Overview of operating system and Active Directory requirements for Exchange Server 2003

This article discusses some considerations that apply when you install Microsoft Exchange Server 2003. It contains information about operating system requirements and Microsoft Active Directory directory service requirements for Exchange Server 2003.

You can run Exchange Server 2003 on the following operating systems:

• Microsoft Windows Server 2003
• Microsoft Windows 2000 Server Service Pack 3 (SP3) and later

Exchange Server 2003 is supported in the following Active Directory environments:

• Windows 2000 mixed mode domains
• Windows 2000 native mode domains
• Mixed Windows 2000 and Windows Server 2003 domains
• Windows Server 2003 native mode domains
• Windows Server 2003 interim mode domains

Domain controllers and global catalog servers must be running either Windows Server 2003 or Windows 2000 Server SP3. Exchange Server 2003 is optimized to run on Windows Server 2003 and several new features in Exchange Server 2003 require Windows Server 2003. When you use Exchange Server 2003 in an environment where all domain controllers are running Windows Server 2003, you can use the new features and the new functionalities that are included in Exchange Server 2003.

You can run Exchange Server 2003 on either a member server or on a domain controller. After you install Exchange Server 2003 on a server, do not change the role of the server. For example, if you install Exchange Server 2003 on a member server, do not use the Dcpromo tool to promote the server to a domain controller. Or, if you install Exchange Server 2003 on a domain controller, do not use the Dcpromo tool to demote the server to a member server. Changing the role of a server after you install Exchange Server 2003 may result in loss of some Exchange functionality and is not supported.

Although Exchange 2000 Server Service Pack 2 (SP2) or later is supported in an environment with Windows Server 2003 domain controllers and global catalog servers, Exchange Server 2003 is the first version of Exchange that is supported on computers that are running Windows Server 2003. Exchange 2000 is not supported on Windows Server 2003. In a situation where you run Exchange 2000 on a Windows 2000-based computer, and you want to upgrade the operating system to Windows Server 2003, you must first upgrade Exchange 2000 to Exchange Server 2003, and then upgrade Windows 2000 to Windows Server 2003.

Exchange Server 2003 can coexist with Exchange 2000. When Exchange Server 2003 is running in Exchange mixed mode, it can coexist with Exchange Server 5.5. You can perform an in-place upgrade from Exchange 2000 to Exchange Server 2003; however, an in-place upgrade from Exchange Server 5.5 to Exchange Server 2003 is not supported. For more information about Exchange Server compatibility with Windows Server operating systems, see the "Microsoft Exchange Server Compatibility with Microsoft Windows Server Operating Systems" White Paper. To view this white paper, visit the following Microsoft Web site:For more information about system requirements for Exchange Server 2003, visit the following Microsoft Web site: For more information about Exchange Server 2003, visit the following Microsoft Web site: