The myths of using a content delivery network (CDN)

In today’s competitive online world, it’s essential for companies to offer reliable, secure and seamless customer experiences online. Internet performance is key to this, encompassing all aspects of the users’ experience from website speed to trust.

Companies face the dreaded question; “how do we make our website faster and more reliable?” on a regular basis. There are many reasons to improve the reliability of your site – from it being the cause of customer complaints to combatting visitor abandonment.

Utilising a content delivery network (CDN) provider is one way to improve site performance, especially if customers are distributed all over the world. As many companies go global it is becoming increasingly important that they don’t have to deploy and manage a data centre in every area.

When applied appropriately, CDNs can deliver impressive performance improvements. However, buying a CDN is not as simple as it sounds, nor is a CDN an automatic cure for all performance issues. Many technology professionals still believe in some common myths, often perpetuated by the largest and most popular CDN providers.

Here we reveal and bust the top CDN myths:

Myth 1: A CDN solves all performance and availability concerns

A CDN is great for serving static content like images, videos, style sheets, and even javascript files, but typically CDNs don’t replace a web server. CDN providers generally source or copy the content from your “origin servers”, either through a special plug-in or by referencing a list of content URLs specified by you, the administrator.

It may be feasible to host your main HTML structure page in the CDN, but most organisations host that key index file on their main server. Overall, dynamic content, that generates unique experiences for each site visitor, usually isn’t a good fit for a CDN. So if you have an application on a site that leverages a database, it’s not likely that a CDN can copy and serve that content.

Even with a powerful optimised CDN deployment, there is a lot of content that will still be hosted on the main web server. For that main hosted content, you should at least deploy redundant servers geographically separated with failover capabilities. For example, traffic management techniques can help to optimise the availability and performance across more than two locations, perhaps even utilising a combination of physical and cloud hosted data centres.

Myth 2: One big CDN provider is all I need for my global presence

Large CDN providers boast about their huge global networks and assert they are the only provider you will ever need. It’s true that some do have large global networks, but just because they have a presence doesn’t mean they’re the best option for you in every geographic area for all content, all the time.

No single CDN provider can deliver excellent performance all of the time, everywhere. Technology just isn’t that reliable. Therefore, a multi-CDN strategy is essential when building a high-performance global presence. In fact, it can require up to five CDN vendors to get the best availability and speed in all markets.

If you are set up to leverage more than one CDN, your site will not only remain operational if a problem arises with one of the large CDNs, but you can distribute traffic to your other CDN providers and still maintain many of the performance benefits.

Having the ability to allocate particular and different CDNs for different locations can dramatically improve your site’s performance in specific regions. For example, in some regions, one CDN provider may perform better than another.

Properly utilising multiple CDNs can save money in addition to improving worldwide performance. Using multiple providers gives a company leverage in negotiations and provides the ability to target specific geographic areas and services, allowing them to purchase only what they need from each CDN provider.

Myth 3: The free or really cheap DNS from my CDN is all I need

While it may seem convenient and cost effective to use the DNS offered by your CDN provider, you are likely paying the price in unexpected areas. Large CDN providers may try to lock you into only using their services by making it difficult to load balance to multiple endpoints outside of their network. This takes away the flexibility that you would have with multiple providers and makes it difficult to scale, add another CDN, or adapt to fluid business requirements. It also prevents or makes it difficult to provide traffic management services for all the other content not served by the CDN, such as the origin servers and dynamic content.

In addition, if your DNS is running on the same network as your CDN and if there is a problem, not only does your CDN go down, but your DNS does too, making it impossible to access your website. A great example of this was in in 2011 when major websites like Facebook experienced downtime when their CDN faced DNS issues.

Overall, be wary of the CDN provider that implies that their DNS services are hosted on their same vast worldwide CDN network and promises that they can provide all you need because their offering is so large. There’s no guarantee that they will be able to deliver excellent performance 24/7 all over the world.