Design Caching Infrastructure for IoT devices
Last updated: November 12, 2025
Quick Overview
Design a low-latency caching system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Twilio
System Design
Product Manager
Twilio
November 12, 2025Product Manager
System Design Round
System Design
Medium
23
16
3,660 solved
Design a low-latency caching system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Twilio asks this during the System Design Round to assess your architectural thinking. They want to see how you decompose a complex problem, choose appropriate technologies, and reason about failure modes. Strong candidates proactively discuss monitoring, alerting, and operational concerns.
What the Interviewer Expects
- Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
- Design a scalable architecture with clear component responsibilities
- Make well-reasoned database and caching decisions with trade-off analysis
- Address consistency vs availability trade-offs specific to the use case
- Discuss partitioning strategy, replication, and data modeling
- Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
Caching strategies (local, distributed, CDN)
Failure handling and fault tolerance
Partitioning and sharding strategies
High-level architecture and component design
Consistency models and replication
Message queues and async processing
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 traffic overnight?
- What would the deployment pipeline look like for this system?
- How would you handle a region-wide outage?
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Requirements
Functional Requirements
- Low-Latency Access: The caching system must deliver responses to IoT devices in under 50ms.
- High Read Throughput: Must support millions of read requests per s...
Capacity Estimation
Capacity Estimation
- Assumptions: Assume Twilio supports 100 million IoT devices.
- Requests per Device: Each device sends an average of 10 requests per second for state updates.
- **Tota...
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