The tech interview process has multiple rounds — from coding interviews to System Design Interviews. System Design Interviews are commonplace at FAANG companies like Netflix and Amazon, and small tech companies. System Design Interview questions prompt you to mock up a high-level design of a large-scale distributed system.
However, creating a high-level design isn’t the only skill that interviewers need candidates to demonstrate. They also need evidence of an appropriate depth of knowledge for the desired role — which comes through discussion.
To make the strongest impression, you need to demonstrate competency in both of these areas within a limited time. So, how should you approach answering System Design Interview questions, and what exactly should you prioritize?
As a former FAANG systems engineer who has conducted hundreds of System Design Interviews myself, I’ll be sharing 3 tips for effectively answering System Design Interview questions. But first, let’s take a closer look at some of the questions you might encounter.
When interviewing for a software engineering role, you could be asked to design a variety of real-world design problems.
Common System Design problems can include:
System Design Interview questions are intentionally vague, and can be as simple as, “How would you design a web crawler?” Your interviewer is trying to evaluate your investigative abilities. Do you know where to start, and what questions to ask? Are you capable of doing the legwork needed to succeed in practical settings with real-world problems?
That’s why from that point on, your priority should be to clarify as much as you can about the requirements of the system they’ve asked for.
Then, you can move on to complete a high-level design based on what you know.
One thing to note is that there isn’t a one-to-one relationship between System Design Interview questions and answers. By this, I mean that there can be multiple correct answers to any given design problem.
That said, at a high level, there are some steps you should cover when answering a System Design question.
Your System Design Interview answer should check off the following boxes:
You can memorize these checkboxes with the RESHADED framework.
Master System Design Interviews today
Only 1 in 5 candidates pass the entire technical interview process at tech companies—their most common pitfall is the System Design Interview. When it comes to System Design Interview preparation, it's not enough to practice System Design Interview questions. This is because, unlike other technical interviews, there are many possible solutions to a given System Design problem. Rather, to excel in these interviews, you must be able to demonstrate the soft skills and thought processes that interviewers are looking for. In this course, you'll learn to master the behavioral aspects of the System Design Interview from a former FAANG engineer with 15+ years of experience designing distributed systems and conducting System Design Interviews. Whether you're interviewing for a role as a software engineer, technical project manager, or engineering leader, this essential System Design Interview prep course will prepare you with actionable best practices so you can confidently enter your next System Design Interview.
Effectively answering a System Design Interview question relies on your ability to demonstrate your thought process and domain-specific knowledge to your interviewers. With many possible answers to a given design question, how you answer a question can be as important as the answer itself. In other words, presentation matters!
Still, I’ve seen highly experienced engineers leave underwhelming impressions during interviews due to a few preventable mistakes.
Here are 3 tips to help ensure your answers to System Design Interview questions leave a positive impression on your interviewers.
When participating in System Design Interviews, it’s critical to demonstrate your ability to recognize and evaluate trade-offs, as it reflects your understanding of various design aspects and their implications.
Designing a large-scale distributed system is rarely straightforward. As we mentioned earlier, there are endless ways to mix and match different components of a system, each with their own strengths and weaknesses.
Trade-offs can occur between various requirements of a system, such as:
Every solution comes with a trade-off. Your goal is to choose the solution with the most workable trade-off. Ultimately, the solution you choose should have a trade-off that doesn’t severely impact the most important requirements of your system.
Discussing trade-offs shows interviewers that you can consider users’ needs, business goals, and constraints, and prioritize the right use cases for a system. As you land on your decision, be sure to narrate your thought process to demonstrate you’re making an informed decision (and when in doubt, you can ask more clarifying questions about requirements and constraints).
Time is of the essence in the interview. You have anywhere from a 30 to 45-minute window to complete a solution, evaluate it, and engage in feedback and discussion. For a 45-minute window, you should budget:
Keep in mind that your goal is not to create a perfect design within this timeframe. Most interviewers understand the constraints you’re working under, and will not expect a flawless solution.
To best manage your time, focus on the following:
By the end of your interview, you should have some time to speak deeper on some topics that showcase your knowledge for your desired role.
For instance, depending on the level (or seniority) of the role you’re applying to, you’ll be expected to have knowledge of different System Design concepts:
Junior System Designers: At this level, you’re expected to possess at least a basic understanding of system design principles, concepts, and best practices. You’ll need to know how to implement small components or features based on given specifications, and understand trade-offs, performance, and scalability at a basic level.
Mid-level System Designers: At this level, you’ll be expected to have a solid grasp of system design, and experience in designing, developing, and implementing system components. Interviewers will expect you to be able to identify and address performance, scalability, and reliability issues in addition to being well-versed in various architectural styles, design patterns, and their trade-offs.
Senior System Designers: At the senior level, you should have strong expertise in this field that enables you to not only tackle some of the most challenging design issues, but also the insight to address long-term issues that may affect a system over its lifetime. In other words, you should be able to speak toward bottlenecks and long-term scalability of the system. In addition, you should feel confident enough to lead and mentor other designers, in regard to system design principles, concepts, and best practices.
Principal/Lead System Designers: Professionals at this level possess both strong expertise in system design, but also extensive knowledge of the field, its history, and industry trends. These designers are often recognized for designing and implementing complex and large-scale systems. They have a deep and thorough understanding of trade-offs, performance optimizations, and long-term scalability.
The best way to ensure you get the time to address these specific talking points is by starting wide and ending deep.
This approach will help you avoid a common mistake of going too deep into the complexities of certain aspects of your system early in your interview. Not only would you risk an incomplete solution by doing this — you might also leave your interviewers with the impression that you’re unable to prioritize your assigned task.
This approach also allows you a chance to demonstrate your knowledge or awareness of how emerging and in-demand technologies can be implemented to improve your solution. For instance, as part of the Evaluation stage of RESHADED method we discussed earlier, you can use this stage to discuss how machine learning technologies and algorithms could be leveraged to further improve your system.
Master System Design Interviews today
Only 1 in 5 candidates pass the entire technical interview process at tech companies—their most common pitfall is the System Design Interview. When it comes to System Design Interview preparation, it's not enough to practice System Design Interview questions. This is because, unlike other technical interviews, there are many possible solutions to a given System Design problem. Rather, to excel in these interviews, you must be able to demonstrate the soft skills and thought processes that interviewers are looking for. In this course, you'll learn to master the behavioral aspects of the System Design Interview from a former FAANG engineer with 15+ years of experience designing distributed systems and conducting System Design Interviews. Whether you're interviewing for a role as a software engineer, technical project manager, or engineering leader, this essential System Design Interview prep course will prepare you with actionable best practices so you can confidently enter your next System Design Interview.
There are various possible answers to any given System Design question, which makes mastering your approach just as crucial as honing your technical skills.
To effectively answer System Design Interview questions in the engineering interview, be sure to:
Keep these tips in mind as you prepare for the interview, and be sure to do mock interviews to ensure you get real-time practice performing them on the spot.
I provide actionable steps on how to implement these tips — along with other best practices — in my free course: The System Design Interview Prep Handbook.
Compiling best practices from my 15+ years of experience designing distributed systems and conducting System Design Interviews, you’ll come away from the course knowing the following:
As you work to master the System Design Interview, you’re investing in an essential skill to keep advancing in your tech career. I’m honored to support you in your journey, and hope you found this article helpful.
Happy learning!
Free Resources