Content Delivery Network, Explained: How a Group of Servers Helps the Web Load Faster

Telecommunications providers worldwide have been offering their own Content Delivery Networks (CDNs) for wholesale customers for nearly two decades. A CDN is aimed at preventing congestion on certain links and ensuring quality of service for users.

However, CDN isn’t a commonly known term among end users, considering it’s typically used by operators and large companies. In this post, we’ll break down what CDNs are and what they're used for.

What Is a CDN and What Is It for?

A CDN is a network of servers spread across different locations that store local copies of various content such as videos, images, music, and documents. These copies are originally stored on servers that are usually far away geographically. The main purpose of a CDN is to serve this content more efficiently.

This efficiency is achieved through better load balancing of the servers hosting the content and the links connecting the different parts of the network. It helps eliminate potential bottlenecks and ensures that data is delivered based on the proximity of the end user.

In other words, CDNs replicate content in various networks and countries. They direct user requests to copies that are closest to their network, which prevents servers from being overwhelmed by excessive requests. This geographical distribution of data also minimizes delays because the path to the content is as short as possible.

For instance, if you want to watch a YouTube video hosted in the UK from New York, you could either access it directly along with millions of other users worldwide through the increasingly congested intercontinental links, or access a local copy on a server in the CDN network installed in New York by a telecommunications provider. This would improve access speed and reduce latency.

CDNs in the U.S.

According to CDN Planet, the U.S. currently has 23 CDNs spread across the country, with several points of presence (POP) in each. The CDN with the most POP locations is Cloudflare, which has a total of 46 in cities including Boston, Chicago, Dallas, Las Vegas, Los Angeles, Miami, Philadelphia, Portland, and Seattle.

Having more POP locations doesn’t necessarily mean a CDN is better, but it does ensure content delivery with lower latency, especially in a large country like the U.S.

Furthermore, Cloudflare has data centers in all continents, with 54 locations in North America, 55 locations in Latin America, 47 locations in Europe, 12 locations in Russia and CIS, 45 locations in Asia (excluding China), 37 locations in China, 14 locations in Oceania, 21 locations in the Middle East, and 24 locations in Africa.

This article was written by Paco Rodriguez and originally published in Spanish.

Images | Tim Reckmann | tlsmith1000

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