Design a large-scale Authentication Platform

Last updated: September 19, 2025

Quick Overview

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

HubSpot
System Design
Software Engineer
HubSpot
September 19, 2025
Software Engineer
System Design Round
System Design
Easy

10

14

1,255 solved


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

This ML system design question from HubSpot's System Design Round tests your ability to think about ML systems at scale. The interviewer expects discussion of data quality, feature stores, model serving infrastructure, and A/B testing strategy.

What the Interviewer Expects
  • Map the business problem to a concrete ML objective
  • Propose reasonable features and a baseline model
  • Discuss basic model evaluation metrics
  • Outline a simple serving architecture
Key Topics to Cover
A/B testing and experimentation
Model selection and architecture
Feedback loops and model retraining
Monitoring and model degradation detection
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 handle the cold start problem?
  • How would you ensure fairness and reduce bias in the model?
  • What would you do if model performance degrades over time?
Practice a Similar Problem on Codemia

Solve a related problem with our interactive workspace, get AI feedback, and view detailed solutions.

Solve on Codemia
Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For large-scale Authentication Platform, key functional requirements incl...

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...


Submit Your Answer
Markdown supported

Related Questions