PCNSE Troubleshoot Practice Question
A company deploys a new application that uses UDP on port 12345. The security policy is configured to allow UDP traffic from the internal network to the application server. However, users report that the application does not work. The firewall logs show that the traffic is allowed. What is the most likely cause?
⚠ Common exam trap
Many candidates assume that because the outbound traffic is allowed and logged, the application should work, but they overlook the requirement for a return policy in stateful firewall operation, especially for UDP which is connectionless and does not have a built-in handshake like TCP.
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 firewall is dropping the return traffic due to a missing policy
Even though the outbound UDP traffic is allowed by the security policy, the firewall must also have a corresponding policy to allow the return traffic from the application server back to the internal clients. Without a return policy, the firewall drops the response packets, breaking the UDP communication. The logs show the outbound traffic as allowed, but the return traffic is silently dropped, which is why users report the application not working.
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 application is using asymmetric routing
Why it's wrong here
Asymmetric routing is possible but less common than a missing return policy.
- ✗
The security policy is not logging the traffic correctly
Why it's wrong here
Logs show allowed, so logging is fine.
- ✗
The firewall is not inspecting UDP traffic correctly
Why it's wrong here
UDP inspection is not required for basic forwarding.
- ✓
The firewall is dropping the return traffic due to a missing policy
Why this is correct
The application may require responses; if the return traffic is not allowed by policy, the application breaks.
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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.