As asked
Checkout latency jumps from 250ms p95 to 2s p95 after a deploy. Walk me through how you use observability data to find the cause.
Sample answer outline
Start with metrics to localise the symptom: which service, route, region, dependency, and percentile changed. Use deployment markers and service dashboards to correlate the regression with a version or config change. Then inspect traces for slow requests to see whether time is spent in app code, database calls, network hops, or downstream services. Use structured logs for exact errors, feature flags, customer segments, or payload patterns, not as the primary latency graph. Good candidates avoid jumping straight to rollback, but they know when rollback is the right mitigation while diagnosis continues.
Expect these follow-ups
- What dashboard panels would you expect every service to have?
- How do you distinguish client-side latency from server-side latency?
- What do you do if traces show missing spans in the suspected service?
incident-debugginglatencytelemetry