How does… a content delivery network work?

We ask some of the industry's most knowledgable boffins to break down jargon to help you through those confusing meetings and indecipherable conferences. Here, George P. Johnson's Chris Hogben explains how a content delivery network works.

A crucial part of any successful website is optimisation – both visually with intelligent UI choices and through performance and architecture leveraged to ensure the user experience delivered is as good as possible.

Research shows that users expect a response within two to three seconds when interacting with software and websites, with anything over three seconds resulting in a noticeable loss in user satisfaction.

One of the key ways a website can be optimised is by using a content delivery network (CDN). A CDN accelerates the delivery of content to users while also adding another layer of security to your site, resulting in a better user experience and a safer site.

How does it work?

A CDN leverages a global network of web servers that host a cached version of your website in thousands of locations around the world, ready to deliver to the end user.

A cached website is a snapshot of a website copied from your host and distributed throughout the CDN. When the site is updated, the cached version will be updated on all the servers so that the user will still get access to the most up-to-date version of the site.

Since the servers are distributed globally, it means there are servers in every region enabling faster delivery of the content to the user. As an example, if you hosted your website in the US, and a user accessed it from Australia, it would take longer to request, process and deliver the content as the latency between the user and the host would be greater than a server that is based in the user’s area.

Why would you use a CDN?

The first reason is obviously speed, as mentioned above, the further your server sits from the user, the higher the latency and the longer it will take to load pages and stream content such as video and audio.

By having a faster website, you’re also helping improve your ranking on search engines, because they understand that users can quickly lose interest, and therefore they will give preference to websites that are quick to load.

A CDN becomes increasingly important when you have a media rich site or app, for example 1080p or 4K videos or live streaming where constantly stopping to buffer isn’t an option.

Another benefit of using a CDN is the added level of security you receive. Since the CDN servers store a cached version of the website, it means that they become a layer of padding between the end user and your server, filtering out malicious requests with what’s known as a Web Application Firewall (WAF).

Top tier CDNs will also offer DDoS protection. DDoS attacks are a form of cyber attack that seek to render a website inaccessible by flooding it with traffic.

GitHub recently made headlines for surviving one of the biggest DDoS attacks ever, thanks to Akamai, a company which offers a CDN. When you are leveraging a CDN, you’re able to better protect against these kind of threats.

Finally, redundancy is another benefit provided by a CDN. If your website isn’t hosted in multiple locations, there is a risk of the site going down if your host’s servers are affected, for example, by a blackout. With a CDN, if a single point fails, it will seamlessly redirect traffic to a different server so users don’t lose access.

A CDN isn’t a magical way to make your website or app faster – it is an important part, however it’s still crucial to compress content where possible and be clever in how your site is designed and developed. CDNs are an excellent tool for improving the user experience, ranking on search engines and the security of your site.

Cyber security is becoming ever more relevant all businesses and protecting user’s data is critical. CDNs offer an additional way to mitigate attacks and potential breaches to keep your users and data safe.

Chris Hogben is a designer at George P. Johnson Australia.


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