Cdn

Hook

A regional warehouse can close while a nearby kiosk still serves items already on its shelf.

Watch

Let a global cached hit bypass the origin. Use the validated parameter controls or edit the JSON scenario, then select Load input to recompute the trace.

How it works

The edge-cache model serves hits before origin app/database work. A simulated origin-region outage still permits existing global edge hits; misses reject when the origin is unavailable.

Every visible outcome comes from the displayed state model. Timings, capacities and failures are illustrative assumptions, not cloud benchmarks or production-protocol guarantees.

Try it

Predict the next admission, delivery, cache, ownership or coordination decision. Introduce one failure at a time and account for every accepted, rejected, pending or committed outcome.

Complexity

The player separates operation counters from architectural trade-offs. State size follows the active keys, tasks, nodes or retained history; the references use bounded scenarios. Container choices and presentation scans can affect simulator costs.

Code

The four references implement the core model or its decision round. Queue/inbox and local ledger atomicity are explicit assumptions. Distributed deployment additionally needs durable shared state, complete protocol rules and operational validation. Reference inputs are fully validated/defaulted by the lesson; standalone callers must provide the shown fields.

When to use

Use for cacheable content near users, with explicit TTL, cache keys, invalidation and private-content policy.

Interview pitfalls

This workload model assumes a target hit fraction and immutable cached responses. It does not implement an HTTP cache or authorize caching private paid content.

Quiz

Justify the model’s decision and name one production concern outside its scope.