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Q87 / 100
What is tail latency and why does it matter for web services?
Correct! Well done.
Incorrect.
The correct answer is B) The high percentile latencies (P99, P999) — the slowest 1% or 0.1% of requests — which disproportionately affect user experience and cascade in microservices
B
Correct Answer
The high percentile latencies (P99, P999) — the slowest 1% or 0.1% of requests — which disproportionately affect user experience and cascade in microservices
Explanation
In a service with 10 dependencies, P99 of the slowest is ~1-(0.99^10) ≈ 10% slow requests at the edge. "The Long Tail of Latency" (Google): optimize P99, not just average. Techniques: timeouts, hedged requests, tail-cutting.
Progress
87/100