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:

Hard skills:


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.