There's more than one way to balance traffic load across multiple Web servers. If you're using rotary DNS for load balancing, consider the devices reviewed here for improved performance and fault tolerance. Rotary DNS is a way of modifying DNS entries so entries for a virtual name can service requests for multiple machines.
Machines move to the head of the list one by one in a round-robin fashion.
If there are three machines listed for a given virtual name, the order of the three will be switched periodically so some of the requests will see one machine as the preferred translation for a name, other requests will see the second, and still others will see the third. Because standard DNS is used by rotary DNS, it is not possible to predict and control client caching, nor, therefore, the actual load on the servers. Adding and removing machines can take many hours as DNS changes are propagated through the network, and a lot of traffic could be sent to a machine that has been removed for hours or even days. Rotary DNS changes the IP address associated with a virtual site - it does not have any effect on which protocols or ports can be used with that address. Because the load-balancing devices map incoming requests to real servers and traffic passes through them to and from the real servers, a count of open connections can be established.