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The Directory Service (DS) has been replaced with Active Directory (AD). AD is the Windows 2000 directory service and the directory service for Exchange 2000. It extends the features of previous Windows-based directory services (including the directory service for Exchange 5.5) and adds entirely new features. AD is designed to work well in any size installation, from a single server with a few hundred objects to thousands of servers and millions of objects. Many new directory service features are provided that make it easy to traverse and manage a high volume of information, saving time for both administrators and knowledge workers.

The Global Address List (GAL) is now provided by the AD's Global Catalog (GC). From the local domain, objects are read-write enabled. From the AD forest, partial objects are available as read-only. The GC server holds a replica of the domain-naming context in which the server is installed, and a partial replica of all other domains in the forest. This server knows about every object in the forest and has representations for these objects in its directory. The GC server might not know about all the attributes for objects in other domains.

Exchange 2000 extends the AD schema with about 1,000 object classes. The schema extensions can be applied ahead of the installation of Exchange by running FORESTPREP. Running FORESTPREP prior to installing Exchange can save a great deal of time due to the fact that Exchange's extending of the schema is very time-consuming.

Schema—The metadata that describes how objects are used within a given structure. In relation to Exchange, this term may be used in the context of Active Directory, but it can also be used to describe the structure within the store or the MTA.

FORESTPREP—This is a switch used with setup.exe; its name is forest, forestprep. This switch is used to extend the AD schema prior to the installation of Exchange 2000.

An administrator can use the ADSIEDIT tool for version information to verify that replication has taken place. These modifications can be readily identified because they all start with the text ms-Exch. For example: ms-Exch-Admin-Role is one of the numerous extensions applied to the AD.

NOTE

You can find the schema changes in the setup\i386\exchange directory on the Exchange 2000 installation CD. Ten separate files containing the LDIF commands are used to load the Active Directory extensions. These files are named SCHEMAx.LDF, where x is equal to 0–9.

ADSIEDIT—Active Directory Services Interfaces Editor.

ADSIEDIT provides for the viewing and editing of the AD objects and schema, similar to REGEDIT in function and power. Caution must be exercised when using this tool.

LDIF—A file format used with LDAP. Can be used for bulk import and export from the Active Directory.

Installing the Exchange 2000 schema extensions is not a reversible action. The extensions will affect all the Domain Controllers (DCs) within the forest. It is a good idea to review these schema extensions with the administrators of the Active Directory. The Exchange 2000 extensions can conflict with custom AD extensions in the existing environment.

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