- A
DNS poisoning
Why wrong: DNS poisoning corrupts the DNS cache to redirect users to malicious sites; it does not involve covert channels using encrypted DNS.
- B
DNS tunneling
DNS tunneling encapsulates data in DNS queries and responses, often using encryption, to bypass firewalls and exfiltrate data.
- C
DNS amplification
Why wrong: DNS amplification is a DDoS attack that uses open resolvers to flood a target; it does not create covert channels.
- D
DNS zone transfer
Why wrong: DNS zone transfer is a legitimate mechanism to replicate DNS records between authoritative servers; not used for covert communication.
Question 398 of 520
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 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 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.
When this WOULD be correct
A question describing a user's browser being redirected to a phishing site despite typing the correct URL, with DNS cache entries showing incorrect IP addresses, would make DNS poisoning the correct answer.
- ✓
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.
When this WOULD be correct
A question describing a DDoS attack where the attacker spoofs the victim's IP and sends queries to open DNS resolvers, causing them to send large responses to the victim, overwhelming the target's bandwidth.
- ✗
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.
When this WOULD be correct
A question describing a scenario where an attacker successfully copies the entire DNS zone file from a misconfigured DNS server to gain reconnaissance data about the network's internal hosts and services.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓DNS tunnelingCorrect answer▾
Why this is correct
DNS tunneling encapsulates data in DNS queries and responses, often using encryption, to bypass firewalls and exfiltrate data.
✗DNS poisoningWrong answer — click to see why▾
Why this is wrong here
DNS poisoning involves corrupting DNS cache to redirect traffic to malicious sites, not establishing a covert channel via encrypted queries over TCP 853.
★ When this WOULD be the correct answer
A question describing a user's browser being redirected to a phishing site despite typing the correct URL, with DNS cache entries showing incorrect IP addresses, would make DNS poisoning the correct answer.
Why candidates choose this
Candidates may confuse DNS poisoning with any malicious DNS activity, or think that encrypted DNS queries are used to poison the cache, overlooking the covert channel aspect.
✗DNS amplificationWrong answer — click to see why▾
Why this is wrong here
DNS amplification is a DDoS attack that uses open resolvers to flood a target with large responses, not a technique for establishing covert communication channels via encrypted DNS queries.
★ When this WOULD be the correct answer
A question describing a DDoS attack where the attacker spoofs the victim's IP and sends queries to open DNS resolvers, causing them to send large responses to the victim, overwhelming the target's bandwidth.
Why candidates choose this
Candidates may confuse 'amplification' with 'tunneling' because both involve DNS traffic, but amplification is about traffic volume, not covert data exfiltration or command-and-control.
✗DNS zone transferWrong answer — click to see why▾
Why this is wrong here
DNS zone transfer is a mechanism for replicating DNS databases between authoritative servers, typically using TCP port 53, not port 853. It does not involve encrypted queries or covert channels.
★ When this WOULD be the correct answer
A question describing a scenario where an attacker successfully copies the entire DNS zone file from a misconfigured DNS server to gain reconnaissance data about the network's internal hosts and services.
Why candidates choose this
Candidates may confuse 'zone transfer' with any unauthorized DNS data exfiltration, or mistakenly think that any unusual DNS traffic pattern is a zone transfer.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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.
Visual reference
What to study next
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FAQ
Questions learners often ask
What does this N10-009 question test?
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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Last reviewed: Jun 11, 2026
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