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.
Which statement best describes the implicit deny policy at the end of a FortiGate policy list?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It is always present and denies any traffic that does not match an explicit allow policy
The implicit deny policy is a built-in rule that denies all traffic not matching any explicit policy. It cannot be moved, modified, or deleted. Traffic that hits it is logged if logging is enabled on the last explicit policy? Actually, logging for implicit deny is not configurable; it is not logged by default. The correct answer is that it denies all unmatched traffic.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
It denies all traffic that does not match any explicit policy, and it logs the denied traffic
Why it's wrong here
By default, implicit deny does not log traffic; logging must be configured on explicit policies.
✗
It can be moved to a different position in the policy list
Why it's wrong here
The implicit deny is always at the bottom and cannot be moved.
✗
It can be disabled or deleted by the admin
Why it's wrong here
The implicit deny cannot be disabled or deleted; it is a fundamental security feature.
✓
It is always present and denies any traffic that does not match an explicit allow policy
Why this is correct
Correct. The implicit deny is always at the end of the policy list and blocks all traffic that does not match a preceding explicit policy.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Standard ACLs match source addresses.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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 ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related NSE4 ACL questions on filtering logic and placement.
Firewall Policies and NAT — This question tests Firewall Policies and NAT — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: It is always present and denies any traffic that does not match an explicit allow policy — The implicit deny policy is a built-in rule that denies all traffic not matching any explicit policy. It cannot be moved, modified, or deleted. Traffic that hits it is logged if logging is enabled on the last explicit policy? Actually, logging for implicit deny is not configurable; it is not logged by default. The correct answer is that it denies all unmatched traffic.
What should I do if I get this NSE4 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related NSE4 ACL questions on filtering logic and placement.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Question Discussion
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