I just attempted to migrate the DHCP service from a 2008r2 server on vlan1 to a 2012r2 server on vlan20. We had the dhcp helpers assigned on the core switch, firewall dhcp relays setup for the any vlans that required it. After the move, the devices on vlan1 could not get an IP address, so same vlan as the old server. All other vlans were able to retrieve addresses from the new server.
My migration process used powershell commands to backup DHCP including leases from the old server and imported them on the new server. Once the new server finished the import I deauthorized the server on vlan1 and authorized the new server on vlan20. The old server remained on as it is still used for other Server Roles.
- When the devices on vlan1 failed to retrieve addresses, I also disabled DHCP Server in services.msc.
- I could ping the servers from either vlan.
My WAN person asked, "Did you shut off DHCP on the old one completely? It's on the VLAN and everything will look locally first b4 going through the Relay". Shouldn't the deauthorize and or stopping the service be enough or would there be more to do?
Any ideas what went wrong?
--Edit/Update--
While the relays were setup correctly, and the migration process used was correct, if I recall correctly there was a Global Relay setting that was preventing the vlan 1 from finding the relay on the new vlan. Thanks for the input.
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