This is an odd one, I haven’t come across it before.
I just purchased a Dell Optiplex 330 for use as an admin console for my server room. It will be connected to both the external campus network (130.xx.xx.xx) and the internal server room network which does not go outside (192.xx)
The onboard NIC of the Dell is Gigabit, as is our internal network switch, and so I have that port connectd to the Internal network. I put in a D-Link 530TX PCI NIC in as well, and that connects to the External campus network.
The problem is that I cannot reach the campus DNS servers, if I try an nslookup let’s say. However, if I disable the onboard NIC, (the Internal network one), then I can reach them just fine. When I re-enable the onboard NIC, then I can once again not contact my DNS servers.
It seems to me that there is some conflict between the two NICs, but I cannot determine the root cause. I would assume that it’s because the onboard NIC is taking some sort of priority and it can’t contact the DNS server (because the switch doesn’t go to the outside).
I switched the cables and IP addresses around, effectively swapping NICs and networks, and at first it did not work that way either. Then I swapped them back and it did work. That was yesterday; when I came in this morning, the problem had re-established itself.
So now I’m not sure at all what’s going on. All I am sure of is that disabling the onboard/Internal NIC allows contact with the DNS server again. Any ideas?
