Question : DNS won't work unless old server is on network

I have migrated my domain from a w2003 server to a W2008 server.  The old server is no longer serving any roles in the domain.  The old server has a different IP address than the new server.
All workstations in the network show the IP of the new server as their DNS controller.

The problem is that if I down the old server or unplug it's network cable DNS stops working.  I can still ping yahoo.com but I cannot display it's web page. I have looked everywhere in my Sonicwall 2040 Pro which is doing the routing and the new server and cannot find any reference to the old DNS server's IP address.

Where could the ghost of this old server be hiding that I cannot shut it down?

Answer : DNS won't work unless old server is on network

If it does turn out to be a DNS server issue with Comcast, you do not have to use Comcast servers for DNS, or Google's or Level3's.

I recommend you run some tool such as GRC's DNSBench at http://www.grc.com/dns/benchmark.htm or Google's namebench at http://code.google.com/p/namebench/ to find the fastest DNS servers for your location. I would also rerun these tools periodically because things do change.

Lee