PCNSE Deploy and Configure Firewalls Practice Question
An administrator adds a new security rule to allow outbound 'web-browsing' and 'ssl' traffic. After committing, users report that some HTTPS sites are still blocked. Traffic logs show that the traffic matches the new rule but is denied. What is the most likely cause?
⚠ Common exam trap
Many exam-takers assume 'application-default' allows any port for the application, when in reality it strictly enforces the default port, causing denial for HTTPS on non-standard ports.
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 service 'application-default' does not match the port used by the site.
When a security rule uses the 'application-default' service, the firewall only allows traffic that matches the default port for the specified application. For 'web-browsing' (HTTP), the default port is TCP 80, and for 'ssl' (HTTPS), the default port is TCP 443. If an HTTPS site uses a non-standard port (e.g., TCP 8443), the traffic matches the rule based on the application but is denied because the service 'application-default' does not recognize that port as valid for the application.
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 service 'application-default' does not match the port used by the site.
Why this is correct
The rule permits only ports 80 and 443 via the web-browsing and ssl applications, but application-default enforces those standard ports. HTTPS sites on non-standard ports therefore match the rule yet fail the service check, producing the deny. Defining a custom service, or using any, resolves the mismatch.
- ✗
A decryption policy is required for HTTPS traffic.
Why it's wrong here
Decryption policy governs whether the firewall can inspect encrypted sessions, not whether it permits them; the rule already matches, so a missing decryption policy would not produce a deny. Decryption is required when you need threat or URL inspection inside TLS, not for basic allow decisions.
- ✗
The application filter does not include 'ssl'.
Why it's wrong here
The rule already matches the traffic, so the application filter is functioning; the denial stems from the ssl application being identified as a dependent on web-browsing rather than from a missing filter entry. Application filters are the right control when restricting which applications a rule permits.
- ✗
The rule is placed too low in the rulebase.
Why it's wrong here
Rule order only matters when an earlier rule shadows the new one; here the log shows the traffic matched this rule, so placement is irrelevant. Administrators reach for rulebase position when a broader deny above blocks traffic, which is the correct fix in that scenario.
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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.