Lightweight Directory Access Protocol
The Lightweight Directory Access Protocol (LDAP) defines a standard method for accessing and updating information in a directory (a database) either locally or remotely in a client-server model.
The protocol is optimized for reading, browsing, and searching directories, and was originally developed as a lightweight front-end to the X.500 Directory Access Protocol. The LDAP method is used by a cluster of hosts to allow centralized security authentication as well as access to user and group information. This functionality is intended to be used in a clustering environment to keep authentication, user, and group information common across the cluster.
Objects in LDAP are stored in a hierarchical structure known as a Directory Information Tree (DIT). A good directory starts with the structural design of the DIT. The DIT should be designed carefully before implementing LDAP as a means of authentication.