The 'nsupdate' protocol is used to submit Dynamic DNS Update requests as
defined in RFC2136 to a name server using the 'nsupdate' command line
utility part of ISC BIND. Dynamic DNS updates allow resource records to
be added or removed from a zone configured for dynamic updates through
DNS requests protected using TSIG. BIND ships with 'ddns-confgen', a
utility to generate sample configurations and instructions for both the
server and the client. See nsupdate(1) and ddns-confgen(8) for details.