PCNSE Deploy and Configure Firewalls Practice Question
This PCNSE practice question tests your understanding of deploy and configure firewalls. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Exhibit
Refer to the exhibit.
Time,Source,Destination,Application,Action,Rule
2024-05-01 10:00:00,192.168.1.100,203.0.113.50,ssl,deny,default-deny
What is the most likely reason the traffic from 192.168.1.100 to 203.0.113.50 is being denied?
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
✓
The application 'ssl' is not allowed in any security rule.
The traffic from 192.168.1.100 to 203.0.113.50 is denied because the application 'ssl' is not explicitly allowed in any security rule. Palo Alto Networks firewalls use App-ID to identify traffic by application, and if the application (e.g., SSL/TLS) is not permitted in a rule, the traffic is denied by default, even if the IP addresses and ports are otherwise allowed.
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 application 'ssl' is not allowed in any security rule.
Why this is correct
The traffic matched the built-in default-deny rule because no user-defined rule allowed the application.
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.
✗
The session ended with TCP FIN, causing the firewall to deny.
Why it's wrong here
TCP FIN is logged as the session end reason after the action; it does not cause denial.
✗
The destination IP is blacklisted.
Why it's wrong here
No evidence of a blacklist; the log shows the rule 'default-deny'.
✗
The security rule 'default-deny' explicitly blocks this traffic.
Why it's wrong here
'default-deny' is a built-in implicit rule, not an explicit user-configured rule.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume a port-based rule (e.g., allowing TCP/443) is sufficient, but Palo Alto's App-ID requires the application itself to be explicitly allowed, not just the port.
Trap categories for this question
Command / output trap
No evidence of a blacklist; the log shows the rule 'default-deny'.
Detailed technical explanation
How to think about this question
Palo Alto Networks firewalls perform application identification (App-ID) on all traffic, and the 'ssl' application is identified by inspecting the TLS handshake (e.g., ClientHello). If no security rule explicitly allows the 'ssl' application, the traffic is denied even if the destination port (e.g., 443) is permitted, because the firewall enforces application-level policies. In a real-world scenario, this often catches administrators who allow port 443 but forget to add the 'ssl' application to the rule, leading to unexpected denials for HTTPS traffic.
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: The application 'ssl' is not allowed in any security rule. — The traffic from 192.168.1.100 to 203.0.113.50 is denied because the application 'ssl' is not explicitly allowed in any security rule. Palo Alto Networks firewalls use App-ID to identify traffic by application, and if the application (e.g., SSL/TLS) is not permitted in a rule, the traffic is denied by default, even if the IP addresses and ports are otherwise allowed.
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.
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Question Discussion
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