Build a fault-tolerant Authentication Pipeline
Last updated: September 8, 2025
Quick Overview
Design a fault-tolerant authentication system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
SpaceX
September 8, 20253
7
1,513 solved
Design a fault-tolerant authentication system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
ML system design at SpaceX 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 debug a model that works well offline but poorly online?
- What would you do if model performance degrades over time?
- What is your model retraining strategy?
- How would you handle the cold start problem?
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Requirements
Functional Requirements
- User Registration: Users must be able to create accounts securely.
- User Login: Support for email/password and OAuth logins (e.g., Google, SpaceX SSO).
- **Mu...
Capacity Estimation
Assuming SpaceX has around 10 million registered users and anticipates 1 million login requests per day:
- Daily Requests: 1 million logins/day = ~11.57 logins/second.
- Peak Load: If we assu...
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