In Active Directory, a domain controller contains which of the following?

• A. A RADIUS authentication server program
• B. An Active Directory database
• C. Both A and B
• D. Neither A nor B

Answer: (B)

The key idea is that a domain controller stores the Active Directory database, which holds all directory data such as users, groups, computers, and the domain’s configuration and schema information. This database (NTDS.DIT) is what authentication and authorization rely on within the domain. A RADIUS server is not part of the Active Directory database by default; it’s a separate service (like Network Policy Server) that can be installed on Windows Server if needed, but it isn’t inherently included in a domain controller. So the domain controller’s essential content is the Active Directory database, not a built-in RADIUS server.