Active Directory

Exchange 2003, like its predecessor, relies heavily on Active Directory for its directory services and extends the Active Directory schema to include a number of Exchange-specific attributes and classes. It would take a chapter in itself to go through all the schema changes made between versions, but the majority of changes were made to support new features or functionality that were introduced with this release.

If you would like to see a list of the exact schema changes that were made to Active Directory, go to the Exchange Server CD. In the i386 folder, you will find a number of .LDF files, named schema0.ldf to schema9.ldf.

MANUAL SCHEMA CHANGES

Any manual schema changes that you made to the Exchange schema within Active Directory in Exchange 2000 disappear when you upgrade to Exchange 2003. You must reapply those manual changes after the upgrade is complete.

Aside from schema changes, the way that Exchange works with Active Directory remains largely unchanged in Exchange 2003. Some of the same planning considerations from the previous versions of Exchange also apply here.

To start, the best practice is to have your Active Directory planned and configured before you attempt to install Exchange 2003 in your organization. Doing so alleviates any conflicts between what is an Active Directory issue and what is an Exchange-related issue.

As in the previous version, you need to run the ForestPrep utility to prepare your Active Directory and extend the schema (which is covered in detail in the next chapter). Also, note that there is still a one-to-one relationship between your Active Directory forests and any Exchange organizations you might create. (A forest can have only one Exchange organization, and an Exchange organization can span only one forest.)

MULTIPLE FORESTS

If your organization has multiple forests, you might want to consider implementing your Exchange organization in its own forest and enabling a trust between the two forests. This raises a number of other issues with duplicate objects, rights, and so on, but it's the only solution for companies that are running multiple forests and want to access the same Exchange organization.

SCHEMA UPDATES IN WINDOWS 2000 DOMAINS

In any Windows 2000 domain or any Windows 2003 forest that is running in anything except a Windows 2003 functional level, schema updates require that all global catalog servers dump their database and rebuild it anew. Global catalog servers play an essential role both in the logon process for users and in address book access for Exchange users. Therefore, be sure to plan your ForestPrep operation for a suitable time.

Other than the issues mentioned in this section, Active Directory integration and administration tasks from Exchange 2000 are still relevant to this version of Exchange.

ACTIVE DIRECTORY PLANNING

For a detailed look at planning your Active Directory implementation on Windows 2000 or Windows 2003, check out the Exchange Web site at http://www.microsoft.com/exchange/ for the latest white papers.