NSE4 Firewall Policies and NAT Practice Question
An administrator wants to ensure that traffic from the engineering department (subnet 192.168.10.0/24) to the internet uses a specific public IP address for source NAT. Additionally, traffic from the marketing department (192.168.20.0/24) should use a different public IP. Which method should be used?
⚠ Common exam trap
Many exam-takers confuse IP pools (used for source NAT) with Virtual IPs (used for destination NAT), leading them to incorrectly select VIP for source NAT.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create two firewall policies, each with its own IP pool, for the respective subnets
The requirement is to map specific source subnets to different public IP addresses. In FortiGate, this is achieved by creating separate firewall policies for each subnet, each with its own IP pool configured for source NAT. A single Central SNAT rule with one IP pool cannot differentiate between subnets to assign different public IPs.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure a single Central SNAT rule with multiple source subnets and a single IP pool
Why it's wrong here
A single IP pool cannot assign different IPs per subnet.
- ✓
Create two firewall policies, each with its own IP pool, for the respective subnets
Why this is correct
This allows granular control over which IP is used for each subnet.
- ✗
Use VIP for source NAT
Why it's wrong here
VIP is for destination NAT, not source NAT.
- ✗
Use a single policy with a dynamic IP pool that randomly assigns IPs
Why it's wrong here
Random assignment would not guarantee different IPs per subnet.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This NSE4 practice question is part of Courseiva's free Fortinet certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the NSE4 exam.