System design interviews are becoming increasingly popular, and important, as the digital systems we work with become more complex. The term ‘system’ here refers to any set of interdependent modules that work together for a common purpose. Uber, Instagram, and Twitter (now X) are all examples of ‘systems’.
The role of a system design engineer includes creating the architecture for different components of a given system, and defining how they interact with each other for a common goal.
Unlike a coding interview question, system design interviews are free-form discussions, with no right or wrong answers. It is very common for engineering managers in a system design interview to ask the candidate to design a web-scale application—perhaps an Instagram, YouTube, or Uber backend from scratch, and then ask follow-up questions on these designs.
The aim is to find developers who can write clean and precise code, understand the complex system that the code will support, and optimize the system with various limitations.
Why system design interviews?
System design interviews are essential because they test a candidate’s ability to think critically and design solutions that meet real-world requirements. These interviews go beyond assessing a candidate’s coding proficiency and delve into their understanding of system scalability, performance optimization, and trade-offs involved in system design.
By evaluating a candidate’s problem decomposition skills, interviewers can measure their ability to break down complex problems into manageable modules and design the interactions between them.
Additionally, system design interviews evaluate a candidate’s holistic understanding of system architecture, encouraging them to consider the entire system rather than focusing on isolated components. This assessment of end-to-end system understanding helps identify candidates who can design cohesive and efficient systems.
Apart from that, system design interviews are great for assessing a candidate for their communication skills. Since system design questions are not just code-oriented, developers are often required to present detailed explanations and diagrams of their thought processes.
Ask a developer to break down the backend of an application, and how it connects to the frontend. Doing so, you will have a direct window into their problem-solving and communication abilities.
System design interviews are important because of the following reasons:
- They allow companies to assess a candidate’s ability to think about the big picture and evaluate based on thinking and creative capabilities and how well a candidate understands a complex system.
- System design interviews are a great way to assess the candidate’s ability to understand the system’s trade-offs, complexities, or limitations. There are multiple ways to design a system, and these interviews are all about checking if the candidate can take the best or most optimized approach to make the system work.
- System design is a challenging but rewarding field, and only candidates genuinely interested in the field can get success in it. A structured interview helps in filtering genuine talent for such roles.
Structuring a successful system design interview
There are various steps involved in conducting a successful system design interview. Here are some tips for you to conduct an effective system design interview:
1. Ask relevant questions
- Focus on questions related to the company and the candidate’s potential role.
- Avoid asking generic or unrelated questions that might make the candidate feel irrelevant.
- Start with simpler design questions to assess the candidate’s approach.
2. Provide hints and guidance
- Help the candidate while they are solving the problem by giving hints and suggestions.
- Praise the candidate when they are on the right track to boost their confidence.
- Steer them in the right direction if they are struggling to find a solution.
3. Encourage a step-by-step approach
- Emphasize the importance of a structured problem-solving approach.
- Evaluate how the candidate breaks down the problem into smaller components and builds the system from scratch.
- Assess the candidate’s understanding of the fundamental principles of system design.
4. Facilitate collaboration
- Engage in the interview process actively and participate in the discussion.
- Ask follow-up questions to increase the complexity of the system or explore optimization opportunities.
- Encourage the candidate to think critically and consider different approaches, pros, and cons.
5. Assess the candidate’s acumen
- Evaluate the candidate’s ability to analyze and choose the appropriate design path.
- Observe how they utilize their skills in a real-life scenario when faced with increasing system complexity.
- Consider the candidate’s adaptability, problem-solving skills, and overall system design acumen.
Remember, the goal is not only to assess the candidate’s skills but also to create a learning experience for them during the interview.
Best practices for interviewers
Here are some best practices you can follow to conduct your next system interview design interview:
1. Interviewer preparation
- Familiarize yourself with relevant questions for the job role.
- Understand the problem description and potential solutions.
- Be knowledgeable about relevant design patterns and technologies.
2. Clearly communicate expectations
- Define evaluation criteria (e.g., scalability, performance, fault tolerance).
- Provide a detailed scope of the system design exercise to help candidates focus.
- Quantify constraints and inputs that the system will need to handle while it is live.
- Share a schedule or breakdown of the interview to help candidates manage their time effectively.
- Use visual representation tools to clearly communicate your expectations to the candidate.
3. Active interview engagement
- Ask follow-up questions to delve deeper into the candidate’s answers.
- Clearly state the possibility of follow-up questions at the beginning of the interview.
- Ensure candidates understand the evaluation criteria and answer accordingly.
- Focus on the edge cases in the candidate’s solution and work with the candidate to improve the solution for scalability.
4. Providing feedback
- Highlight positive aspects of the candidate’s solutions.
- Point out areas for improvement and provide constructive criticism.
- Help candidates understand their performance and identify areas for growth.
5. Value learning and growth
- Ensure the interview provides a learning experience for the candidate.
- Help candidates pinpoint improvement areas and develop their system design skills.
- Give relevant examples in the feedback to call out the areas of improvement on which the candidate needs to improve.
- Encourage candidates to apply feedback in future interviews.
Remember, effective system design interviews require thorough preparation, clear communication, active engagement, constructive feedback, and a focus on the candidate’s learning and growth.
Evaluation rubric for interviewers
How can HackerEarth FaceCode be used in System design interviews?
FaceCode is a live interview platform that allows the candidate to share their screen during an interview. It provides you with a diagram board that contains the various components needed for a system design interview. You can easily ask a candidate to create a simple system design on the diagram board and explain the various components during the live interview. To learn more about FaceCode, read this article.
HackerEarth FaceCode also has diagram-based questions that can be used to test a candidate on their system design skills. You can use these question types to check for the candidate’s understanding of understanding complex systems and also their skills to design a system from scratch. You can give your own diagram-based questions or can use the questions given in the library. To learn more about diagram-based questions, read this article.
System design interviews can be challenging to conduct effectively. However, by following certain tips and using the right platform, you can conduct these interviews effectively. System design interviews are used to assess a candidate’s skill in understanding complex systems or designing one with all the limitations and optimizing the system. It is one of the most important phases of the recruitment process as it allows you to assess the candidate’s overall skill of problem-solving and if they are genuinely interested in the role.
HackerEarth FaceCode interviews can be used to conduct a system design interview by using the diagram board feature. You can also use the diagram-based questions present in HackerEarth’s library or create a question manually to assess the candidate’s skill in understanding the complex system and creating one from scratch.
System design interviews are powerful and mostly used by recruiters to assess the overall approach of a candidate toward the question. We hope this guide will help you to conduct your next system design interview effectively.
Frequently Asked Questions (FAQs)
Q.1. What is the purpose of system design interviews?
System design interviews are a type of interview that is used to assess a candidate’s ability to design and implement a system from conception to the end. They are typically given to more senior candidates (with a few years of experience) who are applying for positions that require system design expertise.
The purpose of system design interviews is to evaluate a candidate’s skills in the following areas:
- System design: The ability to design a system that meets the requirements of the users and the constraints of the environment.
- Problem-solving: The ability to identify and solve problems in a complex system along with all the limitations.
- Communication: The ability to communicate complex technical concepts to both technical and non-technical audiences.
- Collaboration: The ability to work with others to design and implement a system.
Q.2. How can interviewers ensure they’re assessing system design skills effectively?
Here are some key things interviewers can do to ensure they’re assessing system design skills effectively:
- Ask the right questions
- Be prepared to give feedback
- Be patient
- Use a diagram board or other visual aid
- Ask open-ended questions
- Be fair and objective in your evaluation
These tips can help you to conduct an effective system design interview and help to ensure that you are assessing system design skills effectively.