XADM: Administrative Groups and Routing Groups

In Exchange Server 5.5 and earlier, the site defined the boundary for the administrative topology as well as for the routing topology. Real world scenarios differentiate distinctly between these two concepts. Therefore, in Exchange 2000 Server, the site has been split into two distinct concepts--the Administrative Group and the Routing Group.

An Administrative Group is a collection of Exchange objects that are grouped together for the purposes of permission management. The collection of Administrative Groups defines the administrative topology of an organization. An Administrative Group can contain zero or more policies, routing groups, public folder trees, monitors, servers, conferencing services, and chat networks.

A Routing Group is a collection of "well-connected" Exchange Server computers. Messages sent between any two servers within a Routing Group are routed directly from source to target. Full mesh, 24x7 connectivity is assumed. Any messages sent from a server in one Routing Group to a server in another Routing Group must be routed to a bridgehead in the source Routing Group and over to a bridgehead in the destination Routing Group.