HOW TO: Change the LDAP Port for Exchange Server 5.5 in Exchange Server 5.5

This step-by-step article describes how to change the Lightweight Directory Access Protocol (LDAP) port number for the Exchange directory service when you upgrade primary domain controllers (PDCs) or backup domain controllers (BDCs) that run Exchange Server 5.5.

Change the LDAP Port for Exchange Server

1.	In the Microsoft Exchange program group, start Microsoft Exchange Administrator.
2.	Connect to the server. If necessary, click Connect to Server on the File menu to display the Connect to Server dialog box, type the server name, and then click OK.
3.	Expand Site, expand Configuration, and then click Protocols.
4.	Double-click LDAP (Directory) Site Defaults. On the General tab, change the port number to 390, and then click OK to configure the Exchange directory service to use TCP port 390.
5.	Close Microsoft Exchange Administrator, and then restart the computer.

Troubleshooting

Both the legacy Exchange directory service and Active Directory support LDAP. On an Active Directory domain controller, Active Directory starts automatically and locks TCP port 389 for its own use. When Exchange Server starts, Exchange Server cannot use the same port and cannot communicate by using LDAP until you change the LDAP port for the Exchange directory service to a port other than 389.

Note that Microsoft recommends that you change the LDAP port for the Exchange directory service before you upgrade to Windows 2000 and Active Directory.