Head to the directory /var/named and open localhost.zone and localdomain.zone in a text editor such as vi, gedit, kedit, etc.

The file should have information in it pertaining to the IP 127.0.0.1

3 lines into it, the serial is set to 42, with a comment after it in parentheses saying "(d. adams)".

This is a reference to Douglas Adam's book series The Hitchhiker's Guide to the Galaxy, which is famous for stating that the answer to Life, the Universe, and Everything is equal to 42.