How do you design a scalable system for high traffic?
This question assesses your ability to architect systems that handle massive user loads without degradation. It tests knowledge of load balancing, horizontal scaling, and redundancy strategies.
Why Interviewers Ask This
Interviewers ask this to evaluate whether candidates can think beyond code implementation to holistic system architecture. They want to see if you understand bottlenecks in distributed systems and how to mitigate them using proven patterns. The goal is to determine if you can balance trade-offs between consistency, availability, and partition tolerance under real-world constraints.
How to Answer This Question
Start by clarifying requirements like latency, throughput, and consistency needs. Propose a high-level architecture including load balancers, application servers, and databases. Discuss specific scaling techniques such as sharding, caching layers, and CDNs. Address failure scenarios and how the system remains resilient. Finally, mention monitoring and observability practices to maintain system health.
Key Points to Cover
- Load balancing strategies
- Horizontal vs vertical scaling
- Caching mechanisms
- Database sharding
- Fault tolerance
Sample Answer
To design a scalable system, I first define non-functional requirements like 99.9% uptime and sub-second latency. I would implement a multi-tier architecture with a global load balancer distributing traffic across geogra…
Common Mistakes to Avoid
- Ignoring network latency
- Overlooking single points of failure
- Not defining clear requirements
- Focusing only on code rather than architecture
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