Navan·Software Engineer·Technical Phone Screen·Senior

Senior

Apr 2026

Summary

Navan engineering interview, one question about debugging that felt more open-ended than I expected. Not a lot of other context to share but the question itself had some depth to it.

Questions Asked (1)

Walk me through how you debug a problem: reproducing it, narrowing it down, and fixing it. How do you decide whether to patch it quickly or dig for the root cause?

Root Cause AnalysisTechnical Trade-offs

Author's notes

I went with a real example from a previous job where a race condition was causing intermittent failures in prod.

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AI HintsAI Generated

Suggested Approach

Structure your answer as a clear narrative that follows the debugging lifecycle: reproduce, narrow down, fix, and verify. Emphasize how you balance speed and thoroughness by assessing impact, urgency, and risk, and provide a concrete example to illustrate your decision-making.

Pro tip: Show that you think about debugging as a systematic process, not just ad-hoc fixes. Mention how you document your findings and share knowledge to prevent similar issues, which demonstrates leadership and maturity.

1. Reproduce the issue

Start by reliably reproducing the problem in a controlled environment. Gather logs, error messages, and steps to reproduce, and consider edge cases and environmental factors.

2. Narrow down the cause

Use techniques like binary search, logging, debugging tools, and hypothesis testing to isolate the faulty component. Eliminate variables systematically.

3. Decide: patch or root cause?

Assess the impact, urgency, and risk. For critical production issues, apply a quick mitigation (e.g., rollback, feature flag) while planning a deeper fix. For non-urgent issues, invest in root cause analysis.

4. Implement and verify the fix

Apply the fix, ensuring it addresses the root cause if possible. Write tests to confirm the fix and prevent regressions, and monitor after deployment.

5. Reflect and prevent

Document the root cause and solution, and consider process improvements or automation to avoid similar issues. Share learnings with the team.

Key Points to Mention

Systematic debugging methodology (e.g., scientific method, divide and conquer)
Tools and techniques: logging, debuggers, profilers, monitoring, A/B testing
Trade-off analysis: impact vs. effort, urgency vs. long-term health
Risk management: rollback strategies, feature flags, canary releases
Communication: keeping stakeholders informed, especially during critical incidents
Post-mortem and knowledge sharing to prevent recurrence

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