Exchange Server 2010 Roles and Active Directory

Using Hub Transport Servers with Active Directory

Hub Transport contact Active Directory to perform the below functions:-

1. Hub Transport performs message categorization. Categorizer queries Active Directory to perform recipient lookup, retrieves mailbox information and determine any recipient restrictions and permissions.

2. Categorizer also queries Active Directory to expand the membership of Distribution lists.

3. Hub Transport uses Active Directory site configuration information to determine the routing topology and the site in which mailbox is located.

If mailbox is located in a different Active Directory site, Hub transport delivers the message to a Hub Transport server in the remote Active Directory site.

Using Client Access Servers with Active Directory

When a user sends a request for a connection, CAS receives these requests and contacts Active Directory to authenticate and determine the locations of the user's mailbox. If the user's mailbox is in the same Active Directory site as the CAS, the user is connected to his/her mailbox. But if mailbox is located in the remote Active Directory site, the connection is redirected to a CAS in the remote Active Directory domain as the user's mailbox.

Using Unified Messaging Servers with Active Directory

Unifies Messaging Servers contacts Active Directory to retrieve user's global configuration information, such as dial plans, IP gateway details and so on. When a message is received by the Unified Messaging server, the server searches for Active Directory recipients to match the telephone number to a recipient address. When the server has resolved this information, it can determine the location of the mailbox and submit the message to the Hub Transport server.

Using Mailbox Servers with Active Directory

Mailbox servers contact Active Directory to determine the location of Hub Transport servers in their site and use this information for routing messages. Mailbox servers also store information about mailbox users/stores, address lists, recipient policies, mailbox policies, system policies and policies in Active Directory.

Using Edge Transport Servers with Active Directory

Edge Transport server are deployed in a perimeter networks and do not have direct access to the organization's internal domain. Unlike Hub Transport servers, Edge Transport servers cannot contact an Active Directory server to help route messages.

To route messages in to the internal domain, an administrator configures a subscription from Edge Transport to the Active Directory site that allows it to store recipient and configuration information about the Exchange organization. After an Edge Transport server is subscribed to an Active Directory site, it is associated with the Hub Transport servers in that site for the purpose of message routing. Thereafter, Hub Transport servers in the organization route messages being delivered to the Internet to the site associated with the Edge Transport server, and Hub Transport servers in this site relay the messages to the Edge Transport server. The Edge Transport server, in turn, routes the messages to the Internet.