Quick Answer
The answer is the FQDN address object. This is the correct choice because an FQDN address object allows the firewall to dynamically resolve a domain name to its current IP addresses at the time of policy evaluation, ensuring the policy remains effective even when the web server’s destination IP changes. On the Fortinet NSE 4 Network Security Professional exam, this concept tests your understanding of how FortiGate handles dynamic IP scenarios in firewall policies, often appearing in questions about cloud-hosted or CDN-backed services where IPs are not static. A common trap is selecting a subnet or IP range object, which would break when the server’s IP changes. Remember the memory tip: “FQDN for the flier, subnet for the sitter”—use FQDN when the destination IP is subject to change, and a subnet only when the IP is fixed.
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 needs to configure a firewall policy that allows internal users to access a specific web server on the internet using its domain name. The web server's IP address may change. Which type of address object should be used as the destination in the policy?
IP Range object that covers the entire public IP space
Why wrong: This would be overly broad and insecure.
Subnet object with the current IP address
Why wrong: If the IP changes, the policy will break.
FQDN address object
FQDN objects allow DNS resolution to be used, so the policy works even if the IP changes.
Geography object
Why wrong: Geography objects use country codes, not specific hostnames.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
FQDN address object
An FQDN address object resolves the domain name to IP addresses dynamically. This allows the policy to adapt to IP changes, unlike a subnet object.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
IP Range object that covers the entire public IP space
Why it's wrong here
This would be overly broad and insecure.
Subnet object with the current IP address
Why it's wrong here
If the IP changes, the policy will break.
FQDN address object
Geography object
Why it's wrong here
Geography objects use country codes, not specific hostnames.
Common exam traps
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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 block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related NSE4 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Firewall Policies and NAT — This question tests Firewall Policies and NAT — CIDR notation defines the prefix length..
The correct answer is: FQDN address object — An FQDN address object resolves the domain name to IP addresses dynamically. This allows the policy to adapt to IP changes, unlike a subnet object.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related NSE4 subnetting questions on CIDR, address ranges, and subnet selection.
CIDR notation defines the prefix length.
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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 needs to create a firewall policy that allows outbound traffic to the internet but denies access to a specific list of malicious IP addresses. The malicious IP list is updated frequently. Which address object type should be used for the destination addresses to block?
easyWhy B: FQDN address objects can resolve to a list of IP addresses that change dynamically, making them suitable for frequently updated IP lists. Subnet objects are static.
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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