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Must Know SEO Practices for Content Delivery Networks (CDNs)

William Johnson
Must Know SEO Practices for Content Delivery Networks (CDNs)

A content delivery network (CDN) definitely wins the SEO battle when it comes to page speed optimization techniques. Server location does matter a lot for search engine rankings and there are issues with internal web hosting.

Plenty of discussions, how-to-guides and articles supporting CDN usage are already all over the Internet. So, let us not add one more to it. Instead, let's look at how to make the best use of a CDN service without allowing your SEO to suffer.

Installing and configuring a CDN on your website need technical expertise and some ground-up activities. Implementing a CDN on your website requires that you know what values and what devalues your overall page speed optimization so the CDN can boost its performance. Setting up a CDN is not a straightforward process, and doing it wrong can hurt your SEO to a large extent. There are profound examples of it.

Considering most of us know about CDN and its benefits, let me take you through some of the preparatory SEO guidelines that can help you maximize CDN investment. Following them will ensure that you don’t run the risk of losing all your visitors coming through Google image searches.

Step#1: Set up CDN using your own subdomain

In your DNS setup, create a ‘custom domain,’ preferably a sub-domain for your website, like and use that as a CNAME. This ensures that CDN service exists on your own subdomain instead of one of the CDN provider’s subdomains, such as If you are not sure what this difference signifies, it is better that you ask the provider if they can install the service on your own subdomain. Most of the popular CDN services can be set up the way you want.

Enabling CDN using your own subdomain keeps the service proprietary to you and points SEO values of the CDN based resources to your root domain – instead of This approach maintains or even increases domain authority of your main site. This in turn boosts your SEO rankings. And of course, you are not bypassing your domain value to a third party CDN site while improving page speed.

Step#2: Be consistent with the file names and their paths

Sticking to the file naming conventions always pays off. Even if you opt for a CDN service or do some technical changes in your website files, the basics should not change. For example, you have an image at and your CDN provider renames the path to or changes the entire folder structure so that your image file appears as This may result into 404 errors for those old image paths unless automatically redirected to new paths.

If the pre-CDN path of your image file appears as, your post-CDN file path should look like Maintaining the file-path naming conventions avoids unwanted 404 issues and protects your site from negative SEO impacts.

Step#3: Use Webmaster tools to your advantage

Use Google Webmasters Tools and Bing Webmasters Tools to further control your geographical target; it does not matter the location of the IP address of your CDN provider is a different one than of your default place. This step is important as you don’t want search engines to automatically target a different geographical location (based on CDN provider’s IP address) than your intended territory. Most of us know that search engines prefer locally hosted websites.

Setting up and verifying your CDN subdomain in GWT is easy. It also allows you to remove or block certain URLs (pre-CDN or post-CDN) based on your specific needs. Following the Google Webmaster guidelines on geo-targeting basics negates any discrepancy in SEO objectives and adds values to your localized SEO effort.

Step#4: Be sure to add Rel=Canonical tags

A CDN is generally known for hosting or caching website resources like image files, CSS, JavaScript and video files that are heavy in size. However, if you host the entire site on a content delivery network you may run into a duplicate content issue. For example, if the pre-CDN page URL of your “About Us” section is, the post-CDN page URL would look like These two separate URLs pointing to the same page may result in severe SEO issues having duplicate page content.

 Using rel canonical tag can avoid this duplicate content issue. Ensure that you use as a canonical or absolute URL path on the page and apply the same process throughout the other pages hosted in CDN server. Following this approach will help Google to identify the preferred URL path that you wish to be recognized, indexed and shown in the search results. This saves you from losing existing search engine rankings and link juice from previously indexed pages.

For instance: Previously, when introduced “Amazon CloudFront” – a CDN service introduced by Amazon for their website pages, they ran into similar duplicate content issues. Later on Moz had to throw 404 error pages in CloudFront and avoid duplicate content issue. Since Amazon’s CDN don’t cache 404 pages except images, the problem got resolved in few days. The Moz people also had to invalidate every page that was already cached and indexed by Google by using page removal process of Google Webmaster Tools.


Using CDN service is only helpful if it does not harm your SEO efforts. Therefore, a CDN provider needs to follow the best practice CDN installation methods that not only improve page load speed but also render positive effect on search engine rankings.

Do you have experience using a CDN? Let us know about it in the comments.

William Johnson belongs to the most creative field of digital media: web design! Currently, he is obsessed with the latest trends in e-commerce development, online marketing, Magento eCommerce and lots more. William also runs free consultation programs on web designing tips, Internet marketing trends and more for his set of readers. Follow him at Google+ and Twitter.
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Either just recently joined or is too shy to say something.

Great write-up, thank you, will need to take it all into account. I tried doing some testing with and , cloudflare has definitely increased the load speed (even the free plan), but I do not want to assume that immediately means better ranking.
Jyoti Thapa

An experienced member who is always happy to help.

A proper use of CDN can really help you decrease that page loading time and bounce rates, thereby increasing your page rank in various search engines. You get better ranking all over the world and increase your website's visibility, hence you get more impressions and better ranking. I suggest you to properly install the CDN, or else you might have negative impact as well. You need to carefully optimize your CDN settings for performance and fresh contents, especially if you run an ecommerce websites. Try to check webpagetest for First Byte Time which should be under 500ms. Try checking Google page insight for the server response time which should not have any issue. Page caching time on edge servers of about 24hours to 48 hours should be best for performance and fresh contents.

Either just recently joined or is too shy to say something.

I cant believe i had no idea about CDNs! i was aware that loading times
could affect bounce rates but i did not realize it would also affect
rankings. looks like this is something i am now going to have to
consider, many thanks for great article.
William Johnson

Provides valuable insights and adds depth to the conversation.

Thanks for your feedback Vikas. Yes, CDN has both positive and negative effects on SEO. One needs to know how to avoid the negative implications and get the things correct.
John Martin

Asks great questions and provides brilliant answers.

great article william. I´ve few clients (e-commerce) and their sitemap.xml use images urls to cdn address. GWT usually blocks and don´t index the images so I ask to developers use oroginal url in sitemap. Do you think this is the best way?
William Johnson

Provides valuable insights and adds depth to the conversation.

John Martin
SEO Martin: Yes, but that will not stop Google from indexing your cdn based image URLs. In fact that will cause duplicate URL issues for the same images leading to deindexing of images in Google search. You may need to perform a couple of steps: 1) Confirm CDN Subdomain Ownership In Google Webmaster Tools and 2) Switch XML Sitemap Image URLs To Point To CDN Subdomain. For details please read this article:

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