Active Directory Service (ADS) is based on the Lightweight Directory Access Protocol (LDAP), works with the Domain Name System (DNS) for address storage and Kerberos for authentication. The DNS database stores information about network services and the mapping of the complete domain address, the Fully Qualified Domain Name (FQDN), to IP addresses. In the Active Directory (AD) all relevant data ofusers, computers, resources, networks, peripheral devices etc. are stored.
The domain forms the basic unit of the Active Directory. In it, the resources and the users are grouped together. The domains are hierarchically structured in a tree structure, the so-called ADS tree, so that all network resources are visible to all domains included in the ADS tree. When two or more ADS trees are joined together, it is called a forest. In ADS services, an Organizational Unit (OU) forms an object for managing resources. This allows the network administrator to manage Windows clients, print servers, file servers or application servers and to use the AD services without having to operate his own domain controller.