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NAMED(8) BIND 9 NAMED(8)
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named - Internet domain name server
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 #listen-
ers] [-u user] [-v] [-V] [-X lock-file] [-x cache-file]
named is a Domain Name System (DNS) server, part of the BIND 9 distri-
bution 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.
-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.
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 path-
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.
This option sets the daemon's debug level to debug-level. Debug-
ging traces from named become more verbose as the debug level
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.
When applicable, this option specifies the hardware to use for
cryptographic operations, such as a secure key store used for
When BIND 9 is built with OpenSSL, this needs to be set to the
OpenSSL engine identifier that drives the cryptographic acceler-
ator 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 speci-
fied via --with-pkcs11.
-f This option runs the server in the foreground (i.e., do not dae-
-g This option runs the server in the foreground and forces all
logging to stderr.
This option sets the log to the file logfile by default, instead
of the system log.
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 allo-
cated or freed, to assist debugging of memory problems; this is
the implicit default if named has been compiled with
· nofill: disable the behavior enabled by fill; this is the implicit
default unless named has been compiled with --enable-developer.
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>.
This option controls the number of CPUs that named assumes the
presence of. If not specified, named tries to determine the num-
ber 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.
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.
This option is mainly of interest to BIND 9 developers and may be
removed or changed in a future release.
This option allows named to use up to #max-socks sockets. The
default value is 21000 on systems built with default configura-
tion options, and 4096 on systems built with configure
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 sup-
port the specified number of sockets. Note also that the actual max-
imum number is normally slightly fewer than the specified value,
because named reserves some file descriptors for its internal use.
This option tells named to chroot to directory after processing
the command-line arguments, but before reading the configuration
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 privi-
leges to escape a chroot jail.
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.
This option sets the setuid to user after completing privileged
operations, such as creating sockets that listen on privileged
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.
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
This option loads data from cache-file into the cache of the
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
In routine operation, signals should not be used to control the name-
server; rndc should be used instead.
SIGHUP This signal forces a reload of the server.
These signals shut down the server.
The result of sending any other signals to the server is undefined.
The named configuration file is too complex to describe in detail here.
A complete description is provided in the BIND 9 Administrator Refer-
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.
The default configuration file.
The default process-id file.
RFC 1033, RFC 1034, RFC 1035, named-checkconf(8), named-checkzone(8),
rndc(8), named.conf(5), BIND 9 Administrator Reference Manual.
Internet Systems Consortium
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