Design Chat Infrastructure for global users
Last updated: December 1, 2025
Quick Overview
Design a scalable chat system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
NVIDIA
System Design
Software Engineer
NVIDIA
December 1, 2025Software Engineer
System Design Round
System Design
Hard
49
10
131 solved
Design a scalable chat system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
NVIDIA 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
- Drive the design discussion proactively with minimal interviewer guidance
- Perform detailed capacity estimation and use it to inform design decisions
- Design for global scale with multi-region deployment and data consistency
- Deep dive into 2-3 critical components with implementation-level detail
- Address complex trade-offs: CAP theorem, eventual consistency, conflict resolution
- Discuss operational excellence: deployment strategy, chaos engineering, SLOs/SLIs
- Propose a phased rollout plan from MVP to full-scale system
Key Topics to Cover
API design and rate limiting
Failure handling and fault tolerance
High-level architecture and component design
Caching strategies (local, distributed, CDN)
Partitioning and sharding strategies
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 monitoring and alerting would you set up on day one?
- How would you implement rate limiting to protect the system?
- How would you migrate from a monolithic to a microservices architecture?
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Requirements
Functional Requirements
- User Registration and Authentication: Users should be able to create accounts and log in securely.
- Real-time Messaging: Support one-on-one and group chats wit...
Capacity Estimation
Assuming NVIDIA's chat system handles:
- 10 million users
- 100 messages per user per day
- Peak traffic at 10x average usage
Calculations
- Daily message volume = 10 million users * 100 ...
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