Design a Content Delivery Service
Last updated: December 14, 2025
Quick Overview
Design a geo-distributed content delivery system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
xAI
December 14, 202538
15
3,603 solved
Design a geo-distributed content delivery system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
xAI asks this during the System Design Round to assess your architectural thinking. They want to see how you decompose a complex problem, choose appropriate technologies, and reason about failure modes. Strong candidates proactively discuss monitoring, alerting, and operational concerns.
What the Interviewer Expects
- Clearly define functional and non-functional requirements
- Propose a reasonable high-level architecture with core components
- Choose appropriate data storage solutions with basic justification
- Discuss basic scaling strategies (horizontal scaling, caching)
- Identify potential bottlenecks and suggest simple solutions
Key Topics to Cover
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- How would you implement rate limiting to protect the system?
- How would you handle a 10x increase in traffic overnight?
- How would you handle schema migrations with zero downtime?
- What monitoring and alerting would you set up on day one?
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Requirements
Functional Requirements
- Content Delivery: Serve static and dynamic content (images, videos, text) to users based on their geographical location.
- User Authentication: Allow users to c...
Capacity Estimation
Assuming the service needs to handle 10 million requests per day:
- Total Requests per Second (RPS): 10,000,000 requests / (24 hours * 60 minutes * 60 seconds) = ~115 RPS.
- Peak Traffic: Duri...
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