An introduction to CDNs and SEO benefits

When the distance between the server and a user increases, so does the latency.  

The latency is the time the server needs to respond to a request. Due to the global nature of Content Delivery Networks (CDNs), your site can be artificially moved closer to the user.

This will lead to less latency and, in turn, a faster loading site. But the question is, “what is a CDN actually loading?”  

A CDN delivers specific types of internet content known as static content, including HTML, CSS, JavaScript, and image files that stay the same for every user.

The CDN will automatically minify these files and store them cached and compressed ready to deliver to a user.

This process will usually require no server configuration on the back end and will eliminate the significant time needed to minify manually.  

A CDN will strategically place servers at the exchange points between networks to deliver this content effectively.

These Internet Exchange Points (IXPs) are primary locations where different Internet providers connect to provide each other with access to traffic originating on their networks. By connecting to IXPs, a CDN can reduce costs and transit times.  

What are the benefits of CDNs?

You will likely find a smattering of articles and discussions across the internet about why Cloudflare and other such CDNs aren’t beneficial for SEO.

The likelihood, however, is that those articles are written by people whose services aren’t set up properly, as mentioned by John Mueller — Google’s Webmaster trends Analyst.

In fact, using a CDN from a provider, such as Cloudflare, can offer a whole host of benefits for companies that want to strengthen their performance in organic search.

Let’s take a look at some CDN advantages in SEO and how it can improve your site’s organic search campaign.

Improved load times and latency

Distributing static content closer to users will positively impact load times. Users are more likely to stay on the page if it loads quickly, which will decrease bounce rates and increase the time on the page. This improved user experience will also help SEO, as search engines class it as a ranking factor.  

The global positioning of most CDNs improves load times and positively impacts latency. Latency is the time in-between a user’s action and the resulting response. By reducing the distance between the user and the website resources, latency will improve. 

Again, this improvement will only aid in SEO, as search engines use Time to First Byte (TTFB) as a ranking factor. TTFB is essentially the latency time for your website, so the lower this is, the better your ranking prospects will be.

Increased reliability and content availability

The distributed nature of a CDN means it can handle several exogenous challenges. As previously highlighted, website traffic can come in waves, a CDN can handle rapid traffic boost by implementing load balancing across several servers.  

Although technology is more reliable than ever, things hardware failures and server outages can still occur. A CDN can handle hardware failures much better than origin servers and provides an intelligent fail-over that gives uninterrupted service if one or more servers go down.  

This failsafe will have the SEO benefit of ensuring your site is operating and available to be crawled by search engines. This benefit is especially important if you are active in your SEO practices, as it is key that the changes you implement are crawled. 

Better Image optimisation practices

Image files can cause many optimisation issues, especially when delivered in JavaScript. The manual process can become quite involved and grow with the scale of the website.

Employing a CDN can make this process easier in many ways. The caching and compression already highlighted include image files.  

Most CDNs will offer an easy-to-use dashboard that allows you to control the caching policy.

This is important as every website is different and will undoubtedly place varying importance on image optimisations, such as page load speed and image quality. However, what cannot be argued is that image optimisation impacts search rankings.  

Just like FID and TTFB, your image optimisation policy will fall under the area of web core vitals.

The main part of this is the Largest Contentful Paint (LCP) on any page. This process is described as the measurement of how long it takes for the main content of a page to download and be ready to be interacted with by a user.  

A substantial LCP will have a detrimental effect on user experience and, in turn, a website’s performance in Search. Some more advanced CDNs also offer progressive rendering that loads a pixelated version of the image before replacing it with ever-increasing quality variants. 

Why load time matters for SEO  

Page load time matters for both users and search engines.  

Google states that pages should take less than a second to load, but research has consistently found pages that take longer than three seconds to load will suffer higher bounce rates.  

 The BBC found that it lost 10% of users for every second that it took one of their pages to load.  

 In fact, Google has long stated that page speed is an important factor in its ranking algorithms, and upgraded its stance on the matter in July 2018:  

Although speed has been used in ranking for some time, that signal was focused on desktop searches.  

Today we’re announcing that starting in July 2018, page speed will be a ranking factor for mobile searches. 

Other studies have found slower site speeds can affect conversion rates, as faster-loading sites tend to convert at higher rates.  

Walmart, for example, found that by improving page load times by one second, there was a 2% increase in conversions.  

You can read more about why page speed matters, as well as how to improve it on your site in this article.  

Improvements to your website security

Not only will response times be impacted by a CDN, but so will website security. The primary method is Distributed Denial of Service (DDoS) mitigation.  

A DDoS attack is one of the most common threats a website can face, so it is especially helpful that a CDN can help protect against it.

Most CDNs will also have more specific settings to further advance website security, such as forcing an HTTPS connection and even providing the ability to implement the HTTP/2 protocol.  

Moreover, CDNs can provide proper Transport Layer Security (TLS) encryption, a protocol for encrypting data sent over the internet.  

Encryption practices are important to prevent people from snooping on data being exchanged between a website and its users. 

TLS protocol provides three components to websites:

  • Authentication  
  • Encryption  
  • Integrity  

To enable TLS, a site must activate an SSL certificate and a corresponding key.  

This is necessary, as certificates contain files with information about the site, its owner, and the public half of an asymmetric key pair.   

Browsers and search engines typically have a list of certificate authorities they trust. If a website contains a certificate not approved by a browser, the browser in question might alert users that the site does not adhere to its security expectations.  

Furthermore, CDNs provide security to visitors as they connect only to the CDN, which means a site using an older or less secure certificate between the origin server and the CDN will not affect the user’s experience.  

CDNs also reduce file sizes

Another advantage of using a CDN is that they can reduce the overall data transfer amounts between the cache servers and the client, which means both latency and the required bandwidth are reduced.  

Although it might seem odd that a CDN can reduce files belonging to a website, this is done through a minification process.  

This works by reducing the size of code, namely the parts that humans can read and understand, as computers do not have the same requirements.  

Regarding file compression itself, GZip is a common method of compression and is considered best practice.

Many CDN providers have this enabled as a default, which can reduce file sizes by up to 70% of their original size.

Reduction in bandwidth costs  

Implementing a CDN will also decrease the amount of data the origin server must provide. This is a key benefit due to the nature of web traffic, for if traffic exceeds the agreed levels stated on your hosting plan, costs will be incurred.  

It can be argued that any money saved from additional bandwidth costs is now just filtered into the CDN, this investment will give a greater level of control over what is being spent and how.  

The relationship between CDNs and SEO

Integrating a CDN can feel like a difficult decision, with many technical parts to understand, not to mention the abundance of potential providers such as Cloudflare, Fastly, and KeyCDN. Most of these will provide a detailed guide on the setup and, crucially, how the implementation can be done without negatively impacting your SEO.  

Once implemented, the advantages of CDN use include effectively improving load speeds, security, and reliability. All of which have an impact on SEO. So, by employing a CDN alongside good SEO practices, your performance in Search could improve. Users should generally see an improved experience when interacting with your site, which can only be good.  

If you are interested in applying a CDN to your website, you can try out free versions of Cloudflare and Fastly products to see what CDN SEO benefits they provide.  

Further reading about CDNs by is dedicated to researching the latest technologies in both digital and SEO. You can read more about how you can use CDNs and more with our guides below.