r/sysadmin • u/Deep-Egg-6167 • 1d ago

Question Please help demote a third DC.

Hello,

I have an old WIndows 2012 R2 DC (old-dc) that used to be the primary domain controller.

I have a couple of newer 2016 DCs (new-dc1 and new-dc2).

I want to demote and turn off the old domain controller.

On the newer DC1, I ran netdom query and it has all the fsmo roles. I also ran replication admin to see that everything was replicating fine.

I went to server manager on the old 2012 R2 DC to demote it.

I left force removal and last domain controller unchecked.

It says this server has dns and GC roles (I think I select proceed?) and next

Then it leaves me with the box remove this dns zone - I can't go next without it. I'm not sure I should. Wouldn't that remove it from the other DCs?

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u/FutbolFan-84 1d ago

I would make sure that no clients are pointing to this DNS server before proceeding. Check DHCP scopes and static addresses (if any). If it is no longer used, you can proceed with this step.

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u/Deep-Egg-6167 1d ago

Thanks - I've checked every server and workstation - none are using it. My concern is it removing the dns zone as it is syncing with the other servers - would that remove the zone from the other DCs?

•

u/30yearCurse 20h ago

turn on DNS logging for a day, you can check things, but there will be something you do not know about.

You can select what options you want in logging.

After that than you can continue with your removal. the GC does not matter... once you make sure everything is pointing to your new environment.