PCNSA Policy Evaluation and Management Practice Question
A small business has a Palo Alto Networks firewall with a single security policy rule that allows all traffic from the 'Trust' zone to the 'Untrust' zone. The business recently experienced a malware infection originating from an internal host that communicated with known malicious IP addresses. The administrator wants to implement a security policy to block traffic to these malicious IP destinations. The administrator has a list of 500 malicious IP addresses that may change frequently. What is the most efficient way to create a policy to block traffic to these IPs?
⚠ Common exam trap
PCNSA often tests the difference between static address groups (manual updates) and External Dynamic Lists (automatic updates), and the common mistake of placing malicious IPs as source instead of destination in the deny rule.
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 External Dynamic List (EDL) of the malicious IPs and reference it in a security rule as destination address, with action deny, placed above the allow rule.
An External Dynamic List (EDL) is the most efficient way to block a frequently changing list of 500 malicious IPs because the firewall automatically pulls updates from an external source (e.g., a text file on a web server), eliminating manual updates. The EDL is referenced as a destination address in a deny rule placed above the allow rule.
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 security rule with an address group containing the 500 IPs as destination, action deny, placed above the allow rule.
Why it's wrong here
Manually updating an address group containing 500 individual IP addresses fails to satisfy the requirement for frequent changes. This method requires manual configuration updates every time a new malicious destination is identified, whereas External Dynamic Lists automate this process via external files. Creating static address groups is appropriate when managing a fixed set of internal assets or permanent network segments that do not require automated synchronisation with external threat intelligence feeds.
- ✗
Create a security rule with source zone Trust, destination zone Untrust, source address list containing the 500 IPs, action deny.
Why it's wrong here
Placing the malicious IPs in the source address field matches traffic originating from those addresses, not internal hosts connecting outbound to them, so the deny rule never fires. It is tempting because a deny rule with those addresses does block something, and it would be correct when blocking inbound traffic from known malicious sources.
- ✓
Create an External Dynamic List (EDL) of the malicious IPs and reference it in a security rule as destination address, with action deny, placed above the allow rule.
Why this is correct
An External Dynamic List hosts the 500 IPs externally, so the firewall rule references the list and updates happen automatically as the list changes, avoiding manual edits. Placing the deny rule above the allow rule enforces blocking, satisfying the frequently-changing list constraint.
- ✗
Create a security rule with source zone Trust, destination zone Untrust, destination address list containing the 500 IPs as separate address objects, action deny, placed above the allow rule.
Why it's wrong here
500 separate address objects must be maintained individually, so frequent IP list changes become error-prone and operationally heavy. It is tempting because a deny rule above the allow rule does block the traffic, and this approach would suit a small, static set of destinations that rarely changes.
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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.