Can you explain the CAP theorem and its implications?
This question tests your theoretical knowledge of distributed systems consistency models. It evaluates your ability to make trade-off decisions in system design.
Why Interviewers Ask This
The CAP theorem is fundamental to understanding distributed system limitations. Interviewers ask this to see if you grasp why perfect consistency, availability, and partition tolerance cannot coexist. Your answer shows whether you can prioritize system goals based on business requirements and handle real-world network failures gracefully.
How to Answer This Question
Define Consistency, Availability, and Partition Tolerance clearly. Explain that you can only pick two out of three in a distributed system. Give examples of systems prioritizing CP (like banking) versus AP (like social media). Discuss how modern databases often relax strict definitions to offer tunable consistency. Relate this back to designing resilient applications.
Key Points to Cover
- Definition of CAP components
- Trade-off scenarios
- Real-world examples
- Tunable consistency models
Sample Answer
The CAP theorem states that a distributed system can only guarantee two out of three properties: Consistency, Availability, and Partition Tolerance. In practice, most systems sacrifice strong consistency for availability…
Common Mistakes to Avoid
- Misinterpreting partition tolerance as optional
- Confusing consistency with availability
- Failing to provide concrete examples
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