Design Ad Serving Infrastructure for global users
Last updated: May 5, 2026
Quick Overview
Design a real-time ad serving system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Goldman Sachs
System Design
Software Engineer
Goldman Sachs
May 5, 2026Software Engineer
System Design Round
System Design
Easy
1
11
4,929 solved
Design a real-time ad serving system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at Goldman Sachs typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.
What the Interviewer Expects
- Clearly define functional and non-functional requirements
- Propose a reasonable high-level architecture with core components
- Choose appropriate data storage solutions with basic justification
- Discuss basic scaling strategies (horizontal scaling, caching)
- Identify potential bottlenecks and suggest simple solutions
Key Topics to Cover
Monitoring, logging, and alerting
High-level architecture and component design
Failure handling and fault tolerance
Partitioning and sharding strategies
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 handle a region-wide outage?
- How would you migrate from a monolithic to a microservices architecture?
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Requirements
- Functional Requirements:
- Serve ads in real-time to global users based on targeting criteria (location, behavior, etc.).
- Provide an interface for advertisers to upload and manage ad...
Capacity Estimation
- User Base Estimation:
Assume 10 million active users. - Requests per User:
Each user generates approximately 20 ad requests per day. - Total Requests:
Total requests = 10...
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