Author: JT Smith
By hiding out DNS server version number you can improve server security. fpdns is a program that remotely determines DNS server versions. It does this by sending a series of borderline DNS queries which are compared against a table of responses and server versions. (just like nmap command’s remote OS detection facility).
A nameserver basically responds to a query. Interoperability is an obvious requirement here. The standard protocol behavior of different DNS implementations is expected to be the same.
Link: Cyberciti.biz
