Exchange Server 2010 Load Balancing
Load balancing serves two primary purposes. It reduces the impact of a single Client Access server failure within one of your Active Directory sites. In addition, load balancing ensures that the load on your Client Access server and Hub Transport computers is evenly distributed.
A great document online has been published regarding Exchange Server 2010 Load Balancing which you can see in the link below, however it is never bad to not forget the requirements of load balancing when we play it in Exchange protocols… https://technet.microsoft.com/en-us/library/ff625248.aspx.
Understanding Load Balancing in Exchange 2010:
https://technet.microsoft.com/en-us/library/ff625247.aspx