
However, this method is not convenient if there are a lot of computers and in some time unwanted people may stay the members of the privileged group. The easiest way to grant local admin privileges on a computer is to add a user or group to the local security group Administrators using the Local users and groups snap-in ( lusrmgr.msc). When you joining a computer to an AD domain, the Domain Admins group is automatically added to the local Administrators group, and the Domain User group is added to the local Users group.

Local Administrators Group in Active Directory Domain
