What is a CDN?

Back to learning

A Content Delivery Network, or CDN, is a system of strategically located servers that store copies of web content. When you visit a website, instead of retrieving information from a single central server, you get it from the server that's closest to you, the way this is achieved is usually via Anycast networks. This speeds up the time it takes for web pages to load, making your online experience more efficient.

Types of CDN

Push CDN

With Push CDN, website owners send or "push" their content to various CDN servers. This method offers the most control over what gets stored and when it updates. However, it demands more management effort to ensure that the content is consistently delivered to all servers.

Pull CDN

In a Pull CDN, the system is more automated. When a user visits a website, the CDN server nearest to that user will "pull" the latest version of the website from the central server. It then stores this content for future requests. This method is easier to manage but may result in slightly slower loading times for the first visitor who triggers the "pull."

Full-Site Delivery

Full-Site Delivery takes caching to the next level. Instead of storing only specific elements like images or videos, it stores entire web pages, including HTML, CSS, and JavaScript files. This offers a comprehensive way to speed up web page loading.

Integration Methods

Separate URL for Static Resources

Some CDNs require that all your static resources, like images and style sheets, be placed on a new URL. This is often the case with Push CDNs. For example, instead of having images on www.yourwebsite.com/images/, you might need to place them on a CDN-provided URL like cdn.yourwebsite.com/images/.

No URL Changes Required

For Full-Site Delivery CDNs, no such changes are needed. These CDNs can cache and serve your content without requiring you to move resources to a new URL. They often work as a reverse proxy, sitting between your website's original server and the user, making the integration seamless.