To convert IP addresses to host names, you must use the program
logresolve. This can only be done on our servers via Telnet;
unlike other log processing operations, you must be online in order to
perform the necessary reverse nameservice operations.
logresolve is a simple filter. It accepts common logs on its
standard input, and generates those same logs on standard output, with host
names substituted for IP addresses whenever possible. Example:
logresolve < transfer.log > fqdn.transfer
This command would convert your common log.
Please note that logresolve can take a very long time to run, even
though it seems to be doing nothing. This is because each attempt to look
up a host name generates a query to a remote nameserver, which may or may
not answer or be configured properly. In many cases, you will not be able
to obtain host names for an IP address.