Quick Answer
The answer is a firewall policy allowing traffic from internal to the server’s private IP and a Virtual IP (VIP) object. This configuration is required because internal users need a direct policy permitting their traffic to the server’s private address, while external users require a VIP to translate the public IP to the private IP, with a corresponding firewall policy to allow that translated traffic. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this scenario tests your understanding of destination NAT and policy sequencing, often appearing as a multi-select question where one trap is assuming a single policy can handle both source types. To allow internal users access server via private IP external via public IP FortiGate, remember that the VIP handles the public-to-private mapping, but the internal traffic bypasses NAT entirely. A helpful memory tip: “Internal is direct, external needs a VIP reflect.”
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.
An administrator needs to allow internal users to access a public web server using the server's private IP address, while external users access it via a public IP. Which TWO components are required?
Central SNAT policy
Why wrong: Not required.
An IP pool for source NAT
Why wrong: Not required for this scenario.
A static route on the FortiGate for the public IP
Why wrong: The FortiGate will route based on the VIP configuration.
A VIP (Virtual IP) mapping the public IP to the private IP
Needed for external access.
A firewall policy allowing traffic from internal to the server's private IP
Needed for internal access.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
A VIP (Virtual IP) mapping the public IP to the private IP
To allow internal users to access the server via private IP, a firewall policy must allow the traffic. To allow external users, a VIP is used to map the public IP to the private IP, and a corresponding policy is needed.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Central SNAT policy
Why it's wrong here
Not required.
An IP pool for source NAT
Why it's wrong here
Not required for this scenario.
A static route on the FortiGate for the public IP
Why it's wrong here
The FortiGate will route based on the VIP configuration.
A VIP (Virtual IP) mapping the public IP to the private IP
Why this is correct
Needed for external access.
Related concept
Static NAT maps one inside address to one outside address.
A firewall policy allowing traffic from internal to the server's private IP
Why this is correct
Needed for internal access.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Trap categories for this question
Scenario analysis trap
Not required for this scenario.
Detailed technical explanation
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
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
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related NSE4 NAT questions on configuration and troubleshooting.
Firewall Policies and NAT — study guide chapter
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FAQ
Firewall Policies and NAT — This question tests Firewall Policies and NAT — Static NAT maps one inside address to one outside address..
The correct answer is: A VIP (Virtual IP) mapping the public IP to the private IP — To allow internal users to access the server via private IP, a firewall policy must allow the traffic. To allow external users, a VIP is used to map the public IP to the private IP, and a corresponding policy is needed.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related NSE4 NAT questions on configuration and troubleshooting.
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 21, 2026
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