I have a small network with a Win SBS 2k3 (SP1) domain… how do I set it up so that the workstations (they're all DHCP clients) can still resolve domain names if the domain server is down (without messing up any Windows domain stuff)?
Windows – Allow DHCP clients to use public DNS server when domain server is down
dhcpdomain-name-systemwindows
Best Answer
You can supply multiple DNS entries in DHCP. You could provide the public DNS in that list.
BUT, i don't think this will work as well as you might think. The correct way to do this is to have a backup DNS server for your LAN.
The reason it may not work properly is that even when your SBS DNS is running, clients may get a errors resolving hostnames for local machines because they queried an external DNS.
I found this trouble at my ex workplace. Why it didn't work for me is because the local DNS name was the same as the external DNS domain name. So, sometimes we get results and sometimes not. I originally didn't set this up but discovered it. Once I removed the extra entry and put in a backup DNS, I had things working better. The other problem I had, although not entirely sure it was related was queries seemed to take a long time. I'm not really sure if MS windows issues DNS queries in parallel or in sequence to each server. If it's in sequence and the primary DNS is down you might get a long timeout.
So I think it could work, but it's far better to use a backup DNS. (EDIT: That is, a Microsoft Backup DNS server, not just any server!. This doesn't need to be a powerful machine. It can be dedicated to just backing up DNS).
I'm not saying, don't try it, just don't expect smooth sailing with this method.