Planning Namespace
Before you set up your Exchange organization, one of the most important areas that needs to be planned is your internal (organization-facing) and external (Internet-facing) namespace. A namespace is a logical structure commonly represented by one or more domain names in DNS.
Namespace planning is most important for the Client Access Server role. However, many considerations are also needed for the Hub Transport and Edge Transport roles. This section should provide the general basis for understanding the importance for namespace planning. The topics are also discussed in Chapter 4, Chapter 5; and Chapter 7.
During migration or transitions you also might need to consider special namespace requirements. These are addressed in Chapter 14 ...