- A
The service group includes only UDP service objects
Why wrong: This is incorrect because the stem explicitly states that the service group contains both TCP and UDP service objects. Therefore, the issue is not a missing TCP object.
- B
The rule requires a separate application object
This is correct. The rule likely lacks an application object for DNS. In Palo Alto firewalls, even with correct service definitions, the rule must include the appropriate application (e.g., 'dns') to match the traffic using App-ID.
- C
The security policy action is set to deny
Why wrong: This is unlikely because the question states 'the rule is intended to allow DNS traffic,' so the action should not be set to deny. If it were, no DNS traffic would pass, but the issue is specifically TCP DNS, not all DNS.
- D
The service group is incorrectly configured
Why wrong: This is too vague. The service group is configured correctly (both TCP and UDP 53), according to the stem. The issue lies elsewhere, such as missing application objects.
PCNSA App-ID Practice Question
This PCNSA practice question tests your understanding of managing objects. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: app-ID. 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 administrator is troubleshooting a security policy that uses a service group containing both TCP and UDP service objects. The policy is intended to allow DNS traffic (UDP 53 and TCP 53). The rule is not allowing TCP DNS. What is the most likely issue?
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 choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The rule requires a separate application object
Even though the service group includes both TCP and UDP service objects for DNS (ports 53), the rule is not allowing TCP DNS because it lacks a matching application object. In Palo Alto Networks firewalls, App-ID is used to identify traffic based on application signatures, not just ports. If the security rule does not specify an application (e.g., 'dns'), or if the application is set to something that doesn't match DNS traffic, the rule may not allow the traffic. Option B is the most likely issue.
Key principle: App-ID
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 service group includes only UDP service objects
- ✓
The rule requires a separate application object
Why this is correct
This is correct. The rule likely lacks an application object for DNS. In Palo Alto firewalls, even with correct service definitions, the rule must include the appropriate application (e.g., 'dns') to match the traffic using App-ID.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
App-ID
- ✗
The security policy action is set to deny
- ✗
The service group is incorrectly configured
Common exam traps
Common exam trap: answer the scenario, not the keyword
Candidates often assume that a service group with the correct ports is sufficient to allow traffic. However, Palo Alto firewalls require App-ID to be specified in the rule to properly match and allow traffic; otherwise, the rule may not apply even if the port matches.
Detailed technical explanation
How to think about this question
In Palo Alto Networks firewalls, service objects define a protocol (TCP or UDP) and a destination port, and service groups combine multiple service objects. DNS uses both UDP 53 for standard queries and TCP 53 for zone transfers or large responses exceeding 512 bytes. If a service group only includes UDP 53, the firewall will not match TCP packets to port 53, even if the rule is otherwise correct. This is a common oversight when administrators assume a single service object covers both transport protocols.
KKey Concepts to Remember
- App-ID
- Service Object
- Application Object
- Service Group
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
App-ID
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.
Review app-ID, then practise related PCNSA questions on the same topic to reinforce the concept.
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Managing Objects — study guide chapter
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FAQ
Questions learners often ask
What does this PCNSA question test?
Managing Objects — This question tests Managing Objects — App-ID.
What is the correct answer to this question?
The correct answer is: The rule requires a separate application object — Even though the service group includes both TCP and UDP service objects for DNS (ports 53), the rule is not allowing TCP DNS because it lacks a matching application object. In Palo Alto Networks firewalls, App-ID is used to identify traffic based on application signatures, not just ports. If the security rule does not specify an application (e.g., 'dns'), or if the application is set to something that doesn't match DNS traffic, the rule may not allow the traffic. Option B is the most likely issue.
What should I do if I get this PCNSA question wrong?
Review app-ID, then practise related PCNSA questions on the same topic to reinforce the concept.
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?
App-ID
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Last reviewed: Jun 25, 2026
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.
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