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How To Crack System Design Interview

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Different Interview Rounds You Need To Prepare For

How to crack System Design Interview at Facebook , Amazon and Microsoft | Tips & RoadMap

The number of rounds you go through depends on your experience level. But for a Backend developer role below are the standard rounds you go through:

  • Online Coding / Machine coding
  • Problem Solving
  • High Level Design / Low Level Design
  • Hiring Manager / Culture Fit

The way you are evaluated in each round again depends on the role you’ve applied for and your experience level.

For example if you’re interviewing for a Junior developer role, more priority is given to the online / machine coding round, problem solving & LLD rounds. Even though some design knowledge is expected in HLD & LLD rounds, they are not considered very important for a junior developer. Whereas all the rounds + your leadership skills are considered important if you’re applying for a more senior role.

Now let’s discuss in detail what you can expect in each round & how you can prepare for them.

So About That Coming Interview

If you are reading this article, chances are you are preparing for an interview.

Mobile system design interviews are like a puzzle. One you have never built before, but you get to bring the parts to solve it. So make sure to include a broad set of parts in your toolbox and become comfortable scrutinising them and selecting the best ones for the job.

In this article, I have tried to share an approach to face these interviews. But this is just my approach, the one I have compiled from doing dozens of interviews myself and interviewing hundreds of candidates. While describing it, I have purposely tried to cover as many topics as possible, so that you can then shape them to form your own strategy. Don’t just take my approach, make it yours!

Practice before the interview to get great at it, but without memorising it. There not two equal system design interviews, as there are not two equal candidates, nor interviewers. Remember that your interviewer is there to guide you and help you succeed. Please pay attention to the small hints and suggestions your interviewer gives you and incorporate those little nibbles of data to your solution.

Thanks for reading this long. I hope you have a better understanding of what mobile system design interviews entitle: what they consist on, what your interviewer will be evaluating, plus a reliable approach to tackling them successfully.

Good luck interviewing!

System Design Interview Preparation

System design interviews have a lot of weightage in the entire interview process, so it is important to prepare for them before appearing for any FAANG company interviews. System design interview preparation can be divided into the following key points:

1. System Design Interview Preparation Books

Books are an ocean of resources. These books provide dense knowledge and are generally less preferred. However, if you find reading and highlighting important points more effective than watching course videos, then here are some books that might come in handy while preparing for system design interviews:

  • Understanding Distributed Systems– Robert Vitillo
  • System Design Interview: An Insiderâs Guide– Alex Xu
  • Design Data: Intensive Application
  • 2. Refer to System Design Articles and Videos

    There are plenty of interview articles and videos on the internet for aspiring software engineers, coding engineers, and tech leads to refer to while preparing for the technical interview. Articles and videos provide concise information unlike the books and hence is sometimes more preferred.

    3. Interview Prep Courses

    Acing FAANG interviews is difficult, and the process becomes unbearable if one enters the interview arena with no prior knowledge about the process. There are plenty of interview prep courses available to choose from. Interview Kickstart has courses specifically targeting job profiles at FAANG companies. To know more, Sign up for our FREE Webinar.

    4. Mock Interviews

    Read Also: How To Answer The Most Common Interview Questions

    How Can You Prepare For Online Coding / Machine Coding Round

    Online Coding:

    Many companies want to check your coding skills before they take your candidature ahead. Basically they want to know whether you can code for a given problem or not. In this round you’ll be given a timed test on online platforms like HackerRank where you’re expected to write code for a given number of questions. More details on how to prepare for this round are discussed in the .

    Machine Coding:

    Nowadays machine coding round is gaining popularity in which companies want to see your coding skills for a real world application. In this round you’ll be given a set of requirements & you’re expected to design & write the code within 1.5 – 2 hours.

    You don’t need to use any database to store & retrieve the data. Just storing in memory is sufficient for this round.

    The main factors your code is evaluated on are:

    • working solution
    • Code Modularity
    • Concurrency Handling etc

    A working solution is very important in this round. Even if your code is well structured and following all the OOP & SOLID principles you will most probably get rejected if you don’t have a working solution. So focus on completing the requirements first. But also keep in mind about all the other factors.

    The best way to approach this round is to spend 5-10 minutes to think about the entities, classes, inheritance, compositions that might be needed. Also spend some time on how you would structure your code.

    • parking lot
    • database management system
    • cab booking system etc

    Practice Problems For System Design Interview

    Crack the System Design interview: tips from a Twitter ...

    System Design interview questions are broad, open-ended, and have multiple correct answers. Some examples of questions asked during the system design Interview are:

  • Design a tiny URL system
  • Design Facebook messenger
  • Design an autocomplete system, where suggestions will pop up while typing a search query.
  • Design a payment gateway system
  • For more system design interview questions, read:

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    Google Systems Design Interview Questions

    Practicing a good number of systems design questions is vital to acing the design round at Google.

