"Unknown host" when joining

[2Late]

Ok so I'd really like try hunger games but these servers keep telling me "Unknow host *server name*" when trying to join. I tried searching for answers but didn't come across one like this. So does anyone have solutions for this?

 

[RC_4777]

There is a guide at the top of this section. I would link it, but I'm on mobile. That guide worked for me.
Edit: It was in discussions, here it is: http://www.minecraftsurvivalgames.com/threads/cant-resolve-hostname-fix.17539/