When the distance between the server and a user increases, so does the latency, which is the time needed for the server to respond to a request. Due to the global nature of 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 works by delivering specific types of internet content. Known as static content: 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.

To effectively deliver this content, a CDN will strategically place servers at the exchange points between networks. 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.

Improved load times and latency

By distributing static content closer to the users, load times will be positively impacted. 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 from an SEO perspective, as search engines class it as a ranking factor.

The global positioning of most CDNs do not just improve load times but, also has a positive impact on 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.

A CDN will also help to improve your website’s First input delay (FID). Similar to TTFB, FID measures speed from a user perspective. It does this by calculating the amount of time between a user making a request on the website and completing it. FID and TTFB are Google ranking factors that fall under the umbrella of core web vitals.

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, and by implementing load balancing across several servers, a CDN can handle rapid boosts in traffic.

Although technology is more reliable than ever, things can still go wrong such as hardware failures and server outages. A CDN can handle hardware failures a lot 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’s key that the changes you implement are crawled.

Better Image optimization practices

Image files can cause many optimisation issues, especially when they are 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 has an impact on 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.

Improvements to your website security

Not only will response times be impacted by a CDN, but so will website security. The primary method of this is through 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.

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.

CDNs and the SEO implications

Choosing to integrate a CDN can feel like a very 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 CDN will effectively improve 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. In general, users should see an improved experience when interacting with your site, which can only be a good thing.

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 benefit they provide.