Add IAS Servers to Optimize Availability

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Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

It is important to prevent an IAS server from becoming a single point of failure.

To prevent an IAS server from becoming a single point of failure, deploy IAS servers either in pairs (a primary and a backup IAS server) to provide fault tolerance, or in multiples, to balance the load of a large volume of authentication and accounting requests. Add at least two additional IAS servers per forest.

The level of availability that you need to provide depends on the following:

  • How likely it is that a network link will fail

  • How important it is to provide uninterrupted authentication to your clients at all times

Balance your need for availability against your need to minimize the costs of the hardware investment. Keep in mind that you can add IAS to existing domain controllers.

When you deploy more than one IAS server, make sure to design your IAS servers to use RADIUS proxies for load balancing and synchronization of the server configurations.