On-callMediumoc-p077

Subject CapacityLevel Senior~20 minCommon in Reliability & on-call interviewsIndustries Technology

Question

An autoscaler scaled the fleet down during a lull, then traffic spiked and it couldn't add capacity fast enough (slow instance startup), causing an overload. How do you respond and prevent it?

What a strong answer looks like

Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.

Learn the concepts

Diagram & narrate the incident

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Run or narrate your approach, then ask the coach.