- A
Remove the protocol field from the signature.
Why wrong: Removing protocol would make matching less specific.
- B
Use a wider port range and remove data patterns.
Why wrong: This would increase the match scope.
- C
Add a data pattern filter to match a specific payload signature.
Data patterns narrow matching to specific traffic characteristics.
- D
Expand the port range to include more traffic.
Why wrong: Expanding range would match more traffic, not less.
Question 487 of 516
PCNSE Securing Traffic and App-ID Practice Question
This PCNSE practice question tests your understanding of securing traffic and app-id. 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.
During a security audit, it is discovered that a custom application signature matches too broadly, causing benign traffic to be classified as the custom app. What change should be made to narrow the signature?
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
✓
Add a data pattern filter to match a specific payload signature.
Option C is correct because adding a data pattern filter allows the custom App-ID signature to match on a specific payload string or byte sequence, which narrows the scope of traffic classified as that application. Without a data pattern, the signature may rely solely on IP protocol, port, or other broad criteria, causing false positives. By requiring a unique payload signature, only traffic containing that exact data pattern is identified as the custom application.
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.
- ✗
Remove the protocol field from the signature.
Why it's wrong here
Removing protocol would make matching less specific.
- ✗
Use a wider port range and remove data patterns.
Why it's wrong here
This would increase the match scope.
- ✓
Add a data pattern filter to match a specific payload signature.
Why this is correct
Data patterns narrow matching to specific traffic characteristics.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Expand the port range to include more traffic.
Why it's wrong here
Expanding range would match more traffic, not less.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates mistakenly think expanding port ranges or removing protocol fields will narrow the signature, when in fact those actions broaden the match criteria and worsen false positives.
Detailed technical explanation
How to think about this question
Under the hood, Palo Alto Networks App-ID uses a multi-stage classification process: first by IP protocol and port, then by application signatures that can include protocol decoders, SSL/TLS handshake analysis, and data pattern matching. A data pattern filter is a byte-sequence or regex match applied to the payload; when added to a custom signature, it acts as a discriminator to ensure only traffic with that exact content is classified, reducing false positives. In real-world scenarios, this is critical for custom applications that use non-standard ports or share ports with other services, as relying solely on port-based heuristics would cause widespread misclassification.
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 practitioner preparing for the PCNSE exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Visual reference
What to study next
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FAQ
Questions learners often ask
What does this PCNSE question test?
Securing Traffic and App-ID — This question tests Securing Traffic and App-ID — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a data pattern filter to match a specific payload signature. — Option C is correct because adding a data pattern filter allows the custom App-ID signature to match on a specific payload string or byte sequence, which narrows the scope of traffic classified as that application. Without a data pattern, the signature may rely solely on IP protocol, port, or other broad criteria, causing false positives. By requiring a unique payload signature, only traffic containing that exact data pattern is identified as the custom application.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
This PCNSE 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 PCNSE exam.
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