Build a high-throughput Authentication Pipeline
Last updated: September 10, 2025
Quick Overview
Design a high-throughput authentication system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
HashiCorp
September 10, 202576
14
4,847 solved
Design a high-throughput authentication system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
HashiCorp 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
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- How would you optimize costs as the system scales?
- What happens if one of your database nodes goes down?
- How would you implement rate limiting to protect the system?
- How would you handle schema migrations with zero downtime?
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Requirements
Functional Requirements
- User Authentication: The system must authenticate users based on various methods (e.g., username/password, OAuth, SAML).
- Multi-Factor Authentication (MFA): Su...
Capacity Estimation
Capacity Estimation
Assuming HashiCorp manages about 10 million users with a peak authentication load of 100 requests per second (RPS) per user during a high-traffic period:
- Total Peak RPS: ...
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