Design a Content Delivery Network

You are asked to design a content delivery network (CDN). Before proposing a design, pin down the requirements: which kinds of content the system serves, where its user population sits geographically, how frequently that content changes, and what freshness and access-control guarantees the system must uphold. Then walk through the request path end to end, the behavior of the caches along it, how the CDN interacts with origin servers, and how the system recovers when parts of…