Do Content Delivery Networks Really Help?


Lots of bigger sites these days are using content delivery networks (CDNs) to improve their loading speed. The general idea behind a CDN is that you are making a copy of some or all of your website content and putting it on fast servers around the world. So instead of all your website visitors getting content from one lonely server in the middle of Nebraska (which could be a bit overloaded if tons of people are trying to access it at the same time), the visitors can grab the content from any of your CDN servers that are closest to them.

Think of a CDN like a chain of grocery stores. For some unknown reason, I still love Chef Boyardee ravioli, and fortunately I can go get it at any grocery store because the manufacturer distributes it everywhere. No matter where I am in the US, I am only a few minutes from my favorite guilty snack.

But now imagine that the good Chef didn't distribute his tasty canned meat substitute to grocery stores. If the only place to get it were the manufacturer, I would have to drive hundreds of miles to a warehouse, parking would be a nightmare, and I'd stand in huge lines waiting to be served. No matter how big and efficient that main warehouse was, in most cases it couldn't be faster than my local grocery store. That's the idea behind a CDN.

However, I read this article recently claiming that CDNs don't correlate to faster page load times. The author shows a graph of the top 1000 retail websites in the world and plots the points of sites using a CDN versus sites that do not. There appears to be no real difference between the loading speeds of websites with or without CDNs. The author notes, "If CDN use automatically correlates with faster-than-average websites, this graph should look profoundly different."

While I believe the paper makes good recommendations, I completely disagree with the assumptions about CDNs. The author is trying to make the point that using a CDN does not automatically make a website faster based on the logic that CDN-enabled websites should be faster on average than non-CDN websites. This is incorrect - in many cases a CDN, implemented properly, will immediately make a website load faster. The only way to truly know how much a CDN helps is by measuring the performance of the same website with and without a CDN. There are so many other factors that go into the loading speed of a website, such as the number of objects (images, scripts, etc) that are called, the total size of all the objects, etc. With all these variables, it is unfair to simply plot CDN versus non-CDN websites and claim that the CDN sites should load more quickly.

The point the author wants to make is simple: a CDN is not a cure-all for a slow-loading website, and I wholeheartedly agree. However, for many large sites, a CDN alone can cause a substantial improvement.

Read more about web page speed from Google.

Jeff Robertson

Jeff Robertson is a digital marketer and an online development expert with experience stretching back to dial-up. He is partner and Chief Technology Officer at Carbon8, where he helps bridge the gap between the technical and marketing worlds, as well as oversees technical infrastructure.

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