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I have one DHCP server running on my windows 2003 domain. If I install another DHCP server, will this server kick in and take over if the first server is out of commission? for example, installing updates, needs to be rebooted for whatever reason.

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What's the number of clients and what's your lease length? In most cases you're going to be patching, doing maintenance, etc outside of regular business hours so as long as your lease length is good you shouldn't have any problems under normal circumstances. What the other people have said applies though if you need redundancy. – Mitch Oct 21 '10 at 13:28
Remember that any solution that has multiple DHCP servers answering in the same broadcast domain will result in a non-deterministic scenario WRT to which server will fulfill a client's request. It's possible that you could see clients (particularly portable computers that might move to other subnets and back) being assigned different IP addresses at different times. Cleaning up old client-registered PTR records is critical in this situation if you want good reverse DNS. – Evan Anderson Oct 21 '10 at 17:05
But if my DNS is AD integrated (My DNS server is not my DHCP server), how could the PTR records go out of sync? – Mister IT Guru Oct 22 '10 at 9:18
up vote 1 down vote accepted

There shouldn't be any reason you can't run two dhcp servers side by side with the same lease; they just need to be in the same broadcast domain. Lease negotiation should still work as the client will negotiate with the server with the first response.

The dhcp should also check if there is an ip conflict before handing out an ip.

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Which now that I think about it.... it's true. Which would mean that I would have to make sure that everything is in sync, but a couple of scripts, a DFS share, and I can keep these things in sync pretty easily - Thanks Matthew! – Mister IT Guru Oct 21 '10 at 12:32
that's a lot of "should"s, and I know how that generally turns out in the long run. – Chris S Oct 26 '10 at 12:32
One 'should' is a lot? What problems have you run into with this setup? – Ablue Oct 26 '10 at 23:03

Not by default no, you'd need cluster services for that.

What you can do if your ranges are big enough is to run DHCP on both servers and just split your scopes across both machines.

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Cluster Services .. thats on my roadmap to investigate – Mister IT Guru Oct 21 '10 at 12:30
@Mister, The best idea (usually) is to run two simultaneous servers, a primary with 80% of the scope and a secondary with the remaining 20%. (Side note: ISC-DHCPd has an experimental feature for running multiple servers with the exact same scope; it's possible a similar feature works it's way into MS's DHCP Server some day). – Chris S Oct 26 '10 at 12:31

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