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200-201 Practice Question: A host is infected with malware that uses DNS…
A host is infected with malware that uses DNS tunneling to exfiltrate data. Which type of analysis would best detect this activity?
⚠ Common exam trap
Cisco often tests the misconception that firewall logs or NetFlow are sufficient for detecting application-layer tunneling, when in fact only DNS-specific logs provide the granularity to see the encoded payloads within DNS queries.
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
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DNS log analysis
DNS tunneling encodes exfiltrated data within DNS queries or responses, often using TXT or A record types to bypass network security controls. DNS log analysis is the most direct detection method because it reveals anomalous patterns such as unusually long domain names, excessive NXDOMAIN responses, or high volumes of DNS traffic to a single external server, which are hallmarks of tunneling activity.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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DNS log analysis
Why this is correct
DNS logs show query names, sizes, and frequency.
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Windows event log analysis
Why it's wrong here
Windows logs do not capture DNS queries natively.
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Firewall log analysis
Why it's wrong here
Firewall logs show connections but not DNS query details.
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NetFlow analysis
Why it's wrong here
NetFlow shows flow data, not DNS queries.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-201 practice question is part of Courseiva's free Cisco 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 200-201 exam.