The answer is that you must create a Virtual IP (VIP) mapping 203.0.113.10:22 to 10.0.1.10:22, then configure a firewall policy from the WAN to the internal server explicitly permitting the SSH service (TCP port 22), and finally ensure the destination of that policy references the VIP object. This sequence is required because the VIP translates the public IP and port to the private server, but the firewall policy acts as the security gatekeeper—without it, FortiGate drops all inbound packets even with a correct VIP. On the Fortinet NSE 4 Network Security Professional exam, this scenario tests your understanding of the strict separation between destination NAT (VIP) and stateful filtering (policy), a common trap where candidates forget the policy or use the wrong destination interface. A useful memory tip is “VIP maps, policy permits”—the VIP handles the address translation, but the policy must explicitly allow the SSH service object for the traffic to flow.
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.
An administrator needs to allow inbound SSH access from the internet to a specific internal server (10.0.1.10) on port 22. The WAN IP is 203.0.113.10. Which THREE configuration steps are required?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Ensure the firewall policy allows the SSH service (port 22)
Option A is correct because the firewall policy must explicitly permit the SSH service (TCP port 22) from the WAN to the internal server. Without a policy allowing the traffic, the FortiGate will drop the packets even if the VIP is configured correctly. The policy acts as the security gatekeeper, and the service object for SSH ensures only port 22 traffic is allowed.
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.
✓
Ensure the firewall policy allows the SSH service (port 22)
Why this is correct
The policy must explicitly permit the service (SSH) to match the traffic.
Related concept
Read the scenario before looking for a memorised answer.
✓
Create a firewall policy from WAN to internal interface with destination set to the VIP
Why this is correct
The firewall policy must allow traffic destined to the VIP.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure a source NAT IP pool for outbound traffic
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume configuring a VIP alone is sufficient, forgetting that a firewall policy must also be created to permit the translated traffic, and they may confuse source NAT (Option C) with destination NAT required for inbound access.
Detailed technical explanation
How to think about this question
A Virtual IP (VIP) on FortiGate performs destination NAT (DNAT), translating the public IP:port (203.0.113.10:22) to the private IP:port (10.0.1.10:22). The firewall policy must reference the VIP as the destination, and the policy's destination interface must be the internal interface. Without the policy, the VIP translation occurs but the traffic is still blocked by the implicit deny rule at the end of the policy list.
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: Ensure the firewall policy allows the SSH service (port 22) — Option A is correct because the firewall policy must explicitly permit the SSH service (TCP port 22) from the WAN to the internal server. Without a policy allowing the traffic, the FortiGate will drop the packets even if the VIP is configured correctly. The policy acts as the security gatekeeper, and the service object for SSH ensures only port 22 traffic is allowed.
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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Question Discussion
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