DNS Load Balancing

In Microsoft Unified Communications Managed API (UCMA) 2.0, the communications infrastructure needed to deploy hardware-based load balancers to support multiple application instances or Microsoft Office Communications Server 2007/Microsoft Office Communications Server 2007 R2 front ends. In Microsoft Unified Communications Managed API (UCMA) 3.0, there is now inherent support for DNS-based load balancing. When multiple connections are made to a pool that can resolve to multiple IP addresses, connections can be distributed across multiple available servers. If a server instance is offline, the platform can detect this state, and will disable attempts to connect to the offline server instance for ten minutes. This is assumed to be the approximate minimum amount of time required for a server (Microsoft Lync Server 2010 or application) to stop and start, update, and be restored. The ability to perform DNS-based load balancing is helpful for building scalable applications. An application can take advantage of this functionality with no additional code. For more information, see General Application Activation.