Your network contains an Active Directory Domain Services (AD DS) forest. The forest functional level is Windows Server 2012 R2. The forest contains the domains shown in the following table. Name Oper

The "Domain Admins" group in a specific domain (e.g., EAST\Domain Admins) has sufficient permissions to add new domain controllers to that domain, including performing schema updates if necessary, assuming the forest and domain functional levels support the new OS. This adheres to the principle of least privilege as it grants permissions only within the necessary domain.

"Enterprise Admins" is a forest-wide administrative group, providing more privileges than necessary for adding a DC to a specific domain, violating the principle of least privilege.

"Schema Admins" is required for updating the Active Directory schema, which might be implicitly handled by the Domain Admins group. However, explicitly adding Schema Admins is not the primary least privilege requirement just for adding a DC to a domain.

This option combines two highly privileged forest-wide groups, far exceeding the least privilege required to add a DC to a single domain.