Updated: 2022/Sep/29

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NAMED(8)                            BIND 9                            NAMED(8)

       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
       #listeners] [-u user] [-v] [-V] [-X lock-file] [-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 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.

       -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

          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

              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

       -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

          ⊕ 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 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 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.

          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

          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

          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

          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 and build options, and

       -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

       -x cache-file
              This option loads data from cache-file into the cache of the
              default view.

          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.

       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.

              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
       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.


              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

       2022, Internet Systems Consortium

9.16.33                                                               NAMED(8)