The answer is that a rule with a 'deny' action appearing earlier in the security policy is the most likely reason the interzone rule is not matched. This occurs because Palo Alto Networks firewalls evaluate security rules sequentially from top to bottom, and the first matching rule determines the action for the traffic. If an earlier deny rule matches the source, destination, or application before the intended allow rule is reached, the later rule is never evaluated, resulting in the interzone rule not matching earlier deny rule behavior. On the PCNSE exam, this concept tests your understanding of rule order and policy evaluation logic, often appearing in troubleshooting scenarios where traffic is unexpectedly denied despite a seemingly correct allow rule. A common trap is assuming a broader allow rule will override a specific deny rule placed above it. Remember the memory tip: "First match wins, so order your denies before your allows."
PCNSE Deploy and Configure Firewalls Practice Question
This PCNSE practice question tests your understanding of deploy and configure firewalls. 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 engineer is troubleshooting an inter-zone rule that should allow traffic from zone 'Trust' to zone 'Untrust'. The rule has a source address of 10.0.0.0/8 and destination address of any. The traffic is being denied. The engineer checks the log and sees the rule is not matched. What is the most likely reason?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A rule with a 'deny' action appears earlier in the security policy.
The most likely reason the inter-zone rule is not matched is that a preceding rule with a 'deny' action is matching the traffic first. In Palo Alto Networks firewalls, security rules are evaluated in order from top to bottom, and the first matching rule determines the action. If an earlier rule denies the traffic, the later allow rule will never be evaluated, even if it would otherwise match.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 10.0.0.0/8 is not included in the source zone.
Why it's wrong here
The source zone is Trust; the source address is the IP, not the zone.
✗
The destination address is set to 'any', which is not valid.
Why it's wrong here
'any' is a valid destination address in a rule.
✗
The traffic is intra-zone, not inter-zone.
Why it's wrong here
If both zones are the same, it would be intra-zone; but here it's Trust to Untrust.
✓
A rule with a 'deny' action appears earlier in the security policy.
Why this is correct
If a deny rule matches before the allow rule, the traffic is denied.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume the rule itself is misconfigured (e.g., source or destination issues) rather than recognizing that a higher-priority deny rule is preempting the intended allow rule.
Detailed technical explanation
How to think about this question
Palo Alto firewalls use a first-match rule evaluation model, similar to ACLs on routers. The security policy is processed sequentially, and once a match is found, no further rules are checked. This means a deny rule placed above the intended allow rule will block the traffic, and the allow rule will never be hit. In real-world scenarios, misordered rules are a common cause of unexpected denials, especially when administrators add new rules without considering the existing rule order.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Deploy and Configure Firewalls — This question tests Deploy and Configure Firewalls — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A rule with a 'deny' action appears earlier in the security policy. — The most likely reason the inter-zone rule is not matched is that a preceding rule with a 'deny' action is matching the traffic first. In Palo Alto Networks firewalls, security rules are evaluated in order from top to bottom, and the first matching rule determines the action. If an earlier rule denies the traffic, the later allow rule will never be evaluated, even if it would otherwise match.
What should I do if I get this PCNSE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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 network engineer is configuring a new firewall to replace an existing one. The existing firewall has a policy that allows traffic from the 10.0.0.0/8 subnet to the internet. The new firewall must use the same policy but also log the traffic. The engineer creates a security rule with source zone 'Trust', destination zone 'Untrust', source address 10.0.0.0/8, and action 'allow'. Logging is set at rule end. However, traffic from 10.1.0.0/16 is not being logged. What is the reason?
hard
✓ A.Another rule earlier in the policy matches the traffic and allows it before reaching this rule.
B.The firewall is configured to not log interzone traffic.
C.The source address 10.1.0.0/16 is not part of the 10.0.0.0/8 subnet.
D.The logging profile is not applied to the rule.
Why A: Option A is correct because in a Palo Alto Networks firewall, security rules are evaluated from top to bottom, and the first matching rule is applied. If an earlier rule in the policy matches the traffic from 10.1.0.0/16 and allows it, the rule with logging at rule end will never be evaluated, and thus no log entry is generated for that traffic.
Last reviewed: Jun 11, 2026
Question Discussion
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This PCNSE practice question is part of Courseiva's free Palo Alto Networks 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 PCNSE exam.
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