I have a network that has a Win Server 2008r2 with SQL 2008r2 AND a Win Server 2008r2 for a DC. The environment has worked well until this morning.
There is an application that connects to the database and for some reason some workstations cannot find the database while others can. Then the ones that cannot will work and then will have a problem again. I looked at the server and I don't see any bad events.
From the workstation, I can ping the SQL server, perform an NSLOOKUP to the server and can sometimes telnet (telnet servername 1433) to the server.