Design Ad Serving Infrastructure for global users

Last updated: September 22, 2025

Quick Overview

Design a low-latency ad serving system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

NVIDIA
System Design
Software Engineer
NVIDIA
September 22, 2025
Software Engineer
Onsite
System Design
Hard

75

8

867 solved


Design a low-latency ad serving system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

NVIDIA asks this during the Onsite 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
  • Drive the design discussion proactively with minimal interviewer guidance
  • Perform detailed capacity estimation and use it to inform design decisions
  • Design for global scale with multi-region deployment and data consistency
  • Deep dive into 2-3 critical components with implementation-level detail
  • Address complex trade-offs: CAP theorem, eventual consistency, conflict resolution
  • Discuss operational excellence: deployment strategy, chaos engineering, SLOs/SLIs
  • Propose a phased rollout plan from MVP to full-scale system
Key Topics to Cover
Security and authentication
Message queues and async processing
Requirements gathering and capacity estimation
High-level architecture and component design
Failure handling and fault tolerance
How to Approach This
  1. Start by clarifying functional and non-functional requirements with the interviewer.
  2. Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
  3. Draw a high-level architecture first, then deep dive into 1-2 critical components.
  4. Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
  5. Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
  • What monitoring and alerting would you set up on day one?
  • How do you ensure data consistency across multiple services?
  • What happens if one of your database nodes goes down?
  • How would you handle schema migrations with zero downtime?
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Sample Answer
Requirements
  • Functional Requirements:
    • Serve personalized ads to users based on their preferences and behavior.
    • Support A/B testing for ad performance evaluation.
    • Provide user segmentation and tar...
Capacity Estimation

To estimate capacity, let's assume:

  • User Base: 1 billion monthly active users.
  • Ad Requests: Each user makes 10 ad requests per day on average.

Calculations:

  • Total ad requests per da...

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