Distributed Systems Troubleshooting Questions

Focused on diagnosing incidents specific to distributed architectures and multi service systems. Candidates should be able to detect and analyze network latency packet loss service to service communication failures cascading failures load balancing misconfiguration and data consistency anomalies. The topic covers observability practices such as distributed tracing aggregated metrics and logs correlation identifiers health checks and alerting; instrumentation strategies for cross service request flow mapping; and remediation patterns such as timeouts retries circuit breakers backpressure and resynchronization. Interviewers assess the ability to reason about partitioning and consistency models reproduce issues safely across services and propose mitigation and longer term fixes for distributed failure modes.

HardSystem Design

0 practiced

Design a multi-region failover strategy that minimizes downtime when an entire region fails, considering DNS caching and TTL, client resolver behavior, CDNs, Anycast/BGP, health checks, and traffic steering. Explain trade-offs (RTO targets vs complexity) and how DNS TTLs interact with resolver caching to affect failover time.

MediumTechnical

0 practiced

A user updates their profile in Service-A and immediately reads from Service-B and sees stale data. Enumerate possible causes across caching layers, replication lag, eventual consistency, and API layering. Propose an immediate mitigation to minimize user impact and a long-term fix to ensure read-after-write semantics for this use-case.

EasyTechnical

0 practiced

You need a correlation id that follows a single client request across 12 services. Describe where to generate the id, how to propagate it across HTTP/gRPC/messaging (header names and formats), how to persist it for async components (message queues, background jobs), and common pitfalls (e.g., duplicate ids, privacy/leakage). Explain how you'd handle third-party downstream services that don't propagate it.

HardTechnical

0 practiced

Your etcd cluster is experiencing leader election flapping and clients are timing out. Describe steps to diagnose (network partitions, clock skew, resource exhaustion), what logs and metrics to inspect, and how to harden leader stability (tuning election timeouts, isolating resources, QoS). Include non-disruptive checks and when to escalate to rolling restarts.

HardSystem Design

0 practiced

Design an automated safety-net system so that when a service's error-rate crosses a threshold and remains elevated for a configured window, the system will automatically trigger a rollback or divert traffic. Describe the architecture, approval/guardrails, testing strategy, and how you'd ensure the automation itself cannot cause oscillation or additional outages.

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