N10-009 Network Security Practice Question
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?
⚠ Common exam trap
Candidates often 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.
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.
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, also known as DNS cache poisoning, is an attack where forged or incorrect DNS data is injected into a DNS resolver's cache. This manipulation causes the resolver to return malicious IP addresses for legitimate domain names, thereby redirecting users to attacker-controlled websites or services. Unlike tunneling, its primary goal is to misdirect traffic and compromise trust in DNS resolution, not to create a hidden data channel.
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 is a sophisticated technique that abuses the Domain Name System protocol to establish a covert communication channel. It involves encoding arbitrary non-DNS data, such as command-and-control instructions or exfiltrated files, within legitimate-looking DNS queries and responses. This method effectively bypasses many firewalls and intrusion detection systems that typically allow DNS traffic without deep content inspection, making it a potent tool for data exfiltration and maintaining persistence within a compromised network.
- ✗
DNS amplification
Why it's wrong here
DNS amplification is a type of Distributed Denial of Service (DDoS) attack that leverages open DNS resolvers to overwhelm a target system. Attackers send small DNS queries with a spoofed source IP address (the victim's) to numerous vulnerable DNS servers. These servers then respond with much larger DNS responses directed at the victim, amplifying the attack traffic and causing service disruption, rather than establishing a covert communication link.
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
A DNS zone transfer is a standard, legitimate process used to replicate DNS records between authoritative DNS servers, typically from a primary to a secondary server. Its purpose is to ensure redundancy and consistency of DNS data across multiple servers, allowing them to serve identical information. While it involves transferring DNS data, it is a bulk transfer of public records for operational purposes and is not designed or used as a covert, encrypted channel for arbitrary data exfiltration.
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 is a sophisticated technique that abuses the Domain Name System protocol to establish a covert communication channel. It involves encoding arbitrary non-DNS data, such as command-and-control instructions or exfiltrated files, within legitimate-looking DNS queries and responses. This method effectively bypasses many firewalls and intrusion detection systems that typically allow DNS traffic without deep content inspection, making it a potent tool for data exfiltration and maintaining persistence within a compromised network.
✗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?”
Visual reference
Go deeper
Related to this question
Learn chapter
Network Access Control (NAC)
Key term
Security
Security in IT is the practice of protecting systems, networks, and data from unauthorized access, damage, or theft.
Key term
DNS
DNS is the system that translates human-friendly domain names like example.com into machine-readable IP addresses so computers can find each other on a network.
About these practice questions
One of 464 original N10-009 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This N10-009 practice question is part of Courseiva's free CompTIA 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 N10-009 exam.