10 questions to ask when evaluating CDNs

In my last blog post, I discussed why you should use a content delivery network. But after you’ve decided to start using a CDN, you’ll need to pick out the right CDN for your business.

CDNs have been around since the late 1990s, but the industry is changing, with CDNs like Fastly taking advantage of improved hardware and new open source tools to create innovative content delivery solutions.

With a more modern CDN, you can improve your site performance, accelerate content delivery, and get real-time insights. But with a legacy CDN, you might be paying a lot of money for a content delivery solution that doesn’t have the features your business needs — or has a lot of bloated features that you don’t need to be paying for.

Research any CDN you’re considering carefully before making your decision. Here are some questions you should ask during your search.

What kind of content can it handle?

If your site is primarily made up of simple text and images that don’t change frequently (and therefore don’t require many updates), then you’re in luck, because all CDNs generally handle static content. But if your site is more complex, comprising dynamic content (like users' personal data) then you need a CDN that is capable of dynamic content acceleration. There's also category of dynamic content that can be cached, but most CDNs can't cache it — this content is event-driven, or based on an action from either a human or machine (for example, frequently changing content like news headlines, prices, stock quotes, sports scores, and APIs). If your site or application features this type of content, you'll need a CDN that can cache it at the edge. Also, if your site has a lot of video content, make that sure your CDN can handle streaming and on-demand video — or that they partner with a video hosting platform to deliver content. Whatever CDN you choose should be able to cache all of the content you need cached.

What regions does it serve?

First, ask yourself where the majority of your customers are located. Does the CDN have points of presence (POPs) located geographically close to the majority of your customers? When searching for the right CDN for your business, make sure it has POPs in the right locations, and has a sizeable network as well to ensure that content can reach your customers quickly wherever they are.

What kind of hardware does the CDN use?

A CDN using faster, more powerful hardware to build their network can offer your company better page load speeds and better site performance. For instance, look for CDNs that use solid-state drives instead of traditional spinning drives. With solid-state drives, a CDN can fetch cached objects faster and handle more requests per second, which means users get your content more quickly.

What’s the level of support I’ll get?

How reachable is the CDN support team? Are they available during standard business hours only? Are they accessible by phone, email, chat? When you report an issue to the CDN support team, how quickly do you get a response? The longer it takes to fix your issue, the longer your site is not performing optimally. You want a support team that will respond quickly, no matter what time of day it is. A truly excellent support team will find and alert you to issues before you even know about them.

Is it self-provisioning?

Do you have to speak with an account rep, or can you get started on your own? Look for a CDN that lets you sign up and begin testing their services right away. This will offer insight into that CDN’s features, and will give you a clear picture of whether it’s right for your site.

Does it offer flexibility and control?

Is the CDN customizable? With some CDNs, you’ll have to work with an account rep to make any changes, meaning your team won’t be agile and adaptable enough to respond to issues as they happen. A more flexible, customizable CDN is built on a language that allows you to configure settings yourself, with no wait times. Fastly, for example, is built on Varnish, the dynamic web accelerator, creating a transparent solution that lets you deploy changes quickly. Varnish Configuration Language (VCL) allows you to create specialized configurations for more intelligent caching and run application logic at the edge. Because Varnish can load and unload these configurations on the fly, you can make changes to your site and deploy them instantly — which means no waiting for maintenance windows and no server downtime.

This is especially important if your site and/or application features the frequently changing event-driven content discussed earlier in the post. If your business operates in real time and if you aim to deliver the freshest content to your users, you need to be able to configure changes immediately and purge content through your CDN in real time. When evaluating CDN options, real-time configuration and purging is a must.

What kind of analytics are available?

How much information does the CDN track? Can logs be streamed to third party apps and tools? You should be able to see what is going on with your CDN at all times, and should be able to track information such as the percentage of requests per second delivered from cache, total requests, hit ratio, errors, hits, hit time, misses, and miss time. Your CDN should also show you both historical stats and real-time data.

What kind of integrations are available?

Does the CDN you’re looking at offer integrations with other companies? Do they have an open API? If you’re using managed hosting for your own origin servers, you need a CDN that will work with third-party services, such as logging tools, Heroku, and Google Cloud Platform.

Are my competitors using it?

If your competitors (or other companies within your industry) are using a CDN, test how long it takes to load your site versus how long it takes to load your competitor’s site, and look at what else your competitors are doing well (or not doing well) in terms of serving content. Will using the same CDN as your competitors help you stay competitive, or do you need a better solution?

How will the CDN work with my existing stack?

The best content delivery network will act as an extension of your stack and analytics dashboard. The right CDN will ensure a seamless transition — it won’t feel as though you’re using a third-party vendor, but rather as though you had your own CDN built into your site’s existing infrastructure. Look for a CDN that has an API that offers an easy integration into how you already work. You shouldn’t have to change how you do things to cater to your CDN.

It will take time to properly research the various CDNs options available, but it’s worth it to make sure you select the best CDN for your company’s needs.

Anna MacLachlan
Content Marketing Manager

5 min read

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Anna MacLachlan
Content Marketing Manager

Anna MacLachlan is Fastly’s Content Marketing Manager, where she talks to brands and partners to tell stories about scale, security, and performance. She received her MA in Comparative Literature from NYU and loves megafauna and mountains.

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