What Is Round-Robin DNS?

When users try to access your website, they submit a URL and are sent to a specific IP address. Your visitors care that the page loads quickly and accurately. Yet, they are not really interested about what servers are used or where these are located. However, on the back-end, companies work to create better front-end customer experience by improving server location and traffic. And one way to do this is with a round-robin DNS (domain name system).

What Is Round-Robin DNS

The round-robin DNS is a load-balancing technique to improve user experience. When used well, it can enable web pages to load faster and prevent websites from crashing. Learn more about this technique and how it works.

What is load balancing?

Before going into round-robin DNS systems, it helps to discuss load balancing. Load balancing refers to the process of spreading traffic across multiple servers. Instead of hosting your website on one server and sending traffic through this one location, you spread out your efforts. To do so, the DNS might use multiple servers in case one goes down.

This way, load balancing creates a better user experience. A website is more likely to load when an IP address has multiple server options. The webpage might even load faster if the chosen server is closer to the user. What’s more, IT professionals can worry less about servers crashing if there are built-in backups.

You have multiple options when setting up a load balancing system. These range by complexity and the requirements of your company. If you’re just beginning to optimize your DNS management and configuration, consider using a round-robin system to balance your site traffic.

What is round robin load balancing?

A round-robin load balance is one way to spread traffic across multiple servers using equal weight. When a user submits a DNS request, the response includes several IP addresses across multiple servers. Each IP address correlates to the same site. Depending on the availability, the user will connect to the IP address that is most convenient.

DNS round-robin load balancing is methodical. Round-robin refers to a process where each party has its fair turn in line.

This process creates balance with your server use and prevents one location from getting overwhelmed with traffic. This is why round-robin load balancing is ideal for companies with multiple servers that can all handle the same amount of traffic.

A basic load balancing option is ensuring that each server has the same levels of storage and computing capacity. Each server needs to be weighted equally fairly to avoid the issues that come with traffic-spikes and traffic overloads.

If you’re just starting out with load balancing, a round-robin option is a good option to test.

Can a DNS resolve to multiple IP addresses?

A DNS can hold multiple IP addresses or DNS records for the domain name. When you create a load balancing system, you assign multiple IP addresses to different servers. When a user calls for a record (I.E. types in a URL), the DNS pulls all of the IP addresses related to that site.

When the record is pulled, the DNS will follow a series of rules to determine which IP address to send the user to. These are like if-then statements. For example, let’s say you want to allocate users by geography. The DNS configuration would read that if a user is in Dublin then they need to get routed to the Ireland-based server as opposed to the Los Angeles-based one.

While a DNS record can contain multiple IP addresses, the user will only experience one. It doesn’t matter which IP address is sent, as long as the website loads quickly and accurately.

How do I create a round-robin DNS record?

You can set up a round-robin system within your cloud data management system and through your server provider. You will create a list of rules for your DNS to follow depending on your traffic levels and sources.

As you set up your round-robin DNS, determine the type of system you want to create. While this load balancing option is simple, you can make it more complex if you want.

  • Basic round-robin: This option assigns servers randomly. Whichever server happens to be at the top of the list will be assigned first. The servers move up the list without changing their priority levels.
  • Weighted round-robin: With this option, different weight levels are assigned to each server. This is typically labeled based on storage capacity. For example, if Server A can hold twice as much data as Server B, then two site visitors will go through Server A for every one that goes through Server B.
  • Dynamic round-robin: This is the most complex option. The weight is assigned based on current capacity, which changes over time. If Server A has a higher capacity, then it will get skipped in the round-robin.

These are all rules that you can create for your load-balancing system to make sure your site visitors have a positive experience.

If you’re unfamiliar with load balancing, consider investing in a DNS management platform like DNS Manager to make the process easier. Here’s a short example how you can set up basic round robin for an A record in DNS Manager:

Simply create multiple A records: 
www.example.com. IN A
www.example.com. IN A
www.example.com. IN A

As a result, load will be distributed evenly across these servers, for all clients.

How do I check my DNS round-robin?

Once you set up a DNS round-robin configuration, you need to check on it periodically to make sure it is still functioning properly. This can be done by running a test within your DNS management system. If you use DNS Manager, the software will alert you to any issues. You can also download a sample set of site visitors and run it through a traffic generator to make sure each IP address is getting traffic and your system is balanced.

There may also be times when you want to remove certain servers from your round-robin system. For example, if a server goes down and it makes up 25 percent of your traffic, then a large chunk of your site visitors could receive site errors. Within your system, you can create testing rules that remove a server from the round-robin whenever it needs maintenance or goes down unexpectedly.

DNS load balancing is a great and easy way to split traffic across multiple servers. However, having more servers can also have a downside. Namely, if one of the servers goes down, it will take down the percentage of clients it hosts. To eliminate such a dark scenario from ever happening, all you need is proper and continuous monitoring. This will help you prevent downtime. At the same time, let’s not forget that most of the servers will cache results. In other words, even if you, for example, change the affected IP address with another one in your DNS server, clients will still see the old IP address. One way to address such an issue is to use a lower TTL value for that record, so that you can force a quicker change, when necessary. Another way is to use DNS round robin in conjunction with another load balancing system. For example, you can use DNS round robin to distribute traffic to an intermediary level of highly-available load balancers. This way, if one fails, the IP address will be taken over by another redundant load balancer.

Ultimately, regularly checking your DNS settings and functioning can help you catch small problems early on. This allows you to fix minor issues before they balloon into major crises.

How can a DNS management platform help with load balancing?

If you want to set up load balancing for your website, consider investing in a DNS management tool. With a platform like DNS Manager, you can deploy multiple servers to handle increases in DNS requests. When you have a traffic spike, you can use a round-robin DNS record to prevent your servers from getting overwhelmed and maintain a great user experience.

You can also check your DNS round-robin set-up from the web based interface available in DNS Manager. It provides multiple features for complete DNS management and optimization.

Explore DNS round robin as a load balancing option

Knowing what is a DNS round-robin feature can help you balance your traffic and create a better user experience. There are multiple load balancing options to choose from depending on your particular traffic needs and requirements. Decide what is best for your business and your website visitors. And then implement it. Good luck!

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