Design a device configuration system
Company: Palo Alto Networks
Role: Software Engineer
Category: System Design
Difficulty: easy
Interview Round: Onsite
Design a system for about 1,000 admin users to manage configurations for about 1,000 devices. Admins need to update device configuration every day. Explain the main APIs, storage model, rollout workflow, and operational behavior. As follow-up discussion, describe how you would scale the system and how you would preserve strong consistency for configuration updates.
Overview: This question evaluates system design and distributed systems competency, including API design, storage modeling, rollout workflows, operational behavior, and consistency trade-offs for device configuration management.
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Community answers
Answer by Coderka14
An admin changes a device's configuration.
Admin -> Our System -> Device
Example:
Old: firewall = OFF
New: firewall = ON
Our system must make sure the "correct configuration reaches the correct device"
We need simple APIs:
POST /devices/{id}/config -> Update configuration.
GET /devices/{id}/config -> Get current configuration.
POST /devices/{id}/rollback - >Restore an old configuration.
Store configurations with versions.
Device 101
v1 → firewall OFF
v2 → firewall ON
v3 → firewall ON + new rule
Why versions?
Audit history
Know what is currently applied
Easy rollback