System Design Questions: A Curated List for Interview Prep

System design interviews. Are they your favourite cup of tea, or do they send shivers down your spine?

I get it.

They can feel like a high-wire act. You're expected to design scalable, robust systems on the fly, while also communicating your thought process clearly.

I've been there, both as a candidate and an interviewer. And I've seen what works and what doesn't.

That's why I put together this list of system design questions.

It's not just a random collection. It’s a curated set, ranging from fundamental concepts to real-world scenarios. Whether you're just starting your interview prep or looking to fine-tune your skills, this list has something for you. So, let’s jump in.

Basic System Design Questions

These questions test your understanding of core concepts and architectural patterns. They are the building blocks for more complex designs.

Design a URL Shortener (like TinyURL or Bitly)
- Focus Areas: Hashing, database design, scalability.
- Considerations: How to generate unique short URLs? How to handle collisions? How to scale the system for millions of users?
Design a Rate Limiter
- Focus Areas: Concurrency, algorithms, caching.
- Considerations: How to limit the number of requests from a user? Which algorithm to use (e.g., token bucket, leaky bucket)? How to distribute the rate limiter across multiple servers?
Design a Caching System
- Focus Areas: Caching strategies, eviction policies, consistency.
- Considerations: What type of cache to use (e.g., in-memory, distributed)? Which eviction policy to implement (e.g., LRU, LFU)? How to handle cache invalidation?
Design a Load Balancer
- Focus Areas: Load balancing algorithms, high availability, health checks.
- Considerations: Which load balancing algorithm to use (e.g., round robin, least connections)? How to ensure high availability? How to perform health checks on backend servers?
Design a Message Queue
- Focus Areas: Message brokers, asynchronous communication, reliability.
- Considerations: Which message broker to use (e.g., RabbitMQ, Kafka)? How to ensure message delivery? How to handle message ordering?

Intermediate System Design Questions

These questions require you to apply your knowledge to more complex scenarios. They often involve trade-offs and require you to justify your design decisions.

Design a Social Media Feed
- Focus Areas: Database design, caching, fan-out strategies.
- Considerations: How to store and retrieve posts? How to handle real-time updates? How to scale the system for millions of users?
Design an E-commerce Platform
- Focus Areas: Microservices, database design, payment processing.
- Considerations: How to decompose the system into microservices? How to manage inventory? How to handle transactions and payments?
Design a Ride-Sharing App (like Uber or Lyft)
- Focus Areas: Location services, real-time updates, matching algorithms.
- Considerations: How to track drivers and riders in real-time? How to match riders with nearby drivers? How to handle surge pricing?
Design a Video Streaming Service (like Netflix or YouTube)
- Focus Areas: Content delivery networks (CDNs), video encoding, streaming protocols.
- Considerations: How to store and deliver video content efficiently? How to handle different video qualities? How to ensure smooth playback?
Design a Search Engine
- Focus Areas: Indexing, ranking algorithms, distributed systems.
- Considerations: How to crawl and index web pages? How to rank search results? How to handle a large volume of queries?

Advanced System Design Questions

These questions are open-ended and require you to think critically about edge cases, scalability bottlenecks, and long-term maintainability.

Design a Distributed Key-Value Store
- Focus Areas: Consistency, fault tolerance, data partitioning.
- Considerations: How to ensure data consistency across multiple nodes? How to handle node failures? How to partition data for scalability?
Design a Recommendation System
- Focus Areas: Machine learning, data pipelines, personalization.
- Considerations: Which algorithms to use for recommendations? How to collect and process user data? How to personalize recommendations for different users?
Design a Real-Time Analytics Platform
- Focus Areas: Stream processing, data aggregation, visualization.
- Considerations: How to process real-time data streams? How to aggregate data for analysis? How to visualize data for users?
Design a Cloud Storage Service (like Dropbox or Google Drive)
- Focus Areas: Data storage, synchronization, security.
- Considerations: How to store files efficiently? How to synchronize files across multiple devices? How to ensure data security and privacy?
Design a Blockchain Network
- Focus Areas: Consensus algorithms, cryptography, distributed ledgers.
- Considerations: Which consensus algorithm to use (e.g., Proof of Work, Proof of Stake)? How to ensure security and immutability? How to scale the network for a large number of transactions?

How to Approach System Design Questions

Before diving into specific questions, let's cover some general tips for tackling system design interviews.

Clarify Requirements: Always start by asking clarifying questions about the scope and constraints of the system.
Define Use Cases: Identify the key use cases that the system needs to support.
High-Level Design: Start with a high-level overview of the system architecture.
Detailed Design: Dive into the details of each component, including data models, algorithms, and interfaces.
Scalability and Performance: Discuss how the system will scale to handle increased load and ensure optimal performance.
Trade-offs: Be prepared to discuss the trade-offs between different design decisions.
Communication: Clearly communicate your thought process and design decisions to the interviewer.

Resources for System Design Preparation

To help you prepare, here are some useful resources:

Books: "Designing Data-Intensive Applications" by Martin Kleppmann, "System Design Interview – An Insider’s Guide" by Alex Xu.
Online Courses: Educative.io, Grokking the System Design Interview.
Practice Platforms: Coudo AI, LeetCode.

FAQs

What's the best way to practice system design questions?
- The best way to practice is by working through real-world scenarios and getting feedback on your designs.
How important is it to know specific technologies for system design interviews?
- While it's helpful to have experience with specific technologies, it's more important to understand the underlying principles and trade-offs.
What are some common mistakes to avoid in system design interviews?
- Some common mistakes include not clarifying requirements, focusing too much on details, and not considering scalability and performance.

Wrapping Up

System design interviews can be challenging, but with the right preparation, you can approach them with confidence. By studying these questions and following the tips outlined in this blog post, you'll be well-equipped to tackle any system design challenge that comes your way. And don’t forget to practice on Coudo AI to sharpen your skills and get ready for your next interview.

So, what are you waiting for? Start practicing today and take your system design skills to the next level. Good luck, and happy designing!