Resource domains consist of servers that provide file and print services, PCs, and application servers. As additional physical locations and network services are added to the environment new resource domains can be added as needed. This model requires far fewer trust relationships than the full trust model. The master domain model also helps separate user account management from resource management. This allows individual departments to manage their resource domain locally while the user accounts and logon security policies are managed centrally.
Domains can span multiple subnets or geographies.
This allows domain controllers to be placed fairly co-local to all users. For example, if a company had sites in both Boston and Worcester, backup domain controllers from the master domain can be placed in each city. This is a good idea, since logon validation can be time consuming over slow network connections and would be impossible if a wide area link were off-line. Each city could have one or more resource domains which would be managed locally. Users in Boston could be granted access to resources in Worcester.