Chapter Summary

You must deploy Windows 2000 and Active Directory if you are planning to install Exchange 2000 Server. Because Exchange 2000 Server must use the Site Services account for its communication with previous versions, you must first upgrade the PDC of the domain in which the Exchange Site Services account exists. If you are planning to directly upgrade an existing Exchange Server 5.5 system, you need to upgrade its operating system as well, and possibly change the TCP port number for the LDAP interface of the Exchange directory service.

By upgrading the PDC, you migrate Windows NT user accounts to Active Directory. The corresponding mailbox information, however, still resides in the Exchange directory. Consequently, you need to synchronize both directories via a connection agreement to add the mailbox information to the user account objects.

Whether you join an existing site with a new Exchange 2000 server or perform an in-place upgrade, Exchange 2000 Server must replicate directory information with earlier versions of Exchange Server, which is handled by SRS. A configuration connection agreement transfers the directory information from the SRS database into Active Directory, where previous Exchange Server resources are displayed as transparent objects. In the Exchange Administrator program, Exchange 2000 servers appear similar to servers running previous versions of Exchange Server.

To switch an organization to native mode, all computers running previous Exchange Server versions must be upgraded or removed. Switching to native mode permanently disables interoperability with previous versions.