PCNSA Policy Evaluation and Management Practice Question
A company needs to restrict access to a critical server from external IP addresses, but internal users should have full access. Which rule structure should be used?
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
✓
Create an allow rule for internal source addresses, then a deny rule for any source.
Correct answer is C. Rule order is critical: Palo Alto firewalls evaluate rules top-down, and the first match is applied. By placing an allow rule for internal source addresses first, internal traffic is permitted. Then a subsequent deny rule for any source blocks all other traffic, including external IPs. Option A is incorrect because creating a deny rule for external IPs first would block external traffic but does not guarantee internal access if the deny rule is overly broad or if any later rule could inadvertently allow external traffic. Option B is incorrect because placing the allow rule after the deny rule would cause the deny rule to match all traffic first, including internal, since the deny rule typically covers any source. Option D is incorrect because a single deny rule with a user-ID condition cannot differentiate between internal and external users unless all internal users are authenticated, which is impractical for basic IP-based access control.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create a deny rule for external IP addresses, then an allow rule for internal.
Why it's wrong here
If the deny rule matches external IPs first, it is fine; but if the external IP range is broad, it might also match internal if not careful. More importantly, the allow rule for internal must be before the deny to ensure internal traffic is not denied.
- ✗
Place the allow rule after the deny rule.
Why it's wrong here
If the deny rule is first, it would block all traffic, including internal, before reaching the allow rule.
- ✓
Create an allow rule for internal source addresses, then a deny rule for any source.
Why this is correct
Internal traffic is allowed by the first rule, and all other (external) traffic is denied by the second rule.
- ✗
Create a single rule with a 'Deny' action and apply a user-ID condition.
Why it's wrong here
User-ID is for user-based policies, and a single deny rule would block all, not just external.
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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.