PCNSA Policy Evaluation and Management Practice Question
A network administrator adds a new security rule allowing HTTP from the Trust zone to the Untrust zone. After committing, traffic from the Trust zone to the Untrust zone is still blocked. What is the most likely cause?
⚠ Common exam trap
PCNSA often tests policy evaluation order — candidates assume the new rule will take effect because it is more specific, but PAN-OS uses first-match top-down evaluation, so a deny rule above it blocks the traffic.
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 new rule is placed at the bottom of the policy, below an existing deny rule that matches the same traffic.
Palo Alto Networks security policies are evaluated top-down, and the first rule that matches the traffic is applied. If an existing deny rule that matches HTTP from Trust to Untrust sits above the new allow rule, the deny rule wins and traffic remains blocked. The new rule must be moved above the deny rule (or the deny rule modified) to take effect.
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 source zone in the new rule is set to 'Untrust' instead of 'Trust'.
Why it's wrong here
Reversing the zones means the rule matches Untrust-to-Trust traffic, so Trust-to-Untrust sessions still hit the implicit deny and remain blocked. It is tempting because zone selection is the first field checked, and an inverted pair looks superficially similar on a rule listing.
- ✗
The application in the new rule is set to 'ssl' instead of 'http'.
Why it's wrong here
Specifying 'ssl' means the rule matches TLS on port 443, so plain HTTP on port 80 is not permitted and falls through to the default deny. It is tempting because ssl is a common application for web traffic, and it would be correct if the requirement were HTTPS rather than HTTP.
- ✓
The new rule is placed at the bottom of the policy, below an existing deny rule that matches the same traffic.
Why this is correct
Palo Alto evaluates rules top-down and stops at the first match. A deny rule above the new permit shadows it, so HTTP from Trust to Untrust never reaches the new rule despite committing successfully. Moving the permit above the deny resolves the block.
- ✗
The destination zone in the new rule is set to 'Trust' instead of 'Untrust'.
Why it's wrong here
Setting the destination zone to Trust would match traffic destined for Trust, not Untrust, so the rule never applies to the intended flow. It is tempting because zone fields are easily transposed, and a Trust-to-Trust rule would be correct when securing intra-zone traffic between Trust interfaces.
Go deeper
Related to this question
About these practice questions
This PCNSA question is part of Courseiva's 385-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Palo Alto Networks exam blueprint
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.