DHCP Authorization problem - Event ID 1046

I was speaking to a customer yesterday who was telling me about a problem he was having with DHCP in his reasonably small office network (something like three servers). He had recently upgraded to Windows Server 2003 and implemented Active Directory. Previously, he was working in a workgroup and so you can understand it is quite a different situation now. The specific problem he had was that his Windows Server 2003 DHCP machine (also a file server), which had been running quite happily until joined to the new Windows Domain suddenly stopped working.

He showed me a screen-shot of the error which I've replicated through Virtual Machines below. (Click for a bigger image)

The answer (if you know) is simple. You need to authorise your DHCP server in Active Directory. The reason for this step is to stop rogue DHCP servers appearing on the network. From the DHCP snap-in, simply select the server, right-click and authorise it.

After authorising, you will see Event ID 1044 appear in the system log of the DHCP server indicating that it is not :-) authorised to start and is now servicing clients. You do not need to restart the DHCP Server service.