What is a Content Delivery Network OR What is CDN?


Over half of the internet’s traffic gets served through a Content Delivery Network(CDN).

Whether we know it or not, every one of us interacts with CDNs on a daily basis.

You might have heard of it but what does a CDN actually mean and how does it work?

A Content Delivery Network (CDN) is a globally distributed network of web servers that helps to provide fast delivery of data over the internet.

CDN is the backbone of the internet. They solve the major issue of latency.

What does Content Delivery Network do?

The purpose of having a CDN is to solve the problem of latency.

Latency refers to the delay that the users have to face from the moment they request to load a webpage to the moment you can actually see it.

It is sometimes called lag.

It is simply the delay in communication over a network.

Latency can occur due to multiple factors like:

  • If the website content is heavy, with images and videos, it will take more time to render
  • End-user issues like low memory and low CPU can cause delay
  • A physical problem like switches, WiFi or other component failures can also cause latency
  • But the main cause of latency is distance

The distance between the device making request and the server responding to these requests plays a major role in the time taken to load a page on the internet.

If a website is hosted in London, it will respond faster to request from users in and around the UK. On the other hand, users in India (which is very far) will face long delays to open the website.

CDN’s purpose is to reduce latency by reducing the distance between the the user and the point from where data is requested.

How does a Content Delivery Network work?

To reduce the distance between the visitor and your website’s server, a CDN stores a cached version of its content at multiple locations over a geographical area.

These places are called PoPs (Point of presence) and they are strategically located to ensure the geographical vicinity of maximum users.

Each PoP contains a number of caching servers that are responsible to deliver content to the visitors that are near the PoP.

Caching servers are responsible for the storage and delivery of cached files. These servers basically consist of multiple storage drives and a high amount of RAM resources.

Simply put, CDN puts your content in many places at once. So when a user from India requests content that is hosted on a server in England, the network does not load the content from the source server. Instead, the nearest PoP (maybe somewhere in India) delivers the content to the user.

This is much quicker than requesting content from a server that is placed thousands of mile away.