The answer is enabling NAT on the firewall policy and selecting the IP pool. This combination is required because overload NAT, also known as Port Address Translation (PAT), allows multiple internal hosts to share a single public IP address by dynamically mapping each session to a unique source port. To configure this on a FortiGate, you must first create an IP pool with the type set to "Overload" and specify the public IP address, such as 203.0.113.1, then apply that pool in the firewall policy where NAT is enabled. On the Fortinet NSE 4 Network Security Professional exam, this scenario tests your understanding of how PAT differs from static or one-to-one NAT, and a common trap is forgetting that simply enabling NAT without an IP pool will use the egress interface IP instead of the desired single public address. Remember the tip: "Overload equals port overload" — if you need one IP for many users, always pair the policy NAT flag with an Overload IP pool.
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 organization requires that outbound HTTP and HTTPS traffic from the internal network be translated to a single public IP address (203.0.113.1) using overload NAT (PAT). Which TWO configurations are necessary?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create an IP pool with type 'Overload' and specify the public IP address
Overload NAT (PAT) allows multiple internal hosts to share a single public IP by translating source ports. To achieve this, you must create an IP pool with type 'Overload' that specifies the public IP address (203.0.113.1) and then enable NAT on the firewall policy, selecting that IP pool. This configuration ensures outbound HTTP/HTTPS traffic is translated to the single public IP with unique source ports.
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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Disable 'Allow Traffic' on the implicit deny policy
Enable 'NAT' on the firewall policy and select the IP pool
Why this is correct
The policy must reference the IP pool to apply the NAT.
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 often confuse one-to-one NAT (Option B) with overload NAT, or think a VIP (Option D) is needed for outbound traffic, when in fact VIPs are strictly for inbound destination NAT.
Detailed technical explanation
How to think about this question
Overload NAT (PAT) works by modifying the source port in the TCP/UDP header to a unique value while keeping the source IP as the single public IP, allowing up to 65,535 concurrent sessions per protocol. In FortiGate, the IP pool with type 'Overload' creates a dynamic mapping table that tracks these port translations, and the firewall policy must have NAT enabled with the pool selected to apply this translation to outbound traffic. A real-world scenario is a small office with 100 users sharing one public IP for web browsing, where PAT ensures each session is uniquely identified.
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 an IP pool with type 'Overload' and specify the public IP address — Overload NAT (PAT) allows multiple internal hosts to share a single public IP by translating source ports. To achieve this, you must create an IP pool with type 'Overload' that specifies the public IP address (203.0.113.1) and then enable NAT on the firewall policy, selecting that IP pool. This configuration ensures outbound HTTP/HTTPS traffic is translated to the single public IP with unique source ports.
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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