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Interview Questions

Contact Tracing System Design

Asked at Netflix
technical
system design
distributed systems

Design a COVID-19 contact tracing system with the following features:

Requirements:

  1. Mobile Device Logging
  • Maintain 2-week rolling log of encounters
  • Record timestamps and device identifiers
  • Efficient storage management
  1. Data Retrieval & Processing
  • Use Cassandra for log storage
  • Implement BFS for contact network traversal
  • Handle large-scale data efficiently
  1. System Architecture
  • Mobile device encounter logging
  • Central database management
  • Contact network analysis

Example Scenario: When User A reports COVID:

  1. Retrieve User A's contact logs
  2. Perform BFS to identify direct contacts
  3. Continue traversal for indirect exposure
  4. Notify affected users

Warehouse Shortest Path

Asked at Netflix
technical
algorithms
graph

Find the shortest path between two products in a warehouse.

Implementation Requirements:

  1. Data Model
  • Use graph representation
  • Nodes represent locations
  • Edges represent pathways
  • Support for hallways and rooms
  1. Algorithm
  • Implement BFS for shortest path
  • Return path as array
  • Handle invalid paths

Example:

Input:
- Warehouse graph
- Start product: A
- End product: B

Output: Array representing shortest path from A to B

Video Commerce System Design

Asked at Netflix
onsite
system design
architecture

Design a system for video downloads and creator subscriptions.

Key Features:

  1. Video Downloads
  • Purchase individual videos
  • Secure download access
  • Content delivery system
  1. Creator Subscriptions
  • Subscription management
  • Access control
  • Content updates
  1. Payment Processing
  • Secure transactions
  • Refund handling
  • Purchase history
  1. System Requirements
  • User authentication
  • Scalable architecture
  • Transaction management
  • Content delivery optimization

Netflix Infrastructure Interview Experience (2024)

Asked at Netflix
behavioral
interview experience
system design
infrastructure

Interview experience from a Google L4 Infrastructure Engineer:

Phone Screen:

  • Interviewed by Holden Karau (Spark expert)
  • Mostly career discussion and Netflix culture
  • Brief 10-minute technical question
  • Very conversational approach

Virtual Onsite (Day 1):

  1. Concurrency Round
  • Focus on mutex/condition variables
  • Basic operations and trade-offs
  • Emphasis on clear communication
  1. Problem Solving Round
  • LRU Cache variant
  • Leetcode-style implementation
  • Moderate difficulty level
  1. System Design Round
Topic: Scalable Counter System
Requirements:
- Start with single server, bare metal
- Scale up to cloud architecture
- Handle view counts/metrics
- Deep dive into implementation details

Key Focus Areas:
- Open-source tech stack choices
- Partition/replication algorithms
- Component-level deep dives
- Architectural assumptions

Process ended after Day 1.

Key Takeaways:

  • Very professional interviewers
  • High technical bar
  • Deep system design knowledge required
  • Important to understand fundamentals beyond existing platforms
  • Recommended prep: "Designing Data-Intensive Applications"

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