Architect a geo-distributed Caching Engine

Last updated: April 11, 2026

Quick Overview

Design a geo-distributed caching system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

xAI
System Design
Software Engineer
xAI
April 11, 2026
Software Engineer
Onsite
System Design
Easy

2

7

780 solved


Design a geo-distributed caching system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

xAI asks this during the Onsite 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
  • Clearly define functional and non-functional requirements
  • Propose a reasonable high-level architecture with core components
  • Choose appropriate data storage solutions with basic justification
  • Discuss basic scaling strategies (horizontal scaling, caching)
  • Identify potential bottlenecks and suggest simple solutions
Key Topics to Cover
Database selection and data modeling
Monitoring, logging, and alerting
Partitioning and sharding strategies
Failure handling and fault tolerance
Security and authentication
How to Approach This
  1. Start by clarifying functional and non-functional requirements with the interviewer.
  2. Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
  3. Draw a high-level architecture first, then deep dive into 1-2 critical components.
  4. Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
  5. Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
  • How would you migrate from a monolithic to a microservices architecture?
  • How would you handle a 10x increase in traffic overnight?
  • What would the deployment pipeline look like for this system?
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Sample Answer
Requirements

Functional Requirements:

  1. Geo-Distributed Caching: The system must provide caching across multiple geographic locations to reduce latency for users worldwide.
  2. Data Consistency: Suppor...
Capacity Estimation

Assuming xAI serves around 1 million active users globally:

  1. Requests per User: Each user generates an average of 10 requests per minute.
  2. Total Requests:
    • 1,000,000 users * 10 reques...

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