invoked.
10329 <p><span><strong class="command">GlueFetchv6</strong></span></p>
10332 <p><span><strong class="command">SSysQ</strong></span></p>
10336 IPv6 NS address fetches invoked.
10342 <p><span><strong class="command">GlueFetchv4Fail</strong></span></p>
10345 <p><span><strong class="command"></strong></span></p>
10349 IPv4 NS address fetch failed.
10355 <p><span><strong class="command">GlueFetchv6Fail</strong></span></p>
10358 <p><span><strong class="command"></strong></span></p>
10362 IPv6 NS address fetch failed.
10368 <p><span><strong class="command">ValAttempt</strong></span></p>
10371 <p><span><strong class="command"></strong></span></p>
10375 DNSSEC validation attempted.
10381 <p><span><strong class="command">ValOk</strong></span></p>
10384 <p><span><strong class="command"></strong></span></p>
10388 DNSSEC validation succeeded.
10394 <p><span><strong class="command">ValNegOk</strong></span></p>
10397 <p><span><strong class="command"></strong></span></p>
10401 DNSSEC validation on negative information succeeded.
10407 <p><span><strong class="command">ValFail</strong></span></p>
10410 <p><span><strong class="command"></strong></span></p>
10414 DNSSEC validation failed.
10420 <p><span><strong class="command">QryRTTnn</strong></span></p>
10423 <p><span><strong class="command"></strong></span></p>
10427 Frequency table on round trip times (RTTs) of
10429 Each <span><strong class="command">nn</strong></span> specifies the corresponding
10432 <span><strong class="command">nn_1</strong></span>,
10433 <span><strong class="command">nn_2</strong></span>,
10435 <span><strong class="command">nn_m</strong></span>,
10436 the value of <span><strong class="command">nn_i</strong></span> is the
10437 number of queries whose RTTs are between
10438 <span><strong class="command">nn_(i-1)</strong></span> (inclusive) and
10439 <span><strong class="command">nn_i</strong></span> (exclusive) milliseconds.
10440 For the sake of convenience we define
10441 <span><strong class="command">nn_0</strong></span> to be 0.
10442 The last entry should be represented as
10443 <span><strong class="command">nn_m+</strong></span>, which means the
10444 number of queries whose RTTs are equal to or over
10445 <span><strong class="command">nn_m</strong></span> milliseconds.
10452 <div class="sect3" lang="en">
10453 <div class="titlepage"><div><div><h4 class="title">
10454 <a name="id2602312"></a>Socket I/O Statistics Counters</h4></div></div></div>
10456 Socket I/O statistics counters are defined per socket
10458 <span><strong class="command">UDP4</strong></span> (UDP/IPv4),
10459 <span><strong class="command">UDP6</strong></span> (UDP/IPv6),
10460 <span><strong class="command">TCP4</strong></span> (TCP/IPv4),
10461 <span><strong class="command">TCP6</strong></span> (TCP/IPv6),
10462 <span><strong class="command">Unix</strong></span> (Unix Domain), and
10463 <span><strong class="command">FDwatch</strong></span> (sockets opened outside the
10465 In the following table <span><strong class="command"><TYPE></strong></span>
10466 represents a socket type.
10467 Not all counters are available for all socket types;
10468 exceptions are noted in the description field.
10470 <div class="informaltable"><table border="1">
10479 <span class="emphasis"><em>Symbol</em></span>
10484 <span class="emphasis"><em>Description</em></span>
10490 <p><span><strong class="command"><TYPE>Open</strong></span></p>
10494 Sockets opened successfully.
10495 This counter is not applicable to the
10496 <span><strong class="command">FDwatch</strong></span> type.
10502 <p><span><strong class="command"><TYPE>OpenFail</strong></span></p>
10506 Failures of opening sockets.
10507 This counter is not applicable to the
10508 <span><strong class="command">FDwatch</strong></span> type.
10514 <p><span><strong class="command"><TYPE>Close</strong></span></p>
10524 <p><span><strong class="command"><TYPE>BindFail</strong></span></p>
10528 Failures of binding sockets.
10534 <p><span><strong class="command"><TYPE>ConnFail</strong></span></p>
10538 Failures of connecting sockets.
10544 <p><span><strong class="command"><TYPE>Conn</strong></span></p>
10548 Connections established successfully.
10554 <p><span><strong class="command"><TYPE>AcceptFail</strong></span></p>
10558 Failures of accepting incoming connection requests.
10559 This counter is not applicable to the
10560 <span><strong class="command">UDP</strong></span> and
10561 <span><strong class="command">FDwatch</strong></span> types.
10567 <p><span><strong class="command"><TYPE>Accept</strong></span></p>
10571 Incoming connections successfully accepted.
10572 This counter is not applicable to the
10573 <span><strong class="command">UDP</strong></span> and
10574 <span><strong class="command">FDwatch</strong></span> types.
10580 <p><span><strong class="command"><TYPE>SendErr</strong></span></p>
10584 Errors in socket send operations.
10585 This counter corresponds
10586 to <span><strong class="command">SErr</strong></span> counter of
10587 <span><strong class="command">BIND</strong></span> 8.
10593 <p><span><strong class="command"><TYPE>RecvErr</strong></span></p>
10597 Errors in socket receive operations.
10598 This includes errors of send operations on a
10599 connected UDP socket notified by an ICMP error
10607 <div class="sect3" lang="en">
10608 <div class="titlepage"><div><div><h4 class="title">
10609 <a name="id2602685"></a>Compatibility with <span class="emphasis"><em>BIND</em></span> 8 Counters</h4></div></div></div>
10611 Most statistics counters that were available
10612 in <span><strong class="command">BIND</strong></span> 8 are also supported in
10613 <span><strong class="command">BIND</strong></span> 9 as shown in the above tables.
10614 Here are notes about other counters that do not appear
10617 <div class="variablelist"><dl>
10618 <dt><span class="term"><span><strong class="command">RFwdR,SFwdR</strong></span></span></dt>
10620 These counters are not supported
10621 because <span><strong class="command">BIND</strong></span> 9 does not adopt
10622 the notion of <span class="emphasis"><em>forwarding</em></span>
10623 as <span><strong class="command">BIND</strong></span> 8 did.
10625 <dt><span class="term"><span><strong class="command">RAXFR</strong></span></span></dt>
10627 This counter is accessible in the Incoming Queries section.
10629 <dt><span class="term"><span><strong class="command">RIQ</strong></span></span></dt>
10631 This counter is accessible in the Incoming Requests section.
10633 <dt><span class="term"><span><strong class="command">ROpts</strong></span></span></dt>
10635 This counter is not supported
10636 because <span><strong class="command">BIND</strong></span> 9 does not care
10637 about IP options in the first place.
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10655 <td width="40%" align="left" valign="top">Chapter 5. The <acronym class="acronym">BIND</acronym> 9 Lightweight Resolver </td>
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10657 <td width="40%" align="right" valign="top"> Chapter 7. <acronym class="acronym">BIND</acronym> 9 Security Considerations</td>