As every software engineer, technical program manager or technical engineer should be familiar with a system design interview is a difficult one due to the increasing complexity of applications and systems in every industry. We've drawn up a compendium of commonly asked system design interview questions and answers to make the preparation for such interviews easier. With the baseline understanding of popular queries, you will be able to develop your signature responses and distinguish yourself from the competition.
- Explain URL shortening service. Describe how you can shorten any URL.
- Is it possible to design vending machines in Java?
- What are the primary tools used to build large social media platforms?
- What are the essential steps to designing a traffic control system?
- Could you create your own Instagram using System Design?
- What are the steps to design a Twitter clone?
- How would you design global video streaming services like Netflix or Youtube?
- Explain the steps to create a chat system like Whatsapp, Facebook, or a similar one.
- What are the major components used in designing a web crawler?
- Could you design a shared cloud drive such as One Drive or Google Drive?
- Can you describe the basic approach to designing global cab services such as Ola and Uber?
- What are three ways of measuring the performance of systems?
- How do you design an Elevator or a Lift system?
1. System Design Interview: Key Points
As a part of system design interview preparation, you should master the basic terminology such as:
1. What is System Design?
Modules, components, interfaces, and data are the primary elements of a system. System design refers to a process that defines all these elements in one place as per the requirement of the end-user. You can also call the system design architecture of a system. But no matter what you call it, you should keep in mind the purpose of system design - to design any application's architecture for solving specific problems.
2. Specific Features of System Design
A system must possess the following five features:
- Modularity: A system should have various modules to perform specific functions.
- Interconnectivity: All modules must be interconnected.
- Flexibility: A system must be able to adopt any changes.
- Organisational model: A system organisation to achieve the primary goal.
- Security: Does the system ensure its security?
3. Specific Elements of System Design
A system has the following specific elements.
- Architecture: It defines the structure, views, and behaviour of the system
- Data: All information and data used to design the system.
- Interface: It establishes interaction with users.
- Components: Various sub-parts or module that creates systems
- Constraints or business rules: It defines the rules or limitations of the system
2. Essential Studies to Crack the System Design Interview
System design is a wide field of study requiring substantial study time. To simplify the interview preparation, we have broken down the complex subject into the following areas:
- Networking: Focus on understanding protocols like TCP/IP, HTTP, performance metrics, and IPC.
- Operating System: Suggested to acquire deep knowledge of deadlocks, threads, starvation, concurrency, caching, and other relevant topics.
- Advanced Database: Focus on building confidence in understanding how to store data & build a database, how it works, how to connect it with frontend, etc.
- Others: Get depth knowledge on standard topics, including memory/disk storage, latency, system availability, proxies, offline processes, user interaction, and external APIs.
Master your skills in all mentioned areas, and you will be good at answering any system design questions.
3. System Design Interview Questions Pattern
System design interview consists of open-ended processes facilitating a creative discussion between the candidate and the interviewer. Consequently, there are no ready answers to be followed during System Design Interview. However, a typical system design question ends in “designing a system based on the problem.” Therefore, we have created a standard answer framework to crack each question in a systematic way.
A Standard Framework to Answer System Design Interview Questions
While responding to any system design questions, follow the below framework to prepare a well-rounded reply:
The framework allows you to answer questions to design any system based on users’ problems.
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4. Compilation of Commonly Asked System Design Interview Questions and Answers
1. Explain URL shortening service. Describe how you can shorten any URL.
URL shortening service shortens the long URL link up to one-third of the original URL size. This service is helpful in link optimisation, measuring marketing ads performance, and audience analysis. You need all functional, non-functional, and extended requirements to execute this service. Do estimation of memory, bandwidth, storage, and traffic. You need to explain the database scheme, system APIs, and other design constraints to shorten any URL using this service.
Check this detailed solution link.
2. Is it possible to design vending machines in Java?
Yes, it is possible to design vending machines for products like candy, coffee, cold-drink etc., in Java. You need to design and develop Java code for executing this machine which can accept currency coins. While developing code, you need to ensure that once a person inserts a coin, they must get a product back and get a chance back.
Check this detailed solution link.
