Build a fault-tolerant Logging Pipeline

Last updated: June 12, 2026

Quick Overview

Design a fault-tolerant logging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Zoom
System Design
Software Engineer
Zoom
June 12, 2026
Software Engineer
Onsite
System Design
Easy

19

5

2,912 solved


Design a fault-tolerant logging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Zoom 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
Security and authentication
High-level architecture and component design
Caching strategies (local, distributed, CDN)
Consistency models and replication
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 do you ensure data consistency across multiple services?
  • How would you handle a 10x increase in traffic overnight?
  • How would you handle a region-wide outage?
  • What happens if one of your database nodes goes down?
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Sample Answer
Requirements
  • Functional Requirements:
    1. Capture logs from multiple services (e.g., video calls, user interactions) in real-time.
    2. Ensure logs include metadata such as timestamp, user ID, session I...
Capacity Estimation
  • Traffic Estimation:
    • Assume Zoom has approximately 300 million daily active users.
    • In peak periods, let’s say 10% of users are active, resulting in 30 million users.
    • If each use...

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