The Microsoft Exchange Server site topology is configured to reflect the connectivity between regions and sites within a region. It also reflects the distribution of support responsibilities at Microsoft. Microsoft has attempted to minimize the number of sites, while at the same time providing a way to manage bandwidth consumption over dedicated links and enabling regional support of the system. Microsoft has a highly centralized administrative model, which dictates certain choices with regard to management of the system. Planning for sites requires that the number of users and resultant server demands be determined.
Sites provide for greater control over message routing and directory synchronization.
Naming Conventions Naming conventions are another important consideration. There is no way to change an enterprise name, domain name, site name, or server name without rebuilding servers. Likewise, be sure to consider user login IDs. If your messaging system is tied to human resource or other internal systems, you must recognize the limitations imposed by the existing systems and adapt your model to reflect these. Site and server names should reflect generally static information that is not likely to change over time.