типа поднимать/опускать контролеры и обмениваться ролями НТ4 с годами разучилась ?

Anatoly PodgoretskyК сожалению роль для НТ4 задается при установки, ни повысить ни понизить стандартными методами потом нельзя. Единственный путь документированый МС это переинсталяция.
беда прям ...
M$ TechNetPromoting a BDC to PDC Status

When you modify a user's account, the change is written to the master SAM on the PDC and then is replicated to the BDCs within the domain. If the PDC is rebooted during the time that password is being changed, the change does not take place. Only a PDC can accept changes to the SAM database. If no PDC is available, changes are not accepted. This is why it's important to promote a BDC to take over for the PDC when the PDC fails or is unavailable; otherwise, the SAM database becomes static and no changes are possible.

Use Server Manager to promote and demote domain controllers. Member servers cannot become domain controllers, just as domain controllers cannot become member servers. To switch from member server to domain controller or vice versa, you must reinstall Windows NT.

You can perform the following steps to promote a BDC to a PDC:

1. Notify users that the PDC will be shut down.

2. On the PDC, open the Control Panel and then the Services applet.

3. Stop the Server service. This prevents new user logons while the change is taking place.

4. On a domain controller, open Server Manager.

5. Select Properties from the Users menu and click the Computer button.

6. Click the Disconnect All button to disconnect all users.

7. Select the BDC to be promoted.

8. Select Promote To Primary Domain Controller from the Computer menu.

9. Restart the Server service on the PDC.


Promoting a BDC

A PDC that is online when a BDC gets promoted will automatically be demoted to a BDC.

Demoting a PDC to BDC Status

If you need to demote a PDC manually and the preceding procedure won't work (possibly due to hardware or Registry-related failure), try the following approach to perform a PDC demotion:

1. Notify the users that the PDC will be shut down.

2. On the PDC, open the Control Panel and then the Services applet.

3. Stop the Server service. This prevents new user logons while the change is underway.

4. Open Server Manager.

5. Select Properties from the Users menu and click the Computer button.

6. Click the Disconnect All button to disconnect all users.

7. Select the PDC.

8. Select Demote To Backup Domain Controller from the Computer menu.

9. Restart the Server service on the former PDC.

иначе говоря переустанавливать канешна придёцца, но последовательность действий нуно правильно спланировать ... приведённая цитата автору в помощь ...

Anatoly PodgoretskyПроблема то не в том, что PDC <--> BDC, это действительно занимает мало времени, а о PDC <--> Server, вот это на НТ не поддержано, можно только PDC/BDC в Standalone Server, а не наоборот. Правда точно не помню, можно ли вообще. При желании могу взглянуть в документацию.
MS TechNoteMember servers cannot become domain controllers, just as domain controllers cannot become member servers. To switch from member server to domain controller or vice versa, you must reinstall Windows NT.