named - Internet domain name server
named [-4] [-6]
[-c config-file] [-d debug-level]
[-f] [-g] [-i pid-file]
[-m flag] [-n #cpus]
[-p port] [-s]
[-t directory] [-u user]
[-v] [-x cache-file]
named is a Domain Name System (DNS) server, part of the
BIND 9 distribution from ISC. For more information on the DNS, see RFCs
1033, 1034, and 1035.
When invoked without arguments, named will fork into two
processes for privilege separation, chroot(2) to /var/named,
read the default configuration file /var/named/etc/named.conf, read
any initial data, and listen for queries. The privileged process will
communicate with the child and bind(2) to privileged ports on its
behalf. See CAVEATS section below.
- Use IPv4 only even if the host machine is capable of IPv6. -4 and
-6 are mutually exclusive.
- Use IPv6 only even if the host machine is capable of IPv4. -4 and
-6 are mutually exclusive.
- -c config-file
- Use config-file as the configuration file instead of the default,
/etc/named.conf. To ensure that reloading the configuration file
continues to work after the server has changed its working directory due
to to a possible directory option in the configuration file,
config-file should be an absolute pathname.
- -d debug-level
- Set the daemon's debug level to debug-level. Debugging traces from
named become more verbose as the debug level increases.
- Run the server in the foreground (i.e. do not daemonize).
- Run the server in the foreground and force all logging to
- -m flag
- Turn on memory usage debugging flags. Possible flags are usage,
trace, record, size, and mctx. These
correspond to the ISC_MEM_DEBUGXXXX flags described in
- -i pid-file
- Specifies the file that contains the process ID of named. The
default is /var/run/named.pid.
- -n #cpus
- Create #cpus worker threads to take advantage of multiple CPUs. If
not specified, named will try to determine the number of CPUs
present and create one thread per CPU. If it is unable to determine the
number of CPUs, a single worker thread will be created.
- -p port
- Listen for queries on port port. If not specified, the default is
- Write memory usage statistics to stdout on exit.
Note: This option is mainly of interest to BIND 9
developers and may be removed or changed in a future release.
- -t directory
- Chroot to directory after processing the command line arguments,
but before reading the configuration file.
Warning: This option should be used in conjunction
with the -u option, as chrooting a process running as root doesn't
enhance security on most systems; the way chroot(2) is defined allows a
process with root privileges to escape a chroot jail.
- -u user
- Setuid to user after completing privileged operations, such as
creating sockets that listen on privileged ports.
Note: On Linux, named uses the kernel's
capability mechanism to drop all root privileges except the ability to
bind(2) to a privileged port and set process resource limits.
Unfortunately, this means that the -u option only works when
named is run on kernel 2.2.18 or later, or kernel 2.3.99-pre3 or later,
since previous kernels did not allow privileges to be retained after
- Report the version number and exit.
- -x cache-file
- Load data from cache-file into the cache of the default view.
Warning: This option must not be used. It is only
of interest to BIND 9 developers and may be removed or changed in a future
In routine operation, signals should not be used to control the
nameserver; rndc should be used instead.
- Force a reload of the server.
- SIGINT, SIGTERM
- Shut down the server.
The result of sending any other signals to the server is
The named configuration file is too complex to describe in
detail here. A complete description is provided in the BIND 9 Administrator
named runs privilege separated for binding the privileged
ports after an interface or address change. The privileged process will only
allow named to bind(2) to default ports. Make sure you use
unprivileged (>1024) ports if you change any of the default ports in
named's configuration or on the command-line.
- The default configuration file.
- The default process-id file.
RFC 1033, RFC 1034, RFC 1035, named-checkconf(8),
named-checkzone(8), rndc(8), lwresd(8),
named.conf(5), BIND 9 Administrator Reference Manual.
Internet Systems Consortium