The answer is a man-in-the-middle attack. This is correct because a man-in-the-middle attack definition centers on an adversary secretly intercepting and modifying communication between two parties who believe they are directly connected, exactly as described. The attacker places themselves in the logical or physical data path, often by exploiting weak authentication or encryption, to alter data in transit without either party’s knowledge. On the CompTIA Network+ N10-009 exam, this scenario tests your understanding of active interception threats, often appearing in questions about ARP spoofing, session hijacking, or rogue access points. A common trap is confusing this with a replay attack, but remember: MITM involves real-time modification, not just capture and retransmission. For a quick memory tip, think “MITM = Middle Intercepts, Tweaks Messages.”
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.
An attacker intercepts communication between two parties and is able to modify the data in transit without either party's knowledge. Which type of attack is this?
A man-in-the-middle attack precisely describes an attacker intercepting and modifying communications between two endpoints without their knowledge.
B
ARP spoofing
Why wrong: ARP spoofing is a technique often used to execute a man-in-the-middle attack, but it does not inherently involve modifying data; it only redirects traffic. The question describes the broader attack type.
C
DNS poisoning
Why wrong: DNS poisoning corrupts DNS caches to redirect traffic to malicious sites, but it does not directly allow the attacker to modify the intercepted data.
D
Replay attack
Why wrong: A replay attack captures legitimate data and retransmits it later; it does not involve real-time interception or modification.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Man-in-the-middle
A man-in-the-middle (MITM) attack occurs when an adversary secretly intercepts and potentially alters the communication between two parties who believe they are directly communicating with each other. The attacker can modify data in transit without either party's knowledge by placing themselves in the logical or physical path of the data flow, often by exploiting weaknesses in authentication or encryption. This matches the scenario described, where the attacker both intercepts and modifies the data.
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.
✓
Man-in-the-middle
Why this is correct
A man-in-the-middle attack precisely describes an attacker intercepting and modifying communications between two endpoints without their knowledge.
Related concept
Read the scenario before looking for a memorised answer.
✗
ARP spoofing
Why it's wrong here
ARP spoofing is a technique often used to execute a man-in-the-middle attack, but it does not inherently involve modifying data; it only redirects traffic. The question describes the broader attack type.
✗
DNS poisoning
Why it's wrong here
DNS poisoning corrupts DNS caches to redirect traffic to malicious sites, but it does not directly allow the attacker to modify the intercepted data.
✗
Replay attack
Why it's wrong here
A replay attack captures legitimate data and retransmits it later; it does not involve real-time interception or modification.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between the attack type (MITM) and the technique used to achieve it (ARP spoofing, DNS poisoning), so candidates mistakenly select the technique rather than the overarching attack described in the scenario.
Detailed technical explanation
How to think about this question
In a classic MITM attack, the attacker often uses ARP spoofing to intercept traffic on a switched Ethernet network, then forwards packets after modification. For encrypted sessions, the attacker may perform SSL stripping or present a forged certificate to decrypt and re-encrypt traffic, as seen in tools like ettercap or bettercap. The attack exploits the lack of mutual authentication or integrity checks at the transport layer, which is why protocols like TLS with certificate pinning or SSH with host key verification are critical defenses.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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: Man-in-the-middle — A man-in-the-middle (MITM) attack occurs when an adversary secretly intercepts and potentially alters the communication between two parties who believe they are directly communicating with each other. The attacker can modify data in transit without either party's knowledge by placing themselves in the logical or physical path of the data flow, often by exploiting weaknesses in authentication or encryption. This matches the scenario described, where the attacker both intercepts and modifies the data.
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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