10 min read Intermediate Lesson 6 of 8
Part 3 — Speed & Scale

Content Delivery Networks (CDNs)

Light travels through fiber at $\sim 200,000\text{ km/s}$, meaning a round-trip between Tokyo and London takes over 200 milliseconds. Content Delivery Networks (CDNs) cache assets at hundreds of worldwide Points of Presence (PoPs) so users fetch files in 10 milliseconds.

How Anycast BGP Works

With Anycast, hundreds of global edge servers advertise the exact same IP address. Internet routers automatically route user packets to the closest physical PoP geographically!

Quick Summary

  • CDNs eliminate geographic latency by serving cached assets from edge servers.
  • Next, we explore WebSockets & Real-Time Communication.