The answer is that the new policy is placed below the older policy in the policy list. FortiGate processes firewall policies sequentially from top to bottom, so when a new policy is added, it defaults to the bottom of the list. If an older policy with a broader source (such as “All”) sits above it, traffic from ‘Internal_Net’ will match that broader rule first and never reach the new, more specific policy. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this concept tests your understanding of policy order and the “first match” logic, often appearing as a trap where candidates assume new policies automatically take precedence. A common memory tip is to think of FortiGate policies like a bouncer checking IDs in a line: the first rule that fits the description lets the traffic through, so always place your specific “VIP” rules above the general “everyone else” rules. Remember: new policies go to the bottom, so drag them up to win.
NSE4 Firewall Policies and NAT Practice Question
This NSE4 practice question tests your understanding of firewall policies and nat. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 admin creates a new firewall policy with source address object 'Internal_Net' and destination 'All'. After saving, traffic from 'Internal_Net' is not matching the new policy but instead matches an older policy with a broader source. What is the MOST likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
The source address object 'Internal_Net' has an incorrect subnet mask
Why wrong: An incorrect mask would cause the policy to not match the intended traffic, but traffic would then fall through to the implicit deny or next policy, not necessarily an older policy.
B
The new policy is placed below the older policy in the policy list
Policy lookup is sequential from top to bottom. If a broader policy is above, traffic matches it first.
C
The new policy is disabled
Why wrong: A disabled policy would not match any traffic, but the symptom is that traffic matches an older policy, not that it is blocked.
D
Traffic shaping is applied to the new policy and is interfering
Why wrong: Traffic shaping does not affect policy matching.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The new policy is placed below the older policy in the policy list
FortiGate evaluates policies from top to bottom. The new policy must be placed above the broader policy to be matched first. By default, new policies are added at the bottom.
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.
✗
The source address object 'Internal_Net' has an incorrect subnet mask
Why it's wrong here
An incorrect mask would cause the policy to not match the intended traffic, but traffic would then fall through to the implicit deny or next policy, not necessarily an older policy.
✓
The new policy is placed below the older policy in the policy list
Why this is correct
Policy lookup is sequential from top to bottom. If a broader policy is above, traffic matches it first.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
A disabled policy would not match any traffic, but the symptom is that traffic matches an older policy, not that it is blocked.
✗
Traffic shaping is applied to the new policy and is interfering
Why it's wrong here
Traffic shaping does not affect policy matching.
Common exam traps
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 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.
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: The new policy is placed below the older policy in the policy list — FortiGate evaluates policies from top to bottom. The new policy must be placed above the broader policy to be matched first. By default, new policies are added at the bottom.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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