This is the kind of question where you can talk for an hour and still feel like you barely scratched the surface.
Start by clarifying functional and non-functional requirements, such as consistency levels, latency targets, and regulatory constraints. Then propose a multi-region architecture that balances consistency and availability, using techniques like geo-partitioning, consensus protocols, and asynchronous replication. Finally, discuss trade-offs and how to handle failures and conflicts.
Pro tip: Emphasize that perfect global consistency is often impractical; instead, propose a pragmatic approach that uses strong consistency for critical operations (e.g., transfers) and eventual consistency for less critical ones (e.g., balance checks), while ensuring idempotency and auditability.
Ask about consistency needs (strong vs. eventual), latency SLAs, data residency regulations, and expected scale. This shapes the entire design.
Propose a multi-region deployment with data partitioned by customer region. Use a global transaction coordinator or consensus protocol (e.g., Raft, Paxos) for critical writes.
For critical operations like transfers, use synchronous replication within a region and asynchronous cross-region replication with conflict resolution. For balance checks, allow eventual consistency with read replicas.
Design idempotent APIs, use distributed transactions or sagas for cross-region transfers, and integrate with card payment networks via regional processors.
Discuss CAP theorem trade-offs, latency vs. consistency, and how to handle network partitions, region failures, and data conflicts.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.