Failure to log in using just the server name I have more than one PC connected by LAN that I access from Server Management Studio.  

When I try to connect with the DB server, if I place the server IP instead of the server name in the serverName field, it works fine, and I can log in. 

If I use the server name, why does logging in fail? How can I resolve this issue?
Check if server name you use resolved to valid IP address: ping SERVERNAME gives you the same IP address as you assumed it has to be