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System Design Interview Preparation Tips

Posted on 
July 13, 2021
Abhinav Rawat

System design, a process of defining, developing, and designing systems that satisfy a business or organization’s specific needs and requirements, is a complex and challenging role to fill. The role is especially critical when it’s for designing larger systems with various constraints and requirements. Thus, a system design interview at FAANG or Tier-1 companies calls for experienced, dedicated, and competent candidates.

Therefore, to help you stand out, we’ve underlined the essential tips needed for an effective system design interview preparation. Take a look:

1. Focus on What You Already Know

2. Understand the Problem

3. Break Down Your Solution

4. Practice the Pauses

5. Avoid Silver Bullets

6. Keep It Simple, Stupid – KISS

7. Always Justify Your Points

8. Be Updated With Current Tech Solutions and Practices

9. Communicate Your Ideas Clearly

10. Don’t Stop Practicing

How System Design Interviews Differ From Other Coding Interviews

Given its complexity, it is nearly impossible to cover the various topics and trade-offs of system design in a couple of minutes. Also, contrary to other coding-skill interviews, a system design interviewer never seeks an optimal solution, as it does not exist. Therefore, interviewers conduct very different interviews premised on the same questions, focusing on the distinct aspects of the system.

So, think of system design interview as more of a brainstorming session driven by open-ended questions. As a result, a system design interview preparation should equip you to discuss a complex system competently.

A system design interview does not require you to be well-versed with every topic. Here, the final design is not nearly as important as the thought process behind its design choices. Therefore, it presents engineers with considerable freedom to take ownership of open-ended problems and ideate the best solutions.

How to Prepare for System Design Interview – Best Practices

System design interviews use open-ended questions to discover how well you can work on a team and your approach to arriving at solutions to problems. The interview analyzes your problem-solving process and system designs. This interview allows you to present your skills and expertise concretely, while also portraying yourself as a valuable asset to the hiring manager. 

Following are the best practices to employ while preparing for system design interview:  

1. Focus on What You Already Know

There is an infinite amount of information that a system designer can explore. For instance, you can learn about all the available database technologies, and then decide the things you need to know and the irrelevant. However, it might not be possible for you to cover and become familiar with all database technologies during your preparation. Fortunately, you don’t need to either.

The key is to begin with the knowledge you already possess. If you are reading this article on how to prepare for a system design interview, you probably are a software engineer with a significant amount of experience. In addition, you are well-versed with database technologies and software design patterns. So, you can effectively draw on these in your system design interview.

The key to an effective system design interview preparation is to start with what you know. Then, go ahead and fill the gaps. Allow us to explain.

Say you’re well-versed with one broad category, such as:

·       Message handlers

·       Load balancers

·       Database technologies

·       Among others …

For example, if message handlers is your strength, you may have the knowledge of RabbitMQ, Kafka, or a plethora of other related things. For your systems design prep, instead of focusing on mastering these server programs, get yourself familiar with a message handler and how it works.

Moreover, you just need to know one specific technology and use it in your interview. This way, your effort will be streamlined in one area rather than spending precious time covering every intricacy of a small topic.

2. Understand the Problem

Understanding the problem should be a big part of your systems design interview prep. This is not confined to knowing the problem and how to solve it, but involves deeply understanding a given problem through the constraints, the user base, and its size. Make sure you include this approach while practicing problems.

Take a messaging app like Facebook Messenger, for instance, where you’ll have billions of active users messaging each other as well as sharing links, multimedia, etc. On the other hand, consider a messaging app for doctors in hospitals; this kind of system will demand a high level of security wherein one may or may not share multimedia.

Therefore, by determining the core use, you can define your design’s priorities, focal point, and cornerstone. Additionally, you can also make reasonable assumptions about a product, so you need not ask the interviewer any redundant or inessential questions.

You can start with basic assumptions, like:

Ø  Who are the users of the system?

Ø  What is the goal of this system?

Ø  What is the purpose of the system?

Ø  How would users utilize the system?

Ø  What are the system’s inputs and outputs?

You can also pinpoint the differences in these assumptions between the interviewer and you. This will help you focus and demonstrate product sensibility and teamwork.

3. Break Down Your Solution

Once you have a clear understanding of the problem, go ahead and break it down into pieces. Usually, you should have a message handler, server, and data store. So, start with a broad picture of what your system design will look like by using these components. From there, you can map out the specifications. Subsequently, you can pick a solution that is the easiest or the most interesting.

During the interview, this approach will ensure that you do not rush to solve a given problem. This gives the interviewer insight into your approach and confirm that you are thinking straight and not bluffing your way through the problem.

You can even ask some clarifying questions, such as:         

  • Do you require analytics, authentication, or integration with existing systems?
  • Are we to discuss the API or end-to-end experience?
  • What clients are we supporting? (web, mobile, etc.)

4. Practice the Pauses

Avoid getting into the details prematurely. Candidates tend to divulge all details when drawing services, databases, or clients connected to these. So, they delve into one part of the system and get into minute details. Ultimately, this leads to you talking for the most part, something you do not want in a system design interview.

Instead, it’s best if you spoke most of the time while receiving feedback from the interviewer. Here, you can use the 80-20 rule, wherein you talk 80% of the time and leave the 20% for your interviewer.

Besides, when you get into a flow and give unnecessary details that your interviewer does not want, likely, they will not stop you. And if you make a mistake at some point, you’ll have to backtrack, which is not just a waste of time but also a negative point. Here, the key is to take necessary pauses while explaining the design and wait for your interviewer to ask for particulars. So, while you are practicing discussing a solution, practice pausing too.

