Microsoft Exchange Server Roles – Ready Reckoner

This post will serve as a ready reckoner to those who are looking to understand and implement Microsoft® Exchange Server® roles. Exchange Server 2007 and 2010 have a different architecture model when compared to the new 2013.

Server Roles in Exchange 2007 & 2010

There are five server roles in Exchange Server 2007 & 2010 as follows:

1. Mailbox Server: Hosts the mailbox and public folder databases and also provides MAPI access to Outlook clients
2. Client Access Server (CAS): Hosts the client protocols, such as POP3, IMAP4, HTTPS, Outlook Anywhere, Availability service, and Autodiscover service. CAS also hosts Web services.
3. Hub Transport Server: responsible for all email flow in the organization, internal routing and policy enforcement
4. Edge Transport Server: A special transport server intended for installation in DMZ networks to provide secure inbound/outbound email flow for the organization
5. Unified Messaging Server: Provides VoIP capabilities to an Exchange Server in order to integrate e-mail, voicemail and incoming faxes as part of an inbox.

The Mailbox Role is generally installed along with the CAS, Hub Transport Server and Unified Messaging Server roles on a single server. The Edge Transport Server Role sits on the perimeter and is not part of AD.

Server Roles Exchange 2013

Exchange Server 2013 consolidated some of the Exchange Server roles from 2007/2010. After Hub Transport server and Unified Messaging server roles were discontinued in 2013, it now has only 2 server roles for installation as follows:

• Mailbox Server: This server role hosts both mailbox and public folder databases and also provides email message storage. The Mailbox server role has 2 Transport services:
  • Hub Transport Service: Similar to the Exchange 2007/2010 Hub Transport server role, this service provides email routing within the organization, and connectivity between the Front End transport service and the Mailbox Transport service
  • Mailbox Transport Service: This service passes email messages between the Hub Transport service and the mailbox database

Mailbox servers can be added to a Database Availability Group, thereby forming a high available unit that can be deployed in one or more datacenters. DAG is the base component of the high availability and site resilience framework built into Microsoft Exchange Server 2013. A DAG is a group of up to 16 Mailbox servers that hosts a set of databases and provides automatic database-level recovery from failures that affect individual servers or databases.

• Client Access Server (CAS): Exchange Server clients such as Outlook, Outlook Web App and ActiveSync connect to CAS for mailbox access. CAS authenticates, and redirects or proxies those requests to the appropriate Mailbox server. CAS has 2 main components:
  • Client Access Service: This handles the client connections to mailboxes
  • Front-end Transport Service: This handles all inbound and outbound external SMTP traffic for the Exchange organization, and can act as a client endpoint for SMTP traffic

The CAS role does not perform any data rendering functionality in 2013 and only provides authentication and proxy/redirection logic, supporting the client Internet protocols, transport, and Unified Messaging.

Learn More:

Find out how to discover, configure and monitor Exchange Mailbox Server using SolarWinds Server & Application Monitor: http://thwack.solarwinds.com/community/solarwinds-community/product-blog/blog/2013/12/18/appinsight-for-exchange

References:

1. Microsoft Exchange Server News - Tips - Tutorials
2. Resources and Tools for IT Professionals | TechNet