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

33 practiced

In Bash, write a short script (6-10 lines) that tails the last 100 lines of /var/log/myapp.log, filters for the words ERROR and WARNING (case-insensitive), extracts the first line of each stack trace block as a header, and prints unique headers with counts. The script should run on a typical GNU/Linux system and be robust to absent files.

MediumTechnical

31 practiced

Explain a step-by-step approach to debug a container that fails with 'permission denied' when trying to connect to an AWS S3 bucket. Include checks for IAM roles and policies (including IAM Roles for Service Accounts in Kubernetes), ephemeral credentials from instance metadata, SDK credential resolution order, and host-level security like SELinux/AppArmor that could interfere.

HardTechnical

33 practiced

Implement a robust strategy to diagnose and mitigate a production-wide database connection pool exhaustion that occurs under high load. Describe checks at application, driver, and database levels (e.g., checking pool metrics, pg_stat_activity), preventive measures (connection pool tuning, circuit breakers, request queueing), and a safe plan to reduce the number of active connections without downtime.

HardTechnical

37 practiced

You are asked to design an automated Root-Cause Analysis (RCA) helper: given logs, time-series metrics, and traces around an incident window, describe an algorithm or system that highlights and ranks probable root causes. Specify input data formats, features and heuristics (change events, correlated anomalies, dependency graph), possible machine-learning models or rule engines, and how you would evaluate and iterate the system to reduce false positives.

EasyTechnical

46 practiced

Describe what 'git bisect' does and walk through a realistic example of using it to find the specific commit that introduced a flaky test in a CI pipeline. Include automation tips (git bisect run), how to register 'good' and 'bad' commits, and limitations when tests are non-deterministic or when builds are environment-dependent.

Unlock Full Question Bank

Get access to hundreds of Systematic Troubleshooting and Debugging interview questions and detailed answers.

Join thousands of developers preparing for their dream job.