Cloud Architecture: Scenario-Based Questions

A multi-region architecture protects against regional outages and improves latency by serving users closer to their geography. But it adds complexity in data consistency, deployment, and cost.

🌍 Key Design Goals

• Resilience against regional failures (natural disasters, ISP issues).
• Improved performance via geo-distributed traffic routing.
• Business continuity and DR readiness.

🏗️ Core Components

• Global Load Balancer: GCLB, Route 53, Cloudflare for DNS-based routing.
• Region-local compute: App servers, Kubernetes, Lambdas deployed in multiple regions.
• Multi-region storage: S3 Cross-Region Replication, Cosmos DB, Bigtable multi-regions.
• Failover detection: Health checks + automatic routing failover.

🔁 Replication & Consistency

• Use async replication for eventual consistency (high write tolerance).
• Prefer quorum-based databases for strong consistency (e.g., CockroachDB, Spanner).
• For transactional apps, isolate region-specific writes to avoid global contention.

✅ Best Practices

• Design for regional isolation (blast radius control).
• Test failover drills regularly.
• Use infrastructure as code to standardize regions.
• Plan for DNS TTL and cache delays during failover.

🚫 Common Pitfalls

• Assuming data consistency magically works across regions.
• Failing to audit and monitor replication lags.
• Using services not designed for multi-region support (e.g., single-zone databases).

📌 Final Insight

Multi-region design is about trade-offs — between availability, consistency, and cost. With careful partitioning, monitoring, and tooling, it can dramatically increase system reliability and user trust.