Remotely configuring new DC-VM to replace existing physical DC

[HCHTech]

Small client - 12 workstations with existing Server 2012 R2 box (DC) and newer HyperV host (Server 2016) with an existing App Server VM. I'm going to be replacing the physical DC with a new DC VM. Client was a DIY guy before we got him so we're taking this opportunity to fix some bad practices. There will be a new domain name, and we're not trying to migrate from the old DC at all, I'm just going to create the AD users for the new DC manually.

So - I'm trying to do this all remotely until we get to the bit where we need to unjoin the workstations from the old DC and join them to the new. Finally, my question: As long as I don't add DHCP to the new DC-VM, can I do the rest of the configuration while the old DC is still active on the network? I think the answer is yes, but I'm wondering if there are any gotchas I haven't thought of since I've never done it this way before - (remotely, and with the old DC still alive on the network).

 

[Sky-Knight]

You can add DHCP too, just don't authorize it.

DNS is going to be your largest headache, because if you want things to be smooth you'll want both DC's supporting DNS to be available on the workstation in advance, which means getting both to support both domains.

But with only 12 machines, it's probably easier to just turn off DHCP on one server, and turn it on on the other and reboot all the workstations. Hopefully you have an RMM agent on all of them, because the Windows firewall on those units is going to go bonkers on you before it settles into the new domain profile.

 

[YeOldeStonecat]

No worries...just be aware of DHCP running on one, not on the other..and plan the flip. One tip...peel back the lease time to something crazy short on the old server...so clients ARP pretty quick and will pick up the new DHCP lease soon. Kinda like when doing DNS changes....if you want it to go quicker, dial down the TTL on DNS. Same with DHCP for the cutover...dial down the lease time well ahead of time.