200-201 Network Intrusion Analysis Practice Question
This 200-201 practice question tests your understanding of network intrusion analysis. 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.
An analyst is investigating a potential data exfiltration. Which two indicators in network traffic are most indicative of data exfiltration over DNS? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Large DNS response packets
Large DNS response packets (Option B) are indicative of data exfiltration because attackers often encode stolen data into DNS TXT or other record types, causing response sizes to exceed the typical 512-byte limit and triggering EDNS0 extensions. This anomaly stands out against normal DNS traffic, where most responses are small.
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.
Read the scenario before looking for a memorised answer.
✗
DNSSEC enabled
Why it's wrong here
DNSSEC is a security extension, not related to exfiltration.
✗
Frequent DNS query retransmissions
Why it's wrong here
Can occur due to network issues, not exfiltration specific.
✓
High volume of DNS queries to unusual domains
Why this is correct
Indicates potential tunneling for exfiltration.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that any deviation from normal DNS behavior (like retransmissions or non-standard ports) is malicious, but the key indicators for exfiltration are unusually large response sizes and a high volume of queries to suspicious domains.
Detailed technical explanation
How to think about this question
Data exfiltration over DNS exploits the fact that DNS responses can carry arbitrary payloads in resource records like TXT, CNAME, or MX. Attackers use tools like dnscat2 or Iodine to tunnel data by encoding it in subdomain labels, which are then reflected in response packets; the resulting packet sizes often exceed 512 bytes, triggering EDNS0 with a 4096-byte buffer. In real-world scenarios, a sudden spike in DNS queries to a single unusual domain with large TXT responses is a classic red flag for security operations centers.
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.
Network Intrusion Analysis — This question tests Network Intrusion Analysis — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Large DNS response packets — Large DNS response packets (Option B) are indicative of data exfiltration because attackers often encode stolen data into DNS TXT or other record types, causing response sizes to exceed the typical 512-byte limit and triggering EDNS0 extensions. This anomaly stands out against normal DNS traffic, where most responses are small.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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