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?
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.
External Dynamic Lists (EDLs) are designed to manage large, frequently updated lists of IP addresses. They integrate with security rules and can be updated automatically, minimizing administrative overhead.
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
Incorrect. The source address should be Trust zone, but the malicious IPs are destinations, not 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
Correct. EDLs simplify management and allow automatic updates, making them the most efficient choice for frequently changing lists.
- ✗
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
Incorrect. Adding 500 individual objects is inefficient and hard to maintain.
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JA
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.