Concise Guide to DNS and BIND, The

How ncd Works

Before ndc there was the kill command. In the beginning, sending HUP to named caused files to be re-read, as is usual for UNIX daemons. As time passed, other signals were added to do other things. The first versions of ndc, as found in BIND 4, were shell scripts that simply provided a handy tool to send all these signals to named. ndc in BIND 8, however, can use a named pipe to communicate with BIND and get messages back about how and what BIND is doing. But it also can still use signals to deliver the message to BIND. In BIND 9, the evolution is complete, and ndc is called rndc for remote ndc. It uses an encrypted network connection to send commands and a shared secret or key to authenticate itself to named.

However, it is still ...