    Here are a couple of sample System Design interview questions and the approach you should take to solve them:

    Question: Design a video streaming service.

    Designing a global video streaming service like Youtube or Netflix is a commonly asked design interview question. While designing a video streaming service, your ideal solution should:

    • Allow the user to view, search and upload videos.

    General System Design Interview Questions

  • How would you go about creating a TinyURL system?
  • A TinyURL is a URL service that enables users to input a lengthy URL and get a shorter, unique URL in return. A hiring manager may ask this to give you the chance to demonstrate your strong design background. You may concentrate on fundamentals such as how to generate a unique ID for each URL, manage redirection, and remove expired URLs.

  • How do you create a large-scale social media platform?
  • The goal of creating a large social media network like Instagram, Facebook, or Twitter is to create a platform that allows users to see a newsfeed containing postings. The following are the essential characteristics that social media services need:

    • Users have the option of commenting on and liking a post.
    • It should be able to handle many users at the same time.
    • A news feed and recommendation system should be included.
    • Privacy restrictions must also be implemented.
    • Trending posts/tweets should be displayed.

    The following tools may be used in the construction of a large social media platform:

    • Rolling updates and replica nodes to maximize availability
    • A trained machine learning algorithm to suggest articles and news feeds
    • A database schema that stores celebrities and certain users separately
    • A social graph to monitor certain behaviours
  • How do you build a vending machine in Java?
  • How does one go about creating a URL shortening service like or
  • How does one go about designing a traffic control system?
  • Read Also: How Do I Answer Interview Questions

    Automated Interviewing With Coding Challenges

    Unlike the , where the initial assessment is a phone screen, Amazon expands this assessment to sometimes include a coding challenge.

    Some interviewers prefer this method, as the performance anxiety of interacting with another person is absent, and the only requirement on your end is to write code that executes correctly and efficiently.

    This is also positive for Amazon, as they do not need to expend resources on conducting 30-45 minute interviews with candidates. Furthermore, they can also expand their reach substantially, as this process is somewhat automated.

    Oftentimes, these coding challenges are driven through an engine similar to that of HackerRank, where your code is automatically analyzed for syntactic correctness, efficiency, and correctness for the task at hand. This gives a better signal to the interviewee about how well they are performing during the interview itself.

    While all of these coding assessments will have instructions, they will often mimic those of HackerRank insofar as actually using the same submission and judging criteria.

    Therefore, it is most likely a good idea to play around with the HackerRank interface, practicing a few problems to ensure that you do not get tripped up on the interface itself. This way, you can then just focus on solving the problem.

    V: Algorithm Data Structure And Coding

    How To Crack System Design Interviews | Interview Preparation | Webinar With GeeksForGeeks
    • Data structure and algorithms are important to develop a system. As each system design has its own set of algorithms and data structures, it is good to have sound knowledge of data structure concepts and algorithms.
    • Apart from approaching the problem by following the steps mentioned above, it is important to give a real-time update about the complexity of the process and your method of circumventing it so that the discussion is on and the interviewer is keen to see your result.

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    Establish The Design Scope By Clarifying The Problem Statement

    Before you dive deeper into the problem at hand, you should take a few moments and clarify any doubts that you might have. You should know what exactly the problem statement is asking for. The worst thing you can do in this situation is just starting off with the design with half-baked information on the question statement. Further, since you only have limited time during your interview, you need to keep your solution as precise and to-the-point as possible. For that, youll need clarity.

    To do that, here are some questions you can ask the interviewers:

    • What are the use cases of the application?
    • Which audience will be using the app?
    • What is the expected traffic?
    • How much collaboration is required on the application?
    • How reliably does the system need to be and how much data will need to be stored?

    Cracking The System Design Interview

    Technical Program Management at Meta | Building & Scaling highly performant and reliable Instagram

    One of the most common set of questions I get from people who are looking to interview with top tech companies are :

    ‘How to crack the software system design interview?’

    ‘What is enough v/s what is not enough information to give?’

    ‘How do I structure my system design round in the limited 45 mins that I get?’

    While System design round can be difficult, we all need to understand that neither a system cannot be fully designed in 45 mins nor system design has one approved solution. There can be multiple ways to design the system based on what are the top problems you are trying to solve and What requirements are you going to be targeting while you design the system.

    Here’s an interesting approach that you can use to go around your system design interview:

  • Start by collecting the requirement and set the tone of the interview by level setting with the interviewer about what are the specific features or the requirements you are trying to address in this interview.
  • Navigate to some back of the envelope calculations. You may want to calculate the storage and memory requirements of the system considering scaling of the system over the period of 5 or 10 years. You may also want to calculate network bandwidth requirements parameters when required.
    • Data de-duplication.
    • Redundancy and Replication
    • System should not have single point of failure.
    • Scaling
    • Trade-off’s you have made and why?

