1. How to Approach a Design Question
1
The picture to keep in your head2
1.1 What is a system design interview, and what isn't it?3
1.2 What is the interviewer actually scoring?4
1.3 What's the step-by-step framework?5
1.4 How do you manage a 45-minute round?6
1.5 What questions should you ask first?7
1.6 What's the difference between functional and non-functional requirements?8
1.7 What's an API, and why define it before drawing boxes?9
1.8 How do you sketch the data model?10
1.9 What does a good high-level design look like?11
1.10 How do you choose what to deep dive into?12
1.11 How do you talk about trade-offs?13
1.12 What if you get stuck or don't know something?14
1.13 What are the most common mistakes?15
1.14 What does the bar look like: fresher vs SDE-2?16
Memory card and where the analogy breaks17
Practice: five levels18
Interview questions19
Solutions20
Sources21
Code lab1. How to Approach a Design Question
1.1 What is a system design interview, and what isn't it?
3 min read+10 XP
The round
At the architect's desk: There's no single correct house. Two great architects given the same family will draw two different houses, and both can be good. What makes an architect good is that every choice has a reason and the reasons fit what the family needs.
In the interview: A system design interview is a conversation of about 45 to 60 minutes where you design a large software system out loud, and explain and defend your choices as you go.
What it is not:
- Not a quiz with one right answer. There's no answer key. Two strong candidates can draw different designs and both pass.
- Not a coding round. You may write an API or a table, but nobody expects working code.
- Not a memory test. Reciting "Netflix uses X" scores little. Explaining why X fits this problem scores a lot.
- Not a monologue. The interviewer is part of the design. They'll add constraints, push back and steer you.
Memory code: "No answer key, only reasons." You're scored on the reasons behind the design, not on matching a secret diagram.