TL;DR — Content Delivery Network

Design a Content Delivery Network that serves static and dynamic content from edge locations closest to end users. The CDN must cache content at hundreds of Points of Presence (PoPs) worldwide, route users to the optimal edge via DNS or anycast, and handle cache invalidation when origin content changes. Key features: Serve cached content from the nearest edge PoP to the client. Pull-through caching: fetch from origin on cache miss, cache response.