System Design.

Designing scalable, reliable distributed systems. Covers 18 sub-skills.

• System Design · 1 of 3

  Rate Limiting & Backpressure

  Which HTTP header advises the caller how long to pause before issuing a new request once the server signals quota exhaustion?

  ARetry-AfterBBackoff-InCX-Wait-DelayDThrottle-Ms

• System Design · 2 of 3

  Rate Limiting & Backpressure

  What is the chief drawback of the sliding-window log compared with token bucket at scale?

  AIt rejects all bursts regardless of accumulated allowanceBIt cannot distinguish authenticated callers from anonymousCMemory grows linearly with request volume per keyDIt fails when clock drift between nodes exceeds one second

• System Design · 3 of 3

  Rate Limiting & Backpressure

  Which property of Lua scripts on Redis makes them well-suited for atomic rate-limit decisions?

  AScript replicates automatically to every read replica synchronously nowBScript bypasses single-threaded execution for parallel operator speedCScript executes as one unit without interleaving other commandsDScript avoids serialization of large result payloads to the client code