named - Internet domain name server (DNS)
NAMED [-d debuglevel] [-p port#] [-(b|c) config_file] [-f -q -r] [-u user_name] [-g group_name] [-t directory] [-w directory] [config_file]
Named is the Internet domain name server. See RFC's 1033, 1034, and 1035 for more information on the Internet name-domain system. Without any arguments, named will read the default configuration file /etc/named.conf, read any initial data, and listen for queries. A config_file argument given at the end of the command line will override any config_file specified by using the ``-b'' or ``-c'' flags.
NOTE: Several of named's options, and much more of its behaviour, can be controlled in the configuration file. Please refer to the configuration file guide included with this BIND distribution for further information.
Options are:
NOTE: The new debugging framework is considerably more sophisticated than it was in older versions of NAMED. The configuration file's ``logging'' statement allows for multiple, distinct levels of debugging for each of a large set of categories of events (such as queries, transfers in or out, etc.). Please refer to the configuration file guide included with this BIND distribution for further information about these extensive new capabilities.
NOTE: Previously, the syntax ``-p port#[/localport#]'' was supported; the first port was that used when contacting remote servers, and the second one was the service port bound by the local instance of NAMED. The current usage is equivalent to the old usage without the localport# specified; this functionality can be specified with the ``listen-on'' clause of the configuration file's ``options'' statement.
NOTE: This option is deprecated in favor of the ``queries'' logging category of the configuration file's ``logging'' statement; for more information, please refer to the configu ration file guide included with this distribution of BIND.
NOTE: This option can be overridden by and is deprecated in favor of the ``recursion'' clause of the configuration file's ``options'' statement.
Any additional argument is taken as the name of the configuration file, for compatibility with older implementations; as noted above, this argument overrides any config_file specified by the use of the ``-b'' or ``-c'' flags. If no further argument is given, then the default configuration file is used (/etc/named.conf).
The master file consists of control information and a list of resource records for objects in the zone of the forms:
$INCLUDE <filename> <opt_domain>
$ORIGIN <domain>
<domain> <opt_ttl> <opt_class> <type> <resource_record_data>
where:
the SOA record for the zone.
Resource records normally end at the end of a line, but may be continued across lines between opening and closing parentheses. Comments are introduced by semicolons and continue to the end of the line.
NOTE: There are other resource record types not shown here. You should consult the BIND Operations Guide (``BOG'') for the complete list. Some resource record types may have been standardized in newer RFC's but not yet implemented in this version of BIND.
Each master zone file should begin with an SOA record for the zone. An example SOA record is as follows:
The SOA specifies a serial number, which should be changed each time the master file is changed. Note that the serial number can be given as a dotted number, but this is a very unwise thing to do since the translation to normal integers is via concatenation rather than multiplication and addition. You can spell out the year, month, day of month, and 0..99 version number and still fit inside the unsigned 32-bit size of this field. (It's true that we will have to rethink this strategy in the year 4294, but we're not worried about it.)
Secondary servers check the serial number at intervals specified by the refresh time in seconds; if the serial number changes, a zone transfer will be done to load the new data. If a master server cannot be contacted when a refresh is due, the retry time specifies the interval at which refreshes should be attempted. If a master server cannot be contacted within the interval given by the expire time, all data from the zone is discarded by secondary servers. The minimum value is the time-to-live (``TTL'') used by records in the file with no explicit time-to-live value.
The boot file directives ``domain'' and ``suffixes'' have been obsoleted by a more useful, resolver-based implementation of suffixing for partially-qualified domain names. The prior mechanisms could fail under a number of situations, especially when then local nameserver did not have complete information.
The following signals have the specified effect when sent to the server process using the kill(1) command:
SIGTERM Dumps the primary and secondary database files. Used to save modified data on shutdown if the server is compiled with dynamic updating enabled.
SIGUSR2 Turns off debugging completely. (SIGFPEon older systems without SIGUSR2.)
SIGWINCH Toggles logging of all incoming queries via syslog(8) (requires server to have been built with the QRYLOG option).
gethostbyname(3) , hostname(7) , kill(1) , resolver(3) , resolver(5) , signal(2) , RFC 882, RFC 883, RFC 973, RFC 974, RFC 1033, RFC 1034, RFC 1035, RFC 1123, ``Name Server Operations Guide for BIND''