If you have 2 Active Directory Servers that are not replicating, Server1 & Server2, try the following:

check if the secure channel has been corrupted

From Server1, go to Start -> Run and type: \\Server2
From Server2, go to Start -> Run and type: \\Server1

If you get and error message indicating that the target name is incorrect, then the the secure channel has been corrupted.

You will also see error messages in replmon and “repadmin debug” indicating that the target is invalid as well.

Perform the following steps to fix the problem:

Stop the Kerberos Key Distribution Center (KDC) service, and then set it to Manual startup.
Run the following command:

netdom resetpwd /server:<replication_partner_name> /userd:<domain\admin_user> /passwordd:*

Restart the computer, start the KDC, and then set it back to Automatic startup.

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