High Availability and Disaster Recovery Questions

Designing systems to remain available and recoverable in the face of infrastructure failures, outages, and disasters. Candidates should be able to define and reason about Recovery Time Objective and Recovery Point Objective targets and translate service level agreement goals such as 99.9 percent to 99.999 percent into architecture choices. Core topics include redundancy strategies such as N plus one and N plus two, active active and active passive deployment patterns, multi availability zone and multi region topologies, and the trade offs between same region high availability and cross region disaster recovery. Discuss load balancing and traffic shaping, redundant load balancer design, and algorithms such as round robin, least connections, and consistent hashing. Explain failover detection, health checks, automated versus manual failover, convergence and recovery timing, and orchestration of failover and reroute. Cover backup, snapshot, and restore strategies, replication and consistency trade offs for stateful components, leader election and split brain mitigation, runbooks and recovery playbooks, disaster recovery testing and drills, and cost and operational trade offs. Include capacity planning, autoscaling, network redundancy, and considerations for security and infrastructure hardening so that identity, key management, and logging remain available and recoverable. Emphasize monitoring, observability, alerting for availability signals, and validation through chaos engineering and regular failover exercises.

MediumTechnical

65 practiced

Design a robust failover detection strategy that minimizes false positives. Describe how you would combine load balancer health checks, application level probes, distributed heartbeats, and quorum mechanisms to decide when to initiate automated failover. Include recommended timeout and threshold examples and how to avoid flapping.

MediumTechnical

86 practiced

Design a disaster recovery testing plan for a critical service. Include the types of tests you would run (tabletop, partial failover, full failover, chaos experiments), frequency, success criteria, roles and responsibilities, and how you would automate test execution and postmortem collection.

EasyTechnical

83 practiced

Discuss automated failover versus manual failover. List three criteria you would use to decide whether to allow automatic failover for a specific service in production and explain why each criterion matters.

HardTechnical

81 practiced

You are the on call cloud engineer when the primary region suffers a major outage during which a suspected security breach is detected. Walk through your incident response: initial triage, deciding whether to failover or isolate the region, coordination with SRE and security teams, preserving forensic evidence, communicating to stakeholders, and steps for a secure failover if chosen. Be specific about priorities and safety checks.

HardTechnical

66 practiced

Design a concrete strategy to prevent split brain in leader election across multiple regions. Compare lease based leaders, quorum consensus (Paxos/Raft), and cloud conditional write approaches (for example DynamoDB conditional puts), and explain how fencing tokens or monotonic sequence numbers would be used to protect against old leaders continuing to act.

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