Round robin DNS is a technique in which load balancing is performed by a DNS server instead of a strictly dedicated machine. A DNS record has more than one value IP address.

When a request is made to the DNS server which serves this record, the answer it gives alternates for each request. For instance, if you had a three webserver that you wished to distribute requests between, you could setup your DNS zone as follows:

# vi /var/named/

Append/modfiy www entry:

www   IN   A
IN   A

IN   A
IN   A

# /etc/init.d/named restart
When a query is made to the DNS server it will first give the IP of for the www host. The next time a request is made for the IP of www, it will serve and so on.