Cluster Configuration

Front-End and Back-End Topology Advantages

The front-end and back-end server topology should be used for multiple-server organizations that provide e-mail access to their employees over the Internet. Additionally, organizations that use Microsoft® Office Outlook® Web Access, POP, IMAP, and RPC over HTTP on their internal network can also benefit from a front-end and back-end server topology.

Single namespace

The primary advantage of the front-end and back-end server architecture is the ability to expose a single, consistent namespace. You can define a single namespace for users to access their mailboxes (for example, https://mail for Outlook Web Access). Without a front-end server, each user must know the name of the server that stores their mailbox. This complicates administration and compromises flexibility, because every time your organization grows or changes and you move some or all mailboxes to another server, you must inform the users.

With a single namespace, users can use the same URL or POP and IMAP client configuration, even if you add or remove servers or move mailboxes from server to server. Additionally, creating a single namespace ensures that HTTPS, POP, or IMAP access remains scalable as your organization grows. Finally, a single namespace reduces the number of server certificates required for SSL encryption because clients are using SSL to the same servers and using the same namespace.

Offloads SSL Encryption and Decryption

Clients such as Microsoft Office Outlook® 2003 or Outlook Web Access that access your Exchange servers from the Internet should use Secure Sockets Layer (SSL) to connect to their Exchange servers to protect the traffic from interception. However, processing SSL traffic can be a significant overhead for a server. The front-end and back-end architecture allows the front-end to