On-callMediumoc-g073

Subject Api quotaLevel Mid–Senior~30 minCommon in Reliability & on-call interviewsIndustries Technology, Software development

Question

Your delivery app's address-autocomplete and route features go partly dark at 14:20. Dashboards: calls to the Google Maps Platform API start returning HTTP 403 with 'OVER_QUERY_LIMIT' / quota exceeded; the affected features error at ~70%; your own infra is healthy. Recent context: marketing ran a flash promo this morning that ~doubled active users, and last week an engineer removed a client-side autocomplete debounce to 'make typing feel snappier.' Daily quota is a fixed per-project cap. How do you triage and mitigate?

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.