How to Re-Sync PDC/BDC Trust After Event IDs 3210 and 7023

After a Windows NT backup domain controller (BDC) has been offline for some time, it may fall out of synchronization with the primary domain controller (PDC). When you attempt to bring the BDC back online, you may get the following errors in the BDC's Event Viewer:



This is very likely to occur if a BDC is restored from a backup that is more than a few days old or if the BDC is offline for more than a few days.

Domain controllers maintain a password-protected channel between each other. When a BDC is brought into a domain, the PDC gives the BDC the current password to use when connecting to the PDC for authentication, account database replication, and other system activities. This password changes automatically on a regular basis. If the BDC is offline when the password changes, or if a BDC is restored from a backup that has an old password, the BDC will not be able to authenticate with the PDC, and Netlogon will fail.

In the simplest case, all that has happened is that the domain password has changed. To resolve the behavior, do the following:

1. Start the BDC, and open Server Manager
2. Select the BDC's name, and select Synchronize with Primary Domain Controller.

If this procedure is successful, you will get a message that the LSA Database has been updated and Netlogon will start automatically. No other action is necessary.

However, if synchronizing with the PDC does not work on the first attempt, try carrying out the same command again. Often, a second attempt will succeed. However, if the BDC will not synchronize and Netlogon fails to start after three attempts, you should create a new machine account for the BDC. These instructions are taken from a related article, 137987  (http://support.microsoft.com/kb/137987/EN-US/ ) :

1. Using Server Manager, create a new computer name.
2. Synchronize entire domain (check another BDC's event viewer to see if it synchronized).
3. At the problem BDC, use the Network tool in Control Panel to change the name to the new name created in Step 1.
4. Shut down the BDC, restart, and log on to Windows NT. Note any error messages. You must logon to the domain the BDC belongs to, not a trusted domain.
5. Using Server Manager, synchronize the entire domain.
6. From the PDC, delete the old computer name(use Server Manager).
7. Synchronize the entire domain, using Server Manager.
8. Make sure the old BDC name has been deleted in Server Manager before proceeding.
9. After the old BDC name is gone from Server Manager, re-create it.
10. Synchronize the entire domain, using Server Manager.
11. At the problem BDC, change computer name to the old name created in step 9, using the Network tool in Control Panel.
12. Shut down the BDC, restart, and log on to the domain. Note any error messages.
13. Synchronize entire domain.

At this point the BDC should be synchronized with the PDC, netlogon should be running, and the accounts database should be up to date.

Related Articles:

For additional information on authentication issues specific to NWLink, please see the following article in the Microsoft Knowledge Base:

126752  (http://support.microsoft.com/kb/126752/EN-US/ ) DCs Fail to Synchronize or Validate Users Over NWLINK

For additional information on authentication issues when trying to net view, please see the following article in the Microsoft Knowledge Base:

137987  (http://support.microsoft.com/kb/137987/EN-US/ ) NET VIEW May Cause Semaphore Time Out and Event ID 3210

For additional information on authentication from the PDC's point of view, please see the following article in the Microsoft Knowledge Base:

142869  (http://support.microsoft.com/kb/142869/EN-US/ ) Event ID 3210 & 3722 Appear When Synchronizing Entire Domain