- A
DNS amplification attack
Why wrong: DNS amplification attacks send small queries that generate large responses, but the source packets are small; the high volume of small packets from the internal host suggests outbound data exfiltration.
- B
Port scan
Why wrong: Port scans target multiple ports, not a single port with many packets.
- C
Data exfiltration via DNS tunneling
DNS tunneling encodes data in DNS queries to exfiltrate data, often resulting in many small packets to a single external DNS server.
- D
Normal DNS resolution
Why wrong: Normal DNS traffic typically involves queries to various servers, not a high volume to a single IP.
Question 982 of 1,000
200-201 Security Monitoring Practice Question
This 200-201 practice question tests your understanding of security monitoring. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 security analyst is reviewing network traffic and notices a high volume of small packets from an internal IP to a single external IP on port 53. Which type of activity is most likely indicated?
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.
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
✓
Data exfiltration via DNS tunneling
DNS tunneling encodes data within DNS queries and responses, often using small packets to evade detection. A high volume of small packets from an internal IP to a single external IP on port 53, without corresponding internal DNS server traffic, is a classic indicator of data exfiltration via DNS tunneling.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 amplification attack
Why it's wrong here
DNS amplification attacks send small queries that generate large responses, but the source packets are small; the high volume of small packets from the internal host suggests outbound data exfiltration.
- ✗
Port scan
Why it's wrong here
Port scans target multiple ports, not a single port with many packets.
- ✓
Data exfiltration via DNS tunneling
Why this is correct
DNS tunneling encodes data in DNS queries to exfiltrate data, often resulting in many small packets to a single external DNS server.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Normal DNS resolution
Why it's wrong here
Normal DNS traffic typically involves queries to various servers, not a high volume to a single IP.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between a DNS amplification attack (which uses large responses to flood a victim) and DNS tunneling (which uses small, consistent queries for covert data transfer), so candidates may confuse the two due to both involving DNS traffic.
Detailed technical explanation
How to think about this question
DNS tunneling exploits the fact that DNS is often allowed through firewalls. Tools like dnscat2 or iodine encode data in the subdomain labels of DNS queries, with each query carrying a small payload (typically 32-255 bytes). The external server decodes the data from the query names and may respond with encoded commands. This technique can bypass DLP controls because the traffic blends with legitimate DNS, but the volume and lack of normal DNS hierarchy (e.g., no recursive resolver) are red flags.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 200-201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this 200-201 question test?
Security Monitoring — This question tests Security Monitoring — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Data exfiltration via DNS tunneling — DNS tunneling encodes data within DNS queries and responses, often using small packets to evade detection. A high volume of small packets from an internal IP to a single external IP on port 53, without corresponding internal DNS server traffic, is a classic indicator of data exfiltration via DNS tunneling.
What should I do if I get this 200-201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jul 4, 2026
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.
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