named(ADMN)

named -- Internet domain name server

Syntax

named [-d debuglevel] [-p port] [-(b|c) config_file] [-f -q -r v] [-u user_name] [-g group_name] [-t directory] [-w directory] [config_file]

Description

named is the Internet domain name server. See RFCs 1033, 1034, and 1035 for more information on the Internet Domain Name System (DNS). 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 with the -b or -c flags.

NOTE: Several of named's options, and much more of its behavior, can be controlled in the configuration file. Please refer to the named.conf(SFF) manual page for further information.

Options

named takes the following options:

-d debuglevel

Print debugging information. The debuglevel is a number that determines the level of messages printed. If negative, debuglevel is set to 1.

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, and so on). Please refer to the named.conf(SFF) manual page for further information.

-p port

Use the specified remote port number. This is the port number to which named will send queries. The default value is the standard port number: that is, the port number returned by getservbyname(SLIB) for service domain.

NOTE: Previously, the -p port[/localport] syntax 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 local port specified; this functionality can be specified with the listen-on clause of the configuration file's options statement.

-b|-c config_file

Use an alternative config_file; this argument is overridden by any config_file which is specified at the end of the command line. The default value is /etc/named.conf.

-f

Run this process in the foreground; don't fork(S) and daemonize. The default is to daemonize.

-q

Trace all incoming queries if named has been compiled with QRYLOG defined.

NOTE: This option is deprecated in favor of the queries logging category of the configuration file's logging statement. Please refer to the named.conf(SFF) manual page for further information.

-r

Turns recursion off in the server. Answers can come only from local (primary or secondary) zones. This can be used on root servers. The default is to use recursion.

NOTE: This option can be overridden by, and is deprecated in favor of, the recursion clause of the configuration file's options statement.

-v

Report the version and exit.

-u user_name

Specifies the user the server should run as after it initializes. The value specified may be either a username or a numeric user id. If the -g flag is not specified, then the group id used will be the primary group of the user specified (initgroups() is called, so all of the user's groups will be available to the server).

-g group_name

Specifies the group the server should run as after it initializes. The value specified may be either a groupname or a numeric group id.

-t directory

Specifies the directory the server should chroot() into as soon as it is finshed processing command line arguments.

-w directory

Sets the working directory of the server. The directory clause of the configuration file's options statement overrides any value specified on the command line. The default working directory is the current directory

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 with -b or -c. If no further argument is given, then the default configuration file, /etc/named.conf, is used.

Master file format

The master file consists of control information and a list of resource records for objects in the zone of the form:

   $INCLUDE filename opt_domain
   $ORIGIN domain
   $TTL ttl
   domain opt_ttl opt_class type resource_record_data

where:

domain

This is ``.'' for root, ``@'' for the current origin, or a standard domain name. If domain is a standard domain name that does not end with ``.'', the current origin is appended to the domain. Domain names ending with ``.'' are unmodified.

opt_domain

This field is used to define an origin for the data in an included file. It is equivalent to placing an $ORIGIN statement before the first line of the included file. This field is optional. Neither the opt_domain field nor $ORIGIN statements in the included file modify the current origin for this file.

ttl

A integer number that sets the default time-to-live for future records without an explicit ttl.

opt_ttl

An optional integer for the time-to-live field. It defaults to zero, meaning the minimum value specified in the SOA record for the zone.

opt_class

The object address type. Currently only one type is supported, IN, for objects connected to the DARPA Internet.

type

This field contains one of the following tokens. The data expected in the resource_record_data field is in parentheses.

A: a host address (dotted-quad IP address)
NS: an authoritative name server (domain)
MX: a mail exchanger (domain), preceded by a preference value (0 to 32767), with lower numeric values representing higher logical preferences
CNAME: the canonical name for an alias (domain)
SOA: marks the start of a zone of authority (domain of originating host, domain address of maintainer, a serial number and the following parameters in seconds: refresh, retry, expire and minimum TTL (see RFC 883))
NULL: a null resource record (no format or data)
RP: a Responsible Person for some domain name (mailbox, TXT-referral)
PTR: a domain name pointer (domain)
HINFO: host information (cpu_type, OS_type)

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. Refer to ``Configuring the Domain Name Service'' in the Networking Guide for a list of types. Some resource record types may have been standardized in newer RFCs but not yet implemented in this version of BIND.

SOA record format

Each master zone file should begin with an SOA record for the zone. An example SOA record is as follows:

   @    IN    SOA    ucbvax.Berkeley.EDU. rwh.ucbvax.Berkeley.EDU. (
                         1989020501    ; serial
                         10800         ; refresh
                         3600          ; retry
                         3600000       ; expire
                         86400 )       ; minimum

The SOA specifies a serial number, which should be incremented 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 the version number (0 to 99) with the unsigned 32-bit size of this field.

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 cache time-to-live for negative answers (RFC 2308).

Notes

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 the local name server did not have complete information.

The following signals have the specified effect when sent to the server process using the kill(C) command:

SIGHUP: Causes server to read named.conf and reload the database. If the server is built with the FORCED_RELOAD compile-time option, then SIGHUP will also cause the server to check the serial number on all secondary zones. Normally, the serial numbers are only checked at the SOA-specified intervals.
SIGINT: Dumps the current data base and cache to /var/tmp/named_dump.db or to the value of _PATH_DUMPFILE.
SIGILL: Dumps statistics data into named.stats if the server is compiled with -DSTATS. Statistics data is appended to the file.
SIGSYS: Dumps the profiling data in /var/tmp if the server is compiled with profiling (server forks, chdirs and exits).
SIGTERM: Dumps the primary and secondary database files. Used to save modified data on shutdown if the server is compiled with dynamic updating enabled.
SIGUSR1: Turns on debugging. Each SIGUSR1 increments the debug level.
SIGUSR2: Turns off debugging completely.
SIGWINCH: Toggles logging of all incoming queries via syslog(SLIB).

Files

/etc/named.conf: default name server configuration file
/etc/named.pid: _PATH_PIDFILE the process ID
/var/tmp/named_dump.db: _PATH_DUMPFILE, dump of the name server database
/var/tmp/named.run: _PATH_DEBUG, debug output
/var/tmp/named.stats: _PATH_STATS, name server statistics data