What Problems to Identify Before Choosing a CDN
January 7, 2016 | Robert Gibb
This is the first post in a series that covers all 6 steps of the CDN Framework – a guide designed to help you acquire and maintain the best CDN solution possible.
Before choosing a CDN, or an alternative to your existing CDN, it helps to identify problems with your website or current CDN. Investing time in this type of review will help you choose the absolute best CDN for your evolving needs.
In this post we’ll direct common problems that businesses with and without a CDN solution face. We’ll then help you determine if a new CDN can help you resolve these problems. After reading this post and performing any necessary tests and research, check out step 2.
Common Problems for Users Without a CDN
Businesses with an owned online presence typically start investigating CDNs after identifying one of two problems: slowness or downtime.
Because these problems lead to brand degradation and revenue loss, the need for a CDN solution becomes urgent. Growing businesses are especially vulnerable to the impact of these problems:
Consider a business that makes a bold appearance on a widely televised news channel. A compelling link with a special offer is put at the bottom of the screen. Viewers flock to the website in an unanticipated volume. The first thousand viewers that hit the website experience slow loading times. The remaining viewers experience nothing at all (downtime).
After such an event, many businesses would feel pressured to choose a CDN the next day or the day after. But this would be the wrong approach. By making a decision out of urgency and fear, the business could get wrapped up in an expensive contract, or worse, an annual contract with a fledgling CDN.
To avoid replacing one problem with another, identify the causes of performance-related problems.
Slow Loading Time
If your users are experiencing slow page load times, implementing a CDN could only be a “band-aid” fix rather than a complete web performance fix. To figure out why your pages are loading slow, start by running a test with ALL of the following performance testing tools:
The GTmetrix test makes it easy to identify content-related problems in the “Type” column:
Screenshot: A sample GTmetrix report with server and content recommendations. Ideally, before choosing and implementing a CDN, you want to achieve a “green” grade for all content-related recommendations.
Content delivery networks can deliver both optimized and unoptimized content, but you only want to deliver the latter. Delivering optimized content will not only improve page load times, but also help you save on CDN bandwidth costs.
First make the optimizations you know how to, then run more tests to see the impact they have. Once you’ve completed all the optimizations you know how to, hire a web performance expert to complete more complex optimizations. Run tests again, and, once your content is fully optimized, start your search for a CDN.
If you’ve experienced downtime, or simply want to prevent downtime, implementing a CDN is almost always a good move if you have a lot of static content.
Static content, compared to dynamic content, is content that doesn’t change based on user. Every user experiences static content the same. Examples of static content include images, audio files, video files, text files, and .html pages.
Related Blog Post: The Difference Between Dynamic and Static Web Pages
If you’ve ever experienced downtime, you probably know what causes it. But for those who don’t:
Downtime occurs when your server becomes overloaded by serving too many requests at once during a peak traffic event (like a Black Friday sale or getting mentioned in the news). Under such heavy load, it’s not unusual for your website to crash or become unresponsive.
One of the best ways to know if a CDN can help you prevent downtime is to perform a series of load tests on your website. With load testing services like Loadster, performing these tests is relatively easy. They allow you to see how many users your website can handle before an unacceptable page load time is reached or downtime occurs:
According to Andy Hawkes, Founder at Loadster, “Load tests simulate a large volume of users hitting your site in the same way real users would. It’s essential that the test be designed to simulate realistic behavior as closely as possible: All requests to your server, both dynamic and static content, should be included in the test.”
Hawkes recommends running two load tests to determine the potential benefits of a CDN:
- The first test should include both dynamic and static content. Gradually ramp up the simulated user load over the course of an hour or so until you hit your site’s breaking point.
You’ll know when you hit the breaking point because your site’s response times will become unacceptably slow or will start having errors (503 or socket timeouts are among the most common). Keep track of the test results and the number of concurrent users at which your site broke down.
- Run a second load test that’s identical to the first test in every way, except that it EXCLUDES static content (images, stylesheets, etc.) that could be offloaded to a CDN. Ramp up the user load gradually at the same rate as in your first test. Take note of the site’s breaking point in this second test as well.
Hawkes concludes: Comparing the breaking points of the first and second tests will tell you how much potential benefit there is to using a CDN. If your site scales significantly higher without static assets, a CDN is likely to be a great investment.
Common Problems for Users With a CDN
Problems can arise with your current CDN provider in weeks, months, or years after signing your initial contract.
Problems experienced within weeks or months are often due to the provider under-delivering on its promise. This “promise” includes statements made on the provider’s website (best support, fastest response times, etc.) and in the contract (service level agreement).
