Question : Force Windows XP workstations to use a specific DHCP server

I have 2 windows 2003 server Domain controllers on my LAN, once of which is running DHCP (172.17.0.10 - 255). I have about 100 Windows XP SP2/3 clients. The problem is that in the building next door there is another windows 2003 domain (plus DHCP 172.20.0.10 - 255) of our sister company, and when my server is busy then my workstations tend to take their DHCP from the other subnet (172.20.0.x) which prevents them from accessing my Windows 2003 file server.

Is there a way to force the client to only take their DHCP address from my DHCP server. I would have thought that because they are joined to my domain they would automatically only take their address from a DC from the same domain... but this doesn't seem to be the case.

Answer : Force Windows XP workstations to use a specific DHCP server

Indeed, it's called 'on-the-wire'. When a network card goes out on the wire, it will broadcast for a DHCP server - anyone will do. It's not a question of domain specific and having more than 1 DHCP server on the wire will cause all sorts of problems - guranteed!

You will need to  separate them out physically using either a switch to block a network broadcast traveling across to your sister company's DHCP server, or having two network cards in each of your servers so that only they can talk to each other.