Design a large-scale Ad Serving Platform
Last updated: July 2, 2025
Quick Overview
Design a distributed ad serving system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
HubSpot
July 2, 2025104
4
2,165 solved
Design a distributed ad serving system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Software engineering fundamentals questions at HubSpot test your understanding of core CS concepts and their practical application. This Onsite question evaluates how you apply engineering principles to build maintainable, scalable software.
What the Interviewer Expects
- Design a complex system component applying multiple engineering principles
- Reason about system-level trade-offs: performance, reliability, developer experience
- Discuss advanced patterns: event sourcing, CQRS, distributed transactions
- Address cross-cutting concerns: observability, security, backward compatibility
- Demonstrate depth in both theoretical foundations and practical implementation
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
- How would you document this for other engineers?
- How would you handle backward compatibility?
- What testing strategy would you use for this component?
- How would this design change if the team size doubled?
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Core Design Principles
When designing a large-scale Ad Serving Platform for HubSpot, several core design principles must be taken into account:
- Separation of Concerns: The system should separate the responsibilities...
Architecture
The architecture of the Ad Serving Platform will follow a microservices approach:
- Service-Oriented Architecture: Each service will handle a specific function—advertisement management, user tar...
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