Design a Content Delivery Service
Last updated: May 8, 2026
Quick Overview
Design a geo-distributed content delivery system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Elastic
May 8, 202674
7
4,732 solved
Design a geo-distributed content delivery system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Elastic asks this during the Technical Screen 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
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?
- What would the deployment pipeline look like for this system?
- How would you handle a 10x increase in traffic overnight?
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Requirements
Functional Requirements
- Content Delivery: Serve static and dynamic content (such as images, videos, and HTML) to users based on their geographical location.
- User Authentication: Allo...
Capacity Estimation
To estimate capacity, we consider:
- Daily Active Users (DAU): 10 million users.
- Requests per User: Average of 10 requests per day.
- Total Requests: 10 million users * 10 requests = 100...
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