Hey everyone! I hope you're all doing well. I'm in the middle of replacing one of our Domain Controllers, and I'd love some advice on it. Right now, we have two DCs: DC01-16 at 192.168.100.57 and DC02-16 at 192.168.100.60, both running Windows Server 2016. I'm about to switch out DC02-16 for a new server, DC02-25, running Windows Server 2025 and located at 192.168.100.77. This new DC is already promoted and handles DNS and DHCP. Everything seems to be functioning (AD replication, DNS, etc.) except for the DHCP automatic failover replication to DC01-16. My plan is to reassign the old IP address (192.168.100.60) to the new DC, since many clients still reference that. I have a few questions before I make this switch: 1) Should I clear DNS caches or old A records on either DC? 2) Any best practices to avoid issues when reusing an old IP? 3) Is there anything I should be aware of regarding DHCP failover or replication that could cause issues? Any insights would be really appreciated! Thanks in advance!
1 Answer
Your plan sounds solid, but I personally wouldn't recommend running DHCP on a Domain Controller. If you do go ahead with it, just make sure to temporarily assign a different IP to the old server during the transition. Give DNS time to update—about 30 minutes should do—and check the records across all servers. After that's settled, you can assign the old IP to the new DC. I've been through this process many times and it works well!
But isn't DHCP on a DC okay for smaller networks? We have under 150 devices and it seems unnecessary to run a separate machine for DHCP.
Totally agree! It's not a huge deal but can save on licensing costs unless you have insane DHCP traffic.