What is a Content Delivery Network (CDN)? And When Does it Make Sense to Use One?

Matthias Held Updated on 21.10.2020
7 Min.
Last updated on 21.10.2020

Your website, online shop or blog is getting more and more attention and visitors from all over the world? Great, that means you've already been doing plenty of things right! What if you find out in Google Analytics that your biggest fans and visitors are in New Zealand while your office is in London? This is where a content delivery network (CDN) comes into play.

In the vast ocean of digital "trends", it's hard to win over customers and stand out from the competition. As any business-minded person knows, customer loyalty is the key to your success. And the key to customer loyalty? A good user experience. 

Research carried out by Google came to the following conclusion: "[...] a one-second delay in mobile load times can impact conversion rates by up to 20%”. Over 900,000 mobile websites of varying sizes were tested in another Google study and the average loading time was 22 seconds on mobile devices. That's a hell of a long time to keep your users waiting!

So the first step is to optimize your website and content. If you're not sure how to optimize your WordPress site, first read our article on 10 most important performance optimization settings .

Your site is now optimized down to the very last line of code and your performance is still not up to scratch? Latency is the most likely culprit.

Latency is the measure of how long it takes for data to be sent from point A to point B. Suppose we send our website to a user in the same city. In this case, the latency will be quite low because the distance the data has to travel is short.

What is a Content Delivery Network (CDN)? And When Does it Make Sense to Use One?

If we increase this distance, however, then the time needed to send the data from point A to point B will be much longer. 

What is a Content Delivery Network (CDN)? And When Does it Make Sense to Use One?

How can we ensure our website loads fast for visitors? One popular method is to use a Content Delivery Network (CDN). First things first, let's find out exactly what a CDN is and how one could help you.

What is a CDN?

Firstly, I'd like to break the term Content Delivery Network down into its three parts: 

  • Content: The information you provide to your website visitors (webpages, video, image, etc.)  
  • Delivery: How this data is retrieved by the user
  • Network: The places where your data is being stored at any given time

Content Delivery Network is basically an umbrella term for a collection of servers at different locations, which are called PoPs (Points of Presence). Typically these are located in different countries around the globe. The locations are strategically positioned to be closer to a broader user base. In larger countries such as Russia and Brazil there are even regional and national (R/N) CDNs due to their size.

What is a Content Delivery Network (CDN)? And When Does it Make Sense to Use One?

The servers placed around the globe are called proxy servers or edge servers and store your data there (this can be optimized to cache only the most requested content if your database is very large). 

What is a Content Delivery Network (CDN)? And When Does it Make Sense to Use One?

When users connect to your website , they are redirected to the nearest server with the cached data. If the user requests data that is not yet cached, the proxy server will ask your originating server to provide the requested data.  

What is a Content Delivery Network (CDN)? And When Does it Make Sense to Use One?

You can control how the CDN caches your data by setting caching rules. Depending on which CDN service you use, there are several ways to do this. 

The result is a massive benefit for the end user. Especially in terms of the speed at which content can be loaded, due to lower data latency and higher uptime. This is because the number of users connecting to a single server is now distributed regionally. 

Do I even need a Content Delivery Network?

The main advantage of using a CDN is that you can make your data available to the user faster and more reliably. But you need to take into account your target audience and customer base. Let's look at two different examples: 

Example #1: Flower shop

It is very likely that the florist's customer base is largely regional. And unless the store is getting a shoutout from a Kardashian, we can assume that the network traffic (the number of people viewing the site at any given time) is fairly low. Even if we include the occasional overseas website visitor who may be planning to buy flowers on vacation.

This type of website would not experience a massive improvement by using a CDN - local load times are quite fast (unless your hosting server is on the other site side of the planet). And we can probably assume that the romantic vacationer from overseas is quite tolerant of the extra few hundred milliseconds of extra loading time.

Example #2: Video streaming service

On the other site has a video streaming service: 

  • Users in several countries
  • A large user base
  • Most likely large files being streamed
  • Thousands of competing platforms, which makes the user experience especially important for customer retention

For this type of service, the use of a CDN would bring great benefits, as all the above factors could affect the ability of the hosting server to send data to the user. Here is the reason for this: 

  • Users who are further away from the host server have longer waiting times, simply because the data has to travel a greater distance. 
  • If more and more people try to access your content, the server may end up running out of resources (processing power) to send this data back to your users. This is also called a "bottleneck".
  • The continuous requests of the streaming service to the server can then lead to a crash - this is called downtime. 

So how would a CDN help your servers run better? 

Speed - How a CDN can improve load time

First, the CDN of your choice would have servers in different regions, which means that your visitors can access the server that is closest to them. This would help with your loading speed. 

Depending on the configuration of your CDN, you may want to cache only the most frequently requested files. This is very useful if your site is very large, as it can reduce the cost of the data center. 

Distribution - How a CDN improves uptime

Since you now have a large number of servers around the globe, your website visitors will connect to the server that is closest to them. 

This means that instead of 10 million visitors in 10 countries, who all try to connect to a data center, there are now 10 servers available, each of which, for example, receives one million visitors. These servers are called edge servers (the proxy versions of your host server), and this solution is called "load balancing".

Security - How a CDN improves security

Websites (usually larger, popular websites) can be victims of a DDOS attacks (Distributed Denial of Service) This occurs when your server is overloaded with network traffic that prevents other users from contacting your site.  

CDNs can help with some aspects of a DDOS attack, but of course they are not a miracle cure:

PROS:

  • The CDN can redirect a large amount of network traffic by distributing it to different PoPs (Points of Presence). This means that the originating server is not overloaded and should not cause a failure. 

CONS: 

  • CDNs are only cached versions of your source server. Therefore, if your source server falls victim to a DDOS attack, you may not be able to access the data that is not yet cached in your CDN. 
  • In some sophisticated DDOS attacks, the attacker will actually use the CDN to cause the original server to fail. This is done by causing the CDN to make multiple requests to the originating server, which then brings it to its knees.

In this case it is good to remember that a CDN is a "content delivery network" and not a network defense.

How do I get a CDN for my website?

Okay, now you're convinced that you need a CDN. But does that mean that you now have to host your data in multiple locations and pay a fortune for it? 

CDNs have been around for a long time - since the 1990s to be precise. But like most technologies, the cost of them was initially quite high. Fortunately, that has changed and the options for implementing CDNs are now affordable and no longer witchcraft.

There are several providers that specialize in CDNs. The integration is then usually done via nameserver entries (which we also recommend) or sometimes also via WordPress -Plugins. Among the most popular providers are                                                

If you want to use these solutions, you will need to do some configuration to set the caching rules of the CDN. In many cases, yours host can support you with appropriate documentation and advice - or the CDN is already integrated into the hosting plan. We RAIDBOXES will soon have a CDN feature of our own that you can look forward to. 

Conclusion

A Content Delivery Network is a tool in the Internet ecosystem that has the power to deliver our content to the end user faster and more reliably. Some sites will benefit from CDNs, others will not. It is important to remember that a CDN should only be used in conjunction with good optimization and security measures to get the best out of your website visitors. 

Do you have any questions?

Do you use a CDN? And what are your experiences with it? Please leave a comment or contact our support team directly if you have specific questions.

Matthias is the Chaos Calmer at RAIDBOXES. As a plugin and theme developer, WordCamp speaker and active hosting community contributor, he can regularly be found at WordCamps and other WordPress events and is partial to a snack while snacking. If he's not there, he's somewhere with a lap full of cats.

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