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man pages section 1M: System Administration Commands

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Updated: July 2017



rndc - name server control utility


rndc [-V] [-b src-addr] [-c config-file] [-k key-file] [-s server] 
     [-p port] [-y key_id] command


The rndc utility controls the operation of a name server. It supersedes the ndc utility that was provided in previous BIND releases. If rndc is invoked with no command line options or arguments, it prints a short summary of the supported commands and the available options and their arguments.

The rndc utility communicates with the name server over a TCP connection, sending commands authenticated with digital signatures. The only supported authentication algorithm in the current versions of rndc and named(1M) is HMAC-MD5, which uses a shared secret on each end of the connection. This algorithm provides TSIG-style authentication for the command request and the name server's response. All commands sent over the channel must be signed by a key_id known to the server.

The rndc utility reads a configuration file to determine how to contact the name server and decide what algorithm and key it should use.


The following options are supported:

–b source-address

Use source-address as the source address for the connection to the server. Multiple instances are permitted to allow setting of both the IPv4 and IPv6 source addresses.

–c config-file

Use config-file as the configuration file instead of the default /etc/rndc.conf.

–k key-file

Use key-file as the key file instead of the default, /etc/rndc.key. The key in /etc/rndc.key is used to authenticate commands sent to the server if the config-file does not exist.

–s server

The server argument is the name or address of the server that matches a server statement in the configuration file for rndc. If no server is supplied on the command line, the host named by the default-server clause in the options statement of the rndc configuration file is used.

–p port

Send commands to TCP port port instead of BIND 9's default control channel port, 953.


Enable verbose logging.

–y key_id

Use the key key_id from the configuration file. The key_id argument must be known by named with the same algorithm and secret string for control message validation to succeed. If no key_id is specified, rndc will first look for a key clause in the server statement of the server being used, or if no server statement is present for that host, then the default-key clause of the options statement. The configuration file contains shared secrets that are used to send authenticated control commands to name servers. It should therefore not have general read or write access.

For the complete set of commands supported by rndc, see the BIND 9 Administrator Reference Manual or run rndc without arguments to see its help message.


The rndc utility does not support all the commands of the BIND 8 ndc utility.

There is no way to provide the shared secret for a key_id without using the configuration file.

Several error messages tend toward the cryptic.


See attributes(5) for descriptions of the following attributes:

Interface Stability

See Also

named(1M), rndc-confgen(1M), named.conf(4), rndc.conf(4), attributes(5)

See the BIND 9 Administrator's Reference Manual. As of the date of publication of this man page, this document is available at https://kb.isc.org/article/AA-01031https://kb.isc.org/article/AA-01031.