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 wants to allow SSH access from the internet to a server inside the network at 192.168.1.10. Which NAT configuration is needed?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a VIP mapping public IP:22 to private IP:22 and an allow policy from WAN to DMZ
Option B is correct because to allow inbound SSH access from the internet to an internal server, you need a Virtual IP (VIP) that maps a public IP and port (e.g., 203.0.113.5:22) to the private IP and port (192.168.1.10:22), combined with a firewall policy from the WAN zone to the DMZ zone that permits SSH traffic. This is Destination NAT (DNAT), which translates the destination address of incoming packets so they are routed to the internal server.
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.
✗
Use policy-based routing to forward SSH traffic
Why it's wrong here
PBR changes routing, not address translation.
✓
Create a VIP mapping public IP:22 to private IP:22 and an allow policy from WAN to DMZ
Why this is correct
VIP translates the destination address; the policy allows the traffic after translation.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure source NAT on the outbound policy from DMZ to WAN
NAT on interface is for source translation, not destination.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse source NAT (SNAT) with destination NAT (DNAT), thinking that enabling NAT on the WAN interface alone is sufficient for inbound access, when in fact a VIP (DNAT) and an allow policy are required to translate and permit the traffic.
Detailed technical explanation
How to think about this question
In FortiGate, a VIP object creates a static DNAT entry that translates the destination IP and port of incoming packets. The firewall policy then controls access by specifying source (WAN), destination (VIP), and service (SSH). Under the hood, the FortiGate performs a route lookup after DNAT, so the destination IP becomes 192.168.1.10, and the packet is forwarded to the internal network. A common real-world scenario is hosting a public-facing SSH server behind a single public IP, where multiple services (e.g., SSH, HTTPS) are mapped to different internal servers using different ports.
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: Create a VIP mapping public IP:22 to private IP:22 and an allow policy from WAN to DMZ — Option B is correct because to allow inbound SSH access from the internet to an internal server, you need a Virtual IP (VIP) that maps a public IP and port (e.g., 203.0.113.5:22) to the private IP and port (192.168.1.10:22), combined with a firewall policy from the WAN zone to the DMZ zone that permits SSH traffic. This is Destination NAT (DNAT), which translates the destination address of incoming packets so they are routed to the internal server.
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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