PCNSA Decryption and Monitoring Practice Question
A financial services firm deploys inbound SSL decryption to inspect all HTTPS traffic to their customer-facing web application. After enabling decryption, customers report that they are unable to connect to the web app and receive 'This site can’t provide a secure connection' errors. The firewall logs show no decryption errors, and traffic logs show the sessions are matched to the decryption rule but no decryption action is taken. The web app uses a wildcard certificate (*.example.com). The firewall's decryption certificate is imported from the server's private key. What is the most likely cause?
⚠ Common exam trap
Test-takers frequently confuse the forward proxy method (used for outbound decryption) with the SSL Inbound Inspection method (required for inbound decryption), assuming any decryption rule will work for inbound traffic as long as a certificate is imported.
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 decryption rule is configured with the forward proxy method.
Inbound SSL decryption requires the 'SSL Inbound Inspection' method, not the forward proxy method. Forward proxy is used for outbound decryption where the firewall generates a certificate on the fly. For inbound decryption, the firewall must use the server's private key to decrypt traffic, which is configured via an SSL Inbound Inspection rule. Since the rule is set to forward proxy, the firewall attempts to re-encrypt with its own certificate, causing a certificate mismatch and the 'secure connection' error.
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 firewall does not support wildcard certificates for inbound decryption.
Why it's wrong here
Palo Alto firewalls support wildcard certificates for SSL Inbound Inspection.
- ✗
The web server is not properly configured to handle decrypted traffic.
Why it's wrong here
The error occurs at the client side before the server is contacted, so server configuration is not the cause.
- ✗
The decryption profile is set to 'Block sessions with untrusted certificates'.
Why it's wrong here
If blocking were enabled, the logs would show a decryption action and error, but no decryption action is logged.
- ✓
The decryption rule is configured with the forward proxy method.
Why this is correct
Inbound decryption must use 'SSL Inbound Inspection'; forward proxy is for outbound and mismatches cause handshake failures.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.