Servers running Exchange 2000 rely on information stored in Active Directory to function properly.
If you experience problems with the domain controllers in the Windows 2000 domain to which your Exchange server belongs, you must repair those domain controllers immediately. If these problems occur, you may experience minor complications with your servers running Exchange 2000, or your servers may cease functioning altogether.

To secure the availability of the domain controllers in your Exchange 2000 organization, ensure that you have more than one domain controller in your organization. As a result, if a single domain controller fails, the replicated Active Directory information is still available within the remaining domain controllers.

• For more information about domain controller availability, see "Domain Controller Availability".
• For information about how to back up a domain controller, see "Backing up Domain Controllers".
• For detailed information about how to recover a Windows 2000 domain controller and the Active Directory information contained therein, see the technical paper Active Directory Disaster Recovery (http://go.microsoft.com/fwlink/?LinkId=6270).
• For more information about recovering the servers in your organization, see Chapter 3, "System Recovery," of the Microsoft Windows 2000 Operations Guide in Microsoft Windows 2000 Server Resource Kit.

The information in this article applies to:

• Microsoft Exchange Server 2003 Enterprise Edition
• Microsoft Exchange Server 2003 Standard Edition
• Microsoft Windows Small Business Server 2003, Premium Edition
• Microsoft Windows Small Business Server 2003, Standard Edition
• Microsoft Exchange 2000 Server