What Is A Content Delivery Network (CDN) And How It Works

Last updated on Feb 15th, 2024 | 7 min

TL;DR: A Content Delivery Network (CDN) consists of a number of geographically distributed servers at various points of presence (PoP) around the world. A CDN’s main job is to shorten the physical distance between a user and the web server, resulting in faster load times, increased server uptime, reduced bandwidth usage, improved security, and better website performance. Websites that operate globally can benefit the most from using a CDN.

Do you know what Facebook, YouTube, and Netflix have in common? Besides being one of the most visited websites, they all use CDNs to serve their content! 

A CDN, or Content Delivery Network, is a technological solution that addresses the challenge of distributing massive amounts of data/content rapidly to the end-users on the Internet. 

In fact, the article you’re about to read is served through a CDN. But let’s not waste any more time on shallow explanations.

Here’s what we’re going to cover in this article:

What is a CDN?

Before proceeding with the definition of a CDN, it is important to address the issue it was designed to solve. 

Network latency is that annoying delay that occurs from the moment that you request to load a web page to the moment its content is actually visible on your screen. 

Although the delay interval could be affected by a number of factors, most of which are specific to a given web page, one of the most impactful aspects is the physical distance between you and that website’s hosting server.

Network Latency

And here, a CDN can provide a solution. 

Simply put, a CDN’s main job is to shorten the physical distance between a user and the web server, which results in better website performance.

Here’s how that’s done: 

A CDN consists of multiple geographically distributed servers at various points of presence (PoP) around the world. 

This group of servers allows for the fast transfer of things needed for loading Internet content, such as HTML pages, JavaScript files, stylesheets, etc.

CDNs help serve different types of resources, including: 

  1. Static content which doesn’t change very often and does not require generation, such as images, JavaScript, CSS, etc. There are even image CDNs, which focus solely on the transformation, optimization, and delivery of images.
  2. Dynamic content, which is generated on the fly by a web server, using various common web programming languages such as PHP, Ruby, and Java.
  3. Streaming contents, which are videos or audio files that are played via a web browser control.

Notably, Ruby language is particularly useful in many web developments, including web scraping. In fact, web scraping with Ruby is a popular technique used to scrape data from websites where APIs may not be provided. Leveraging Ruby in this way can be advantageous in enhancing the speed and efficiency of your server responses.

How Does a CDN Work?

I’ve already clarified that a CDN consists of geographically distributed servers all around the world. 

To better understand how a CDN actually works, let’s look at the following example:

Let’s say that you have a website and the origin server where all the files of your website are stored is in Paris, France. 

Because you offer high-quality products, you attract hundreds of visitors to your site from all over the world. However, you don’t have servers worldwide, and because of that, you run into the latency problem (the distance between the user and the origin server is too large).

Without CDN

For instance, if a user in Beijing wants to access your website that is hosted in Paris, each request will have to travel through a series of routers to reach the server. 

And that “travel” will repeat for each resource request. The latency will happen, namely because of the geographical distance of about 5000 miles between Paris and Beijing. 

In this case, the CDN can virtually shorten that distance and thus improve the site’s performance.

A CDN will store a cached version of your content in multiple geographical locations (also known as points of presence). Each PoP consists of multiple caching servers responsible for distributing your website’s content based on the user’s proximity.

with CDN

Therefore, the user from Beijing who requested to visit your website will be served content from the nearest point of presence/caching server - possibly, from a server in the same city. Thus, the latency will be drastically reduced, and your website will load faster.

On that note, let’s have a closer look at all the benefits of using a CDN.

Benefits of Using a CDN

The benefits of using a CDN will depend on the size of the web page, its location in relation to the main traffic source, and the amount of traffic generated. 

Side note: If you’re familiar with the benefits of using a CDN, you can skip this part and proceed with the information about what companies can take full advantage of using a Content Delivery Network. 

