PCNSE Core Concepts and Architecture Practice Question
This PCNSE practice question tests your understanding of core concepts and architecture. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company uses a Palo Alto Networks firewall to decrypt all outbound SSL traffic. Recently, users have reported slow internet performance. The network administrator notices that the firewall's CPU utilization is consistently above 90%. The traffic logs show that a large portion of decrypted traffic is from software update services (e.g., Windows Update, Adobe, etc.) that do not require inspection. The firewall is a mid-range model with hardware decryption acceleration. What is the most effective action to reduce CPU usage while maintaining security?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure a decryption policy exception to exclude high-volume, low-risk services from decryption.
Option A is correct because excluding high-volume, low-risk services like Windows Update and Adobe updates from SSL decryption reduces the CPU load from decrypting traffic that does not require security inspection. This approach maintains security by focusing decryption resources on traffic that poses a genuine risk, while leveraging the firewall's ability to bypass decryption for trusted sources. The mid-range model's hardware deceleration is already in use, so the most effective step is to reduce the volume of decryption itself.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Configure a decryption policy exception to exclude high-volume, low-risk services from decryption.
Why this is correct
This reduces the decryption load significantly while still protecting against threats from other sites.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the decryption session buffer size in the SSL/TLS proxy settings.
Why it's wrong here
Buffer size affects memory, not CPU; it would not reduce CPU utilization.
✗
Enable hardware decryption offload on the firewall.
Why it's wrong here
The firewall already has hardware acceleration; enabling it further may not be possible or may already be active.
✗
Add an additional firewall in an active/passive HA pair to distribute the decryption load.
Why it's wrong here
Adding hardware is expensive and configuration changes may be complex; better to optimize policy first.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume hardware decryption offload is not already enabled or that adding HA will magically balance load, when in fact the question explicitly states hardware acceleration is present and active/passive HA does not distribute processing load.
Detailed technical explanation
How to think about this question
Palo Alto Networks firewalls use a decryption policy with a 'no-decrypt' action to bypass SSL/TLS inspection for specific traffic categories, such as software update services identified by URL categories or application IDs. The hardware decryption offload (e.g., using the Cavium Nitrox or similar crypto accelerator) handles cryptographic operations but does not eliminate the CPU cost of reassembling and processing decrypted traffic streams. In practice, excluding low-risk traffic like Windows Update (which uses HTTPS but is signed by Microsoft) can reduce CPU usage by 30-50% without compromising security, as the firewall can still inspect the initial handshake and certificate validity.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the PCNSE exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Core Concepts and Architecture — This question tests Core Concepts and Architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure a decryption policy exception to exclude high-volume, low-risk services from decryption. — Option A is correct because excluding high-volume, low-risk services like Windows Update and Adobe updates from SSL decryption reduces the CPU load from decrypting traffic that does not require security inspection. This approach maintains security by focusing decryption resources on traffic that poses a genuine risk, while leveraging the firewall's ability to bypass decryption for trusted sources. The mid-range model's hardware deceleration is already in use, so the most effective step is to reduce the volume of decryption itself.
What should I do if I get this PCNSE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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