How does a CDN Work?

The CDN is a network of servers that store content and deliver it to an audience spread across any area. The concept is to keep content on the CDN server closest to the end user, wherever they are, to speed up the page load time and avoid global network bottlenecks. The CDN can also host web performance optimization and application acceleration solutions that can speed the delivery of web content even more.


Each CDN is architected differently, but they mostly share some basic traits in common. CDNs are built in data centers (or Points of Presence – PoPs) that are located throughout the world. Within each of these data centers there are multiple servers – the number may range from dozens to thousands. When a client requests a specific resource (HTML page, Javascript, CSS file, image, etc.) served by a CDN, DNS directs the request to a specific server located in a CDN provider’s PoP. PoPs are generally selected based on proximity to the end-user – both in a geographic sense, and with regards to network topology, though other selection factors are often leveraged. Similarly, different CDN providers use a variety of methodologies for selecting an optimal server within a PoP. The content is then delivered to the client directly from the CDN, rather than from the content owner’s origin servers.

Continue reading?

Share this article