    Recommended Reading: How To Write A Thank You Letter For An Interview

    Acing The Systems Design Interview Preparation

    Now that weve understood that the interview will mostly be around you trying to come up with a design outline for some or the other complex system, lets look at a framework that you can use to structure your answer. You can also use this framework to arrive at your answer in a methodical manner. Here are the steps you can take:

    Iii: Design The System As Per The Required Scale

    How To Crack System Design Interviews
    • It is important to define the system’s scalability before developing it to confirm whether the data you are working on will fit on the machine or some alteration will be needed.
    • Scale is important as a lot depends on it, like the response time, the data limitation, and expected read to write ratio.

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    Dev Community Is A Community Of 761468 Amazing Developers

    We’re a place where coders share, stay up-to-date and grow their careers.

    System Designing has become one of the important rounds to crack a Software Developer job interview, especially for a senior-level position. Preparing for this round is necessary to crack interviews of some of the popular companies like Amazon, Netflix, Google, Twitter, etc.

    In this round, you are basically expected to discuss the design of a large-scale distributed system like Twitter, Uber, Facebook, Dropbox, etc.

    There is no one right solution when it comes to designing a system. There can be multiple ways to solve a problem and thus this round is going to be an open-ended round where the focus will be on a working design + your thought process.

    Top 25 System Design Interview Questions And Answers

    Following are frequently asked questions in interviews for freshers as well as experienced system designers.

    1) What is System Design?

    System design is a process of defining the elements of a system such as the architecture, components, modules, and various interfaces.

    2) What are the three most essential skills of system designer?

    Important skills for system designer are:

    • User interaction
    • Offline processes

    3) How to design traffic control software?

    To design a system for the traffic control system, as a software engineer, you need to make sure you know how to transition from one state to another. For example, Red to Green and from Green to Orange to Red, etc.

    4) What is the benefit of a designing system like Pastebin?

    Pastebin helps you design a system to paste code or text. You can share a link to that code anywhere you want. Its not an online code editor, yet you can use this, a tool to store any text.

    5) As a system designer, how you can design a universal file sharing and storage apps like Google Drive or Dropbox?

    The above mention apps are used to store and share files, photos, and other media. We can design things like allowing users to upload/search/view files or photos. It checks permissions for file sharing and enables multiple users to make changes in the same document.

    6) How can you design an ATM system?

    An ATM helps a user to deposit and withdraw money. It also allows users to see their account balance. You need to make a design plan to create this system.

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    Facebook System Design Interview Questions

    Here are some commonly asked system design interview questions at :

  • Design Facebook News Feed
  • Design Facebook Messenger or WhatsApp
  • Design Live Commenting
  • Design Privacy Settings at Facebook
  • Design Top N Songs
  • Design Web Crawler
  • Other frequently asked system design interview questions include topics on concurrency , caching, database partitioning, replication, sharding, CAP theorem, networking , real-world performance , availability and reliability , data storage and data aggregation, QPS capacity or machine estimation , and byte size estimation.

    System Interface Definition And Establish Scope

    What is a web crawler? How to design a web crawler? Cracking System Design Interviews EP2

    After the first step, you need to identify what kind of APIs your system needs to get the job done based on whatever features you have included. Also, discuss the scope and availability of the system, discuss some relevant questions like do you both care about only end-to-end experience or just the API?. Client support . Authentication, analytics, integration, performance, etc. Is the system going to work if the host is down or the entire data system is down? So discuss with the interviewer how much availability he/she care about the system. From both, the above two steps make sure you know the exact scope of the problem and the complexity of the system.

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    What Are The Best Resources To Crack System Design Interviews

    I have seen many resources about algorithms and leetcode questions, but as engineers became senior, there is more emphasis on “System Design interviews” and “SW architecture”.

    There are many important components in any system design interview, some also dive deeper into the database storage engine, need to explain the algorithms and data structures that the storage engine uses on disk, and how it affects the whole system performance-wise.

    I am trying to compile a list of these resources . The typical suspects are always these two

    I have read also Designing Data-Intensive Applications book.

    Please feel free to recommend some of the things that you found rewarding in your journey as an experienced developer.

    How Would You Create Your Own Instagram

    Instagram is a photo-sharing application that provides some custom filters to enhance your photo quality. Your application should have photo upload functionality, tagging photos for search, and some basic filters. If you could add share or social network that could be great.

    Btw, if you stuck, you can see the free solution provided on the Educative Grokking System design course as well.

    7. How do you design global file sharing and storage apps like Google Drive or Dropbox?These are used to store and share files, photos, and other media. How do you go about designing things like allowing users to upload/view/search/share files or photos? track permissions for file sharing, and allow multiple users to edit the same document?

    If you like Youtube video, here is a nice one which will teach you how to design a Dropbox or Google Drive or any other document hosting solution:

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