After some time ssh to local servers doesnt work anymore.

Example:

ssh localserver name <— doesnt work

ssh localserver IP <— works

Solution:

In Terminal type;

sudo killall mDNSResponder

Google helps me:

URL: http://www.mac-forums.com/forums/os-x-operating-system/164649-snow-leopard-keeps-dropping-dns.html

URL1: http://discussions.apple.com/message.jspa?messageID=10090153#10090153