How to get TEXT name for IP address on internet via command line.

I am in the process of writing a small script to analise access to our
internet site - logs.
I can extract the data well enough but a list of visiting IP addresses is
not wholly useful.
I would like, much like the NT TRACERT command to be able to use a command
to translae the IP address to a text representation. ( I don't need the
route )
To date I have not found a practical way of doing this !

Suggestions !