The answer is that the traffic is denied by the 'Block-FTP' rule. This occurs because Palo Alto firewalls evaluate security policies in sequential order from top to bottom, and the 'Block-FTP' rule explicitly matches FTP traffic on TCP port 21 before any subsequent rule can allow it. The firewall identifies the application as FTP through port-based or App-ID inspection, and since the rule is set to deny, the session is blocked immediately, never reaching an implicit deny at the bottom. On the PCNSA exam, this scenario tests your understanding of policy ordering and application-specific blocking—a common trap is assuming a later "allow all" rule will override an earlier deny, but Palo Alto firewalls stop at the first match. Remember the mnemonic "First Match Wins" to avoid this pitfall: always check the rule order before assuming traffic will pass, especially when blocking specific services like FTP.
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.
Exhibit
Refer to the exhibit.
admin@PA-5000> show running security-policy
Rule Name Source Zone Dest Zone Application Action
------- ----------- ----------- ----------- ------
Allow-Web Trust Untrust web-browsing allow
Allow-SSL Trust Untrust ssl allow
Block-FTP Trust Untrust ftp deny
admin@PA-5000> show app ftp
application ftp
description: File Transfer Protocol
ports: tcp/21
category: file-sharing
subcategory: file-protocol
technology: client-server
risk: 3
default: yes
Refer to the exhibit. A user on the Trust zone is trying to download a file from an FTP server on the Untrust zone using FTP on TCP port 21. The firewall's security policy is as shown. What will happen?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The traffic is denied by the 'Block-FTP' rule.
The correct answer is C because the security policy explicitly includes a rule named 'Block-FTP' that denies FTP traffic. FTP uses TCP port 21 for control traffic, and the firewall matches this traffic against the policy rules in order. Since 'Block-FTP' matches the FTP application (or port 21) and denies it, the traffic is blocked before reaching any implicit deny rule.
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 traffic is denied by the implicit deny rule at the end.
Why it's wrong here
There is an explicit deny before the implicit deny.
✗
The traffic is allowed because 'Allow-Web' matches web-browsing over port 80 or 443.
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may assume traffic is allowed by default or only blocked by an implicit deny, overlooking the explicit 'Block-FTP' rule that matches before the implicit deny and specifically denies the FTP traffic.
Detailed technical explanation
How to think about this question
Palo Alto Networks firewalls use App-ID to identify applications regardless of port, but when a security policy rule explicitly blocks an application (like FTP) or a specific port (TCP 21), the firewall enforces that rule based on the first match in the policy order. In this scenario, even if the FTP traffic were to use a non-standard port, the 'Block-FTP' rule would still match if App-ID identifies it as FTP, but here the standard port 21 ensures a straightforward match. This highlights the importance of rule ordering and the use of explicit deny rules to control specific application 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 traffic is denied by the 'Block-FTP' rule. — The correct answer is C because the security policy explicitly includes a rule named 'Block-FTP' that denies FTP traffic. FTP uses TCP port 21 for control traffic, and the firewall matches this traffic against the policy rules in order. Since 'Block-FTP' matches the FTP application (or port 21) and denies it, the traffic is blocked before reaching any implicit deny rule.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This PCNSA 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 PCNSA exam.
Question Discussion
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