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What Is DNS Load Balancing, Why It Matters and How to Do It

Have you recently heard about DNS load balancing and are curious to learn more? 🤔

You’ve landed on the right page then.

We know how important the domain name system (DNS) is and how vital it is to the way the internet functions. It translates human-readable domain names (like into unique numerical IP addresses (like that computers use to locate websites and services. This makes the internet a lot more user-friendly for us humans.

But what happens when websites experience high traffic or increased demand?

This is where DNS load balancing comes into play. 🤾‍♂️

In this article, we’ll dive deep into the world of DNS load balancing and explore why it matters for modern web applications. By the end, you’ll understand how this powerful approach enhances website performance, improves availability, and maintains reliability even during traffic spikes. You’ll also learn some of its limitations, ways that those limitations are being addressed, and of course, how to implement it.

Let’s get started! 🎬

📚 Table of contents:

What is DNS load balancing

Before we go any further, let’s first establish the definition of DNS load balancing so that we’re all on the same page.

💡 DNS load balancing is a strategic approach that distributes incoming web traffic across multiple servers to optimize performance and prevent overloading any single server. By employing this technique, domain owners can ensure smoother user experiences, even during times of high demand.

How DNS load balancing works

Believe it or not, DNS load balancing can be achieved in several different ways. The two most common methods are the round-robin method and the weighted load balancing method. Let’s take a look at them more closely.

Round-robin load balancing method

In this method, DNS servers rotate the order of IP addresses associated with a domain in a circular manner. Each user request is directed to the next IP address in the sequence, distributing the traffic evenly among the servers.

Weighted load balancing method

With this method, administrators assign different weights to each IP address based on server capacity or performance. DNS servers then use these weights to guide the allocation of traffic, ensuring that more capable servers receive a larger share of incoming requests.

To reiterate, these are not the only methods, but they are the most frequently employed ones.

Advantages of using DNS load balancing

Based on what we’ve discussed so far, you probably already have a good idea of why it’s smart to use DNS load balancing for your website – particularly if you have a high-traffic site. If you run a small personal blog then you probably don’t need to worry about it. However, if you have a large ecommerce store, and your goal is to maintain a high standard of service for your customers, then DNS load balancing might be a great option for you.

By spreading the demand on your site across multiple servers, DNS load balancing can reduce your response times and minimize server bottlenecks. This leads to faster loading times for web pages and enhances the overall experience of your website’s visitors – and happy visitors are more likely to become happy customers.

Beyond that, DNS load balancing also provides a level of redundancy to withstand server failures. The last thing you want is for your website to go down due to a server failure just as someone is putting in their credit card details to make a purchase. With DNS load balancing, if one server becomes unavailable, the load balancer automatically directs traffic to the remaining operational servers, ensuring continuous service availability.

A man working with multiple computers, including a desktop and a laptop.

Use case scenario for DNS load balancing

To give you an idea of what DNS load balancing might look like in the real world, let’s take a look at a hypothetical use case scenario. In our scenario, we will examine a business called “Bob’s Bathtubs and Basins.” We’ll first explain the challenge that they faced with their online storefront. Then we’ll go over how they resolved it with strategic use of DNS load balancing.

The challenge

As the name implies, Bob’s Bathtubs and Basins sells equipment for bathrooms, including bathtubs, sinks, toilets, and plumbing fixtures associated with these larger items. They sell to both individual homeowners and professional service providers like plumbers and installers. The store experiences significant fluctuations in traffic due to seasonal sales, promotional events, and advertising campaigns.

In the winter, for example, a lot of pipes freeze due to extreme temperatures in certain regions. As a result, their website gets an uptick in traffic. During peak times, they struggle to handle the surge in user requests, which results in slow loading times, page timeouts, and, in some cases, website unavailability. This situation leads to poor customer experiences, increased bounce rates, and a loss of revenue for the business.

Load balancing to the rescue

To address these challenges, the web admin team for Bob’s decided to implement DNS load balancing. They distributed incoming traffic across multiple backend servers, and by doing so, they were able to efficiently manage the spikes in user requests.

By ensuring that no single server was overwhelmed, the website’s performance significantly improved during peak periods. Visitors experienced faster page loads, and Bob’s website remained stable even during traffic surges. This enhanced user experience translated to higher customer satisfaction and improved conversion rates.

Although this was just a made-up story, the underlying idea behind it is something that applies to many ecommerce stores and other high-traffic websites. Maybe yours is among them, in which case, you should consider implementing DNS load balancing.

Does DNS load balancing affect SEO?

DNS load balancing does not have a direct negative impact on SEO or search engine rankings. Major search engines are capable of crawling and indexing websites with multiple IP addresses resulting from DNS load balancing.

However, ensuring that search engine crawlers can access and index all relevant content is essential. Implementing proper sitemaps, using consistent URLs, and avoiding cloaking practices are crucial for SEO performance.

Potential challenges and limitations of DNS load balancing

So we’ve established that DNS load balancing does not negatively affect SEO, but that doesn’t mean that it’s all sunshine and rainbows. We’re not snake oil salesmen here. If we’re going to share the benefits of load balancing, then we’re also going to tell you about some of its limitations. These include:

DNS caching

DNS caching is a fundamental mechanism employed by clients and resolvers to store DNS responses locally for a certain period. It is specified by the Time-to-Live (TTL) value in DNS records.

💡 What is Time-to-Live (TTL)? TTL defines the amount of time that a DNS resolver or client should cache a DNS record before requesting fresh information from the authoritative nameservers.

