To add a new computer to a domain, you must specify the domain you want to join. The adjoin program then locates an appropriate domain controller for the domain you specify and connects to Active Directory through that domain controller. By default, the domain controller to contact is determined by the Active Directory site topology. If the nearest domain controller in the site is not available, the agent attempts to connect to the next closest domain controller in the site. If no domain controller can be contacted or the connection takes too long to complete, the join operation fails.
If you don’t want to agent to select a domain controller based on the site topology, you can specify a master domain controller on a zone-by-zone basis. If you specify a master domain controller, the agent will connect to the appropriate domain controller based on the zone you are joining.