Hey everyone! I'm in the process of swapping out one of our Domain Controllers, specifically **DC02-16** (Windows Server 2016) with a new server, **DC02-25** (Windows Server 2025). The new DC is set up and running DNS and DHCP, but I'm having issues with automatic DHCP failover replication to **DC01-16** (also Windows Server 2016). My plan is to reassign the old IP address (192.168.100.60) to the new DC since many clients still point to that address. Before I switch the IP, I need to know if there's anything specific I should watch out for, like clearing DNS caches, best practices for reusing an IP, or any special considerations regarding DHCP failover and replication. I'd appreciate any insights you all might have! Thanks!
2 Answers
Your plan sounds solid! Generally, I'd advise against running DHCP on a DC, but if you must, just ensure you follow the right procedures. I recommend using a temporary IP for a brief time during the switch. Reassign the old server to a temporary IP, check that DNS updates across all servers (give it around 30 minutes for replication), and once confirmed, you can safely give your new DC the old IP. I've done these swaps before with success!
Why is it a problem to run DHCP on DCs? For smaller setups, like ours with under 150 devices, it seems unnecessary to complicate things just to save a few bucks.
You can definitely reuse the IP without issues! Keep in mind that DHCP configurations don't replicate automatically, so you'll have to configure failover settings for both the old and new DC manually. DHCP and AD replication are independent, so this shouldn't be a big roadblock.
Exactly! Just remember to double-check any policies that might interfere with LDAP queries after the switch.
I’m also hearing some concerns about Windows Server 2025 as a DC. I’d stick with 2022 for now unless you have a specific need for the new features.
It's not a huge deal if you’re cautious. It can save costs on licenses, although if the DHCP load is high, you might want to reconsider.