Design a Caching Service

Last updated: November 24, 2025

Quick Overview

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

Adobe
System Design
Software Engineer
Adobe
November 24, 2025
Software Engineer
System Design Round
System Design
Medium

10

5

1,341 solved


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

Adobe 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
  • Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
  • Design a scalable architecture with clear component responsibilities
  • Make well-reasoned database and caching decisions with trade-off analysis
  • Address consistency vs availability trade-offs specific to the use case
  • Discuss partitioning strategy, replication, and data modeling
  • Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
Database selection and data modeling
Load balancing and horizontal scaling
Consistency models and replication
Caching strategies (local, distributed, CDN)
Requirements gathering and capacity estimation
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 would the deployment pipeline look like for this system?
  • How would you optimize costs as the system scales?
  • What happens if one of your database nodes goes down?
  • How would you migrate from a monolithic to a microservices architecture?
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Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For Caching Service, key functional requirements include: what are the co...

Capacity Estimation

Estimate the scale to drive design decisions. Assume 100M DAU with an average of 10 actions per user per day = 1B requests/day ~ 12K QPS average, ~36K...


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