Step 4: Wrap up, plus dos and don'ts
Play this lessonThis lesson comes with a chapter quiz.In the final minutes, the interviewer may ask follow-up questions or let you discuss other points:
- Bottlenecks and improvements. Never say your design is perfect. There's always something to improve.
- Recap your design, especially if you proposed a few options.
- Error cases: a server failure, a network loss…
- Operations: how to monitor metrics and error logs, and how to roll out the system.
- The next scale curve: if the design supports 1 million users, what changes for 10 million?
- Other refinements, if you have time.
✅ Do
- Always ask for clarification. Don't assume your assumption is correct.
- Understand the requirements.
- There's no single right answer. A design for a startup differs from one for a giant company.
- Let the interviewer know what you're thinking. Communicate!
- Suggest multiple approaches if possible.
- Agree on the blueprint first, then go into details. Start with the most critical components.
- Bounce ideas off the interviewer, like a teammate.
- Never give up.
❌ Don't
- Show up unprepared for typical questions.
- Jump into a solution before clarifying requirements and assumptions.
- Go into too much detail on a single component at the start.
- Stay silent when you're stuck. Ask for hints.
- Think you're done once you give the design. You're not done until the interviewer says so. Ask for feedback early and often.
Key takeaways
- Close with bottlenecks, failures, monitoring and next-scale ideas.
- Communicate constantly; never go silent.