named
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## Name

named — Internet domain name server

## Synopsis

`named` [`-4`] [`-6`] [`-c `config-file``] [`-d `debug-level``] [`-E `engine-name``] [`-f`] [`-g`] [`-M `option``] [`-m `flag``] [`-n `#cpus``] [`-p `port``] [`-s`] [`-S `#max-socks``] [`-t `directory``] [`-U `#listeners``] [`-u `user``] [`-v`] [`-V`] [`-x `cache-file``]

## DESCRIPTION

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 read the default configuration file `/etc/named.conf`, read any initial data, and listen for queries.

## OPTIONS

-4

  Use IPv4 only even if the host machine is capable of IPv6. `-4` and `-6` are mutually exclusive.

-6

  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.

-E `engine-name`

  Use a crypto hardware (OpenSSL engine) for the crypto operations it supports, for instance re-signing with private keys from a secure key store. When compiled with PKCS#11 support `engine-name` defaults to pkcs11, the empty name resets it to no engine.

-f

  Run the server in the foreground (i.e. do not daemonize).

-g

  Run the server in the foreground and force all logging to `stderr`.

-M `option`

  Sets the default memory context options. Currently the only supported option is `external`, which causes the internal memory manager to be bypassed in favor of system-provided memory allocation functions.

-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 `<isc/mem.h>`.

-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 port 53.

-s

  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.

-S `#max-socks`

  Allow named to use up to `#max-socks` sockets.

  ### Warning

  This option should be unnecessary for the vast majority of users. The use of this option could even be harmful because the specified value may exceed the limitation of the underlying system API. It is therefore set only when the default configuration causes exhaustion of file descriptors and the operational environment is known to support the specified number of sockets. Note also that the actual maximum number is normally a little fewer than the specified value because named reserves some file descriptors for its internal use.

-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 `#listeners`

  Use `#listeners` worker threads to listen for incoming UDP packets on each address. If not specified, named will calculate a default value based on the number of detected CPUs: 1 for 1 CPU, and the number of detected CPUs minus one for machines with more than 1 CPU. This cannot be increased to a value higher than the number of CPUs. If `-n` has been set to a higher value than the number of detected CPUs, then `-U` may be increased as high as that value, but no higher. On Windows, the number of UDP listeners is hardwired to 1 and this option has no effect.

-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 `setuid(2)`.

-v

  Report the version number and exit.

-V

  Report the version number and build options, 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 release.

## SIGNALS

In routine operation, signals should not be used to control the nameserver; rndc should be used instead.

SIGHUP

  Force a reload of the server.

SIGINT, SIGTERM

  Shut down the server.

The result of sending any other signals to the server is undefined.

## CONFIGURATION

The named configuration file is too complex to describe in detail here. A complete description is provided in the BIND 9 Administrator Reference Manual.

named inherits the `umask` (file creation mode mask) from the parent process. If files created by named, such as journal files, need to have custom permissions, the `umask` should be set explicitly in the script used to start the named process.

## FILES

`/etc/named.conf`

  The default configuration file.

`/var/run/named/named.pid`

  The default process-id file.

## SEE ALSO

RFC 1033, RFC 1034, RFC 1035, named-checkconf (8) , named-checkzone (8) , rndc (8) , lwresd (8) , named.conf (5) , BIND 9 Administrator Reference Manual.

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