CDN (Content Delivery Network)

Speed isn't just about fast servers; it's about physics. Learn how CDNs beat the speed of light by moving content closer to your users.

What you will learn

• Understand the geography of Origin vs Edge
• Compare Pull (Lazy) vs Push (Proactive) strategies
• Master cache invalidation techniques (TTL vs Purging vs Versioning)
• Leverage Edge Computing (Cloudflare Workers, Lambda@Edge)

You have a server in New York. A user visits from Tokyo. The speed of light is 300,000 km/s. Even if your server processes the request in 0 milliseconds, the Network Latency alone will be ~200ms round trip.

To the user, your site feels "laggy". You cannot beat physics. But you can cheat.

• The Origin Server: Your Factory in New York. It creates the product (the HTML/Images).
• The User: A Customer in Tokyo.
• Without CDN: Every time a customer wants a widget, you ship it from NY to Tokyo via FedEx (15 hours).
• With CDN: You rent a Warehouse in Tokyo. You ship a crate of widgets there once. When a customer orders, the local warehouse delivers it via bike messenger (15 minutes).

Key Concept: CDNs bring the content physically closer to the user.

A CDN is a network of thousands of servers scattered around the globe.

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