Which statement best describes the role of domain controllers in Active Directory Domain Services?

• A. They store directory data and provide authentication for users and computers within the domain.
• B. They act as file servers for user data only.
• C. They configure network routing between VLANs.
• D. They are used only for DNS hosting.

Answer: (A)

Domain controllers are the servers that host the Active Directory Domain Services database and handle the core security functions for the domain. They store the directory data—the objects such as users, groups, computers, and policies—and they process authentication and authorization requests. When someone tries to log in or access a resource, the domain controller verifies credentials (for example, via Kerberos) and issues the appropriate access tokens, enforcing policies and permissions across the domain. It’s this combination of data storage and credential verification for domain members that defines their role.

Other statements miss the mark because domain controllers are not just file servers for user data, they don’t route network traffic between VLANs, and they aren’t used only for DNS hosting (though they often host DNS as part of AD DS).