VOGONS

Demote NT4 PDC to BDC

Topic actions

First post, by Gopher666

Posted on 
User metadata
Rank Member
Rank
Member

I wonder if anybody ever managed to do this successfully of so please write it down how. There is no official solution for it, you could PROMOTE a BDC to PDC in NT4 domain but not vice versa.
Why bother with it? To save couple of hours work. I installed an NT4 PDC all service packs, option pack, resource kit, internet explorer 5, regular tools etc so I would just clone it to another CF card rename it, change the ip, remove it from the domain and rejoin it. Even tho this by itself might not change the PDC role.

Here is what the AI smarty says:

CORRECTED DEMOTION STEPS:
Step 1: Stop Services and Remove NETLOGON
batch
REM Stop Netlogon (stops DC authentication)
net stop netlogon /y

REM Remove NETLOGON share if it exists
net share | find "NETLOGON" && net share NETLOGON /delete

REM Rename Repl folder (since Export/Import are empty anyway)
if exist C:\Winnt\System32\Repl rename C:\Winnt\System32\Repl Repl.old
Step 2: Leave Domain
batch
Control Panel → Network → Identification
Change: Domain MYRETRO → Workgroup TEMP
Reboot
Step 3: Change ProductType
After reboot (in workgroup):

batch
regedt32
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ProductOptions
Change: LanmanNT → WinNT

This is the point when his theory fails, NT does not allow changing this value saying it violates the product blah blah.

Reboot
Step 4: Rejoin as Member Server
After reboot:

Network → Identification

Join domain MYRETRO (as member server)

Use PDC admin credentials

Reply 1 of 2, by Disruptor

Posted on 
User metadata
Rank Oldbie
Rank
Oldbie
Gopher666 wrote on 2026-01-26, 20:01:

I wonder if anybody ever managed to do this successfully of so please write it down how. There is no official solution for it, you could PROMOTE a BDC to PDC in NT4 domain but not vice versa.

Whenever you promote a BDC (backup domain controller) to a PDC (primary domain controller) in a pre-AD (active directory) system the old PDC will be demoted to BDC.
The only exception will be when your PDC is no longer working. Then you can promote any BDC to your new PDC.
If you want to reintegrate that former and now defunct PDC into your domain you have to remove it from the domain, convert it to a single server and then rejoin the domain.

However, you need ONE PDC for that what you want to do.

Reply 2 of 2, by Gopher666

Posted on 
User metadata
Rank Member
Rank
Member

Well it might be easier just to reinstall it from the get go, for that pdc dance I would need another bdc installed already. Yeah there is aint no problem with removing it from the domain, it just seems like it does not want to give up with its own pdc role even then plus it might complicates things that since it's a clone there are sids and other ids in the registry which are identical.

Go to top of page Go to top of page
Back to Software
Close window
Close window