PCNSE Deploy and Configure Firewalls Practice Question
A security administrator notices that traffic to a specific website is being denied. The traffic log shows that the application is 'ssl' and the action is 'deny' with the rule being 'Allow-SSL'. What is the most likely cause?
⚠ Common exam trap
Many exam-takers assume the 'Allow-SSL' rule should match all SSL traffic regardless of port, but Palo Alto Networks tests the nuance that 'application-default' restricts the rule to only the default port for that application, causing a deny on non-standard ports like 8443.
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 security rule 'Allow-SSL' has 'service' set to 'application-default' but the website uses port 8443.
The security rule 'Allow-SSL' is configured with 'service' set to 'application-default', which means it only permits traffic on the default port for SSL (TCP 443). Since the website uses port 8443, the traffic is denied because the rule does not match the non-standard port. The firewall's application identification still correctly identifies the traffic as 'ssl', but the service constraint prevents the rule from applying, resulting in a deny action.
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 destination IP is in a blacklist.
Why it's wrong here
A destination blacklist is enforced through a separate block or URL-filtering policy, so the log would reference that policy rather than the Allow-SSL rule. Blacklisting is tempting because it denies traffic to specific sites, but here the deny is attributed to the Allow-SSL rule itself, indicating an application or service mismatch within that rule.
- ✗
The security rule is placed too low in the rulebase.
Why it's wrong here
Rule position only matters when an earlier rule already matches the traffic; the log names Allow-SSL as the deciding rule, so ordering is not the cause. Rulebase placement is tempting because shadowing denies traffic unexpectedly, but a lower-placed rule that still matches would simply be the one logged.
- ✓
The security rule 'Allow-SSL' has 'service' set to 'application-default' but the website uses port 8443.
Why this is correct
With 'application-default' as the service, the rule permits only the standard ports for ssl (443). Traffic on port 8443 is not application-default, so it fails the service match and is denied despite the rule name.
- ✗
The SSL certificate is expired.
Why it's wrong here
An expired server certificate causes a browser or client-side decryption error, not a firewall deny logged against an Allow-SSL rule; the firewall still matches the ssl application and applies the rule action. Certificate expiry is tempting because it breaks HTTPS, but that failure occurs after the firewall has already permitted the session.
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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.