This sounds like a test question: I was at a friend's site today that had two subnets for a network with 2 offices, 6 employess at one office(192.168.100.x), 4 at the other(10.0.100.x). The 6 user offcie had a win2k3 DC that also did DHCP to that office but not to the 4 user office which was doing static IP addressing. The two offices are connected via dedicated T1 line using an Adtran and Cisco on each end. The firewall on the 6 user office has a route added to support web browsing for the 4 user office. Does he need two subnets for such a small network on a dedicated ptp? Why can't the dhcp server respond to requests made from the 4 user office?

Need is a relative term. If he doesn't want the two separate sites communicating, then he "needs" two separate subnets.

Having them in a same subnet suppose a same broadcast domain. To be compliant with the 80/20 rule and have an efficient network design, you really "need" to have at least 1 subnet per office. However a much better design would be to have the 2 subnets being part of a same network address. Otherwise, you have to double the number of firewalling rules (one entry per subnet). They should use the 192.168.100.0 network splited in the following 2 subnets: 192.168.100.0 255.255.255.240 (office1) 192.168.100.16 255.255.255.240 (office2) This one will be much efficient, easier to manage and less prone to administration error than yours. Danny Larouche, cwna ciw

Concerning DHCP, you should rememeber that DHCP requests are broadcasted within a broadcast domain (the subnet). Some routers are able to relay dhcp requests to a DHCP server located on the other interface. Also, this site should have a secondary DC on the second office to authenticate its users and DHCP. Danny Larouche, cwna ciw