3.1 The Organization

Some messaging systems come together as a loose federation of servers. In such an arrangement, servers do not necessarily know about the other servers and must connect through central routers, perhaps by reference to a directory. Other systems, such as Exchange, use a far tighter arrangement. Exchange organizes servers into a single hierarchy called the organization and then divides the organization into administrative groups, all of which exist at the same level within the hierarchy. The concept and overall structure of the organization has not changed much since Microsoft introduced it in Exchange 4.0, except that the major organizational subunit is now administrative groups rather than sites.

Because all configuration data is in a single AD container, there can only be one Exchange organization per AD forest. The administrative group is core to Exchange and provides the foundation for management through permissions and policies.

As explained in Chapter 2, the AD holds details of the Exchange organization in the Microsoft Exchange container in the configuration NC (Figure 3.1), which the AD replicates to every domain controller in the forest. Therefore, every domain controller contains knowledge of every Exchange server in the forest, including the routing topology that connects all the servers.

Figure 3.1: Contents of the Microsoft Exchange AD container.

You can have up to 1,000 Exchange servers in an organization. The limit is not hard coded as such but results from the fact that the default page size for results returned by the AD for...