5. Avoid Silver Bullets

Erase any fixed architecture in your mind. Many interviewees have something already thought out when they go about their system design interview. Then, they try to squeeze the requirements into the system.

The danger here is, interviewers often take it upon themselves to break this set architecture to test a system designer’s flexibility. So, although one may be satisfied with his/her system, an interviewer may abruptly throw in completely different requirements.

Every system designer has a unique background. You bring a set of skills, values, and expertise to the table that varies widely from the next candidate. Therefore, look at your interview as an opportunity to demonstrate your strengths and do not waste it trying to mold your capabilities to suit someone’s expectations. Do not restrict yourself and roll with the punches.

6. Keep It Simple, Stupid – KISS

A very famous acronym among programmers, KISS, states that most systems work best when they are kept simple instead of being overly complicated. Therefore, a rule of thumb is to strive for simplicity. Goods ideas are often made irrelevant due to product complexity. On the other hand, system designers refine complex stands to derive a simpler and stronger result.

So, you do not want to pick up one point of the system and go on about it. Furthermore, the more you get into the specifics of architecture, the narrower your view becomes. Take a step back, view your diagram on the whiteboard, and evaluate its entire architecture. Then, check if one part of the system is outsized while others appear minuscule. If this is the case, consider changing your system or simplify it by extracting components from one part and extending them to others.

7. Always Justify Your Points

A grave mistake in a system design interview is to make points without justifications. When designing components, one logical question that challenges you is – why did you make that choice? So, make it a point to back up your ideas with justifications that answer all “Whys.”

For instance, let’s say you opt for a NoSQL database, be precise by specifying to your interviewer that it is a Casandra database. Here, in all likelihood, you will face this question – Why Casandra?

This may pressure you to succumb to make points and maintain the flow of conversation continuously. As a result, you may resort to giving half-baked reasoning for using Casandra. Moreover, if the Casandra database is not suitable for the system, that’s a negative point for you. So, think through all the points, form your thoughts and then communicate those thoughts.

8. Be Updated With Current Tech Solutions and Practices

While your preferred technology can be your expertise, your circle of knowledge should not be narrow. The fast-paced tech industry demands updated technologies to be implemented swiftly. So, another critical element of a sound system design interview preparation is to be adept at current technologies.

An awareness of updated databases and existing off-the-shelf solutions is an indication of your knowledge and expertise. Additionally, it also shows that you will require lesser time and testing to implement the entire system.

Here are some ways to brush up your knowledge on technological advancements:

Ø  Set aside time from your day-to-day workload to learn from various material, such as articles, blogs, online tutorials, or books.

Ø  Access insights through industry events, like tech conferences and trade shows.

Ø  Find innovators in your line of work and follow them. You can reach out to them through social media platforms or by subscribing to their newsletters.

9. Communicate Your Ideas Clearly

Good communication is a lot more than just saying the right thing; it’s about communicating thoughts clearly and concisely. Before you begin a discussion, frame the purpose of your statements and the information you wish to deliver or obtain from the communication. Moreover, lack of cohesion and clarity leads to poor decisions and confusion, thereby presenting badly.

Additionally, do not shy away from asking the interviewer clarifying questions. After all, “Good design is a lot like clear thinking made visual.” – Edward Tufte.

10. Don’t Stop Practicing

While it is easy to hone down the theory, the final piece of the puzzle is to practice. Therefore, remember to apply these steps time and again in your system design interview preparation. Ultimately, every success is a combination of knowledge, skills, and practice.

Additional Tips to Prepare for System Design Interview

Now that you understand the best practices on “how to prepare for a system design interview,” go ahead and implement them in your system design interview preparation. And while you are at it, here are some additional tips:

·       System designers who invest their time to clearly define the end goals of a system have a higher chance of success than those who do not. Therefore, ensure that you understand the goals of the system. If not, do not hesitate to ask clarifying questions to your interviewer.

·       Next, establish the scope by defining all the system’s features by their importance to the user.

·       Determine and design for the right scale. Evaluate if your data can fit on one machine or you need to scale the reads. When in doubt, ask clarifying questions about the read-to-write ratio, number of concurrent requests, average expected response time, data limit, etc.

·       Most decisions involve a trade-off in some shape or form. So, you must know them and describe them as you are suggesting solutions. This will indicate that you know that complex systems sometimes require compromises. Moreover, you can also demonstrate your knowledge of the pros and cons of various approaches.

·       When faced with an issue, do not throw bluff your way out by throwing around incoherent tidbits. Instead, exude honesty, coupled with confidence and a willingness to learn in your interview. This way, you will leave a remarkable impression on your interview.

Are You Ready to Nail That System Design Interview?

It’s a lot — doing all the work by yourself, and you’ll agree that help is needed especially when it comes to what to focus on to ace your system design interview easily. So, if you’re looking for guidance to help crack system design interviews at any FAANG or top-tier firm, sign up for our free webinar.

As pioneers in the field of technical interview prep, we have trained thousands of software engineers to crack the toughest coding interviews and land jobs at their dream companies, such as Google, Facebook, Apple, Netflix, Amazon, and more!

Sign up now!

Last updated on: 
August 8, 2023

Abhinav Rawat

Product Manager @ Interview Kickstart | Ex-upGrad | BITS Pilani. Working with hiring managers from top companies like Meta, Apple, Google, Amazon etc to build structured interview process BootCamps across domains

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