PCNSE Securing Traffic and App-ID Practice Question
A managed security service provider (MSSP) manages firewalls for multiple customers. One customer reports that their ERP application traffic is being dropped intermittently. The firewall logs show that the traffic is sometimes identified as 'erp-app' and allowed, and other times identified as 'unknown-tcp' and denied. The ERP application uses a proprietary protocol over TCP port 5555. The firewall has a custom application definition for 'erp-app' that uses a data pattern. The administrator verifies that the data pattern is correct. What should the administrator do to ensure consistent identification?
⚠ Common exam trap
A common mix-up: candidates think the data pattern alone is sufficient for identification, overlooking that App-ID may need a port condition to anchor the classification when the pattern is not in the initial packet, leading them to choose irrelevant options like session timeout or SSL decryption.
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
✓
Modify the custom application to include a port condition (default port 5555).
The issue is that the custom application 'erp-app' relies solely on a data pattern for identification, but if the first packet of a session does not contain the pattern (e.g., due to TCP segmentation or the pattern appearing later in the flow), App-ID may classify the traffic as 'unknown-tcp' and deny it. By adding a port condition (default port 5555) to the custom application, the firewall will first match the traffic based on the TCP port, then inspect subsequent packets for the data pattern, ensuring consistent identification even if the pattern is not in the initial packet.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the session timeout for the application.
Why it's wrong here
Session timeout affects session duration, not application identification.
- ✗
Create a vulnerability protection profile to inspect the traffic.
Why it's wrong here
Vulnerability protection does not improve application identification.
- ✗
Enable SSL decryption on the firewall.
Why it's wrong here
The protocol is not SSL; decryption would not help.
- ✓
Modify the custom application to include a port condition (default port 5555).
Why this is correct
This provides a reliable port-based fallback when the data pattern is not seen.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.