Final answer:
Domain controllers are computers that hold the directory containing information about objects in a domain, authenticate users, enforce security policies, and manage access to network resources.
Step-by-step explanation:
The directory containing information about objects in a domain resides on the computers called domain controllers.
Domain controllers are servers that authenticate users, enforce security policies, and manage access to network resources within a Windows domain.
For example, in a Windows Active Directory domain, the domain controller holds the directory database, which includes information about user accounts, group memberships, and security policies.