named -- Internet domain name server (DNS)
named [-d debuglevel] [-p port#] [-(b|c) config_file] [-f -q -r -v]
[-u user_name] [-g group_name] [-t directory] [-w directory]
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/namedb/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.
Print debugging information. The debuglevel is a number
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,
etc.). Please refer to the configuration file guide included
with this BIND distribution for further information about
these extensive new capabilities.
-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, i.e., the port number returned by
getservbyname(3) for service ``domain''.
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.
Use an alternate 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/namedb/named.conf.
-f Run this process in the foreground; don't fork(2) and daemonize.
(The default is to daemonize.)
-q Trace all incoming queries if named has been compiled with
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 configuration
file guide included with this distribution of BIND.
-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
-v Report the version and exit.
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).
Specifies the group the server should run as after it initializes.
The value specified may be either a groupname or a
numeric group id.
Specifies the directory the server should chroot() into as
soon as it is finished processing command line arguments.
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 by the use of the ``-b'' or
``-c'' flags. If no further argument is given, then the default configuration
file is used (/etc/namedb/named.conf).
Master File Format [Toc] [Back]
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>
<domain> <opt_ttl> <opt_class> <type> <resource_record_data>
domain 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. The
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 number for the time-to-live field. If
not set the ttl is taken from the last $TTL statement. If
no $TTL statement has occurred then the SOA minimum value
is used and a warning is generated.
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..32767), with lower
numeric values representing higher logical
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 and RFC 2308)).
NULL a null resource record (no format or data)
RP a Responsible Person for some domain name
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. 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.
SOA Record Format [Toc] [Back]
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 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 cache
time-to-live for negative answers (RFC 2308).
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
The following signals have the specified effect when sent to the server
process using the kill(1) 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 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 Saves any modified dynamic zones to the file system, and shuts
down the server.
SIGUSR1 Turns on debugging; each SIGUSR1 increments debug level.
(SIGEMT on older systems without SIGUSR1.)
SIGUSR2 Turns off debugging completely. (SIGFPE on older systems
SIGWINCH Toggles logging of all incoming queries via syslog(3) (requires
server to have been built with the QRYLOG option).
/etc/namedb/named.conf default name server configuration
/var/run/named.pid (_PATH_PIDFILE) the process id
/var/tmp/named_dump.db (_PATH_DUMPFILE) dump of the name server database
/var/tmp/named.run (file: _PATH_DEBUG) debug output
/var/tmp/named.stats (file: _PATH_STATS) nameserver statistics data
named.conf(5), gethostbyname(3), hostname(7), kill(1), resolver(3),
resolver(5), signal(3), RFC 882, RFC 883, RFC 973, RFC 974, RFC 1033, RFC
1034, RFC 1035, RFC 1123, RFC 2308 ``Name Server Operations Guide for
4th Berkeley Distribution February 1, 1996 4th Berkeley Distribution
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