Quote from REDHAT website:
"BIND includes a utility called rndc which allows you to use command line statements to administer the named daemon, locally, or remotely. The rndc program uses the /etc/rndc.conf file for its configuration options, which can be overridden with command line options.
In order to prevent unauthorized users on other systems from controlling BIND on your server, a shared secret key method is used to explicitly grant privileges to particular hosts. In order for rndc to issue commands to any named, even on a local machine, the keys used in /etc/named.conf and /etc/rndc.conf must match."
The 953/tcp means it is using a TCP connection on Port 953.