Two DHCP servers on the same network

dhcproutingwindows-server-2008

We are setting up a routing link between the Windows Server 2008 networks of two different buildings in my organisation. Each network uses a different IP addressing scheme (one uses public addresses, the other one uses private), but the goal is having a single Windows Server domain across the gap between the buildings. The link is provided by a 100-Mbps point-to-point line.

I have always understood that you should not have more than one DHCP server on a network. However, we are planning to put a domain controller on each building, and each domain controller will be a DNS server and a DHCP server as well. The intention is that a machine booting up in building A gets its IP address from the DHCP server closer to it, in building A, while a machine booting up in building B gets an address from the DHCP server in building B. Since the two buildings will be linked and the network will be only one, will this work? How can I avoid that a machine booting up in building A gets an address from the DHCP server in building B (or vice versa)?

Thanks.

Best Answer

Yes, this will work. DHCP is a broadcast based technology and since broadcasts are not forwarded across routers by default (unless you configure them to by enabling broadcast forwarding or configuring a dhcp helper address) you should have no problems with machines getting their ip addressing information from the correct DHCP server.