The correct answer is to enable NAT on the firewall policy. This is required because in NAT/Route mode, enabling NAT on the outbound policy performs source NAT (SNAT) by default, automatically translating the private IP addresses of internal users to the public IP address of the FortiGate’s WAN interface, allowing them to access the internet while hiding their internal addressing. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this concept tests your understanding of how a NAT policy allows internal users internet FortiGate access without needing a separate IP pool, and a common trap is assuming you must manually configure a central NAT rule or an IP pool for basic internet access—when in fact, the simple checkbox on the policy suffices. Remember the memory tip: “Check NAT, forget the pool” for standard outbound internet traffic.
NSE4 System and Network Administration Practice Question
This NSE4 practice question tests your understanding of system and network administration. 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 FortiGate is deployed in NAT/Route mode. The administrator wants to create a policy that allows internal users to access the internet and also translates their private IP addresses to the public IP of the FortiGate's WAN interface. Which policy configuration is required?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable NAT on the firewall policy
Option D is correct because in NAT/Route mode, enabling NAT on the firewall policy performs source NAT (SNAT) by default, translating the private source IP addresses of internal users to the public IP address of the FortiGate's WAN interface. This is the standard method for allowing internal users to access the internet while hiding their private addresses behind a single public IP.
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.
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Configure a virtual IP (VIP) for the WAN interface
Enabling NAT on the policy performs source NAT to the outgoing interface IP.
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 may confuse source NAT (enabled on the firewall policy) with destination NAT (configured via VIPs) or mistakenly think NAT is a routing feature, leading them to select options like static route with NAT or VIP configuration.
Detailed technical explanation
How to think about this question
When NAT is enabled on a FortiGate firewall policy, the FortiGate performs source NAT (also known as IP masquerading or PAT) using the IP address of the egress interface (typically the WAN interface). This behavior is defined by the FortiGate's central NAT table, which automatically creates dynamic translations for outbound sessions, and the NAT mode can be set to 'Use Outgoing Interface Address' or a specific IP pool for more granular control.
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.
System and Network Administration — This question tests System and Network Administration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable NAT on the firewall policy — Option D is correct because in NAT/Route mode, enabling NAT on the firewall policy performs source NAT (SNAT) by default, translating the private source IP addresses of internal users to the public IP address of the FortiGate's WAN interface. This is the standard method for allowing internal users to access the internet while hiding their private addresses behind a single public IP.
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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