Minecraft Server can't resolve hostname?

I have a minecraft server up and running, and my roommate can't seem to get on it. It says can't resolve hostname. I know for a fact he has everything typed in correctly and his firewalls are turned off. Any idea what it could be?

Added (1). The server is set up completely. Ports are forwarded, Both me and him have the newest versions of FTB and the server is updated to the newest version. Me and another friend can get on it but for some reason he can't. I'm sure we're doing something wrong, but i have no idea what.

ImRightYourWrong

Try pinging his IP with CMD, just do ping (IP) -t -l 32
Then CTRL + C to stop

Guest

Try with Hamachi, works every time you don't need to port forward, just get everyone in your hamachi network and if that doesn't work which I highly doubt it won't host a LAN, Go into singleplay hit on the LAN button on the pause menu and your LAN world will appear on your roommates server list

Guest

Is he trying to connect directly to your (I)nternet (P)rotocol address? Or a host like myftbserver.no-ip.biz?

Also - make sure he has proper connection (may seem stupid - but happens)

Guest