Quick Answer
The answer is Overload NAT, also known as Port Address Translation (PAT). This method is correct because it allows many internal IP addresses to share a single public IP by dynamically mapping each internal session to a unique source port number, enabling the FortiGate to distinguish between multiple concurrent connections. On the Fortinet NSE 4 Network Security Professional exam, this concept tests your understanding of how to conserve public IP addresses while providing internet access to an entire internal network—a common scenario in the “Firewall Policies and NAT” domain. A frequent trap is confusing Overload NAT with static NAT or one-to-one NAT, which require multiple public IPs; remember that Overload NAT is the only method that multiplexes traffic through a single IP. Memory tip: think “Overload = One IP, Many Ports.”
This NSE4 practice question tests your understanding of firewall policies and nat. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 administrator wants to ensure that traffic from the internal network to the internet is translated to a single public IP address. Which NAT method should be used?
Central SNAT
Why wrong: Central SNAT is a global NAT configuration, not a specific method.
One-to-one NAT
Why wrong: One-to-one maps a single private IP to a single public IP.
Fixed port range NAT
Why wrong: Fixed port range allocates a range of ports per internal IP.
Overload NAT
Overload NAT uses PAT to allow many-to-one translation.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Overload NAT
Overload NAT (Port Address Translation) allows many internal IPs to share one public IP by using unique source ports.
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
Why it's wrong here
Central SNAT is a global NAT configuration, not a specific method.
One-to-one NAT
Why it's wrong here
One-to-one maps a single private IP to a single public IP.
Fixed port range NAT
Why it's wrong here
Fixed port range allocates a range of ports per internal IP.
Overload NAT
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.
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: Overload NAT — Overload NAT (Port Address Translation) allows many internal IPs to share one public IP by using unique source ports.
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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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A FortiGate administrator wants to ensure that traffic from the 192.168.1.0/24 network to the internet is translated to a single public IP address using overload (PAT). Which NAT configuration should be used?
mediumWhy D: IP Pool with Overload (PAT) allows many private IPs to be translated to a single public IP using port address translation. This is the most common configuration for internet access.
Last reviewed: Jun 21, 2026
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.
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