Design a Ad Serving for Goldman Sachs
Last updated: February 19, 2026
Quick Overview
Design a fault-tolerant ad serving system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Goldman Sachs
February 19, 202632
5
4,178 solved
Design a fault-tolerant ad serving system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Goldman Sachs asks this during the Onsite 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
- 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
- What are the security implications of this design?
- What testing strategy would you use for this component?
- How would this design change if the team size doubled?
- How would you document this for other engineers?
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Core Design Principles
For the ad serving system at Goldman Sachs, we should adhere to the SOLID principles to ensure maintainability and scalability. Specifically:
- Single Responsibility Principle: Each component...
Architecture
The architecture for the ad serving system will be based on a microservices approach:
- Ad Service: Responsible for serving ads based on user requests, integrates with targeting services.
- *...
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