DNS Bytes: Load Balancing with Round Robin

Today’s tip is about Round Robin Load Balancing and how it can benefit your domain. 

Let’s dive in!

What Is Round Robin Load Balancing?

One of the most widely used load balancing techniques is Round Robin. In this type of DNS configuration, two or more IP addresses are assigned to the same DNS record. Once assigned, traffic is evenly dispersed across your endpoints and is cycled through each one in a circular fashion.

Constellix also offers Weighted Load Balancing. While conceptually the same as its counterpart, Weighted Round Robin lets you distribute weight unevenly amongst endpoints.

Benefits of Round Robin

Because traffic is split equally between servers, no single resource will bear the full burden of your traffic load. When using Weighted Round Robin, you can balance your traffic volume by server capacity, location, performance, or based on cost. As a bonus for either configuration type, speed and performance are also improved. 

Limitations of Round Robin

While Round Robin is an excellent load balancing technique, it doesn’t provide true redundancy. If one of your endpoints in any Round Robin configuration goes down, some traffic will still hit the problematic endpoint, in which case, these users won’t be served your content.

Bulletproof Your Round Robin Configurations

There is a simple, yet extremely effective way to circumvent the downside to Round Robin configurations. And that is to pair it with DNS Failover. When combined, your servers run at optimal levels, are protected from being overloaded, and your domain is protected from outages. That’s because Failover will automatically redirect traffic to a healthy resource in the event of a server failure. Traffic will then be cycled between the available, healthy resources until the failed one comes back online.

Round Robin Configuration Tips:

 In Constellix, Round Robin is configured via DNS record pools. Here are two examples of each type:

Load balancing with no endpoint preference: Equal Round Robin

*IPs shown are for example purposes only and are not live endpoints.

With equal distribution, the weight value would be the same for all IP addresses/hosts. 

Load balancing with prioritization: Weighted Robin Robin.

*IPs shown are for example purposes only and are not live endpoints.

As you can see from the example above, the IPs have different weights. In Constellix, weight values do not need to add up to 100. The higher the weight, the more traffic will cycle to that particular server.

Whether using equal or weighted distributions, you can also choose the minimum number of endpoints to return, as well as the minimum resources that must be available in your pool.