I own two domain names that both point to the static ip address of my server. DNS points somewhere else?

I own random-irc.net and twilight-irc.net. They both point to 66.252.30.126, which is proven using a DNS resolver. However, going the other way, 66.252.30.126 resolves to irc.rpggalaxy.org, which doesn't do much of anything if used somewhere else. Inside IRC (that's what running on the server at 66.252.30.126), connections from the server (such as eggdrop or irssi) won't resolve to any hostname. Am I doing something wrong? Or is GoDaddy doing something wrong? Or does this just not work the way I think it does and nothing is wrong?