The answer is that the URL Filtering profile’s ‘uncategorized’ category is set to ‘block’, which prevents access to any website not yet listed in Palo Alto Networks’ URL database. This is the most likely cause because the profile was configured to ‘alert’ for all known categories except ‘malware’, but the default action for ‘uncategorized’—often overlooked—remains ‘block’. Since legitimate sites like online banking portals or cloud apps may be new or rarely visited, they fall into the uncategorized bucket and are blocked, even though the rule appears permissive. On the PCNSA exam, this scenario tests your understanding that URL Filtering operates on category-based actions, and the uncategorized category is a common trap: candidates assume ‘alert’ on known categories covers everything, but uncategorized must be explicitly set to ‘allow’ or ‘alert’ to avoid blocking legitimate traffic. Memory tip: “Uncategorized is the default deny—if you don’t set it, you’ll block the unknown.”
PCNSA Securing Traffic Practice Question
This PCNSA practice question tests your understanding of securing traffic. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 financial services company uses a Palo Alto Networks PA-5220 firewall in an active/passive HA pair at their headquarters. They have a single zone 'Trust-LAN' for internal users and a single zone 'Untrust-WAN' for internet traffic. The security policy currently includes a rule that allows all outbound HTTP/HTTPS traffic from 'Trust-LAN' to 'Untrust-WAN' with no security profiles applied. Recently, users have been complaining about slow internet performance, and the IT team suspects malware or botnet activity. The firewall's logs show numerous sessions to known malicious IPs, but the firewall is not blocking them. The network architect decides to implement URL Filtering and Threat Prevention profiles on the outbound rule. However, after committing the changes, some users report that legitimate websites (e.g., online banking, cloud apps) are being blocked. The IT team verifies that the URL Filtering profile is set to 'alert' for all categories except 'malware' which is 'block', and the Threat Prevention profile is set to 'default' action. What is the most likely cause of the legitimate website blocking?
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 URL Filtering profile's 'uncategorized' category is set to 'block', blocking sites not in the URL database.
Option A is correct because the URL Filtering profile is set to 'alert' for all categories except 'malware' which is 'block'. However, if the 'uncategorized' category is set to 'block', any website not yet categorized in Palo Alto Networks' URL database (e.g., new or less common legitimate sites like online banking portals or cloud apps) will be blocked. This explains why legitimate sites are being blocked despite the profile being permissive for known categories.
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 URL Filtering profile's 'uncategorized' category is set to 'block', blocking sites not in the URL database.
Why this is correct
This is a common cause: uncategorized URLs are blocked by default if the action is not 'alert'.
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 security rule order is incorrect; a deny rule above the allow rule is blocking legitimate traffic.
Why it's wrong here
The issue is not about rule order; the allow rule is still in place.
✗
The URL Filtering profile is applied at the zone level, not per rule, causing all traffic to be filtered.
Why it's wrong here
URL profiles are applied per rule, not per zone.
✗
The firewall has insufficient memory to process URL lookups and is dropping packets.
Why it's wrong here
Resource exhaustion is unlikely; the firewall should handle the load.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume only the explicitly mentioned categories (e.g., 'malware') matter, overlooking the 'uncategorized' category which is often set to 'block' by default or inadvertently, causing legitimate traffic to be blocked.
Detailed technical explanation
How to think about this question
Palo Alto Networks URL Filtering uses a cloud-based database to categorize URLs. The 'uncategorized' category includes sites that have not been reviewed or assigned a category by the URL filtering vendor. In a financial services environment, many legitimate internal or partner cloud apps may fall into this category if they are new or rarely accessed. Setting 'uncategorized' to 'block' is a common misconfiguration that leads to false positives, as the firewall cannot determine the site's risk level. The Threat Prevention profile set to 'default' action would not block traffic unless a specific threat signature matches, which is unlikely for legitimate sites.
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.
Securing Traffic — This question tests Securing Traffic — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The URL Filtering profile's 'uncategorized' category is set to 'block', blocking sites not in the URL database. — Option A is correct because the URL Filtering profile is set to 'alert' for all categories except 'malware' which is 'block'. However, if the 'uncategorized' category is set to 'block', any website not yet categorized in Palo Alto Networks' URL database (e.g., new or less common legitimate sites like online banking portals or cloud apps) will be blocked. This explains why legitimate sites are being blocked despite the profile being permissive for known categories.
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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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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