Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool queries the Active Directory® directory service to determine the value of the dNSHostName attribute for all domain controllers in Active Directory. After retrieving the names of the domain controllers, the Exchange Server Analyzer opens a TCP socket connection to port 389 on each domain controller. This connection is made by using a custom object processor that returns a specific string if the connection is successful. If the Exchange Server Analyzer does not receive 389 Available as part of the returned string, a warning is displayed.

This warning indicates that the domain controller did not respond to a connection attempt on TCP port 389. TCP port 389 is the default port for Lightweight Directory Access Protocol (LDAP) communications.

If you are receiving this warning, it could be because of connectivity issues between the Exchange Server Analyzer and the domain controller. There are many reasons why LDAP requests may not be properly serviced by a domain controller when the Exchange Server Analyzer queries it.

To correct this warning

  1. Verify that the account running the tool is authorized to query the domain controller. You will need User level permissions in the domain where the domain controller is running. More information about permissions required to run the Exchange Server Analyzer can be found in the Help file included with the tool. Open the Help file by opening the Exchange Server Analyzer, clicking Help, and then clicking Microsoft Exchange Server Analyzer Tool Help.

  2. Verify that there are no firewalls or port restrictions between the computer running the Exchange Server Analyzer and the domain controller that failed to respond.

  3. Verify that the domain controller is connected to the network and functioning properly.

For more information about troubleshooting Active Directory connectivity issues, see the Microsoft Knowledge Base article 816103, "HOW TO: Use Portqry to Troubleshoot Active Directory Connectivity Issues" (

For more information about configuring Microsoft Windows® Time on domain controllers, see the Knowledge Base article 816042, " How to configure an authoritative time server in Windows Server 2003" (