Active Directory Application Mode

What Does Active Directory Application Mode Mean?

Active Directory Application Mode (ADAM) is a Lightweight Directory Access Protocol (LDAP)-compliant directory service used for building directory-enabled applications.


ADAM is intended for users who do not want to set up a domain controller to enable directory services. It runs on Windows Server 2003 and Windows XP Professional.

Following the release of Windows Server 2008m ADAM came to be known as Active Directory Lightweight Directory Services (AD LDS).

Techopedia Explains Active Directory Application Mode

ADAM runs as a non-OS service with multiple instances running concurrently on the server. Each instance uses LDAP to communicate with other ADAM instances and can be configured independently. By integrating with Active Directory Federated Services (ADFS), ADAM can be used to achieve single sign-on functionality.

ADAM consists of the following components:

  • Interfaces (LDAP and Replication): Allows directory clients and other directory servers to communicate with the data store
  • Directory System Agent: Enforces directory semantics, maintains schema, guarantees object identity and enforces data types on attributes
  • Database Layer: Application programming interface between the application and directory database
  • Extensible Storage Engine: Manages the table of records that forms the directory database
  • Directory Database: Data store that stores directory information in a single database file

ADAM can be used as an application component or as a stand-alone LDAP directory in scenarios such as:

  • Storing personalization data relevant to an application and active directory (AD) used for authentication and service publication
  • As a development environment for prototyping an application that uses AD
  • In Web portal applications that manage extranet access to business applications
  • During migration, to support legacy applications

ADAM is designed to be deployed in organizations so as to support both the network operating system (NOS) and the applications that leverage any security built into the NOS infrastructure. This can be accomplished without any overhead in training, additional licensing or operational costs for installing additional directory technology that would otherwise be necessary for supporting directory-enabled applications. ADAM facilitates cross-directory integration to meet the diverse needs of authentication. Its benefits include easy deployment, reduced infrastructure costs, increased security, flexibility, reliability and scalability.

The key features of ADAM are:

  • Flexible and extensible schema resulting in faster directory deployment
  • Multimaster replication model similar to AD
  • Easy setup and removal
  • Multiple instance support
  • Usage of familiar AD tools
  • Backup and restore capability
  • Integration with Windows security model
  • Support for multiple processors
  • Password policies

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Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…