What is a Content Delivery Network?

John Spacey, updated on December 14, 2016

A content delivery network, or CDN, is a system of servers distributed to strategic points on the internet designed to have low latency with respect to users in different regions. They are used to speed the delivery of static content such as html, text, scripts, media, software downloads, documents, videos, images and other media.

Technical Overview

Content delivery networks act as a global network of proxy servers that are strategically connected to internet backbones and other internet interconnections that offer low latency to a large number of users. Such proxy servers obtain content from a source server. Content such as web pages and mobile apps are structured such that each user is served content from the proxy server closest to them.

Example

A user in Singapore searches for a video on a social network. Their browser connects to a CDN proxy in Singapore. The proxy doesn't have a copy of the video so it fetches it from a source server in the United States. The video is a bit slow. Two seconds later, another user in Singapore accesses the same video. This time the CDN proxy server in Singapore has a copy and serves it without need to connect to the server in the United States. The video is fast as it is served from optimized servers in close proximity to the user.

Overview: Content Delivery Network
Type	Networking Cloud Computing
Definition	A system of strategically distributed proxy servers for delivery of content within close proximity to users in different regions.
Also Known As	CDN
Related Concepts	Internet Backbone Internet Exchange Point Colocation Networking Cloud Computing