This NSE4 practice question tests your understanding of firewall policies and nat. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A FortiGate has multiple WAN interfaces (port1, port2) connected to different ISPs. The administrator wants traffic from the internal network to use port1 for general internet access but use port2 for traffic to a specific cloud service (203.0.113.0/24). Which feature should be used to achieve this?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use policy-based routing (PBR) to route traffic based on destination
Policy-based routing (PBR) allows you to override the default routing table based on criteria such as source/destination IP, protocol, or port. In this scenario, PBR can match traffic destined to 203.0.113.0/24 and force it out through port2, while all other internet traffic follows the default route via port1. This provides granular control without affecting the general routing behavior.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
Static routes cannot differentiate by source IP or destination subnet beyond the routing table.
✗
Use SD-WAN rules to load balance
Why it's wrong here
SD-WAN can also achieve this, but PBR is the straightforward answer for static routing.
✓
Use policy-based routing (PBR) to route traffic based on destination
Why this is correct
PBR can match specific traffic and route it out a specific interface.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse SD-WAN load balancing with policy-based routing, assuming that SD-WAN rules can enforce a strict 'always use this interface for this destination' policy, when in fact SD-WAN is primarily for dynamic load balancing and failover, not for static, deterministic path selection based solely on destination.
Detailed technical explanation
How to think about this question
PBR in FortiGate is implemented via policy routes, which are evaluated before the routing table lookup. The policy route matches traffic based on fields like source/destination address, protocol, and port, and then sets the output interface and optionally the gateway. This is similar to Cisco's 'route-map' PBR but uses a simpler policy-based structure. A common real-world scenario is directing Office 365 traffic through a dedicated MPLS link while sending general web traffic over a broadband connection.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Firewall Policies and NAT — This question tests Firewall Policies and NAT — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use policy-based routing (PBR) to route traffic based on destination — Policy-based routing (PBR) allows you to override the default routing table based on criteria such as source/destination IP, protocol, or port. In this scenario, PBR can match traffic destined to 203.0.113.0/24 and force it out through port2, while all other internet traffic follows the default route via port1. This provides granular control without affecting the general routing behavior.
What should I do if I get this NSE4 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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.
Question Discussion
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