System design interview question
"Design a content delivery network. Customers point their domains at you, and you serve their static content — images, video, JavaScript — from locations near their users. Hundreds of points of presence worldwide, tens of terabits per second. Tell me how a user's request reaches the right PoP and what happens on a cache miss."
request routing across a global topology, plus cache hierarchy. The distinguishing content is: how a user is directed to a nearby PoP at all (anycast versus DNS), why a flat edge tier fails under a cache miss storm, and cache-key design. It is one of the few questions where the network layer is part of the answer.
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