Complex System Troubleshooting and Incident Diagnosis Questions

Tests systems thinking and approaches for diagnosing problems that span multiple components services layers or domains and present multiple related symptoms. Candidates should show how they map interdependencies prioritize which symptoms to address first generate and test hypotheses correlate telemetry across logs metrics and traces and distinguish root causes from secondary effects. The topic includes using instrumentation and monitoring to isolate failures reproducing issues in controlled environments understanding cascading failures and failure modes across networking storage database and application layers and applying mitigations rollbacks or fixes while minimizing user impact. Candidates should also describe incident communication documentation and post incident analysis to prevent recurrence.

HardTechnical

0 practiced

During an incident you must choose between an emergency patch that disables a non-critical feature (fast, reversible) and an invasive schema migration that fully fixes the root cause but requires downtime. Outline a decision framework under time pressure that covers risk assessment, rollback safety, SLO impact, customer experience, and stakeholder coordination to choose between the two options.

EasyTechnical

0 practiced

You observe a sudden spike in TCP retransmissions for a critical service. List the immediate steps and simple tools you would use to identify whether the root cause is application-level, OS/network-stack, data-center network, or cloud provider network. Mention specific telemetry to check and which commands to run.

HardTechnical

0 practiced

Design a tabletop incident simulation exercise to teach teams how to diagnose cross-service failures. Provide learning objectives, a scenario outline (for example: partial network partition plus cascading retries), role assignments, an inject schedule, success criteria, and post-exercise evaluation metrics. Explain how the exercise should produce actionable improvements.

HardSystem Design

0 practiced

Your Recovery Time Objective (RTO) for a critical service is 2 minutes, but median recovery during incidents is 15 minutes due to slow diagnostics and manual approvals. Propose an engineering and process plan to achieve a 2-minute RTO: automation candidates, runbook redesign, permission model changes, pre-approved mitigations, chaos exercises, and the metrics you would track to prove improvement.

HardSystem Design

0 practiced

Your service operates in two active regions behind a global load balancer. One region begins degrading (high latency and 50% errors) due to networking issues within that region. Explain, step-by-step, how you'd perform a safe failover to the healthy region while minimizing user impact and data loss. Cover DNS or anycast strategies, failover criteria, session affinity, database replication consistency, and rollback plans.

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