Provided by: bind9_9.16.48-0ubuntu0.20.04.1_amd64 
NAME
named - Internet domain name server
SYNOPSIS
named [ [-4] | [-6] ] [-c config-file] [-C] [-d debug-level] [-D string] [-E engine-name]
[-f] [-g] [-L logfile] [-M option] [-m flag] [-n #cpus] [-p port] [-s] [-S #max-socks] [-t
directory] [-U #listeners] [-u user] [-v] [-V] [-X lock-file] [-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 RFC 1033, RFC 1034, and RFC 1035.
When invoked without arguments, named reads the default configuration file
/etc/named.conf, reads any initial data, and listens for queries.
OPTIONS
-4 This option tells named to use only IPv4, even if the host machine is capable of
IPv6. -4 and -6 are mutually exclusive.
-6 This option tells named to use only IPv6, even if the host machine is capable of
IPv4. -4 and -6 are mutually exclusive.
-c config-file
This option tells named to use config-file as its configuration file instead of the
default, /etc/named.conf. To ensure that the configuration file can be reloaded
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.
-C
This option prints out the default built-in configuration and exits.
NOTE: This is for debugging purposes only and is not an accurate representation of the
actual configuration used by named at runtime.
-d debug-level
This option sets the daemon's debug level to debug-level. Debugging traces from
named become more verbose as the debug level increases.
-D string
This option specifies a string that is used to identify a instance of named in a
process listing. The contents of string are not examined.
-E engine-name
When applicable, this option specifies the hardware to use for cryptographic
operations, such as a secure key store used for signing.
When BIND 9 is built with OpenSSL, this needs to be set to the OpenSSL engine
identifier that drives the cryptographic accelerator or hardware service module
(usually pkcs11). When BIND is built with native PKCS#11 cryptography
(--enable-native-pkcs11), it defaults to the path of the PKCS#11 provider library
specified via --with-pkcs11.
-f This option runs the server in the foreground (i.e., do not daemonize).
-g This option runs the server in the foreground and forces all logging to stderr.
-L logfile
This option sets the log to the file logfile by default, instead of the system log.
-M option
This option sets the default (comma-separated) memory context options. The possible
flags are:
• external: use system-provided memory allocation functions; this is the implicit
default.
• internal: use the internal memory manager.
• fill: fill blocks of memory with tag values when they are allocated or freed, to
assist debugging of memory problems; this is the implicit default if named has been
compiled with --enable-developer.
• nofill: disable the behavior enabled by fill; this is the implicit default unless
named has been compiled with --enable-developer.
-m flag
This option turns 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
This option controls the number of CPUs that named assumes the presence of. If not
specified, named tries to determine the number of CPUs present automatically; if it
fails, a single CPU is assumed to be present.
named creates two threads per each CPU present (one thread for receiving and
sending client traffic and another thread for sending and receiving resolver
traffic) and then on top of that a single thread for handling time-based events.
-p port
This option listens for queries on port. If not specified, the default is port 53.
-s This option writes 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
This option allows named to use up to #max-socks sockets. The default value is
21000 on systems built with default configuration options, and 4096 on systems
built with configure --with-tuning=small.
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 slightly fewer than the specified value, because named reserves some file
descriptors for its internal use.
-t directory
This option tells named to 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 is defined
allows a process with root privileges to escape a chroot jail.
-U #listeners
This option tells named the number of #listeners worker threads to listen on, for
incoming UDP packets on each address. If not specified, named calculates 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
This option sets the 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 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.
-v This option reports the version number and exits.
-V This option reports the version number, build options, supported cryptographics
algorithms, and exits.
-X lock-file
This option acquires a lock on the specified file at runtime; this helps to prevent
duplicate named instances from running simultaneously. Use of this option
overrides the lock-file option in named.conf. If set to none, the lock file check
is disabled.
-x cache-file
This option loads data from cache-file into the cache of the default view.
WARNING:
This option must not be used in normal operations. 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 This signal forces a reload of the server.
SIGINT, SIGTERM
These signals 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),
named.conf(5), BIND 9 Administrator Reference Manual.
AUTHOR
Internet Systems Consortium
COPYRIGHT
2024, Internet Systems Consortium