How do I demote a PDC to a BDC?
January 8, 2000
A. Normally when you promote a BDC to the PDC, the existingPDC is automatically demoted to a BDC, but in the event that the PDC was takenoff line and then a BDC promoted when the old PDC is restarted it will stillthink its the PDC and when it detects another PDC it will simply stop its ownnetlogon service.
To actually modify the machine to be a BDC the registry needs to be changeddirectly:
Logon to the machine as an Administrator
Start the registry editor (regedt32.exe)
Move to HKEY_LOCAL_MACHINESecurity
Select Permissions from the Security menu
Select Administrators and change the access type to Full Control, check the"Replace Permission on Existing Subkeys" and click OK. Click Yes tothe confirmations dialog box
You can now navigate the Security menu, move down to PolicyPolSrvRo
Double click on the default value and change the seconddigit (which should be 3 for a PDC) to a 2 (which means BDC). Click OK. E.g.03000000 to 02000000.
You should now reset the Security on the Security part of the registryusing the same method as before but changing back to Special Access forAdministrators. The permissions for Administrators should be
- Write DAC
- Read ControlRestart the machine and it will come up as a BDC
To avoid having to set security perform the registry change from the systemaccount by submitting the registry editor via the schedule service.
C:> net start schedule (only if not already running)
C:> at /inter regedt32.exe
C:> net stop schedule (only if you had to start it)
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