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CAS-004 Practice Question: A threat hunter hypothesizes that a sophisticated…
A threat hunter hypothesizes that a sophisticated attacker is using DNS tunneling for command and control. Which data source would most likely confirm this activity?
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
✓
DNS query logs from authoritative/internal DNS servers
DNS logs contain queries and responses; anomalous patterns like large TXT records or high frequency indicate tunneling. Option A is wrong because firewall logs may show traffic but not DNS content. Option C is wrong because antivirus may not detect tunneling. Option D is wrong because web proxy logs show HTTP traffic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Network flow data (NetFlow)
Why it's wrong here
Flow data shows volumes but not DNS payload details.
- ✓
DNS query logs from authoritative/internal DNS servers
Why this is correct
DNS logs contain query names and types; tunneling leaves unusual patterns.
- ✗
Endpoint antivirus alerts
Why it's wrong here
Antivirus is unlikely to detect DNS tunneling.
- ✗
Web proxy logs
Why it's wrong here
Proxy logs show HTTP traffic, not DNS.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CAS-005 practice question is part of Courseiva's free CompTIA 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 CAS-005 exam.