Design Load Balancing Infrastructure for global users
Last updated: December 29, 2025
Quick Overview
Design a low-latency load balancing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
SpaceX
December 29, 2025192
6
2,091 solved
Design a low-latency load balancing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
ML system design at SpaceX 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
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
- What would you do if model performance degrades over time?
- How would you handle the cold start problem?
- How would you handle a 10x increase in prediction requests?
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Requirements
Functional Requirements
- Global Load Balancing: Distribute incoming requests from users worldwide to multiple servers based on proximity and current load.
- Health Checks: Regularly mon...
Capacity Estimation
Assuming SpaceX has an estimated user base of 100 million globally, we can estimate traffic:
- Peak Requests: 10% of users active at peak times => 10 million users.
- Requests per User: Averag...
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