XADM: ADC Replication Is Not Successful and an Event 8026 Message Is Logged

Objects from Microsoft Exchange Server 5.5 may not be propagating to Active Directory, and the following error message may be logged in Windows NT Event Viewer:

This issue can occur if the Active Directory Connector (ADC) cannot bind to the Lightweight Directory Access Protocol (LDAP) port of the Exchange Server 5.5 computer. The ADC cannot bind to the LDAP port if the port number is not correctly configured in the Connection Agreement or if there are network issues that prevent communication between the computer that is running the ADC and the Exchange Server 5.5 computer.

To resolve this issue, verify that the Exchange Server 5.5 computer is listening on port 389 (LDAP communications occur on port 389 by default):

1. On the computer that is running the ADC, click Start, and then click Run.
2. Type the following command:
   telnet (servername or IP address) 389

If LDAP is configured on port 389, when you run this command, a Telnet window opens, but you do not see a banner response. If LDAP is not configured on port 389, you receive the following message: If you cannot connect to port 389 of the Exchange Server 5.5 computer by using Telnet, use the Microsoft Exchange Server Administrator program to check the configuration:

1. Start the Administrator program.
2. Click to expand the Site container, and then click to expand the Configuration container.
3. Click Protocols, and then double-click LDAP.
4. Click the General tab, and then verify that the port number is set to 389.
5. Compare this setting to the configuration of the Connection Agreement in the ADC. These settings must match.

For additional information about scenarios where a port other than 389 is used, click the article number below to view the article in the Microsoft Knowledge Base: For additional information about how to troubleshoot ADC issues, click the article number below to view the article in the Microsoft Knowledge Base: