The case for separating DNS from your CDN 

If you’re signing on with a content delivery network (CDN) provider, you’ll probably see DNS as part of the standard service package. It’s only natural—to access your content delivered by the CDN, the Internet has to know where to send the traffic. CDNs make it easy to configure and manage those DNS settings. 

It’s easy to accept DNS services as part of a CDN package. Most organizations that are just starting out with a CDN probably don’t give DNS a second thought. They just assume that the two services should naturally go together. 

From a management perspective, co-location of DNS within a content delivery service certainly makes sense. The ability to configure and manage DNS alongside other CDN settings saves a little bit of time and effort, and who doesn’t want to save time and effort? 

Here’s the issue: that seemingly minor DNS feature actually has a significant impact on how much you pay for content delivery, the quality of what you deliver and the resilience of what you’re delivering. Even that ease of use argument gets flipped on its head. 

We’re more than a little biased here, but that’s because we believe that for many CDN users the case for using a separate DNS service is overwhelming. 

It all boils down to this: if you’re using multiple CDNs now or see yourself using multiple CDNs in the future, you’ll want to avoid getting locked into a single provider’s ecosystem and cost structure. Doing this effectively requires a separate DNS system that works across providers, allowing you to pick the best option at any particular moment. 

Let’s look at some of the benefits of using an independent DNS provider, including: 

  • cost 
  • performance 
  • ease of management 


The DNS offering that comes bundled with CDN services has one job: to make that CDN stickier. They make it possible to steer traffic elsewhere using DNS, but it’s not exactly in the CDN’s interest to send you anywhere else—they only get paid when they’re delivering your content, after all. 

The cost of content delivery varies greatly across different ISPs and geographical regions. The CDNs don’t use this data to optimize traffic as it would impact their bottom line. 

While the cost differences can seem miniscule for individual queries, when you multiply those by the number of queries around the world and look at it over time, the total adds up quickly. The ability to steer traffic to the lowest cost CDN using DNS can end up saving you quite a lot. 


Just as the cost of content delivery can change from moment to moment, there are significant differences in performance between CDNs. Here’s a random sample of real user monitoring data from some of the major content delivery providers. 

As you can see, the data is all over the place. At any given point in time, various CDNs might deliver significantly better (or worse) performance. 

If you’re using the default DNS that comes with your CDN, it’s very difficult to switch to a better performing CDN in real time. Doing that would require both the knowledge of which CDN is the best option and the ability to rapidly configure DNS to steer traffic between providers. CDN providers don’t provide that data. 


Any CDN worth its salt has a 100% uptime SLA. Even so, outages are inevitable and more frequent than the providers care to admit. ( has an excellent piece about this.) 

When these outages occur, your content will go offline if you don’t have a way to easily fail over to a different service. Because the DNS that comes bundled with CDN packages is only designed to send traffic to one place, it can leave you without many options when that one place goes dark. 

Using an external DNS provider gives you the ability to automatically switch from one CDN to another in the event of an outage, keeping your content online and the revenue flowing. 


Remember at the beginning when we said that managing your DNS settings from within a CDN platform can save you some time and effort? That’s true, but only if you’re only using one CDN

If you’re using multiple CDNs, however, managing DNS can be a big hassle. Any time you want to shift traffic between providers, you have to go into each platform and manually reconfigure it all. And let’s face it: nobody wants to do that. Separate DNS configuration steps usually means that only a major change prompts any shift in wherever traffic is going. That’s how the CDN providers like it. 

The benefits of a separate DNS layer 

If you’re using multiple CDNs, separating out the DNS layer helps you optimize for the best of each provider through the magic of traffic steering. 

Want to optimize for cost? A DNS provider that sits apart from your CDNs can analyze the data in real time and automatically steer traffic to the cheapest option for that particular moment. 

Want to optimize for performance? Analysis of geographies, ISPs, devices and other factors can be fed into an automated DNS logic, which sends users to the best CDN available. 

Want to keep your content online in the face of periodic outages? Dedicated DNS providers can automatically fail over to whichever CDN is up and running at that moment, offering seamless content delivery across providers. 

Want to save time on DNS management? Using a single, fully automated DNS control plane across CDNs gives you the power to make necessary changes without the annoyance of manual configurations. 

Needless to say, NS1 is designed to do all of this and more. We leverage the power of DNS so some of the biggest, most consequential content platforms out there can deliver the lowest cost, best-performing, most resilient, easiest to manage operations available. Our advanced traffic steering options make it all possible. 

Learn more about application traffic optimization with IBM NS1 Connect®

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