We need the following three tools:
- Newsfeed generation system: to keep all updates from friends, followers, or connections
- Efficient data storage: Able to manage the bulk of data, especially multi-media data
- Social graph or (Directed Acyclic Graph or DAG model): To create a social map
Check this detailed solution link.
4. What are the essential steps to designing a traffic control system?
You need to understand the basic principle of state transition, “how to change the transition from one state to another.” Since a traffic control system uses three colours to control traffic, lights’ colours change as per transitions. This point needs to be considered while designing. Besides, other mandatory system design constraints would also need to be followed. Check this video link to know more.
5. Could you create your own Instagram using System Design?
Yes, it is possible to use system design and create your own Instagram. We all know that Instagram is a multi-media social media platform that provides many customised image editing features and filters. We can create a system that can capture & upload pictures, edit them using filters, and tag them to increase search visibility. Check this detailed solution link or check this video link.
6. What are the steps to design a Twitter clone?
Twitter's main objective is to post tweets and follow others. The most straightforward steps to designing a Twitter clone are implementing Twitter's main features like tweets, hashtags, followers, and audio chat in the system. We can create a Twitter clone by implementing all these features into the new system. Check this video link to know more.
7. How would you design global video streaming services like Netflix or Youtube?
We need to follow the same process to design global video streaming services as other system designs. Because every day, social media users are increasing, especially in live video streaming. Since this service allows users to not only view but also upload and search videos, thus you have to take care that the system should be scalable. Check this video link to know more.
8. Explain the steps to create a chat system like Whatsapp, Facebook, or a similar one.
We all know the standard working of a chat system. It permits users to chat either one-to-one or group chat. The steps are as follows:
- Understand all required features present in chat systems
- Find out all possible problems which might happen like encryption, notification etc.
- Determine all essential tools such as database schema, storage, connectors, and push notifications
Check this video link to get details.
9. What are the major components used in designing a web crawler?
The primary function of a web crawler is to enhance Google search results by crawling and indexing page links. Storage systems and APIs are mandatory components of designing a web crawler. Also, we have to assess various things: how to find new web pages and how to prioritise web pages. Check this video link to get details.
This type of shared cloud drive allows us to store data in the cloud. We can easily access, share, delete, search, or upload any form of data. By creating a system able to perform all these functionalities, we can design such a shared cloud drive. Check this video link to get details.
11. Can you describe the basic approach to designing global cab services such as Ola and Uber?
The fundamental approach to designing such a global cab service is to develop a system that can establish effective communication between two objects. Since these cab services succeed only when passengers and drivers interact with each other, you must create modules for maintaining GPS, current locations, pricing, and driver's & passenger's data. Check this video link to get details.
12. What are three ways of measuring the performance of systems?
We must use the following three performance metrics to measure the system's performance.
- Availability: To check the response time
- Latency: To check the speed of message delivery time
- Throughput: To study the transmitted data at a specific time
Integrating these metrics would help assess the whole system design, its workings, and user interaction.
13. How do you design an Elevator or a Lift system?
The basic functionality of an elevator or lift is to reach the following levels quickly. It mostly comes in pairs like the upstairs/downstairs elevator and two lifts aligned in one row. We can design the best elevator or lift system by creating a program code that can fulfil these functionalities.
Check this video link to know in detail.
5. Interview System Design: 3 Points to Consider
Cracking a System Design Interview might be challenging but considering the below points, you may score yourself some points and go some ways towards acing the interview:
- Never hesitate to clarify with the interviewers regarding the asked system design question. Clear your doubts, define the requirements, ask about the business context of the application and show confidence in your knowledge.
- Bring out both positive and negative aspects of all possible system design solutions. Don't focus only on the positive, as every system has some drawbacks. You will score some extra brownie points if you also mention time and budget.
- Practice your logical, analytical, and problem-solving skills before the interview, as the interviewer will likely be looking out for these soft skills during the interview
6. Final Thoughts
Did you know that companies evaluate your problem-solving, communication, and technical skills through system design interviews? You must upskill your soft skills, problem-solving, and technical knowledge for these technical interviews. We have provided you with a compiled list of standard system design interview questions and answers. Don't forget to leave a comment if you have any questions or if you enjoyed the reading.
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