Step 1 of 12 · Intro

Design a CDN

Serve the world from the edge and keep the origin calm.

How it works

• ›Read: users fetch files, almost all repeats (read-heavy).
• ›Publish: owners upload new versions and purge old ones (rare writes).
• ›Miss: a cold file must be fetched from the origin once.

What you'll build

1. The API and cache entry data
2. A CDN in front of the origin
3. A shield tier that merges edge misses
4. Geo-routing capacity across the globe
5. Designs that survive a cold cache, a lost edge and a lost origin server