Overview and limitations of using CDN for your websites

Ever since Google has considered page load time as one of the search engine ranking factor, websites started using CDNs to speed up their sites and improve performance. Typically, content delivery network (CDN) stores the cached version of static website content (such as JavaScript, CSS, images) in edge servers located in various geographical places. The intention is to serve end users from the nearest possible servers. Today, over half of the top 10K websites are already being served by CDNs and the usage is increasing rapidly every year. Since the files are served from the cache node servers and not directly from hosting company, CDN obviously has many benefits as it reduces the server load. Often doubts arise in the minds of site owners, whether CDN is viable for their sites and the issues that occur during server outages.

CDNs are not for every website

CDN is intended to reduce the distance between visitors & website server and facilitate the delivery of content faster through global network of edge servers. Using CDN for localized websites is not a viable option especially if most of its users are located in the same region as the hosting service. In fact, it results in negative impact on site's performance because of adding extra check point between user and the main web server.

Sometimes, CDN services become inefficient if servers offered by CDN are at a significant distance from the users. This means CDNs are impractical for websites that draw visitors from all over the world. Despite these limitations, some companies use CDN to reduce their bandwidth consumption, handle high web traffic loads and minimize the possibility of downtime.

What CDNs can do if the main server faces downtime?

While CDNs are not permanent solutions for downtime issues, it can still keep the web pages alive when the web server is down. This means there will be couple of minutes to work on the issue before users will notice. However, the visitors may not see the latest version of the web page, but they can see content that has been cached a few minutes back from the main server. While it is not a replacement to the hosting service, some CDNs facilitate their users to upload content directly. This allows the site to run even during downtimes, but with restricted features. Nevertheless, there is no guarantee that this would work as well, because CDNs are not designed for regular hosting and there can be outage issues even with CDN services.

Dealing with CDN outages

It is true that CDNs have a good reliability record, but they can be fallible too when downtime occurs. While using CDN service a regular redundant check on the website functioning is important otherwise the outage issue will be known only after the site goes down. When issues happen there is nothing that website owners can do but wait for the service to get back, which is the most undesirable and frustrating aspect. The damage that can happen during this downtime is much worse than the losses incurred by having a slow speed website without CDN. In such instances, the website owners can just forego using CDN services if it is not possible to effectively implement on their sites. Instead they can deploy an efficient monitoring service which tracks the entire site functionality along with the added advantage of alerting users during downtime.