BIND permits simple load distribution using an address-shuffling method known as round robin. You set up a pool of IP addresses for several hosts mirroring the same content, and BIND cycles the order of these addresses as it responds to queries.
Round robin can’t monitor current server load or processing power. It only cycles the order of an address list for a given host name.
You enable round robin by adding multiple IP address entries for a given hostname. For example, suppose you want to distribute web server traffic between three servers on your network that all mirror the same content. The servers have the IP addresses 192.168.12.12, 192.168.12.13, and 192.168.12.14. You would add three machine records with three IP addresses, each with the same domain name.
When DNS service encounters multiple entries for one host, its default behavior is to answer queries by sending this list in a cycled order. The first request gets the addresses in the order A, B, C. The next request gets the order B, C, A, then C, A, B, and so on.