Content Delivery Network (CDN)

A Content Delivery Network (CDN) is a geographically distributed system of proxy servers that caches and delivers content from locations closer to users. In system design interviews, CDNs appear whenever you're designing systems that serve static content globally—they're how Netflix streams video, how websites load images instantly, and how applications achieve sub-100ms response times worldwide.

This page covers what you need to know for interviews: why CDNs matter, how they work, push vs pull models, cache consistency strategies, and how to route users to the nearest edge server. Understanding these concepts helps you design systems that serve millions of users with low latency regardless of their geographic location.