Cloud Resilience: Scenario-Based Questions

Multi-region architectures increase fault tolerance and reduce latency, but introduce challenges in data consistency, cost, and operational complexity. Designing for resilience requires trade-offs and planning across layers.

🌐 Why Go Multi-Region?

• Mitigate region-level outages or disasters.
• Improve latency for global users.
• Meet data residency or compliance requirements.

🏗️ Architectural Patterns

• Active-Passive: Primary region handles traffic; failover region on standby.
• Active-Active: Traffic distributed across regions (more complex to implement).
• Edge Termination: Front traffic via CDN/load balancers with regional backends.

📊 Design Considerations

• Data Consistency: Use CRDTs, global DBs (Spanner, DynamoDB Global Tables), or async replication.
• DNS & Routing: Use Route 53, Cloudflare, GCP Traffic Director with health checks and geo rules.
• State Management: Keep services stateless or replicate session data (e.g., global Redis).
• Automation: Sync infrastructure and secrets via CI/CD across regions.

✅ Best Practices

• Test failover regularly (chaos drills, game days).
• Version deployments to ensure compatibility across zones.
• Monitor inter-region latency and replication lag.
• Use region-isolated metrics and alerting for accurate response.

🚫 Common Pitfalls

• Using single-region services in an otherwise HA setup.
• Assuming eventual consistency is “good enough” without business alignment.
• Failover complexity not documented or automated.

📌 Final Insight

Multi-region architecture is powerful but not free. Balance redundancy with complexity and ensure every layer — from DNS to DB — supports failover gracefully.