Round Robin DNS

[~Phil~]

Domain pointing to two servers.

If you want to host a website one domain on two servers ..

This can be achieved with the help of Round Robin DNS. It is very simple concept. You just need to create an additional "A" record (IP address) in DNS for your domain that points to the other server.

Suppose you have website "test.com" on two different server, on one server the domain has the IP address 1.1.1.1, and on other server the website uses Ip address 2.2.2.2.
Make sure that the nameservers responsible for your domain "test.com" has two "A" records - 1 for each IP address (the default is one "A" record, since your site only exists on 1 IP address by default).

Round robin DNS is a technique of load distribution, load balancing, or fault-tolerance provisioning multiple hosts e.g. Web servers, FTP servers, by managing the Domain Name System's (DNS) responses to address requests from client computers according to an appropriate statistical model.

In simple langauge Round-robin DNS works by replying to DNS requests not only with a single IP address, but a list of IP addresses of different servers. With each DNS response, the IP address sequence in the list is permuted. Usually, basic IP clients attempt connections with the first address returned from a DNS query so that on different connection attempts clients would receive service from different servers, thus distributing the overall load among all the servers.

But the Round Robin DNS has many problems associated with it like the one arising from record caching in the DNS servers or caching of the DNS recoreds for the domain at client end like client ISP namserver cache..