Active Directory - Introduction

Active Directory is a repository that records information of the entire network resources like users,groups, computer,domain controllers and makes it available to all the users.

Directory was used to create single centralized repository of information that securely manages a company resources. Active Directory is Microsoft trademark directory service which is released with Windows 2000 Server edition, and the extended functionality and Improved administration released in Windows 2003 Server Edition.

Before understanding the concept of Active Directory services, it is better to know the limitations in the previous versions i.e Windows NT 4.0 where helps us to understand why this feature is introduced.

Limits in Windows NT
* NT domains are flat entites where the multiple domains in the organisation are cannot be taken into hierarchial structure.
* Administration of multiple domains will be complicated quickly and management intensive.
* NT suits for small to medium business only, where it can handles only thousands of users only.

Why Active Directory:
* Significant Improvement Over Windows NT 4.0 domain
* An Object oriented Storage organisation which allows easier access to information.
* AD has centralized Administration Mechanism
* It provides Redundancy and Fault Tolerance when two or more domain controllers deployed within a domain.
* It provides Single point of access for Manageement of User accounts, Clients, Servers, Applications, Domain Controllers, Trusts, redundance and errors.

Directory Service
I hope you all aware the term 'directory services' is used to collects information about the specific resources and makes it available to the people whenever requested. For example, when you wants to find out for hospital in the city, You would give a call to the directory service provider and query for the hospital name, specialist, or by area. Here the name of the hospital is object and the properties of the objects are Address, Phone number, fax number, email id. You can find the hospital name from, Address, phone number very quickly since all the hospital information stored in the directory.