Directory Services

Directory services are databases for storing and maintaining information about users and resources in an organization. Directory services store information about usernames, passwords, devices, user preference and more entities. Furthermore, directory service is simply a piece of software that can store and retrieve information about user accounts, groups, devices, resources, security settings, system information and more. Network and system administrators employ directory services to register users, manage access privileges, monitor and control access to applications, infrastructures and other organizational assets or resources. As X.400 set of standards are for email systems, X.500 standards are used format directory services.

Main components of directory services include:

• Schema to describe directory objects and attributes
• Universal database or catalog to store detail information about objects
• Index and query to search and retrieve information from the directory
• Replication functionality for disseminating directory information across distributed servers and systems
• Peering functionality for directory services federation across many different organizations and namespaces
• Secure architecture

Some unique characteristics of directory services include the following:

• Hierarchical naming structure
• Extended search capability
• Replicated data
• Shared network access
• Database optimized for reads
• Extensible schema

Some common directory services in use today include:

• Microsoft Active Directory (AD)
• Lightweight Directory Access Protocol (LDAP)
• Novell Directory Services (NDS)