Design a high-throughput Ad Serving System
Last updated: March 7, 2026
Quick Overview
Design a high-throughput ad serving system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Expedia
March 7, 2026293
4
1,619 solved
Design a high-throughput ad serving system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Expedia asks this during the Technical Screen to assess your depth in software engineering. They want to see understanding of design patterns, system architecture, and the trade-offs involved in different technical approaches.
What the Interviewer Expects
- Apply engineering principles to a realistic design scenario
- Discuss trade-offs between different approaches with concrete examples
- Demonstrate understanding of testability, maintainability, and extensibility
- Connect theoretical concepts to production engineering practices
- Discuss how the approach scales with team and codebase size
Key Topics to Cover
How to Approach This
- Apply SOLID principles. Single Responsibility makes code testable, Open/Closed makes it extensible.
- Choose data structures based on access patterns, not familiarity.
- Prefer immutable data and message passing over shared mutable state for concurrency.
- Design APIs with RESTful conventions, versioning, meaningful errors, and pagination from day one.
Possible Follow-up Questions
- What testing strategy would you use for this component?
- How would this design change if the team size doubled?
- How would you measure the performance of this component in production?
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Core Design Principles
For designing the high-throughput ad serving system at Expedia, we will emphasize the following core design principles:
- Separation of Concerns: This principle ensures that different functional...
Architecture
The architecture of the ad serving system will follow a microservices approach, which is suitable for Expedia's needs due to its modularity and scalability:
- Service Layer: We will have dedicat...
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