PCNSE Securing Traffic and App-ID Practice Question
During an audit, it is discovered that some traffic from a legacy application is being incorrectly identified as 'ssl' because the application uses a custom encryption scheme over TCP port 443. The engineer has created a custom application signature that matches the legacy application's handshake. What additional configuration is needed to ensure the legacy application is correctly identified?
⚠ Common exam trap
Many candidates assume creating a custom signature alone is sufficient to reclassify traffic, but they overlook that App-ID's port-based heuristics for well-known ports like 443 can override signature matches unless an explicit application override is configured.
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
✓
Create an application override rule to force the identification.
An application override rule forces App-ID to classify traffic based on the custom signature, bypassing the default identification that incorrectly flags the legacy application's custom encryption over TCP 443 as 'ssl'. Without the override, App-ID may still match the traffic to the built-in 'ssl' application due to port-based heuristics, even with a custom signature defined. The override ensures the custom application is applied to the session, overriding any conflicting App-ID results.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Create an application override rule to force the identification.
Why this is correct
Correct: Application override ensures the custom signature is used, overriding the default identification.
- ✗
Create a security policy rule that explicitly allows the custom application.
Why it's wrong here
Security policy rules use the identified application; they do not affect identification.
- ✗
Change the default port of the custom application from 443 to a different port.
Why it's wrong here
Changing the port would not match the actual traffic.
- ✗
Disable SSL decryption for that traffic.
Why it's wrong here
Disabling decryption does not change App-ID identification.
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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.