DNS Round Robin - IIS
Open up the attachment below. It demonstrates how DNS round robin works.
DNS Round robin is a common solution for enabling load balancing for Internet server farms. Consider the following example in which there are three IP address entries for the same host name on a DNS server.
In DNS, there are three entries:
192.168.1.100 WebApp1
192.168.1.101 WebApp1
192.168.1.102 WebApp1
You can also replicate this example some time just by playing with your own DNS server. If you create three host records with the same name but with three different IP addresses, you will have implemented DNS round robin as a solution. What happens is that the first client receives the first address, the second client receives the second address, the third client receives the third address, the fourth client receives the first address, and they continue to loop. Using DNS round robin, it is possible to spread the load among multiple servers.
The problem with round robin DNS, is that it is completely unable to handle a down server. In the event one of the servers fail, its address will continue to be given to clients and a portion of the clients will basically be pointed to an invalid address and a portion of the clients will fail to connect.
Round Robin DNS is not a high availability solution.