Question : Why won't my 'authorised' clustered DHCP server recognise on the network?

Hey all,

I'm running a Windows 2003 R2 File/Print/DHCP 2-server cluster, and everything's working ok except for DHCP. There is an existing DHCP server there (also running 2003(, and I've set this new one up to have exactly the same ranges/reservations etc., not by importing/exporting but by setting it up manually to be the same. DHCP rolls successfully from server to server, as do the rest of the clustered services.

Once we were completely ready to roll, I unauthorised the existing DHCP server, waited until it was no longer running, then authorised the new DHCP server (a virtual name), which popped into the authorised list and appears to be running - this is where the problem lies...

I am a domain admin, but NOT an enterprise admin. I know that that normall stops authorisation, but in this case I've checked AD Sites and Services, and for this site Domain Admins have all rights except 'delete all child objects'. Both servers are unregistering and registering without throwing up any errors (although it takes about 25mins - worldwide network, can be slow?), however the new DHCP server cannot be found by any workstations on the network. The cluster itself can see everything on the network, and the virtual name can be seen by everyone once a fixed IP is assigned, and re-authorising the original DHCP server will return fnuctionality to the network, but I cannot for the life of me figure out why this new one will not return any leases.

I've tried waiting for an hour, rebooting the workstations time and time again, checking Group Policy to make sure there's nothing interfering, checking Microsoft walkthroughs and other questions here to make sure I haven't missed anything obvious, and no luck. The only two things I can think of are the Enterprise Admins thing, and I found a single reference to DHCP servers being in a router's IPhelper table, but to my knowledge that hasn't needed to be done before. I have previously changed DHCP over to clusters on 4 sites (WITHOUT changing the server name - just used a virtual name of the same for it to run off) without a hitch, however in this case the original server cannot move or change for various reasons, but we do need to cluster DHCP.

Any help is GREATLY appreciated, thanks!

Answer : Why won't my 'authorised' clustered DHCP server recognise on the network?

To start with gthe basics: have you checked if a machine in the same network as your DHCP server can obtain an IP address (create a temporary scope, if necessary)?
As far as "and I found a single reference to DHCP servers being in a router's IPhelper table, but to my knowledge that hasn't needed to be done before" is concerned: this may be obvious, too, but it seems as if the new DHCP server has a different IP address than the old one; if this is the case, then you will have to change the IP helper addresses on your routers, otherwise workstations in another network won't be able to find the DHCP server, because the routers will continue to forward the DHCP requests to the old server.
You have two options to change that:
1. Add the new DHCP server's address to all routers as secondary target for DHCP queries; this is usually possible, and if the first server doesn't react, the next one will be used. That way, you have all the time in the world to change your routers, and when that is done, you can just shutdown the old DHCP service and use the one on the cluster.
2. Shut down the old DHCP server (or change its IP address), then use its old IP address for the DHCP cluster resource.
And just in case: in the properties of the clustered DHCP server, make sure it's (only) listening on the public IP address you want to use.