I think you have it backwards, the original poster asked for a way to convert IP addresses to hostnames, not hostnames to IP addresses.

What do you think my code does? It reads in a list of IP addresses and converts them to hostnames. Your code on the other hand converts hostnames into (possibly multiple) IP addresses, which is what your quote above says is what the OP did not ask for... You're not making sense. Your text and your code say two different stories :)