The correct answer is DNS tunneling. This technique is being employed because the analyst observed encrypted DNS queries over TCP port 853, which is DNS over TLS, being used to establish a covert communication channel. DNS tunneling works by encapsulating non-DNS data, such as command-and-control traffic, inside DNS query and response packets, allowing attackers to bypass security controls by hiding malicious activity within legitimate DNS traffic. On the CompTIA Network+ N10-009 exam, this scenario tests your ability to recognize how attackers abuse DNS protocols for data exfiltration or C2 channels, often appearing with port 53, 853, or unusual query patterns. A common trap is confusing DNS tunneling with simple DNS poisoning or amplification attacks, but the key differentiator here is the covert, bidirectional channel. Memory tip: think of DNS as a delivery truck—tunneling is when attackers hide contraband inside the packages, not just redirecting the truck’s route.
N10-009 Network Security Practice Question
This N10-009 practice question tests your understanding of network security. 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 notices that a user's workstation is sending encrypted DNS queries to an external IP address over TCP port 853. This traffic is being used to establish a covert communication channel to bypass the company's security controls. Which technique is being employed?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
DNS tunneling
DNS tunneling is the correct answer because the analyst observed encrypted DNS queries over TCP port 853 (DNS over TLS) being used to establish a covert communication channel. This technique encapsulates non-DNS data (e.g., command-and-control traffic) within DNS query and response packets, allowing the attacker to bypass security controls by hiding malicious traffic inside legitimate DNS traffic.
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 poisoning
Why it's wrong here
DNS poisoning corrupts the DNS cache to redirect users to malicious sites; it does not involve covert channels using encrypted DNS.
✓
DNS tunneling
Why this is correct
DNS tunneling encapsulates data in DNS queries and responses, often using encryption, to bypass firewalls and exfiltrate data.
Related concept
Read the scenario before looking for a memorised answer.
✗
DNS amplification
Why it's wrong here
DNS amplification is a DDoS attack that uses open resolvers to flood a target; it does not create covert channels.
✗
DNS zone transfer
Why it's wrong here
DNS zone transfer is a legitimate mechanism to replicate DNS records between authoritative servers; not used for covert communication.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse DNS tunneling with DNS poisoning or amplification because all involve DNS abuse, but only tunneling uses DNS as a covert data carrier, not for cache corruption or traffic amplification.
Detailed technical explanation
How to think about this question
DNS tunneling works by encoding arbitrary data into DNS query names (e.g., base64-encoded payloads as subdomains) and receiving responses in TXT or other record types. Using DNS over TLS (DoT) on TCP 853 adds encryption, making the tunnel harder to detect via deep packet inspection, as the payload is hidden within the TLS session. In real-world scenarios, tools like dnscat2 or Iodine leverage this to exfiltrate data or establish C2 channels, often bypassing firewalls that allow outbound DNS traffic.
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 N10-009 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this N10-009 question in full detail.
Network Security — This question tests Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: DNS tunneling — DNS tunneling is the correct answer because the analyst observed encrypted DNS queries over TCP port 853 (DNS over TLS) being used to establish a covert communication channel. This technique encapsulates non-DNS data (e.g., command-and-control traffic) within DNS query and response packets, allowing the attacker to bypass security controls by hiding malicious traffic inside legitimate DNS traffic.
What should I do if I get this N10-009 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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