Architect a real-time Notification Engine
Last updated: August 17, 2025
Quick Overview
Design a real-time notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Palo Alto Networks
August 17, 202540
7
2,655 solved
Design a real-time notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at Palo Alto Networks typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.
What the Interviewer Expects
- Clearly define functional and non-functional requirements
- Propose a reasonable high-level architecture with core components
- Choose appropriate data storage solutions with basic justification
- Discuss basic scaling strategies (horizontal scaling, caching)
- Identify potential bottlenecks and suggest simple solutions
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 handle a region-wide outage?
- How would you handle schema migrations with zero downtime?
- What would the deployment pipeline look like for this system?
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Requirements
Functional Requirements
- Real-time Notifications: The system should send notifications in real-time to users based on events (e.g., security alerts, updates).
- User Preferences: Allow ...
Capacity Estimation
Assuming Palo Alto Networks has around 1 million users with an average of 5 notifications per user per day:
- Total Daily Notifications = 1,000,000 users * 5 notifications = 5,000,000 notification...
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