There are two types of directories that participate in the directory synchronization process - a central directory and several secondary directories.
The central directory is a fully LDAP-compliant directory that stores and maintains a wide range of user and system information, including component configurations, message routing data, and end-user records. The central directory also organizes and facilitates access to information needed to convert and route messages. It provides users inside and outside the organization the ability to locate people and access a variety of information about them.
The secondary directories are separate directories maintained by each mail system, which the central directory must coordinate and communicate with to provide transparent connectivity among mail systems. The information stored in the secondary directories must be synchronized with other directories so information is consistent across all directories.Within SMCS, every user data change is owned and administered through secondary directories and propagated to the Central directory.