As technology advances, more and more companies distribute their website content over Content Delivery Networks (“CDN”), instead of hosting sites on a single server.
This new approach may lead to some questions about SEO and issues that could be of main concern are as follows:
- Sites distributed over CDN might seem to be hosted on multiple IPs.
- There are many sites using the same set of IPs.
- Sites distributed over global CDN might affect the geo-location.
According to Google engineer’s response, Google do not treat sites hosted on CDNs any differently and sites distributed via CDN will be crawled and indexed correctly. If the sites are distributed over CDN and are set up to be multiple hostnames that serve the same exact content (that is, to create a duplicate content issue), it’s strongly recommended to implement rel=”canonical” or another canonicalization technique to avoid the duplicate content problem.
One of the signals the search engines use to geotarget websites is the IP address. If the sites are distributed over a very large, global CDN, the sites might associate with many IPs over different regions and search engines may associate the website with an incorrect geographic region based on the IP address. For Google, the solution to such a situation is to set the correct geotargeting by using Google Webmaster Tools.
In accordance with Baidu’s Search Engine Guidelines, when discussing if the CDN will affect indexation, Baidu says that the way Baiduspider crawls sites is just like a user visiting the websites. Once visitors can access the site content, Baiduspider can crawl that content as well.
When properly designed and implemented, a CDN can improve access to the data it caches by increasing access bandwidth and redundancy and reducing access latency. For search engines such as Google, one of the signals the algorithms use to determine crawl rate is the server response as perceived by search engine bots. To distribute the site content over CDN properly not only improves the user experience but also makes the website more search engine friendly. All in all, we can say that the impact from using CDN on SEO is positive, so if you are now considering using CDN to distribute your content, just go ahead.