Active Directory serves as a central directory server (LDAP v2/v3, DNS, Kerberos) for storing application settings, user profiles, and group data. It is responsible for authenticating and authorizing all users and computers within a network of Windows domain type, assigning and enforcing security policies for all computers in a network and installing or updating software on network computers. Active Directory verifies users or machine login credential and allows different level of access to the systems as well as applies and enforces policies