What Is A CDN (Content Delivery Network)?

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Have you ever wondered how big websites like Verge, Google, or WordPress manage to have fast connections everywhere in the world? Or have you perhaps ever seen a website address like “http://cdn.something.com/iudhfg76/” or read about it in a tech article? CDNs are an important part of the internet’s infrastructure, and this article explains what they are and how they work.

What is a CDN? Well, the acronym C.D.N. stands for “Content Delivery Network”, and it is a way for large numbers of internet requests to be handled at once. What does this mean? Allow me to explain: 

The Basics

Before tackling the topic of what a CDN(Content Delivery Network) is, perhaps we should look at a few basic terms.

The internet consists mainly of servers, connections, and computers (in very overly-simplified terms) which share information and content between each other. For instance, if you were to open up a web browser like Firefox or Chrome on your computer, type in a website or a search, and then receive a page or search results, you will have these three elements. Your computer is known as a “client”, the web page or search results come from a “server” which holds the website content or search results, and they are sent over a “connection”.

what is a cdn

Connections Without A CDN(Content Delivery Network)

If there is only one single server for a website, search engine, or any other web service, which could handle connection requests and send the content to the client computers, it would have to handle them one at a time, or if it were a high-end server, just a few at a time. Once the request had been processed, the server would then need to send the content – whether a web page, search results, or streaming music – back to each client itself.

connections without a cdn

This is the cheapest and easiest way to serve a website, search engine, or other type of web-based software solution. It requires minimal setup and low cost, and little infrastructure.

However, if this website or search engine were to become popular, or if it were under attack, this single server would have too many requests to process, and it would fail, crash, or simply not be able to keep up, and people wanting to access the website or software would no longer be able to do so.

This is where a CDN comes in.

Connections With A CDN

A CDN, or content delivery network, is a network of different servers, distributed in different locations all over the world, all with the same purpose of handling connections and delivering the same content to many clients in many different locations at once.

If a client requests a website, search engine, or other content, they would be connected to the closest or best available server in this network of servers, which would then process the request and send the content back to the client. This would then happen for every client according to where they are in the world, and each one would be connected to the nearest or best available server.

connections with a cdn(Content Delivery Network)

If a website or web service is served over a CDN, not only is the connection shorter and faster since there is, more often than not, a server in a closer location than just one somewhere far away, but they can also handle heavier loads and many, many more connections than a single server (or even a rack of servers) ever could. Each server handles fewer connections and is often much closer to the client.

Simply put, CDNs can provide faster connections and can handle exponentially more connections than a single server.

Summary

CDNs provide a vital contribution to a faster, safer internet, since they can handle high volumes of internet traffic, and can help to protect websites or web services against attacks. Many large websites pay to have their content distributed via a CDN, and so provide their content to more clients, faster. Without CDNs, much of the web today would grind to a halt.

Chances are, if you use search engines or social networks, they are being distributed to you and all other users via a CDN.

Do you or your company make use of a CDN? Let us know in the comments, as well as how well that CDN works for you! And we will soon discuss the top CDNs for WordPress. So keep visiting.

One thought on “What Is A CDN (Content Delivery Network)?”

  1. Fincken says:

    Excellent. Yet .. in my opinion you don’t need a CDN.
    You will only need it in these 2 cases:
    1) your webhost does not have varnish caching for static files to deliver them quickly (and to keep you site up in case of high traffic peaks)
    You should move to a decent webhost with varnish (and memcached) by default.
    2) your site actually has substantial amounts of traffic outside the country where your server is located. Preferably in other continents.

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