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What is a CDN?

A content delivery network (CDN) refers to a geographically distributed group of servers which work together to provide fast delivery of internet content. Learn more with this CDN guide.

What is a CDN?

Learning Objectives

After reading this article you will be able to:

  • Define a content distribution network (CDN)
  • Understand some of the benefits of using a CDN
  • Explore more details of how a CDN works

What is a CDN?

A content delivery network (CDN) refers to a geographically distributed group of servers which work together to provide fast delivery of internet content. A CDN allows for the quick transfer of assets needed for loading internet content including HTML pages, javascript files, stylesheets, images, and videos.

What are the benefits of using a CDN?

Although the benefits of using a CDN vary depending on the size and needs of an internet property, the primary benefits for most users can be broken down into 4 different components.

  1. Improving website load times - By distributing content closer to website visitors by using a nearby CDN server and other optimizations, visitors experience faster page loading times. As visitors are more inclined to bounce away from a slow loading site, CDNs reduce bounce rates and increase the amount of time that people spend on the site. Or, in other words, a faster a website means visitors will stay longer.
  2. Reducing bandwidth costs - Bandwidth consumption costs for website hosting is a primary expense for websites. Through caching and other optimizations, CDNs are able to reduce the amount of data an origin server must provide, thus reducing hosting costs for website owners.
  3. Increasing content availability and redundancy – Large amounts of traffic or hardware failures can interrupt normal website function. A CDN network can handle more traffic and withstand hardware failure better than many origin servers.
  4. Improving website security – A CDN may improve security by providing DDoS mitigation, improvements to security certificates and other optimizations.

At its core, a CDN is a network of servers linked together with the goal of delivering content as quickly, cheaply, reliably, and securely as possible. In order to improve speed and connectivity, a CDN will place servers at the exchange points between different networks. These internet exchange points (IXPs) are the primary locations where different internet providers connect in order to provide each other access to traffic originating on their different networks. By having a connection to these high speed and highly interconnected locations, a CDN provider is able to reduce costs and transit times in high speed data delivery.

Beyond placement of servers in IXPs, a CDN makes a number of optimizations on standard client/server data transfers. CDNs place Data Centers at strategic locations across the globe, enhance security and are designed to survive various types of failures and internet congestion. This guide will explore the technology behind CDN design and functionality.

Latency - How does a CDN improves website load times?

When it comes to website loading content, users drop off quickly as a site slows down. Explore the ways in which a CDN helps websites load faster.

Bandwidth Expense – How does a CDN reduce bandwidth costs?

Every time an origin server responds to a request, bandwidth is consumed. See how a CDN cuts down on origin requests. (coming soon)

Reliability and Redundancy – How does a CDN keep a website always online?

Website uptime is a critical component for anyone with a website. Learn how CDNs help keep website online. (coming soon)

Data Security – How does a CDN protect data?

Information security is an integral part of a CDN. Investigate the security concerns surrounding CDNs, and lean what can be done to securely host content. (coming soon) Cloudflare CDN