System Design Interview Cheat Sheet
General Principles
Understand Requirements:
Clarify functional and non-functional requirements.
Ask about user load, data consistency, latency, and availability.
High-Level Architecture:
- Break down the system into components (e.g., frontend, backend, database).
- Consider using microservices vs. monolithic architecture.
Scalability:
- Vertical vs. horizontal scaling.
- Load balancing and caching strategies.
Data Storage:
- SQL vs. NoSQL databases are based on the use case.
- Understand data modeling and indexing.
APIs:
- REST vs. GraphQL; design endpoints considering CRUD operations.
- Rate limiting and versioning.
Reliability and Fault Tolerance:
- Redundancy, failover strategies, and data backups.
- Circuit breakers and retries for failed requests.
Security:
- Authentication (OAuth, JWT) and authorization mechanisms.
- Data encryption and secure communication (HTTPS).
Monitoring and Logging:
- Set up metrics, alerts, and logs for system health.
- Use tools like Prometheus, Grafana, ELK stack.
💣 Common System Design Problems
Design a URL Shortener:
- Components: API for shortening, database for storing mappings.
- Consider collision handling and analytics.
Design a Social Media Feed:
- Components: User service, post service, feed generation.
- Consider real-time updates and caching strategies.
Design a Chat Application:
- Components: WebSocket server for real-time communication, user management.
- Handle message delivery guarantees (e.g., at least once).
Design a Ride-Sharing Service:
- Components: User location tracking, matching algorithm, payment processing.
- Consider scalability and latency in real-time updates.
Design a Video Streaming Service:
- Components: Video storage, transcoding, content delivery network (CDN).
- Consider adaptive bitrate streaming.
✔️ Useful Tips
- Think Aloud: Communicate your thought process clearly.
- Use Diagrams: Sketch architectures on a whiteboard or paper to illustrate your ideas.
- Iterate on Designs: Start with a simple version and add complexity as needed.
- Trade-offs: Discuss the trade-offs for design decisions (e.g., consistency vs. availability).
- Practice: Work through common problems with peers or use online platforms for mock interviews.
🔎 Example Questions to Practice
- How would you design a system to handle millions of concurrent users?\
- Describe the architecture of a payment processing system.
- How would you design a distributed cache system?
- What considerations would you make for a system that requires high availability?
🔦 Conclusion
Keep this cheat sheet handy for quick reference and practice system design problems frequently to become familiar with various architectures and trade-offs. Good luck with your interview preparation!
