Design a Authentication for Roblox
Last updated: March 4, 2026
Quick Overview
Design a fault-tolerant authentication system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Roblox
March 4, 202645
9
2,559 solved
Design a fault-tolerant authentication system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
ML system design at Roblox goes beyond model selection. This Technical Screen 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
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?
- How would you debug a model that works well offline but poorly online?
- How would you run A/B tests on different model versions?
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Requirements
Functional Requirements
- User Registration: Allow new users to create accounts with username, password, and email.
- User Authentication: Support login with username and password, includi...
Capacity Estimation
Assuming Roblox has approximately 200 million monthly active users (MAUs) and each user logs in 5 times a week, we can estimate:
- Daily Active Users (DAUs): 200M / 30 days = ~6.67M DAUs
- **T...
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