How does a Content Delivery Network (CDN) function?

A Content Delivery Network (CDN) functions by distributing web content to servers located around the world to reduce latency.

A CDN is a network of servers that are strategically located across the globe. The primary purpose of a CDN is to improve web performance by reducing the distance between the user and the website's server. When a user requests content from a website, the CDN redirects the request from the originating site's server to a server in the CDN that is closest to the user and delivers the cached content. This process ensures faster delivery of content to the user.

The CDN copies the pages of a website to a network of servers (known as points of presence, or POPs) that are dispersed at geographically different locations, caching the contents of the page. When a user requests a webpage that is part of a CDN, the CDN will redirect the request from the originating website's server to the server in the CDN that is closest to the user and deliver the cached content. CDNs will also communicate with the originating server to deliver any content that has not been previously cached.

The process of bouncing through CDNs is nearly transparent to the user. The only way a user would know if a CDN has been accessed is if the delivered URL is different than the URL that has been requested.

CDNs are extremely beneficial for websites that have a global reach. If a website's server is based in London, for example, a user in Australia would experience slower load times without a CDN. But with a CDN, the user in Australia would be able to access the site via a local Australian server, significantly improving the site's performance.

In addition to improving web service speed, CDNs are also designed to be robust and secure, protecting websites from large surges in traffic, malicious attacks and hardware failures. They can handle more traffic and withstand hardware failure better than many origin servers.