The problem occurs when you have dual homed servers with only one server having connectivity to a DNS server. The problem is that an unidentified network is effectively shut down and will not accept any inbound connections. There has been a number of discussions on resolving this, but the solution is quite simple.
TCP/IPv4 solution
Open up the IP V4 properties from the problem Network adaptor
Click the Advanced tab
Click the DNS tab
in 'DNS Suffix for this connection', enter your local AD Domain Name