Problems experienced years after are often related to price and lack of features. For instance, a provider that satisfied your needs at the start may not be generating the features you now need to scale. In addition, the provider could now be charging you more for a platform that’s stayed relatively the same over the years.
Here are the most common problems that cause a business to start researching other CDN providers:
- Unfavorable pricing
- Poor performance
- Poor support
- Lack of features
Identifying these problems, and the reasons behind these problems, will help you choose a better CDN moving forward. If you choose a new CDN without investigating problems with your current CDN, you risk getting stuck with an inadequate CDN all over again.
There are three issues related to CDN pricing: lack of transparency, bandwidth costs, and feature costs.
According to Dan Rayburn, EVP of Streaming Media, there’s a lack of transparency in regards to CDN pricing. “In my experience,” he says, “it’s not uncommon for a customer to receive a statement from their provider that says X amount is owed this month without any specific breakdown of services used.”
As a CDN customer, you should know what every charge on your bill means – and you should expect it. If you’ve been charged ambiguous fees, and, furthermore, have a hard time getting in touch with billing to understand the charges, there’s a problem.
According to Steve Lerner, Senior Member of Technical Staff at eBay, Inc: “Bandwidth pricing has come down to be close to transit pricing, so CDN decisions aren’t based so much on bandwidth economics but on efficiency and performance.” This is true, but as a CDN provider ourselves, we know that bandwidth pricing is still a pain point.
Fortunately, CDN bandwidth is starting to become commoditized, making it easier to negotiate pricing. Because of this, you should speak to your CDN provider before choosing another CDN, especially if bandwidth cost is the only problem. It’s always unfortunate and inconvenient to have to leave a provider you like because of bandwidth pricing.
Additional features that support new best practices for the open web should be supported at minimal cost. Take SSL for instance. As we found in some brief research, securing CDN content can be as little as $99 and as high as $1500.
For something that is becoming a web standard – and is already a ranking signal for Google – a feature like this should not cost an exorbitant amount. (The provider should even offer a free shared SSL option for smaller companies.)
If you believe your provider is overcharging for SSL and other common features, a switch may be in store.
Poor performance is any network-related issue that negatively impacts your website and bottom line. It’s often related to downtime or high latency.
While it’s uncommon for a CDN to experience a complete outage, it does happen. What’s more common is for a single edge location to experience downtime. In either case, if your CDN has experienced consistent downtime that has caused you and your users frustration, you may want to start researching other providers.
Some ways to find out if your CDN is experiencing downtime is to 1) draw correlations between user complaints and your CDN’s status pages (here’s our status page), and 2) schedule regular synthetic monitoring tests for CDN objects.
Related Blog Post: How to Test and Benchmark CDNs
Compared to downtime, high latency is often less of a problem. This is because top providers tend to achieve around the same average latency. Testing by Cedexis shows that average latency is around 60ms:
But latency varies based on location. While a user in the United States could experience latency of 60ms, a user in China could experience much higher latency.
Latency becomes more of a problem when your website begins to attract a wider audience – an audience that your current CDN doesn’t cater to. If this is the case, you can either load balance your current CDN with a regional CDN, or choose a different CDN that serves a global audience.
Related Blog Post: DNS Load Balancing - Comparison of 4 Services
Some CDNs are faceless. They give you a network, but no personnel to help you effectively leverage that network. According to Dan Rayburn, it’s the CDN’s duty to do the following:
- Hold your hand through initial setup
- Show you how to interact with the control panel
- Offer transparency through status reports
- Provide near-instant support in your preferred format (phone, web chat, written tutorials)
If your CDN is not providing this level of support and you’ve had support-related issues in the past, you may want to consider choosing a new CDN.
Lack of Features
Different people have different ideas of what features are needed to make a CDN great. But these don’t matter as much as the CDN features you need to deliver a great content experience. Definitely leverage expert recommendations, but don’t abide to a single recommended feature set when making your decision.
For instance, these features are considered important by Ilya Grigork, a web performance engineer at Google who’s adamant about making secure connections fast:
If you’re delivering HTTPS-enabled pages, many of these features could be very important to you. But if your bottom line doesn’t rely on delivering secure pages, these features may not be as important.
Related Blog Post: The SSL Performance Myth, and Tips for Making Secure Connections Fast
All this goes to say that no one chart can tell you what features your CDN should have. Indeed expert guidance like this helps, but only you can determine what features are important to your business. In our follow-up post, we help you discover what these features are, then give you several resources to find a CDN that has these features.