200-201 Network Intrusion Analysis Practice Question
Which of the following is a common indicator of DNS tunneling used for exfiltration?
⚠ Common exam trap
Cisco often tests the distinction between a general anomaly (like large DNS responses) and a specific tunneling indicator (long subdomain strings), where candidates mistakenly focus on response size or protocol choice rather than the query structure.
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 queries with long subdomain strings
DNS tunneling exploits the DNS protocol to encapsulate non-DNS data within DNS queries and responses. A common indicator is DNS queries with unusually long subdomain strings, as attackers encode exfiltrated data into the query name to bypass network security controls.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
DNS queries with long subdomain strings
Why this is correct
Correct. Long subdomain strings are a sign of DNS tunneling.
- ✗
Frequent DNS queries to known domains
Why it's wrong here
Frequent queries to known domains are normal.
- ✗
DNS responses with large payloads
Why it's wrong here
Large responses are more associated with amplification attacks.
- ✗
DNS queries using TCP instead of UDP
Why it's wrong here
DNS over TCP is used for zone transfers or large responses, not necessarily tunneling.
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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.