The Basics of DNS Load Balancing: How Round Robin Works

DNS load balancing is a technique that makes multiple devices appear as one single device. When you browse the Internet, your computer sends out requests for the website URL and its IP address. The DNS server responds with an IP address, and it’s from this IP address that the browser knows how to reach the desired website. If you have a website with limited traffic or an application, you might not want all that traffic going directly to one device. These situations call for DNS load balancing to distribute the entire range of IP addresses among several devices to appear as one device instead of several. This article will cover the basics of DNS load balancing, so you understand how Round Robin DNS works.

Round-Robin DNS Basics

Round-robin DNS is one of the most common DNS load balancing techniques. When a client sends a request for a website, the DNS server responds with a list of IP addresses. The order of the IP address list varies based on the round-robin function. The DNS server then sends the first IP address in the list to the browser. The next time the server receives a request for the same website, it will give the browser the second IP address in the list. The server will continue to cycle through the list of IP addresses, giving each one a turn. When a client requests a website, the DNS server responds with the exact IP address that hosts the website. The server sends back the same IP address for a given domain name, even though it may change the actual IP address during the round-robin process. Round robin DNS is a basic DNS load balancing solution that distributes IP addresses for a particular domain name among several devices.

How Does a Round-Robin DNS Work?

A round-robin DNS server cycles through a list of IP addresses for a particular domain name. It will send out the first IP address, followed by the second IP address, the third IP address, and so on, until the list is exhausted. The server will then start the cycle and send out the first IP address again. The most basic round-robin DNS solution will send out the same IP address multiple times. However, more advanced solutions will add a time frame to each IP address. You can also configure round-robin DNS to send out a random list of IP addresses for a particular domain name. This protects against DDoS attacks, as the address list is constantly changing. Round robin DNS gives each IP address a chance to service requests and prevents any one device from getting overloaded.

Conclusion

DNS load balancing is useful for load distribution, failover, and scalability. When a device sends a request for a website, the DNS server responds with an IP address. The server sends back the same IP address for a given domain name, even though it may change the actual IP address during the round-robin process. Round robin DNS is a basic DNS load balancing solution that cycles through a list of IP addresses for a particular domain name. It works best when a single device receives requests and doesn’t give you any control over which device processes the request.