Active Directory Domain Services

  • Active Directory Domain Services (ADDS) is a directory service from Microsoft which allows you to store objects. Objects are nothing but users, computers, printers, groups, OUs etc.
  • When ADDS is installed it creates its own database with the name NTDS.dit and is stored in C:WindowsNTDS folder.

Components of Active Directory

Components are divided into 2 parts viz, Logical and Physical

Logical Components

  • Domain
  • Tree
  • Forest
  • Organizational Unit

Physical Components

  • Domain Controller
  • Site
  • Global Catalog


  • A domain is a logical representation of network. 
  • Domain is denoted by triangle symbol


  • A tree is a hierarchical structure of one or more domains
  • It follows a parent-child relationship.
  • The first domain in the tree is the root domain. The rest of the domains attached to the root domain are called child domains.
  • It follows a contagious namespace. i.e. it shares a same root name to other child domains.


  • A forest is a collection of one or more domain or domain trees
  • It is a boundary to one logical representation of domain network

Trust Relationship

  • It is a connectivity between two or more forests.
  • It creates a trust relationship between two different name-spaces.

Domain Controller

  • Any computer hardware where ‘Active Directory Domain Services’ is installed and promoted becomes Domain Controller (DC).

Global Catalog

  • The Global Catalog (GC) allows users and applications to find objects in an Active Directory domain tree, given one or more attributes of the target object.
  • A global catalog is a multi-domain catalog that allows for faster searching of objects without the need for a domain name.
  • It helps in locating an object from any domain by using its partial, read-only replica stored in a domain controller.
  • Partial information  means it uses the set of attributes that are most commonly used for searching, the objects from all domains, even in a large forest, can be represented by a single database of a global catalog server.