Reaping Maximum CDN Benefits for SEO

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As a marketer, you want to reach better ranking in the SERPs. Although Google’s requirements and designs keep changing, a lot of bloggers and online entrepreneurs rely on organic search, and it will stay this way. Before creating gripping content and building backlinks together with social media presence, you should care about speeding up your website, because it’s one of the best ways to improve Google index and rank your website higher. With a CDN (content delivery network), you can easily achieve faster speed and really improve your SEO.

What is a CDN (content delivery network)?

Some of web developers are even not familiar with the concept of CDN. This is a system of edge servers (also called PoPs, or points of presence) that are scattered strategically around the world. Edge servers store and cache copies of your website’s static assets (JavaScript, images, HTML). When a visitor opens your website, its assets are served from PoPs located as close to them as possible.

How does a CDN Work?

Say, you host your website in a data-center in New York. When someone from Europe visits your website, they will have to download your entire pages from the States. That will cause latency because of the distance the data has to travel. With a content delivery networks, a request is made for the initial HTML doc, but all page static assets are served from the closest PoP, for instance, in Amsterdam. A CDN can greatly decrease latency and minimize the risk of packet loss, which improves the quality of content delivery.

How does a CDN improve your SEO?

There are many misbelieves concerning CDN and how it affects your SEO, and we will discuss those in the post. But first we should understand how CDN is connected with SEO value.

  1. Speed is #1 ranking factor

Acceleration of website is very important, because a faster website means satisfied visitors. In fact, this one aspect affects many others, including bounce rate, time spent on your website, conversion rates and the entire user experience.

Since 2010, Google considers website speed as a ranking factor: we don’t know how much it matters, but it has a significant impact on user’s experience, so its weight will only increase with the time being. Especially today, when mobile devices account for more than 50% traffic.

Although CDN can greatly boost the speed of your website, you should still keep in mind that it’s not a versatile solution of your problems. It delivers your assets the way they’re set up on your page. Therefore, if you have many render-blocking resources, you can experience delays. Render-blocking concerns such assets as CSS and JavaScript that block the DOM, or keep a page from rendering until it’s downloaded and processed by the browser. A CDN will not fix it for you, so you should make appropriate settings on your origin server.

Here’s how you can fix render-blocking JavaScript:

  • If your JS is small, you can inline it.
  • Load the scripts asynchronously with the help of HTML async attribute.
  • Defer your JavaScript.
  • Move JS to the footer (however, it’s not always the best option)
  • Change methods to defer JavaScript

Now it’s time to fix render-blocking CSS:

  • Appropriately call your CSS files.
  • Use media queries to mark some CSS resources as not render-blocking
  • Decrease the number of CSS files unite your CSS files into one file, noting that this becomes less important with HTTP/2).
  • Minify your CSS (get rid of extra spaces, characters, comments and so on).
  • Use less CSS overall.
  1. HTTPS as the new golden standard

You can serve data over HTTPS with a CDN, even if you don’t run your main website over HTTPS. That cannot be done in the opposite direction, because you will get mixed-content warnings. A web server and CDN require different SSL certificate, so these are separate processes.

Since HTTP/2 was introduced (which requires HTTPS supported by browser), there appeared to be many performance advantages with using HTTPS. These benefits include HPACK compression, server push, one connection per origin and multiplexing. Therefore, HTTPS is not as slow as it used to be: it’s 20% faster than SPDY/3.1.

How is it connected with a CDN? Many CDN providers have encryption integrations including “Let’s Encrypt”. It allows enabling HTTPS on your CDN without payments. If you CDN provider supports HTTP/2, you can freely serve your assets via this connection, which will improve the quality and speed of delivery and overall page loading. Optionally, you can upload your custom certificate and enable HTTPS on your CDN provider.

If you haven’t switched to HTTPS yet, you can perform it in a 2-step process: sometimes it’s simpler to move CDN provider to HTTPS first, and then migrate your web server to HTTPS.

  1. Faster image indexing for SEO

A CDN network can boost image indexing in the SERPs. Although Google image search is often neglected, it’s pretty important for SEO, too, because it also helps to generate traffic. About 63% of Google image search results into website traffic, though this variable is different in every niche.

By hosting your pictures and photos on a CDN, you can make sure that they’ll index as quickly as possible, and Google will crawl them more often. There’s an evident correlation with ranking positions in Google search and traffic.

