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Google·Product Manager·Onsite - Product Sense / Strategy·Senior

Senior
Jun 2026

Summary

Google PM interview with a system design question focused on disaster resilience. One question, pretty open-ended, and I spent way too long on the wrong part of it.

Questions Asked (1)

Q1

How would you design an ATM system that continues to function during a natural disaster?

System DesignProduct Sense & IdeationTechnical Trade-offs
Author's notes

I jumped straight into offline mode and cached transaction logs, which felt smart at the time, but I kind of forgot to anchor on the user first.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the scope and constraints of the ATM system, such as the types of natural disasters, user needs, and regulatory requirements. Then, propose a resilient architecture that includes offline capabilities, redundant connectivity, and alternative power sources. Finally, discuss trade-offs between cost, complexity, and reliability, and how you would prioritize features for an MVP.

Pro tip: Emphasize the importance of designing for graceful degradation rather than perfect uptime—focus on ensuring core cash withdrawal and balance inquiry functions remain available even when the network is down. Also, mention the need for a post-disaster recovery plan and how you would measure success.

1. Clarify Requirements and Constraints

Ask questions to understand the scope: which disasters (earthquake, flood, hurricane), expected duration of disruption, regulatory constraints, and user needs (cash withdrawal, deposits, balance inquiry).

2. Define Core Functionality and Priorities

Identify the must-have features during a disaster, such as cash withdrawal and balance inquiry, and deprioritize non-essential features like fund transfers or bill payments.

3. Design Resilient Architecture

Propose a system with redundant power (solar, battery), multiple network connections (satellite, mesh), and offline transaction capabilities with local storage and synchronization when connectivity is restored.

4. Address Security and Fraud

Discuss how to maintain security in offline mode, such as limiting withdrawal amounts, using biometrics, and implementing tamper-proof logs that sync later.

5. Evaluate Trade-offs and Metrics

Weigh cost, complexity, and reliability; define success metrics like uptime during disasters, transaction success rate, and user adoption; and outline a phased rollout plan.

Key Points to Mention

  • Offline transaction mode with local storage and later synchronization
  • Redundant power sources (solar, battery) and network connectivity (satellite, mesh)
  • Graceful degradation: prioritize cash withdrawal and balance inquiry
  • Security measures for offline transactions (limits, biometrics, encryption)
  • Regulatory compliance and partnerships with local authorities
  • Post-disaster recovery and data reconciliation processes

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.