Microsoft KB Archive/250989

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XADM: Installing the ADC on a Windows 2000 Domain Controller That Also Runs Exchange Server

Article ID: 250989

Article Last Modified on 1/27/2007


  • Microsoft Exchange Server 5.5 Standard Edition
  • Microsoft Windows 2000 Standard Edition

This article was previously published under Q250989


When you are setting up a new connection agreement for the Active Directory Connector (ADC) on a Windows 2000 domain controller (DC) that is also running Exchange Server 5.5, you may receive the following error message:

The Microsoft Exchange specified on the Connections page is invalid. Enter a valid server name.

ID no c1031b9e
Microsoft Active Directory Connector Management.


Lightweight Directory Access Protocol (LDAP) is the protocol used by the ADC to communicate with Exchange Server. By default, the ADC tries to communicate with the Exchange Server directory by means of port 389 (the default LDAP port in Exchange Server). On a domain controller, Active Directory locks up port 389 as it starts, and the ADC cannot set up the connection agreement.


  1. Start the Microsoft Exchange Server Administrator program.
  2. To change the LDAP port for all servers within the site, make the following changes:
    1. Click to expand Site, click to expand Configuration, click to expand Protocols, and then click to expand the LDAP (Directory) Site Defaults object.
    2. Change the port assignment from 389 to a port that is not currently in use. You can gather the status of the TCP ports by typing the following command at the command prompt:

      netstat -a

      This command displays all active ports that are listening on all interfaces. Choose a port number that is not currently in use; 390 is commonly available.
    3. Stop and restart the Exchange Server directory.


This behavior is by design.


For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

224447 XADM: How To Change LDAP Port Assignments in Exchange Server

Additional query words: win2k

Keywords: kbprb KB250989