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DNS round-robin

(also round-robin DNS)

DNS round-robin definition

DNS round-robin is a technique that provides load balancing, load distribution, or fault tolerance for DNS servers. DNS round-robin uses multiple identically configured servers to distribute incoming traffic evenly among them, which reduces the load on each server and improves the efficiency of the network.

All servers use the same domain name, but each has an individual IP address associated with the said domain. This allows servers that have DNS round-robin enabled to respond to requests in a rotating manner, handing out a different address each time. For instance, the first request gets the IP address of the first server, the second one gets the IP of the second server, and so on. Basically, each IP address and server gets a chance to respond to a request and is then moved to the back of the line to wait for its next turn.

See also: round robin DNS, DNS server

DNS round-robin drawbacks

  • The combination of DNS caching and client-side caching can be challenging to manage, which means that DNS round-robin cannot always provide load balancing.
  • If one server fails, the DNS will still give out that server’s address in the rotation, and clients that get that IP will not be able to reach the service they are looking for.