Design a geo-distributed A/B Testing System
Last updated: April 3, 2026
Quick Overview
Design a geo-distributed a/b testing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
NVIDIA
System Design
Software Engineer
NVIDIA
April 3, 2026Software Engineer
Onsite
System Design
Easy
26
3
1,539 solved
Design a geo-distributed a/b testing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
ML system design at NVIDIA goes beyond model selection. This Onsite question evaluates your ability to design end-to-end ML pipelines, from data collection to model serving, while considering production constraints like latency and reliability.
What the Interviewer Expects
- Map the business problem to a concrete ML objective
- Propose reasonable features and a baseline model
- Discuss basic model evaluation metrics
- Outline a simple serving architecture
Key Topics to Cover
Online vs offline evaluation
Feature engineering and feature stores
Model selection and architecture
Data collection and labeling strategy
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 would you handle a 10x increase in prediction requests?
- How would you ensure fairness and reduce bias in the model?
- What would you do if model performance degrades over time?
- What is your model retraining strategy?
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Requirements
Functional Requirements
- User Segmentation: The system should allow for user segmentation based on geographic location to facilitate targeted A/B testing.
- Experiment Management: Enabl...
Capacity Estimation
Back-of-Envelope Calculations
- User Base: Assume 10 million active users per month.
- Daily Requests: If each user makes 10 requests daily, that totals 100 million requests per day.
- ...
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