2.2.1 Directory Protocols


Protocols in this table enable protocol clients and protocol servers to authenticate, authorize, manage, and search for users. These protocols describe the data that Communications Server reads from the Active Directory directory service (DS) and stores in its data store while keeping this information synchronized with any changes made in Active Directory. The directory service (DS) serves as the authoritative source of user information and forest-level settings used by Communications Server. This information is used for many purposes, including authentication, authorization, management, and searching users.

Protocol name


Short name

Address Book File Structure

Describes the format of the Address Book files that are produced daily by the Address Book Server (ABS) and accessed by protocol clients to search for users, contacts, and groups stored in Active Directory. In addition, this data can be used to perform reverse number lookup for voice calls.


Distribution List Expansion Protocol

Identifies a protocol for Office Communicator to discover members of a distribution list.