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How to Answer System Design Questions
Jul 4, 2024
Answering System Design Questions
Purpose of System Design Interviews
Evaluates ability to design a system/architecture for complex real-world problems
Focus is on blueprint design, problem analysis, multiple solutions, and pros/cons evaluation
Not about creating a perfect solution
Approach to System Design Interviews
Open-ended design problems
Use a framework to organize thoughts, manage time, and communicate clearly
Important due to the complexity of problems and limited time (45 minutes)
Five-Step Framework
1. Define the Problem Space
Understand and define the problem and scope of the design
Ask questions to narrow scope from broad to specific with system constraints
Clarify functional and non-functional requirements
State assumptions and decisions
Take interviewer on a guided tour of your thought process
Consider if creating system from scratch or integrating with existing systems
Non-functional requirements: availability, consistency, speed, security, reliability, cost
Focus on most critical constraints
Estimate data volume for storage and bandwidth requirements
Validate assumptions with the interviewer
2. Design the System at a High Level
Lay out fundamental pieces and illustrate how they work together
Develop APIs based on system requirements (choose type & explain why)
Design client and web server communication
Create high-level design diagram showing data and control flow
Avoid diving into scalability details yet
3. Deep Dive into the Design
Examine components and relationships in detail
Consider non-functional requirements' impact on design choices
E.g., data freshness, large data storage, load balancing
Present different design options with pros and cons
Explain why one option is preferred
4. Identify Bottlenecks and Scaling Opportunities
Check for single points of failure and robustness improvements
Consider data replication and consistency
Support for global service with multi-geo data centers
Address edge cases like peak usage or hot users
Plan for scaling to support more users
Concepts: horizontal sharding, CDN, caching, rate limiting, SQL/NoSQL databases
5. Review and Wrap Up
Summarize major decisions, justifications, and trade-offs
Ensure design meets requirements
Identify further improvement areas
Total interview: ~45 minutes (5 minutes for intro and questions)
Additional Resources
Website offers interview prep content, coaching, and mock interviews
Good luck!
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Full transcript