Systematic Troubleshooting and Debugging Questions

Covers structured methods for diagnosing and resolving software defects and technical problems at the code and system level. Candidates should demonstrate methodical debugging practices such as reading and reasoning about code, tracing execution paths, reproducing issues, collecting and interpreting logs metrics and error messages, forming and testing hypotheses, and iterating toward root cause. Topic includes use of diagnostic tools and commands, isolation strategies, instrumentation and logging best practices, regression testing and validation, trade offs between quick fixes and long term robust solutions, rollback and safe testing approaches, and clear documentation of investigative steps and outcomes.

EasyTechnical

38 practiced

Explain the difference between 'symptom' and 'root cause' in troubleshooting. Provide a concrete example from systems administration where a symptom could mislead the investigation, and describe how you would move the diagnosis from symptom to root cause.

MediumTechnical

33 practiced

Provide a Python script (or short program) that parses a large JSON-lines application log file and computes the error rate for each endpoint over the last hour. Assume each line is a JSON object with fields: timestamp (ISO8601), endpoint, status. Describe any performance considerations and how to scale this for multi-GB log files.

MediumTechnical

34 practiced

A Java service in production steadily grows in memory until it triggers an OOM after 6–8 hours. Describe a methodical debugging plan to find the memory leak: what metrics and logs to collect, which JVM tools to use (names and purposes), when to capture heap dumps, and how to analyze them. Also mention safe practices for collecting diagnostics in production.

HardTechnical

48 practiced

A proprietary binary on a production host crashes with no source code available. Describe how you would obtain and analyze core dumps to find the crash cause: enable core dumps, collect build-ids/symbols, use gdb/addr2line, and approach vendor coordination if necessary. Include container-specific considerations and how to configure the environment to capture useful symbols.

EasyTechnical

28 practiced

On a Windows server, a critical service that runs under a domain service account fails to start with 'Access Denied' in the Event Viewer. Outline the steps and checks you would perform to diagnose and fix this permission-related service failure. Include Windows-specific tools and policies you would inspect.

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