System Design Questions: Top Interview Topics Explained
System Design
Interview Prep

System Design Questions: Top Interview Topics Explained

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Shivam Chauhan

15 days ago

So, system design interviews. They can feel like climbing Mount Everest. I remember prepping for mine, feeling like there was just too much to learn. Where do you even start? What are the key things you really need to know?

I've been through the wringer with these interviews, both as a candidate and an interviewer. And I've noticed patterns. Certain topics come up again and again. That's what we're going to focus on. No fluff, just the core knowledge you need to tackle those system design questions with confidence. Let’s dive in.

Why This Stuff Matters?

Think about it. Companies want engineers who can build systems that scale, that don't crash under pressure, and that solve real-world problems. These interviews aren't just about showing off your knowledge; they're about proving you can design solutions that work.

I’ve seen brilliant coders stumble because they couldn't think about the bigger picture. They could write perfect algorithms, but they couldn't design a system to handle millions of users. That’s why these topics are crucial.

Top System Design Interview Topics

Alright, let's get down to business. These are the areas you should be laser-focused on:

  1. Scalability:

    • Horizontal vs. Vertical Scaling: Know the difference and when to use each. Horizontal scaling means adding more machines; vertical scaling means beefing up the existing one. I usually mention that horizontal scaling is preferred as it provides fault tolerance and is more cost effective
    • Load Balancing: Understand how to distribute traffic efficiently. Load balancers prevent any single server from becoming overwhelmed.
    • Caching: Master different caching strategies (like CDN, client-side, server-side) to reduce latency and improve performance.

  2. Databases:

    • SQL vs. NoSQL: Know their strengths and weaknesses. SQL databases are relational; NoSQL databases are not. For example, SQL databases are useful for transactions and NoSQL databases are useful for unstructured data
    • Database Sharding: Understand how to partition data across multiple databases to handle large datasets.
    • ACID Properties: Be familiar with Atomicity, Consistency, Isolation, and Durability and how they apply to database transactions.

  3. Consistency and Availability:

    • CAP Theorem: Understand the trade-offs between Consistency, Availability, and Partition Tolerance.
    • Eventual Consistency: Know how systems achieve consistency over time, especially in distributed environments.

  4. Message Queues:

    • Asynchronous Communication: Learn how message queues enable decoupled communication between services.
    • Popular Technologies: Be familiar with Amazon MQ and RabbitMQ. Know when to use one over the other. For example, RabbitMQ is a good choice if you want open source with a large community, while Amazon MQ is a good choice if you want simplicity and integration with AWS services

  5. Microservices:

    • Service Decomposition: Understand how to break down a large application into smaller, independent services.
    • API Gateways: Learn how to manage and route requests to different microservices.

  6. Security:

    • Authentication and Authorization: Know the difference and how to implement them.
    • Common Security Threats: Be aware of vulnerabilities like SQL injection and cross-site scripting.

  7. Networking:

    • TCP/IP: Understand the basics of how data is transmitted over the internet.
    • HTTP and HTTPS: Know the difference and why HTTPS is essential for secure communication.

  8. Real-Time Systems:

    • WebSockets: Understand how to maintain persistent connections for real-time data transfer.

  9. Object-Oriented Design:

    • SOLID Principles: The SOLID principles are key to designing maintainable and scalable software. Learn SOLID principles (Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation and Dependency Inversion) to build robust and flexible systems.
    • Design Patterns: Learn how to apply common design patterns (e.g., Factory, Observer, Strategy) to solve design problems. For example, the Factory pattern is useful for creating objects, while the Observer pattern is useful for managing events.

Diving Deeper: Examples and Use Cases

Okay, so you know the topics. Now, let's see how they apply in real-world scenarios.

  • Building a URL Shortener:

    • Scalability: How do you handle millions of URL shortening requests per day?
    • Databases: Which database is best for storing the shortened URLs and their original counterparts?
    • Caching: How do you cache frequently accessed URLs to reduce database load?

  • Designing a Social Media Feed:

    • Consistency and Availability: How do you ensure that users see the most up-to-date posts without sacrificing availability?
    • Message Queues: How do you handle the asynchronous delivery of new posts to users' feeds?

  • Creating an E-commerce Platform:

    • Microservices: How do you decompose the platform into services for product catalog, payments, and order management?
    • Security: How do you protect user data and prevent fraud?

Resources to Level Up

Alright, where can you go to actually learn this stuff? Here are some resources I've found helpful:

  • Coudo AI: Practice machine coding challenges and system design problems. Coudo AI offers a range of problems that encourage you to map out design details, design patterns and more.
  • Books: "Designing Data-Intensive Applications" by Martin Kleppmann is a must-read.
  • Online Courses: Platforms like Educative.io and Udemy have excellent system design courses.
  • Blogs: Read engineering blogs from companies like Netflix, Uber, and Airbnb to see how they solve real-world problems.

FAQs

1. How much detail do I need to know for each topic?

Know enough to discuss the trade-offs and explain the core concepts. You don't need to be an expert in every area, but you should be able to hold a conversation.

2. Should I focus on one area more than others?

Scalability, databases, and consistency are fundamental. Make sure you have a solid grasp of those.

3. How important is it to know specific technologies?

It's more important to understand the underlying principles. However, knowing popular technologies like Amazon MQ and RabbitMQ can be a plus.

Closing Thoughts

System design interviews can be tough, but with the right preparation, you can ace them. Focus on the core topics, practice with real-world examples, and use the resources I've mentioned. I hope this guide helps you prepare better for your next interview. Remember, understanding these topics and applying them practically will not only help you in interviews but also make you a better engineer. If you are curious to get hands-on practice, try Coudo AI problems now.

I know it feels like a lot, but you can do it. Keep learning, keep practicing, and you'll be designing awesome systems in no time!

About the Author

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Shivam Chauhan

Sharing insights about system design and coding practices.