The answer is to add HTTPS to the allowed services in policy 1. This resolves the issue because the firewall policy is explicitly configured to permit only HTTP and HTTPS traffic from the 10.0.0.0/24 subnet, but if HTTPS is not correctly defined or missing from the service list, the FortiGate will drop those packets, while HTTP traffic passes successfully. On the Fortinet NSE 4 Network Security Professional exam, this scenario tests your understanding of policy ordering and service object definitions—a common trap is assuming that simply naming a service in the policy is enough, when in fact the service object itself must be properly configured to include the correct port (TCP 443). A key memory tip is "check the service, not just the policy": always verify that the service object for HTTPS is defined and applied, because a deny-all catch-all policy will block any traffic not explicitly allowed.
NSE4 Firewall Policies and NAT Practice Question
This NSE4 practice question tests your understanding of firewall policies and nat. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 is troubleshooting a connectivity issue where users in the 10.0.0.0/24 subnet cannot access the internet. The FortiGate has the following policies (in order):
1: allow 10.0.0.0/24 -> any, service: HTTP, HTTPS
2: deny any -> any, service: all
Users can browse HTTP but not HTTPS. Which TWO actions would resolve the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Verify that the HTTPS service object is correctly defined and not misspelled
Policy 1 only allows HTTP and HTTPS. If HTTPS is not working, check if HTTPS is correctly defined. Also, policy 2 denies all other traffic. The solution is to ensure HTTPS is allowed in policy 1 and that it is correctly defined.
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
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Verify that the HTTPS service object is correctly defined and not misspelled
Why this is correct
A typo in service name could cause the policy to not match.
Common exam trap: usable hosts are not the same as total addresses
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
How to think about this question
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.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
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
How this comes up in practice
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
Got this wrong? Here's your next step.
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.
Firewall Policies and NAT — This question tests Firewall Policies and NAT — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Verify that the HTTPS service object is correctly defined and not misspelled — Policy 1 only allows HTTP and HTTPS. If HTTPS is not working, check if HTTPS is correctly defined. Also, policy 2 denies all other traffic. The solution is to ensure HTTPS is allowed in policy 1 and that it is correctly defined.
What should I do if I get this NSE4 question wrong?
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.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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