Sharing Directory Information

Each site server stores a copy of the directory that is virtually identical to all other copies of the directory in the organization. Changes made to one copy of the directory are periodically propagated to all other copies of the directory on all other servers. This process is known as directory replication.

This means that, subject to a small latency period for the replication process, every Microsoft Exchange Server directory within an organization has the same directory objects. Furthermore, any object in the directory information tree (DIT) has the same distinguished name within all copies of the directory throughout the organization.

Administrators and applications frequently add, delete, and modify directory objects. In some cases, applications track the changes made to directory objects. For example, a service may keep track of which recipients have been added to a site, or which have recently been modified.

Tracking changes to directory objects can be done using two attributes, each of which are defined on all objects:

• Update sequence number
• Object version number

Directory replication within a Microsoft Exchange Server system is automatic. Microsoft Exchange Server also has the capability of sharing this information with other systems. This capability allows the directory address book to be synchronized with other sites and other organizations running Microsoft Exchange Server, as well as with systems that use other messaging and storage technologies.

The following sections describe the transfer of directory information between a Microsoft Exchange Server system and a foreign system. They also include a brief overview of the different methods you can use to transfer directory information, when each method is appropriate, and where to find further information.