Software Engineer – Debugging
Practice debugging questions for software engineer interviews. Cover bugs that only happen in production, CI failures, memory leaks, and how you prove a fix. First 2 questions are free with full feedback.
- Level Intermediate
- Questions 12
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Software Engineer – Debugging interview questions
All 12 questions on this track, in the order you answer them. In the quiz you answer one at a time — type or speak — then get a score and feedback.
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How do you start when a bug only happens in production?
What a strong answer includes
The symptom, the first signal you check, and how you reproduce or narrow it without guessing.
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A test passes locally and fails in CI. What do you check?
What a strong answer includes
Environment differences, order dependence, time, data, and how you isolate the failing step.
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How do you debug a performance problem you cannot reproduce on your machine?
What a strong answer includes
Production metrics, a smaller reproduction, and what you change one variable at a time.
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Walk through how you would find a memory leak.
What a strong answer includes
What grows, a heap or profile snapshot, and how you tie the growth to a code path.
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A user reports the wrong number on a dashboard. How do you investigate?
What a strong answer includes
The definition of the number, the source data, and where the pipeline could drop or double-count.
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How do you decide when to add logging versus when you already have enough?
What a strong answer includes
The question the log would answer, the cost of more logs, and what you would remove later.
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Describe a bug caused by timing or a race. How did you find it?
What a strong answer includes
The intermittent symptom, how you made it happen more often, and the ordering bug you fixed.
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When do you use a debugger, and when do you prefer logs?
What a strong answer includes
A case for stepping through state, and a case where logs or a query are faster.
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An API returns 500 for one customer only. What is your process?
What a strong answer includes
Request id, that customer’s data, recent deploys, and how you compare a failing request with a healthy one.
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How do you confirm a fix actually solved the bug?
What a strong answer includes
A regression test or a production signal, and what would still be true if the fix were wrong.
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How do you debug a problem that spans two services?
What a strong answer includes
The boundary, correlation ids, which side is wrong, and how you avoid fixing the symptom in the wrong service.
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Tell me about the hardest bug you have tracked down.
What a strong answer includes
Why it was hard, the wrong turns, the evidence that found it, and what changed afterward.