Module 11 - Interview Prep

Interview Framework

A structured approach to tackle any system design interview question.

1The Job Interview Reality

Simple Analogy
System design interviews are not about perfect answers-they're about demonstrating how you think. The interviewer wants to see your thought process, communication, and ability to navigate ambiguity. A structured framework helps you stay organized under pressure.

A 45-60 minute interview typically covers: requirements (5-10 min), high-level design (15-20 min), deep dive (15-20 min), and wrap-up (5-10 min).

2The RESHADE Framework

R
Requirements5-10 min
Clarify functional and non-functional requirements. Ask questions!
E
Estimation3-5 min
Back-of-envelope math: users, QPS, storage, bandwidth
S
System Interface3-5 min
Define key APIs. What are the inputs and outputs?
H
High-Level Design10-15 min
Draw the architecture. Core components and data flow.
A
Articulate Deep Dive10-15 min
Dive into 1-2 components. Show depth of knowledge.
D
Discuss Trade-offs5-10 min
Justify your choices. What are the alternatives?
E
Edge Cases & Wrap-up3-5 min
Error handling, monitoring, future improvements

3Common Mistakes

Jumping to Solution

Don't start drawing boxes immediately. Clarify requirements first.

Fix: Spend 5-10 minutes asking questions before any design.

Over-Engineering

Adding every component you know: Kafka, Redis, Elasticsearch...

Fix: Start simple. Add complexity only when requirements demand it.

Silent Thinking

Thinking quietly leaves interviewer guessing.

Fix: Think out loud. Share your reasoning continuously.

Ignoring Scale

Designing for 1000 users when they said 100 million.

Fix: Always confirm scale and design accordingly.

Not Managing Time

Spending 30 minutes on requirements, none on deep dive.

Fix: Keep rough time allocation. Move forward proactively.

4What Interviewers Look For

Problem Solving

Can you break down ambiguous problems? Do you ask the right questions?

Technical Depth

Do you understand trade-offs? Can you dive deep when asked?

Communication

Can you explain clearly? Do you drive the conversation?

Practical Knowledge

Have you built real systems? Do your solutions work in practice?

Handling Feedback

Do you adapt when challenged? Are you collaborative?

Scope Management

Can you prioritize? Do you know what to skip?

5Time Management

45-Minute Interview Breakdown
Requirements & Scope5-8 min
Estimation3-5 min
High-Level Design12-15 min
Deep Dive12-15 min
Trade-offs & Wrap-up5-8 min

Pro tip: If interviewer seems ready to move on, ask "Should I continue here or move to [next phase]?" Shows awareness and collaboration.

6Template Questions to Ask

Users

  • • How many users?
  • • Geographic distribution?
  • • User behavior patterns?

Scale

  • • Read vs write ratio?
  • • Peak vs average load?
  • • Growth expectations?

Features

  • • Core features only?
  • • MVP vs full product?
  • • Any features to exclude?

Constraints

  • • Latency requirements?
  • • Availability target?
  • • Budget constraints?

7Key Takeaways

1RESHADE: Requirements → Estimation → System Interface → High-Level → Articulate → Discuss → Edge cases
2Spend 5-10 min on requirements. Never jump to solution.
3Think out loud. Silent thinking is wasted time.
4Time management: 15 min HLD + 15 min deep dive for 45-min interview
5Interviewers evaluate process and communication, not just the answer

?Quiz

1. Interviewer asks 'Design Twitter'. First thing you do?

2. You've been talking for 20 minutes and haven't drawn anything. Problem?