Summary

The better you understand how the system works, the better you ‚ ll be able to plan a viable network and troubleshoot that network when problems occur. This chapter examined three basic aspects of Exchange Server 2003 architecture: how Exchange is integrated with Active Directory, how information is stored on an Exchange server, and how messages flow within an Exchange organization.

At the top of the Active Directory hierarchy is the domain forest, which represents the outside boundary that any Exchange organization can reach. A domain tree is a hierarchical arrangement of domains that share a common namespace. The first domain in a tree is called the root domain. Domains added under this are called child domains. Within the domain tree, domains establish trust relationships with one another that allow objects in a trusted domain to access resources in a trusting domain. A domain is a group of computers and other resources that are part of a network and share a common directory database. Each domain contains at least one domain controller. Multiple domain controllers per domain can be used for load balancing and fault tolerance.

When Exchange is installed, many objects, such as users, are enhanced with Exchange- related features. A global catalog is used to hold information about all of the objects in a forest. Objects can be grouped into containers called organizational units that allow administrators to effectively manage large groups of similar objects at the same time.

In Exchange Server 2003, the Information Store is responsible for data storage and management. It supports access through numerous Internet and application programming protocols. This Information Store is also referred to as the Web Store, a nod to its support for web-based protocols and access.

SMTP is the native transport protocol in Exchange Server 2003, and it ‚ s used to route messages within and between routing groups. Internet Information Services (IIS) handles the SMTP protocol and transfers information with Exchange via the ExIPC service.

Multiple servers in an Exchange Server 2003 organization are grouped in routing groups. Servers within a routing group must share full-time reliable connectivity. Different routing groups are linked to one another using one of three types of connectors: the Routing Group Connector, which is the easiest to set up; the SMTP connector, which can be fine- tuned a bit more than the Routing Group Connector; and the X.400 Connector, which is used for very low-bandwidth connections.