DNS A record setup with Round-Robin is a simpler, cheaper way to setup load balancing. Other ways of load balancing includes Network load balancing, MSSQL load balancing etc. This DNS A record based Round-Robin is for load balancing done at the Active Directory level.
In a nutshell, whenever we access a server cluster, DNS will resolve different server within the cluster. Assume there are 5 server in the cluster, if we try to access the cluster name, DNS will point out to server 1. If another person tries to access server cluster, DNS will point out to server 2. Thus it is an alternate way of load balancing.
To do this, Open DNS manager (Run -> Dnsmgmt.msc) in your Domain controller. Now right click the server and select properties. Make sure the DNS Round Robin is enabled. It is enabled by default.
Now we need to add the Entries in the DNS. Assume I have 5 servers.
Serv-cluster01 – 198.19.1.100
Serv-cluster02 – 198.19.1.101
Serv-cluster05 – 198.19.1.104.
I need to give a common cluster name in the DNS but with the IP of the servers as shown below.
Now ping serv-cluster from different servers, you will get name resolved in these 5 IPs.