What type of server is responsible for managing Active Directory?

A domain controller is specifically designed to manage Active Directory (AD) services, which are essential for a Windows Server environment. It authenticates and authorizes all users and computers within the domain, enforces security policies, and provides information about the domain to the network. This includes handling user logins, password management, and group policies that dictate security settings and access controls.

In contrast, file servers primarily store and manage files, web servers host websites and serve content over the internet, while application servers provide a platform for running applications. None of these servers have the capability or purpose to manage the critical functions of Active Directory as a domain controller does. The unique role of a domain controller in maintaining and safeguarding directory information is what makes it the correct answer to the question.