However, DNS caching can lead to inconsistent traffic distribution in a load-balanced environment. This is because when a client or resolver caches a DNS response, it continues to use that cached information until the TTL expires – even if the load balancing configuration has changed in the meantime.

In practice, this means that if a DNS resolver caches an IP address associated with a specific server, it might direct subsequent user requests to that server. This can happen even if the load balancing algorithm should have selected a different server.

Uneven server load

In certain scenarios, DNS load balancing might not distribute traffic evenly, especially if backend servers have varying capacities or if there are significant differences in network conditions.

Lack of real-time adaptation

Traditional DNS load balancing methods do not provide real-time adaptation to changing server conditions. Newer solutions – which we’ll discuss in a later section of this article – are addressing this limitation.

DNS propagation delay

DNS changes can take time to propagate globally due to DNS caching and TTL settings. This delay might impact how quickly load balancing changes take effect.

DNS load balancing can reduce the strain on individual servers.

How to implement DNS load balancing

Now that you have a thorough understanding of what DNS load balancing is, including its advantages and limitations, it’s time to learn how to actually do it.

Regardless of whether or not you choose to use the round-robin method, the weighted load method (or some other method), there are a few different ways to set things up. We will share five options below, ordered by their level of difficulty from easiest to most challenging.

DNS management tools

Many domain registrars and hosting providers offer DNS management tools that simplify DNS configuration, including load balancing. These tools typically have options to create round-robin or weighted round-robin configurations, making it easier for users to set up load balancing without extensive technical knowledge.

Content delivery networks (CDNs)

Some content delivery networks offer DNS-based load balancing as part of their services. CDNs automatically handle traffic distribution across their edge servers, making it easier for users to leverage load balancing along with content caching and delivery benefits.

Manual configuration with domain registrar or hosting provider

This method allows you to directly manage your DNS settings with your domain registrar or hosting provider. You can manually create multiple A records or add multiple IP addresses to your domain’s DNS configuration. It is suitable for simpler setups or situations where you want direct control over your DNS settings.

Load balancer appliances or software

If you have a more complex setup or work for an organization that does, then you might want to use a dedicated load balancer software like NGINX. These tools sit between users and servers and handle traffic distribution. Load balancer configurations can be done through their management interfaces.

Third-party DNS load balancing services

Finally, we have third-party DNS load balancing services like Amazon Route 53, which provide a more sophisticated and scalable approach. These services can handle traffic distribution across multiple servers and may include additional features like geographic load balancing and real-time monitoring. They may require a higher level of technical expertise to set up and integrate with your existing infrastructure.

Each method has its pros and cons, and the choice depends on your specific requirements, technical expertise, and budget.

As you’d probably expect, in today’s web environment individuals and organizations are constantly trying to innovate and iterate. DNS load balancing is no different in that regard. As beneficial as it is, it’s not without its limitations – as we just discussed above. Luckily, there are emerging technologies, some of which have already been deployed, that are working on addressing these issues. Among the more popular is the use of edge servers with content delivery networks and adaptive DNS load balancing.

Edge servers and CDNs

Edge servers can efficiently distribute content and handle user requests. They complement traditional load balancing approaches and providing enhanced performance for globally distributed applications. A perfect example of this is Cloudflare’s CDN, which relies on edge servers for its service.

Cloudflare operates a vast global network of edge servers, strategically placed in various data centers around the world. These edge servers cache and serve static content, such as images, videos, and website assets, closer to the end-users, reducing latency and speeding up content delivery.

Adaptive DNS load balancing

One of the most promising trends in DNS load balancing is the emergence of adaptive DNS load balancing. This innovative approach goes beyond traditional static load balancing methods by dynamically adjusting traffic distribution based on real-time conditions.

Adaptive DNS load balancing makes decisions based on status indicators retrieved from backend servers. These are determined by custom programs running on each server. The load balancer regularly queries each server for this status information and then sets the dynamic weight of the real server appropriately. By analyzing these indicators and understanding the health and performance of each server, the adaptive load balancer steers traffic to the most optimal servers.

Additionally, adaptive DNS load balancing incorporates features like adaptive routing, which modifies the routing of requests to pools and origins in response to dynamic conditions.

💡 What’s the difference between pools and origins? Pools refer to groups of identical servers serving a common purpose (e.g., hosting a website or providing a specific service), while origins are the original sources or authoritative servers holding definitive versions of content (e.g., the primary server where the website’s content is hosted).

This means that the load balancer can react quickly to changes in server health and automatically remove non-responsive servers from the pool. This, in turn, ensures continuous service availability and failover protection.

Computer servers with many wires

Final thoughts on DNS load balancing 🏁

In conclusion, DNS load balancing is a powerful technique that optimizes the distribution of internet traffic across multiple servers, ensuring enhanced performance and availability for web applications.

By employing round-robin and weighted load balancing methods, organizations can efficiently manage incoming requests and achieve a balanced server utilization. The advantages of DNS load balancing include improved website performance, enhanced fault tolerance, and redundancy.

However, despite its benefits, traditional DNS load balancing techniques face challenges like DNS caching and the lack of real-time adaptation. Luckily, newer iterations like adaptive DNS load balancing address some of these limitations.

👇 The bottom line is this:

If you run a high-traffic website then you should absolutely explore the various DNS load balancing options that are out there and consider employing them on your site.

Now that you’ve learned how to improve your website’s performance with load balancing, you might want to check out our comprehensive list of all DNS best practices.