Level up your System Design Interview: Drive the Conversation

This is my most important tip to pass 10+ onsite at Senior+ FAANG level companies. After my interviews, I started doing mock interviews for senior+ level and helped people improved their system design skills significantly. Few have passed senior interviews at FAANG.

One very common mistake is to be passive during your interviews and only respond to questions from interviewers. For senior+ level, you must drive the conversation and engage the interviewer.

A very common script for a system design went as follow:

• First, the interviewer provided the questions.
• Candidate started solving the problems, maybe ask clarifying questions here and there.
• During the candidate’s explanation, interviewer asked the questions on specific parts of the design and candidate answered.

If your interviews were similar like this, most likely you will fail. A senior engineer needs to drive design discussion and guide the audience to focal part of design. It is part of the job that he needs to guide junior engineers to follow his thinking process and convince stakeholders on the proposed approach.

It is not hard to be on the driving seat. Here are few simple ways you can drive the conversation.

Drive the structure your interview

Before starting the interview, I try to set the outline of the interview. This also helps align my approach with the interviewer’s.

“Let me walk you through how I will approach this problem. We will start with the requirement, functional and non functional, then I will come up with a high level design and APIs that will work functionally, then we can go into specific components and talk about the pros and cons of the design regarding availability and scalability. How does that sound?”

Steer the conversation

After finishing every parts of the design, I always ask for feedback and try to provide options for the next discussion points:

“Do you think I miss anything in [Functional/NonFunctional] Requirements?

“Now that our requirement is ready, let’s go into high level system design and APIs. What do you think?”

“This design have pros and cons. It’s simple but there is a few points of failure in the QueueConsumer, Databases, just to name a few. Do you want to discuss them or you have other topic in mind?”

The key here is instead of letting the interviewer guide you through the conversation, you want to flip it around and guide them instead. Provide them with options of where you want to go next, at the same time take it as an opportunity to gather feedback and steer the conversation towards where the interviewers want.

Get Immediate Feedback

It is very common for candidate to start a long ramble. After all, we are trying to showcase our knowledge. However, in the worst case, you might be talking about stuff that the interviewers does not care about. Try not speaking for a long time without getting a read on the audience. I have found it very useful to stop after a few minutes and ask if (1) the interviewer has any questions, or (2) they want to go deeper or move on to a different topic. If you are doing well, they will say go ahead. Otherwise, they will help you guide the conversation back to the right place.