A pure java DNS client implementation. Consists of a library and utilities for looking up the Internet domain names. The utilities are also able to fetch an entire domain zone and save it in the standard DNS zone file format.
DDNSNotify logs into a (telnet-enabled) router and retrieves the WAN IP Address, only IF the IP Address differs from the DNS IP address for the domain name. It's useful to update DNS records using another external DDNS script (such as zoneclient.py).