I seem to remember an incident or two where various game developers set the address of their master server to a specific IP address, rather than a DNS name.

Can you guess what happened to those games when that server was moved to a different IP?

DING DING DING DING DING DING! That's right - it all broke. Vana - tell our lucky player what s/he's won!

Well, if you're lucky (there are more than 100 servers, the game company is still in business, there is at least one person still working activly on the codebase, and management is willing to QA, support and publish it) they might release a patch. But only if you're lucky ;-)

But if you're unlucky - well... say hello to a new friend - the ulcer.