Content delivery network (CDN) - SEO ad­vant­ages

The goal of search engine op­tim­isa­tion is to gain the best possible placing in Google’s organic search results list. Achieving this requires strong content, a solid backlink profile, and a con­sist­ent social media presence. But it is also technical aspects that are very important, too. Google demands from website operators that they design their offers as user- and search engine friendly as possible. A content delivery network (CDN) can help with technical op­tim­isa­tion, par­tic­u­larly when it comes to the likes of per­form­ance and loading speed. Here, we outline how you can gain an SEO advantage with the help of a CDN.

A CDN is a net of servers that are spread globally across various data centers and connected with one another. An outgoing server keeps a website’s original and current content ac­cess­ible. The job of the so-called replica server is the flexible dis­tri­bu­tion of content. To do this, files are sourced from the original server. These are then ‘mirrored’ by the replica server, and then regularly checked to be kept up to date. When a user visits the website, he/she will then be auto­mat­ic­ally connected with the server files that are geo­graph­ic­ally closest to him. The shorter the distance between the file and the server, the faster the loading time of the website will be. It is also the case that the buffering of data on the CDN servers has a positive effect on per­form­ance. CDNs are primarily used for static website files like for example images, JavaS­cript, and CSS; the selection and extent of files is chosen by the user. CDNs can be employed above all with the streaming of audio and video content, and with web projects that have a wide reach. More in­form­a­tion on this can be found in our digital guide article ‘What is a content delivery network?’.

The term SEO is often heard in con­nec­tion with content delivery networks.  This is because CDNs offer a clear advantage when it comes to search engine op­tim­isa­tion – a CDN sig­ni­fic­antly improves a page’s loading speed. And this is un­doubtedly an asset. The likes of Google, Amazon, and Yahoo have all un­der­taken studies to see what effect PageSpeed has on consumer and visitor behaviour. Amazon found that an extra load time of just 100 ms (mil­li­second) caused a 1 per cent drop in sales, while Google dis­covered that a 500 ms increase in load time resulted in 20% fewer searches. What these figures reveal is that longer loading times lead to unhappy users and consumers, and in the worst case, none at all. This is of course something that should be avoided at all costs.

A website’s loading speed is hugely important for SEO success as it has an influence on many different para­met­ers, such as the bounce rate. If it is the case that a page loads slowly or not at all, then many visitors will simply leave the website. This leads to an increase in the bounce rate, something which is neg­at­ively re­gistered by Google. Even if the bounce rate isn’t an official ranking factor, it does still have an influence on other eval­u­ation stat­ist­ics, such as the amount of returning visitors and denoting what kind of website it is.

Bounce rate aside, long loading times can also have negative effects on the length of stay and the con­ver­sion rate – in short, it takes away from the whole user ex­per­i­ence. Google has compiled a list of over 100 different ranking factors with the aim of creating the ideal user ex­per­i­ence.

Be careful though: Even if a CDN improves the page speed, it is still no remedy for per­form­ance-based mistakes that may have already been made. An example of this are page resources that prevent rendering. This is often the case with JavaS­cript or CSS files. Mistakes like this can be addressed with tools like Google’s PageSpeed Insights. More on the topic of op­tim­ising loading speeds via CSS com­pres­sion can be found here.

The fact that a CDN can bring about sig­ni­fic­ant benefits regarding SEO does not mean that the whole subject is immune to certain myths and false­hoods.

Duplicate content becomes a problem

One falsehood that is often heard is that using a CDN can lead to the creation of duplicate content; something which is not viewed fa­vour­ably by Google. Search engines appraise duplicate content neg­at­ively because it is of no value to users. It is possible that a CDN can cause the creation of duplicate content, but by following a few rules, this can be easily avoided.

• Canonical Header: Every CDN user should in­cor­por­ate a so-called ‘Canonical Header’. This par­tic­u­lar HTTP header lets Google know that the content in the CDN is just a copy. Most CDN providers will offer a cor­res­pond­ing feature, which allows you to integrate such a header in just a few clicks.

• Robots.txt file: When the Google bot scans a website, it is looking for robots.txt files. This allows website providers to set down the guidelines which the bot should follow for scanning content – and which of them should be entered into the index. This then allows you to avoid duplicate content. If there is no file, then the bot will simply scan all the content. Usually it is the case that CDN providers will not activate the robot.txt file. Everything will be scanned, but the canonical header is usually enough to prevent duplicate content being created.

Using a CDN is expensive

There are numerous providers out there that offer content delivery networks across a whole spectrum of uses. Everything is available: from the expensive en­ter­prise package to the much cheaper solution for small to medium web projects. At the end of the day, the idea that a CDN solution has to be expensive is in no way true.

Some packages are even available com­pletely free of charge, e.g. the beginner’s offer from Cloudfare. Others are a bit more expensive, such as Amazon Cloud­front or Akamai, which are both well tried and tested. Amazon charges per gigabyte, while Akamai will provide a price quote upon request for in­di­vidu­al projects. There are even cheap CDN solutions for WordPress projects.

Help setting up a CDN

From the point of view of a layman, the principle of a CDN may not always be im­me­di­ately clear – but at the same time the setup is by no means rocket science. Depending on the provider and the type of package, support will be offered through­out the im­ple­ment­a­tion process, and there is also a lot of in­form­a­tion online. The most important job for the provider is to decide which files should be con­sidered in the CDN. From here, the ap­pro­pri­ate con­fig­ur­a­tion follows, which looks after which file requests need to be sent to the CDN. Nowadays there are also plugins that assist with the in­stall­a­tion, mainly aimed at larger content man­age­ment and shop systems.