NAMED(8) BIND 9 NAMED(8)

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] [-t directory] [-U #listeners] [-u user]
[-v] [-V] [-X lock-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).

-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:

+o 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.

+o 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 and record. These correspond to the
ISC_MEM_DEBUGXXXX flags described in <isc/mem.h>.

-n #cpus
This option creates #cpus worker threads to take advantage of
multiple CPUs. If not specified, named tries to determine the
number of CPUs present and creates one thread per CPU. If it
is unable to determine the number of CPUs, a single worker
thread is created.

-p value
This option specifies the port(s) on which the server will
listen for queries. If value is of the form <portnum> or
dns=<portnum>, the server will listen for DNS queries on
portnum; if not not specified, the default is port 53. If
value is of the form tls=<portnum>, the server will listen for
TLS queries on portnum; the default is 853. If value is of
the form https=<portnum>, the server will listen for HTTPS
queries on portnum; the default is 443. If value is of the
form http=<portnum>, the server will listen for HTTP queries
on portnum; the default is 80.

-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 is deprecated and no longer has any function.

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 #dispatches
This option specifies the number of per-interface UDP
#dispatches that named should use to handle the outgoing
(recursive) UDP connection, to reduce contention between the
resolver threads.

If not specified, named calculates a default value based on
the number of detected CPUs: 1 for a single 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 (see -n on how to override the value).

WARNING:
This option should be unnecessary for the vast majority of users,
and will be removed in the next version of BIND 9.

-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.

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.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

2025, Internet Systems Consortium

9.18.37 2025-05-09 NAMED(8)