CDN (Content Delivery Network)

The Content Delivery Network is acceptably and commonly known by its abbreviated form, CDN, and is a system of servers acting within a geographic framework that deliver expedited web content to the end-user.

CDN also provides protection from heavy traffic surges, and works on the principle that the closer the user is to the CDN server geographically, the faster the content will be delivered.

How does CDN work to deliver content to users?

A CDN typically consists of a global network of servers. When a web user enters a request, the servers nearest to the user responds. The network is dispersed geographically, so the originating CDN copies the website information/data/pages and caches them, before redirecting the data to the CDN that is closest to the user.

Communication between CDN servers continues, ensuring that content is delivered in its entirety, even if it has not been cached previously.

Complex algorithms are used to determine how content should be delivered to the end-user, and locations are the most commonly-used element. This is largely due to the cost reduction and increase in performance that using the closest geographical server gives, but can also depend upon the type of information required.

Most CDN providers deliver their services over PoPs (Points of Presence) dependent upon the preferred coverage, and these can be varying or defined.

The delivery of content via a CDN is virtually unnoticeable by the end-user. One of the biggest giveaways to access of CDN, and re-routing of information, sometimes referred to as ‘bouncing,’ is the change in final URL from the requested URL.

What type of content is handled by a CDN?

CDN is often referred to as an ‘umbrella’ and covers many different types of data delivery, and is a complex system involving content owners from all sectors. Although most commonly used for B2B use, the growth of online applications for everyday, domestic use, is contributing to the acceleration of dynamic content delivery.

Typically, the types of content handled include, but are not limited to:

  • Webpages
  • Downloadable products
  • e-Commerce applications
  • Live video streaming
  • On-demand streaming
  • Social networks

CDN operators are employed by content owners to deliver their content to users, and CDNs employ ISPs and network operators to host information in global servers.

Private CDNs can also be set up by content owners, which consists of PoPs that serve only content for the owner, and can be as small as two servers.