A pro tip: use a CNAME for your CDN URL. As a rule, developers have two options: 1) a shared CDN URL name, that’s created automatically; or 2) a custom URL. If you set up a custom URL with CNAME, you can point your assets to a subdomain on your domain, such as

Why opting for a custom CDN URL?

  1. With a custom CDN URL, you can implement a sitemap to check indexed images data in Google Search Console. With the default zone URL, this data is not visible, though you can still use URL search operator.
  2. You have overall control over custom CDN URL, and can change CDN provider easier saving the same URLs.
  3. A custom CDN URL makes up for better branding, because visitors can see image URLs, and it’s easier for Google to associate the domain.

If you use WordPress, and you see that your CDN images get de-indexed from Google Search Console account, there must be a sitemap structure problem with Yoast. You should add one snippet and the top of your functions.php file to activate image indexing from CDN domain. When you use this snippet, make sure you update CDN URLs accordingly.

function wpseo_cdn_filter( $uri ) { return str_replace( ‘’, ‘’, $uri ); } add_filter( ‘wpseo_xml_sitemap_img_src’, ‘wpseo_cdn_filter’ );

Debugging CDN myths

As we have mentioned before, there’s a bunch of misconceptions about CDNs suggesting that using this technique is bad. Let’s debug some of them.

  1. A CDN causes content duplication

That only happens when you set it up incorrectly. Here’s what you should consider:

  • Make sure you have a canonical header setup. It’s an extra HTTP header that’s added to CDN to inform Google crawler that the content on your CDN is just a copy. As soon as you add a HTTP header, images will start indexing normally, because crawler will be aware that these are copies and won’t replicate them. Most CDN providers have this feature, and it can be enable in one click.
  • Don’t forget about robots.txt file, because search engines scan the root of your website by looking for it. If the file is revealed, they follow instructions, but if no file is present, they scan everything. By default, most CDN providers won’t enable this, because everything is indexed. The canonical header truly helps. However, if it is enabled, make sure you allow everything to be crawled.

Here is an example of a robots.txt file on a CDN for allowing to crawl everything:

User-agent: *


Don’t forget to retain similar file structure when migrating to a CDN! Otherwise, there may be problems with images and Google indexing.

For instance, if your path looked like that before a CDN:

Afterwards it should look like:

This way, with a proper canonical header in place, you will make sure that images are indexed correctly, and you retain traffic in Google image search.

  1. A CDN is expensive

That’s not true at all! Some CDN networks are available for $0.04/GB, and there are free solutions, as well (though they’re not efficient enough). Some providers work with pay-as-you go system, while others prefer monthly payment – it’s up to you to choose the method. No matter which one you select, CDN is much more affordable than it used to be several years ago. The price is based upon bandwidth, but if your website tends to have normal traffic without spikes, you can end up paying less than you would for a cup of coffee.

  1. A CDN is hard to implement

If you are a beginner (means you don’t know a thing about CDN), you will need to dedicate an hour or two to the process of leveraging. But there’s a lot of information concerning CDN implementation, and many provides even have their proprietary WordPress plugins and integrations for every platform including Magento, Joomla, Drupal, Laravel, and Ruby.

Anyway, you can ask your provider to help: customer support service will kindly answer your questions and get you through the process of installation. Don’t hesitate to ask the company for assistance.

Now when you get the idea of how beneficial CDN is, you can guess that it’s useful for SEO. If set up correctly, a CDN can be a very cost-efficient method for accelerating your website and making image indexing faster.

Vadim Kolchev

52 publications

Vadim has graduated from Moscow Institute of Entrepreneurship and Law as finance and credit specialist. Prior to starting to work in hosting business directly, he occupied various roles in several companies, including but not limited to banking sphere and sports. As of 2015 he works for INXY Holding, with SpaceCDN being a vital part of the hosting branch of its business. Being tech enthusiast, he has started writing articles about dedicated servers, CDN, storage solutions and other hosting services long ago, and since then accumulated a lot of experience and knowledge in the field. Building hosting sales and support departments from scratch has added even more experience and knowledge and allowed to see the business from the inside and build required expertise. Now Vadim is CPO and COO of a successful hosting business. Having several important interviews and publications at platforms such as Hosting Journalist and Forbes, he continues to share knowledge about this branch of technology that has become not only his job but also a passion.

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