The answer is that the custom App-ID is not included in the security rule. Even after applying an application override to identify the traffic on TCP 8443, the firewall still evaluates traffic against the existing security policy, which only allows 'web-browsing' and 'ssl'. Since the custom application is not listed in the rule's Application field, the traffic is denied and logged as 'unknown-tcp'—the override merely reclassifies the traffic, it does not automatically grant permission. On the PCNSA exam, this scenario tests your understanding that application override and security policy are separate controls; a common trap is assuming an override alone permits traffic. Remember: override identifies, policy permits. Memory tip: "Override the label, not the rule."
PCNSA App-ID and Content-ID Practice Question
This PCNSA practice question tests your understanding of app-id and content-id. 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 global company uses a Palo Alto Networks firewall at its headquarters. They have a security policy that allows 'web-browsing' and 'ssl' for all users. Recently, they deployed a new custom web application for internal use that runs on TCP port 8443 with SSL. The application is not identified by App-ID as 'web-browsing' or 'ssl', but as 'unknown-tcp'. The security team wants to ensure that only this specific application is allowed, and all other unknown traffic is blocked. They have created a custom App-ID for the application using application override. However, after applying the override, the traffic is still shown as 'unknown-tcp' in logs. 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
✓
The security rule that allows the traffic does not include the custom application.
Option C is correct because the security rule that allows 'web-browsing' and 'ssl' does not automatically permit the custom application. Even though an application override was created to identify the custom application on TCP 8443, the security policy must explicitly include that custom application in the rule's 'Application' field. Without that, the firewall still matches the traffic against the existing rule, which only allows 'web-browsing' and 'ssl', so the traffic is denied and logged as 'unknown-tcp'.
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.
✗
SSL decryption is not enabled for the custom application.
Why it's wrong here
Decryption is not required for App-ID.
✗
The custom application needs to be added to the 'ssl' application group.
Why it's wrong here
Groups are not required.
✓
The security rule that allows the traffic does not include the custom application.
Why this is correct
The traffic may be matching a different rule that doesn't have the custom app.
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 application override was not committed.
Why it's wrong here
Assuming it was committed.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume an application override alone will make the traffic match an existing rule that allows 'ssl' or 'web-browsing', but the override creates a new App-ID that must be explicitly added to the security rule's application list.
Detailed technical explanation
How to think about this question
Application override works by creating a custom App-ID that matches traffic based on destination port, source/destination IP, and protocol. However, the override only changes how the traffic is identified in the session's App-ID field; it does not automatically update security rules. The firewall still evaluates traffic against the first matching security rule, and if that rule does not list the custom application, the traffic is denied (or allowed only if the rule's action is 'allow' and the application is not restricted, but here the rule explicitly allows only 'web-browsing' and 'ssl'). In real-world scenarios, this is a common misconfiguration: administrators create application overrides but forget to update the security policy, leading to dropped 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 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
App-ID and Content-ID — This question tests App-ID and Content-ID — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The security rule that allows the traffic does not include the custom application. — Option C is correct because the security rule that allows 'web-browsing' and 'ssl' does not automatically permit the custom application. Even though an application override was created to identify the custom application on TCP 8443, the security policy must explicitly include that custom application in the rule's 'Application' field. Without that, the firewall still matches the traffic against the existing rule, which only allows 'web-browsing' and 'ssl', so the traffic is denied and logged as 'unknown-tcp'.
What should I do if I get this PCNSA 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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