The answer is to enable policy-based routing on the firewall policy and specify port2 as the egress interface. This is correct because policy-based routing (PBR) allows you to override the default routing table for specific traffic, such as traffic from server 10.0.1.100, based on criteria like source IP, giving you granular control over which WAN path that server uses. On the Fortinet NSE 4 exam, this scenario tests your understanding that PBR operates at the policy level, not the static route level—a common trap is confusing PBR with simple static route load balancing or SD-WAN rules. Remember that PBR is applied directly within a firewall policy’s advanced options, making it the precise tool for forcing a specific server’s internet traffic out a designated interface while leaving all other traffic to follow the routing table. A helpful memory tip: “Policy picks the path; routing follows the table.”
NSE4 Firewall Policies and NAT Practice Question
This NSE4 practice question tests your understanding of firewall policies and nat. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 company has a FortiGate with two WAN interfaces (port1 and port2) connected to different ISPs. The admin wants to ensure that traffic from a specific internal server (10.0.1.100) destined to the internet always exits via port2, while all other traffic uses port1. Which feature should the admin configure on the firewall policy for that server?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "always"
Why it matters: Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
Why wrong: VIPs are for destination NAT, not for steering traffic to a specific egress.
B
Enable policy-based routing on the policy and specify port2 as the egress interface
Policy-based routing overrides the routing table for traffic matching that policy.
C
Configure a static route with a higher distance for port2
Why wrong: Static routes are for destination-based routing, not per-policy source-based routing.
D
Set the outgoing interface to port2 in the firewall policy
Why wrong: The outgoing interface in a policy is used for NAT and logging but does not force the route; the routing table still decides the egress interface.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable policy-based routing on the policy and specify port2 as the egress interface
Policy-based routing (PBR) allows you to override the routing table for specific traffic based on criteria such as source IP, destination, or application. By enabling PBR on the firewall policy for server 10.0.1.100 and specifying port2 as the egress interface, the admin ensures that all traffic from that server exits via port2, while the routing table continues to direct all other traffic via port1. This is the correct approach because PBR operates at the policy level, not the routing table level, giving granular control over traffic path selection.
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.
✗
Create a VIP to redirect the traffic to port2
Why it's wrong here
VIPs are for destination NAT, not for steering traffic to a specific egress.
✓
Enable policy-based routing on the policy and specify port2 as the egress interface
Why this is correct
Policy-based routing overrides the routing table for traffic matching that policy.
Clue confirmation
The clue word "always" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure a static route with a higher distance for port2
Why it's wrong here
Static routes are for destination-based routing, not per-policy source-based routing.
✗
Set the outgoing interface to port2 in the firewall policy
Why it's wrong here
The outgoing interface in a policy is used for NAT and logging but does not force the route; the routing table still decides the egress interface.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the 'outgoing interface' field in a firewall policy as a configurable option, when in fact it is automatically derived from the routing table unless policy-based routing is explicitly enabled.
Detailed technical explanation
How to think about this question
Policy-based routing on FortiGate is implemented by enabling 'policy-based routing' under the firewall policy's advanced options, which then allows you to specify a 'set dst-intf' action to override the routing table lookup. Under the hood, FortiGate uses a separate PBR rule table that is evaluated before the routing table, and it supports matching on source/destination IP, protocol, port, and even application control. In real-world scenarios, PBR is critical for asymmetric routing prevention or for directing traffic from specific servers (e.g., a mail server) through a dedicated ISP with better reverse DNS reputation.
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: Enable policy-based routing on the policy and specify port2 as the egress interface — Policy-based routing (PBR) allows you to override the routing table for specific traffic based on criteria such as source IP, destination, or application. By enabling PBR on the firewall policy for server 10.0.1.100 and specifying port2 as the egress interface, the admin ensures that all traffic from that server exits via port2, while the routing table continues to direct all other traffic via port1. This is the correct approach because PBR operates at the policy level, not the routing table level, giving granular control over traffic path selection.
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.
Are there clue words in this question I should notice?
Yes — watch for: "always". Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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