PCNSA Decryption and Monitoring Practice Question
A firewall administrator notices that traffic from an internal user is being decrypted, but the user's browser shows a certificate warning. The firewall uses a CA certificate issued by the company's internal PKI. What is the most likely reason for the browser warning?
⚠ Common exam trap
A common mix-up: candidates confuse a missing trusted root CA certificate with a server certificate revocation or a decryption policy misconfiguration, failing to recognize that the browser warning specifically indicates a trust chain issue rather than a revocation or policy error.
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's root CA certificate is not installed in the user's browser trusted root store.
The browser warning indicates that the firewall's decrypted traffic is being signed with a certificate that the browser does not trust. When a firewall performs SSL/TLS decryption using a CA certificate from the company's internal PKI, the browser will only trust the decrypted connections if the root CA certificate of that PKI is installed in the browser's trusted root certificate store. Without this trust anchor, the browser cannot validate the certificate chain presented by the firewall, resulting in a certificate warning.
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 decryption policy has the action 'decrypt' but no certificate profile.
Why it's wrong here
A decrypt rule without a certificate profile cannot re-sign traffic, so the firewall forwards the original server certificate and no warning should appear from re-signing. Certificate profiles are required when the firewall performs forward proxy decryption and must present its own certificate to the client.
- ✓
The firewall's root CA certificate is not installed in the user's browser trusted root store.
Why this is correct
Decryption requires the firewall to re-sign traffic with its own CA certificate. If that root CA is absent from the browser's trusted root store, the browser cannot validate the forged certificate chain and raises a warning, even though decryption itself succeeds.
- ✗
The user's browser does not support TLS 1.2.
Why it's wrong here
TLS version support does not cause a certificate warning; the browser is rejecting the firewall's re-signed certificate because its issuing CA is not trusted in the browser's trust store. TLS 1.2 capability matters for cipher negotiation failures, which surface as handshake errors rather than certificate warnings.
- ✗
The server certificate is revoked.
Why it's wrong here
Revocation of the origin server's certificate would produce a warning only if the browser checks revocation and the firewall forwards that certificate unchanged. The scenario describes decryption with an internal-PKI CA, so the warning stems from the re-signing CA not being trusted, not from server revocation status.
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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.