The key is the most important statement in /etc/rndc.conf.

key "<key-name>" { algorithm hmac-md5; secret "<key-value>"; };

The <key-name> and <key-value> should be exactly the same as their settings in /etc/named.conf.

To match the keys specified in the target server's /etc/named.conf, add the following lines to /etc/rndc.conf.

options { default-server localhost; default-key "<key-name>"; };

This directive sets a global default key. However, the rndc configuration file can also specify different keys for different servers, as in the following example:

server localhost { key "<key-name>"; };

For more information about the /etc/rndc.conf file, refer to the rndc.conf man page.