PCNSA Securing Traffic Practice Question
Which TWO actions should be taken to protect against DNS tunneling? (Choose two.)
⚠ Common exam trap
Many exam-takers 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.
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
✓
Enable DNS Security on the outbound DNS traffic.
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.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Enable DNS Security on the outbound DNS traffic.
Why this is correct
DNS Security detects tunneling attempts.
- ✓
Configure DNS policies to block requests to unknown domains.
Why this is correct
This restricts DNS to known domains only.
- ✗
Allow all TCP traffic on port 53.
Why it's wrong here
TCP DNS can also be used for tunneling.
- ✗
Enable logging on all DNS traffic for analysis.
Why it's wrong here
Logging does not prevent tunneling.
- ✗
Block all UDP traffic on port 53.
Why it's wrong here
This would block legitimate DNS and cause outages.
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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.