Quick Answer
The answer is DNS query logs from authoritative or internal DNS servers. This is the correct choice because DNS tunneling relies on encoding data within DNS queries and responses, often using large TXT record payloads or an unusually high frequency of lookups to a specific domain, and only DNS logs capture the full content and metadata of these transactions. On the CompTIA SecurityX CAS-004 exam, this question tests your ability to distinguish between data sources for detecting covert channels; a common trap is to assume firewall or web proxy logs will reveal the tunneling, but they lack the DNS-specific fields like query type, response size, and domain name patterns. A useful memory tip is to think of DNS logs as the only source that sees the "conversation" inside the protocol itself—firewalls see the door, but DNS logs see what’s being whispered through it.
This CAS-004 practice question tests your understanding of security operations. 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 threat hunter hypothesizes that a sophisticated attacker is using DNS tunneling for command and control. Which data source would most likely confirm this activity?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Network flow data (NetFlow)
Why wrong: Flow data shows volumes but not DNS payload details.
DNS query logs from authoritative/internal DNS servers
DNS logs contain query names and types; tunneling leaves unusual patterns.
Endpoint antivirus alerts
Why wrong: Antivirus is unlikely to detect DNS tunneling.
Web proxy logs
Why wrong: Proxy logs show HTTP traffic, not DNS.
Answer choices
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
Option B is correct because 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.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Common exam traps
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Trap categories for this question
Command / output trap
Flow data shows volumes but not DNS payload details.
Detailed technical explanation
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CAS-004 NAT questions on configuration and troubleshooting.
Security Operations — study guide chapter
Learn the concepts, then practise the questions
Security Operations practice questions
Targeted practice on this topic area only
All CAS-004 questions
510 questions across all exam domains
CompTIA SecurityX CAS-004 study guide
Full concept coverage aligned to exam objectives
CAS-004 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise CAS-004 questions linked to Scripting, Containers and Automation.
Practise CAS-004 questions linked to Application Environment, Configuration and Security.
Practise CAS-004 questions linked to Governance, Risk and Compliance.
Practise CAS-004 questions linked to Security Engineering.
Practise CAS-004 questions linked to Security Architecture.
Practise CAS-004 questions linked to Security Operations.
Practise CAS-004 questions linked to CAS-004 fundamentals.
Practise CAS-004 questions linked to CAS-004 scenario.
Practise CAS-004 questions linked to CAS-004 troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Security Operations — This question tests Security Operations — Static NAT maps one inside address to one outside address..
The correct answer is: DNS query logs from authoritative/internal DNS servers — Option B is correct because 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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CAS-004 NAT questions on configuration and troubleshooting.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Static NAT maps one inside address to one outside address.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 24, 2026
This CAS-004 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-004 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.