I’m finally in the process of switching off the Compaq Evo D510SFF PC which acted as my main server for many years until it was replaced earlier this year with some more suitable hardware (a Dell PowerEdge 840). Even though the Dell Server has been running for the last ten months, I’ve not found the time to move over a few critical services and, as I write this, the files are being transferred to my new Netgear ReadyNAS and the last two VMs are being converted for use with Hyper-V.
There were a couple of infrastructure services to transfer too – DNS and DHCP. One of the DHCP services that I wanted to run in my new infrastructure is to provide IP addresses to computers that are deliberately on a different network to my Active Directory (devices like my iPhone, the Cisco IP Phone on my desk, and guest computers using my Wi-Fi connection) but the DHCP server in Windows Server 2003 R2 wouldn’t serve clients until it had been authorised by Active Directory. I didn’t want the DHCP server to even see AD (there is a firewall between them) but so I had to find a way to make Windows think that the server is authorised.
It turns out that this occurs if the DHCP Server service is running on a workgroup server and it sees a domain-joined DHCP server on the network (for a few days during the transition, my clients could see the legacy, domain-joined, DHCP server and the new, workgroup-only, one on the same network). The answer is to create a new registry value to disable rogue detection:
Windows Registry Editor Version 5.00
After restarting the DHCP Server service, my DHCP server sprang into life and started servicing clients.