The Interview Loop: System Design Round

You're in the system design round. You have 45 minutes. Here's the framework.

The Structure

First 5 minutes: Clarify requirements. Ask about scale, latency targets, consistency requirements. Don't assume.

Next 20 minutes: High-level design. Draw boxes: load balancer, API servers, databases, caches. Explain data flow.

Next 15 minutes: Deep dive. Pick one component and explain in detail. Your choice. Usually database design or caching strategy.

Last 5 minutes: Trade-offs. Every design has them. Explain yours. Be honest about weaknesses.

What They're Evaluating

Can you think systematically? Do you ask clarifying questions? Do you decompose the problem? Or jump to solutions?

Do you know relevant technologies? Don't deep-dive into something you don't actually understand.

Can you communicate? Interviewers should follow your thinking easily.

Do you think about trade-offs? There's no perfect design. Show you understand costs and benefits.

Common Mistakes

• Jumping to solutions before understanding requirements
• Using obscure tech to sound smart
• Designing for Google-scale when the problem is Startup-scale
• Over-engineering
• Not explaining your reasoning

AI-Specific Considerations

If it's an AI system design (RAG, fine-tuning, etc.):

• Explain the data pipeline (embedding, chunking, retrieval)
• Address cost and latency
• Discuss evaluation metrics
• Plan for iterating on quality

The same principles apply. Clarify requirements, design high-level, deep-dive on one area, discuss trade-offs.