Question 630
An API reports a healthy 90 ms average latency, but customers complain about intermittent five-second checkout responses. Which limitation must be considered before claiming the issue is fully resolved?
Explanation
Correct Answer
A drop in average latency may coexist with worsening p99 behavior. This caution prevents extrapolating beyond the specific evidence or product boundary. Observability should measure user-relevant distributions, not only aggregates. The unresolved point should be tested using Cloud Monitoring latency distribution, p95/p99 charts and trace exemplars rather than assuming a working interface proves full compliance or resilience.
Incorrect Answers
Percentile latency metrics are unnecessary when CPU utilization is stable. This limitation is framed as a blanket exception, but the case requires a different, narrower caution. The relevant boundary is that a drop in average latency may coexist with worsening p99 behavior. Observability should measure user-relevant distributions, not only aggregates. Inspect Cloud Monitoring latency distribution, p95/p99 charts and trace exemplars.
A lower p99 always guarantees that every single response is fast. The proposed claim mistakes an incomplete signal or product feature for a universal guarantee. The relevant boundary is that a drop in average latency may coexist with worsening p99 behavior. Observability should measure user-relevant distributions, not only aggregates. Inspect Cloud Monitoring latency distribution, p95/p99 charts and trace exemplars.
A single p95 value proves all individual request delays remain under its threshold. This claim exceeds the evidence and ignores an important risk or operational dependency. The relevant boundary is that a drop in average latency may coexist with worsening p99 behavior. Observability should measure user-relevant distributions, not only aggregates. Inspect Cloud Monitoring latency distribution, p95/p99 charts and trace exemplars.