What is Microsoft Exchange?
Microsoft Exchange is a widely used and one of the most popular mail servers developed by Microsoft. It is a server program that runs on Windows Server and is part of the Microsoft Servers line of products. Exchange Server Enterprise Edition supports clustering of up to 4 nodes when using Windows 2000 Server, and up to 8 nodes with Windows Server 2003. Exchange Server 2003 also introduced active-active clustering, but for two-node clusters only. In this setup, both servers in the cluster are allowed to be active simultaneously. Microsoft Exchange Server can be purchased as a hosted service from a number of providers