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CDN (Content Delivery Network)

What is a CDN?

CDN is an abbreviation for Content Delivery Network. 

A CDN is a network of servers and data centers spread geographically across the globe, to help accelerate the rate at which internet content is delivered. 

CDN is commonly used by high-traffic websites, such as those that offer streaming services, to efficiently and effectively serve users around the world. 

It reduces the distance between the user and the content, or server delivering the content. This increases the speed of the website and improves its connectivity, security, and overall performance.

How does a CDN work?

If your site uses a lot of files such as stylesheets, images, and videos, it might slow down your site. You can take that load off of your site’s server by using a CDN. 

CDN distributes the static content of a website, such as pictures and videos, to servers and data centers that are closer to the people requesting the information.

It does this by involving servers that push content onto the CDN, and servers that pull requests to give to the user.

At the top of the delivery network is the root source or origin server. It stores the original content of the website and pushes it onto a CDN server that is closer to the user.

These CDN servers are called server nodes and are spread throughout the world to deliver content locally. Server nodes cache, or take a snapshot of, a website’s content via data compression so it can pull the content when a local user requests it. 

Here’s the simplified process:

  1. A website is hosted on the origin server in one location, however, it has users all around the world.
  2. For global users to view the website’s content, they’d have to request for the content through the DNS and onto the closest server, geographically. 
  3. Then, the local server node pulls the cached version of the website and delivers it to the end-user.

Benefits of using a content delivery network

Faster loading websites

With a CDN, content is distributed and shared globally on different servers. This shortens the distance from the origin server to the end-user, and thus results in faster service. 

CDN also compresses data from the server which makes it faster to load on the local server as files are much smaller than the original.

Apart from the geographical aspect of CDN, content delivery networks typically come with TLS or SSL certificates.

Improved uptime and reduced server load

Because content is distributed evenly across the delivery network, it takes the load off of the origin server and doesn’t overwhelm the system. 

This allows your website to have high amounts of traffic at any given time, without crashing the server.

Using a CDN also allows you to fall back on other servers in case one is down, which is a great way to minimize downtime.


Other than loading speed, CDNs help with security.

CDN provides security through obscurity, as it becomes difficult to target the origin server because it is covered by all the server nodes within the delivery network.

CDNs improve the security of your site through three different strategies:

  • Web Application Firewall (WAF) – filters out malicious requests from ever reaching your site, blocks bots, and detects vulnerabilities within your system.
  • DDoS mitigation – protects the server from DDoS attacks and threats. 
  • TLS/SSL certificates – encrypts website information during transmission.


One of the best ways to ensure you can deliver your content to your audience in the most efficient way is through content delivery networks.

Being on a CDN ensures that no matter where the end-user is, the website loads fast. Through a CDN, end-users also experience an improved overall stream quality.

For businesses, this means you can reach a much wider audience and ensure the same quality content for all of your customers.


Buying additional bandwidth capacity from a web provider can be expensive if your website traffic is constantly increasing. 

Using a CDN is a good alternative to that as it typically costs less per GB, so you can reduce bandwidth costs.

Some CDNs even have free versions that you can try out.

Downsides of using a content delivery network

Although using a CDN provides many advantages, there are some drawbacks to consider too, including:

  • Vulnerability – makes your website potentially more vulnerable as all your files are stored on multiple server nodes.
  • Hidden costs – there may be some hidden costs associated with your CDN service, such as cost per data transfer, so be sure to read their terms and conditions.
  • Restrictions – some countries restrict access for CDNs which means your audience could not be able to view your content. You’ll have to research this before signing up for a CDN service.

However, the advantages of using a CDN, especially if your site has high traffic, seem to outweigh the disadvantages.

Written by

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Olivia is a writer for Zyro and an eCommerce know-it-all. Having spent many years as a retail buyer, she loves writing about trend forecasting, brand building, and teaching others how to optimize online stores for success. She lives in London and spends a lot of time exploring the city’s parks with her whippet.

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