The answer is to configure DNS policies to block requests to unknown domains and enable DNS Security to inspect for anomalous DNS traffic. DNS Security on Palo Alto Networks firewalls uses machine learning and threat intelligence to detect tunneling attempts by identifying unusual patterns like excessively long domain names or abnormally high query rates, which are hallmarks of data exfiltration through DNS. On the PCNSA exam, this question tests your understanding of layered DNS tunneling protection—combining policy-based blocking with signatureless detection—and often traps candidates who mistakenly rely only on static block lists or confuse DNS Security with DNSSEC validation. A key memory tip is “Block the unknown, inspect the anomaly,” reminding you that policies handle unknown domains while DNS Security catches the behavioral red flags.
PCNSA Securing Traffic Practice Question
This PCNSA practice question tests your understanding of securing traffic. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which TWO actions should be taken to protect against DNS tunneling? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable DNS Security on the outbound DNS traffic.
Option A is correct because DNS Security (DNSsec) on Palo Alto Networks firewalls can inspect and block DNS tunneling by identifying anomalous DNS queries and responses, such as those with unusually long domain names or high query rates. This feature uses threat intelligence and machine learning to detect tunneling attempts without relying solely on static domain block lists.
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.
This would block legitimate DNS and cause outages.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse passive monitoring (logging) with active prevention, or mistakenly think blocking all UDP on port 53 is a viable solution, not realizing it breaks legitimate DNS traffic.
Detailed technical explanation
How to think about this question
DNS tunneling exploits the DNS protocol to encapsulate non-DNS data (e.g., exfiltrated files or C2 commands) within DNS queries and responses, often using base64 encoding or TXT records. Palo Alto Networks DNS Security uses signature-based detection and behavioral analysis to flag patterns like high entropy in domain names or excessive NXDOMAIN responses, which are common in tunneling. In a real-world scenario, an attacker might use a tool like dnscat2 to tunnel SSH over DNS, bypassing traditional firewall rules that only inspect IP addresses or ports.
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 PCNSA 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.
Securing Traffic — This question tests Securing Traffic — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable DNS Security on the outbound DNS traffic. — Option A is correct because DNS Security (DNSsec) on Palo Alto Networks firewalls can inspect and block DNS tunneling by identifying anomalous DNS queries and responses, such as those with unusually long domain names or high query rates. This feature uses threat intelligence and machine learning to detect tunneling attempts without relying solely on static domain block lists.
What should I do if I get this PCNSA 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.
About these practice questions
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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.
Question Discussion
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