Oct 15, 2021
Software development companies often test their industry candidates for system design skills during interviews.
We invited a senior engineer and manager (L5/SDEIII), from a FAANG company, to conduct a mock system design interview at our event. We also invited an experienced developer and individual contributor (L4/SDEII) from another FAANG company as the interviewee. More than a hundred software developers joined our event.
Our interview took an hour. It was pretty different from many learning materials online, such as YouTube videos covering system design interviews. Here are a few of the key differences:
| A typical system design interview video online | Our mock system design interview |
| Requirements are quickly gathered within the first 5 minutes, and written down as "functional requirements" and "non-functional requirements" | We spent 15 minutes to break down high level requirements into multiple critical user journeys |
| Detailed system design typically satisfies the full requirements | Detailed system design was for one of the several user journeys |
| Little to no discussion comparing alternative technology choices, such as what database to use ( mysql, DynamoDB, etc.) | The interviewer and interviewee discussed consistency and performance characteristics of DynamoDB. Interviewer also expected additional alternatives to be presented, and design choices to be justified. |
 After the interview portion of our online event, our interviewer let us know some of the essential soft and hard skills he looks for in a candidate. ( To be clear, these are NOT official FAANG interview rubrics, but a high-level summary of the interviewer's experience interviewing for different companies and projects)
Soft skills:
- Gathering requirements
- Making decisions and justifying tradeoffs
- Describing the solution using concise language and accurate technical terms
Hard skills:
- Design quality: scalability, reliability, efficiency (L4/SDE II, L5/SDE III)
- Essential facts about existing software solutions and hardware capabilities (L4/SDE II, L5/SDE III)
- Project lifecycle awareness, such as how a project is developed and maintained (L5/SDE III)
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Ming Dao School uses 1-1 coaching and group events to help high-tech professionals grow their careers and handle career transitions.
If you like to join our upcoming mock system design interview events or other coaching programs, please contact us on LinkedIn.