Content Delivery Networks

A Content Delivery Network (CDN) is a network of servers spread around the world. Instead of serving content from your main server, users get it from the server closest to them. This makes your website faster and reduces load on your server.

Typically, CDNs handle static content like:

Images and videos
CSS and JavaScript files
HTML pages

Some CDNs, like Amazon CloudFront, can even handle dynamic content.

Why Use a CDN?

Users get content faster because it's served from nearby locations.
Your main server doesn’t get overloaded with requests the CDN can handle.

Types of CDNs

Pull CDN Explained

Pull CDNs fetch content from your origin server the first time someone requests it. After that, the CDN caches the content.

How It Works

You keep content on your main server
CDN rewrites URLs to serve cached content
TTL (Time-to-Live) controls how long content stays in the CDN
Good for high-traffic sites where content changes often

Examples and Decisions

Example 1: News Website

A news website publishes articles several times a day and has heavy traffic.

Content changes often
Users are global
Decision: Pull CDN → automatically caches new articles when requested

Example 2: Marketing Site

A small company website with mostly static pages and low traffic.

Content rarely changes
Few updates per month
Decision: Push CDN → upload content once and serve reliably

Example 3: Video Streaming Platform

A streaming service hosts large video files. Users frequently watch the same content.

High bandwidth usage
Popular content reused by many
Decision: Pull CDN → cache popular videos while keeping storage efficient

Summary Decision

Use Pull CDN for high-traffic or frequently updated sites.
Use Push CDN for smaller, stable sites or content that rarely changes.