Design Rate Limiting Infrastructure for IoT devices
Last updated: July 14, 2025
Quick Overview
Design a distributed rate limiting system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Palo Alto Networks
July 14, 2025120
6
750 solved
Design a distributed rate limiting system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Palo Alto Networks asks this during the System Design Round to assess your understanding of the full ML lifecycle. They want to see how you translate a business problem into an ML objective, design the feature pipeline, and plan for model monitoring and retraining.
What the Interviewer Expects
- Define clear ML objectives with appropriate loss functions and metrics
- Design a comprehensive feature engineering pipeline
- Discuss model selection with trade-offs (complexity vs interpretability vs latency)
- Plan online and offline evaluation strategies including A/B testing
- Address serving infrastructure: batch vs real-time, latency requirements
- Consider data quality, labeling strategy, and feedback loops
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 is your model retraining strategy?
- How would you handle the cold start problem?
- How would you run A/B tests on different model versions?
- How would you ensure fairness and reduce bias in the model?
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Requirements
- Functional Requirements:
- Implement rate limiting for IoT devices based on device ID and request type.
- Support configurable rate limits per device and per request type (e.g., 100 re...
Capacity Estimation
To estimate the capacity needed for our rate limiting system, we consider the following:
- Total IoT Devices: Let's assume there are 50 million IoT devices.
- Requests Per Device: Each dev...
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