Any design involves applying available features with adequate safeguards for failures. When laying out sites for your organization, keep the following guidelines in mind:
Minimize convergence time without swamping WAN links.
Localize client access to domain controllers for authentication and Active Directory services. This includes Global Catalog queries.
Prepare for possible failure of bridgehead servers.
Prepare for possible loss of WAN links.
Ensure that all naming contexts have a replication path through each site.
The site plan depends on the network infrastructure. Begin with an evaluation of that infrastructure. Figure 7.8 shows a typical WAN layout for a medium-sized organization. The company has four offices ...