Design a global real-time notification system

Company: Google

Role: Software Engineer

Category: System Design

Difficulty: medium

Interview Round: Onsite

Quick Answer: This question evaluates competency in designing large-scale distributed systems for global real-time notifications, covering scalability, multi-region ingestion and delivery, multi-channel fallback (push, email, SMS), delivery semantics, idempotency/deduplication, latency/throughput SLAs, and observability.