'domtools' is a set of DNS information extraction utilities.

The commands in the 'domtools' package allow you to traverse DNS domain 
hierarchies, list all hosts (or subdomains) within a given domain, 
convert host name to IP address and vice-versa, convert a normal IP address 
to the "in-addr.arpa." format and vice-versa, and more. These commands can be 
used manually, or included as building blocks for higher level DNS tools. 
They generate output that is easily computer parsable.

See also the net/dlint port.

WWW: http://www.domtools.com/dns/domtools.shtml