There are four main benefits of using a CDN:

  1. Increased Speed - It takes less time for your content to reach the end-user, as a nearby CDN server distributes it. Because of the numerous points of presence, your website will load faster, resulting in a better user experience, lower bounce rate, and increased conversions. 
  2. Reduced Bandwidth - Bandwidth refers to the rate of data transferred (inbound or outbound) for a fixed period of time. Bandwidth can be one of the biggest expenses with some hostings and often is used in pricing services, such as a CDN. Multiplying the PoPs conserves the amount of bandwidth needed to handle the traffic of the web page. This happens by caching, which puts data into temporary storage on different computers or mobile devices for easier access.

    NitroPack Pricing Plans
  3. Improved Security - When data is transferred from a single server, it’s more vulnerable to malicious events such as denial-of-service attacks (DDoS). That’s because all of your users communicate directly with your origin server. Whereas when using a CDN, users send requests to the caching server. Additionally, a CDN can prevent malicious events by keeping hackers away, refreshing TLS/SSL certificates, and thus providing higher authentication standards.
  4. Improved Content Distribution - Heavy traffic on a web page, along with hardware malfunctions, leads to a lot of downtime on a website. A CDN allows you to spread the load over multiple servers and lessen the burden on your infrastructure, resulting in an increase in uptime. 

Do You Need a CDN?

Let’s make something clear right from the beginning:

A small local business with a physical location that serves a small geographic area might not benefit as much from CDN.

In fact, you might worsen your website’s performance by introducing another point of connection between your visitors and your origin/nearby server.

CDNs are inefficient for websites that operate on a local level

So, bear this in mind when you decide whether to integrate a CDN or will be better off without it.

Now that we know when you won’t need a CDN let’s get to the juicy part - who actually needs a CDN? 

Pretty much every online business that operates on a larger scale:

  • Global E-Commerce stores (Amazon, Alibaba, etc.)  benefit a lot because they have heavy traffic from all around the world;

  • Advertising businesses (like Yahoo or Forbes) use multimedia-based ads because they are more attractive and engaging, but at the same time, they require more resources to load properly;

  • Online games need even more resources in order to deliver the best gaming performance;

  • The entertainment industry attracts lots of people from all around the world with its downloading and streaming options.

The reality is that more than half of the web content is served by a CDN. As I mentioned at the beginning of the article, all of your favorite websites use a CDN to deliver your desired content in a glimpse of a second - Netflix, Facebook, 9GAG, UpWork, etc.

Do CDNs Affect SEO?

Being on this quest of learning more about the CDNs, how they work, and what benefits they can offer to your online business, you might run into some common misconceptions.

A popular one is that Content Delivery Networks (CDNs) can harm a website’s organic rankings.

However, Google representatives have dispelled this myth by stating that using CDN URLs is completely fine:

John Mueller Tweet about CDNs

Furthermore, they make it crystal clear that hosting images on the same host/domain as your website (cdn.yourwebsite) instead of on a separate site/subdomain (yoursite.cdnprovider) won’t give you an SEO boost:

John Mueller tweet on CDNs

In fact, there are more misconceptions that aim to discredit CDNs’ value. In our article - Will Using a CDN Hurt My Organic Ranking (SEO)? - we look at other popular myths and why they’re wrong. 

Spoiler alert: CDNs have been on the market for more than 20 years. The largest websites/companies in the world use CDN services daily. If these services harmed organic rankings, it’s improbable that they would’ve ever become so widely used.


How NitroPack’s CDN Can Help You

There are numerous CDN providers out there. However, when we first started building NitroPack, we knew that we wanted to create a site speed solution that offers out-of-the-box features for complete website optimization.  

That’s why we offer a built-in CDN with all of our plans (including our free plan).

NitroPack’s CDN is pre-configured, which means that you don’t have to set it up manually, saving you time and effort. Our CDN automatically serves fonts, CSS, JS, and image files via HTTP2 from the nearest edge location.

Furthermore, NitroPack’s CDN serves resources between 5 and 20 ms, which is a huge benefit, given the fact that very few resources take longer than 10 ms.

Niko Kaleev
Web Performance Geek

Niko has 5+ years of experience turning those “it’s too technical for me” topics into “I can’t believe I get it” content pieces. He specializes in dissecting nuanced topics like Core Web Vitals, web performance metrics, and site speed optimization techniques. When he’s taking a breather from researching his next content piece, you’ll find him deep into the latest performance news.