Design a large-scale Content Delivery Platform
Last updated: August 26, 2025
Quick Overview
Design a distributed content delivery system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Capital One
System Design
Software Engineer
Capital One
August 26, 2025Software Engineer
Onsite
System Design
Medium
150
12
1,234 solved
Design a distributed content delivery system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Capital One asks this during the Onsite 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
- Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
- Design a scalable architecture with clear component responsibilities
- Make well-reasoned database and caching decisions with trade-off analysis
- Address consistency vs availability trade-offs specific to the use case
- Discuss partitioning strategy, replication, and data modeling
- Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
Security and authentication
Monitoring, logging, and alerting
Failure handling and fault tolerance
Database selection and data modeling
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 do you ensure data consistency across multiple services?
- How would you implement rate limiting to protect the system?
- What would the deployment pipeline look like for this system?
- What happens if one of your database nodes goes down?
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Requirements
- Functional Requirements:
- Serve static and dynamic content including images, videos, documents, and APIs.
- Support user authentication and authorization for sensitive content.
- Pr...
Capacity Estimation
- QPS Calculation:
- Assuming a peak load of 10 million requests per second (QPS) based on user growth projections and marketing campaigns.
- Each request might average around 1KB of data ...
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