-Me and two friends are playing on a new 1.7 vanilla amplified minecraft world.
-First night, no problem; hostile mobs were spawning, everything seemed okay.
-I walk about 1000 blocks to make my base.
-I find almost 0 hostile mobs every night from that night.
-I find a very small amount of hostile mobs in caves.
-Pigmen and ghasts spawn in nether.
I am not sure if this is supposed to go in server support or unmodified minecraft client support but I am posting it here because it is a problem with a server. Please move this topic if I am wrong.