Design Search Infrastructure for IoT devices

Last updated: January 13, 2026

Quick Overview

Design a scalable search system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Mastercard
System Design
Software Engineer
Mastercard
January 13, 2026
Software Engineer
Technical Screen
System Design
Hard

6

8

587 solved


Design a scalable search system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

This is a common system design question asked during Technical Screen at Mastercard. The interviewer expects you to demonstrate your ability to design large-scale distributed systems, make well-reasoned trade-offs, and communicate your thought process clearly. Mastercard values engineers who can think about scalability from day one.

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
Requirements gathering and capacity estimation
API design and rate limiting
Load balancing and horizontal scaling
Failure handling and fault tolerance
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
  • What happens if one of your database nodes goes down?
  • How do you ensure data consistency across multiple services?
  • How would you handle a region-wide outage?
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Sample Answer
Requirements

Functional Requirements:

  1. Search Capability: The system should allow IoT devices to perform keyword-based searches across various data types (e.g., transactions, device statuses).
  2. **Filte...
Capacity Estimation

Assuming the system needs to support 10 million IoT devices, and each device generates an average of 10 search queries per day:

  1. Total daily searches = 10 million devices * 10 searches/device =...

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