[tedivm]

Most ISPs don't change their IPs nearly that often. This isn't the 90s where everyone was dialing in, and changing an ip address would cause existing connections to fail, making the service look crappy. Most of the time the IP only changes when there's maintenance or something that requires it, or the modem gets disconnected.

Using a geolocation service isn't needed for the scenario you're replying to. If it was me, and I had this trolls ip, the first thing I would do it compare it to the other emails and connections that occurred simply to group the troll's crap together. In this situation the friend's email would have shown up to (being sent from the same house), and I doubt Mr. Traynor needed a geolocation service to look up the address of his friend.