The answer is IP spoofing, because the attacker is forging the source IP address of packets to impersonate the company’s internal DNS server. In an IP spoofing attack with fake source IP, the adversary crafts packets that appear to originate from a trusted host—here, the internal DNS server—allowing them to bypass access controls, launch reflection-based DDoS attacks, or flood the network with seemingly legitimate traffic. On the CompTIA Network+ N10-009 exam, this scenario tests your ability to distinguish IP spoofing from other attacks like DDoS amplification or ARP poisoning; a common trap is confusing it with a man-in-the-middle attack, but the key clue is the falsified source address matching a known internal server. To remember this, think of the mnemonic “Spoof the Source, Trust the Force”—the attacker exploits trust by faking the source IP, not by intercepting traffic in transit.
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 the network has been flooded with packets that have the same source IP address as the company's internal DNS server. This is likely an example of which type of attack?
Why wrong: A Smurf attack uses ICMP echo requests with a spoofed source IP to cause a flood of replies to the victim, but the description here does not mention ICMP or amplification.
B
IP spoofing
IP spoofing involves forging the source IP address in packets to make them appear to come from a trusted source.
C
Man-in-the-middle
Why wrong: A man-in-the-middle attack involves intercepting and possibly altering communications between two parties; the scenario describes a flood of packets, not interception.
D
ARP poisoning
Why wrong: ARP poisoning manipulates ARP tables to redirect traffic, not to flood the network with spoofed packets.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
IP spoofing
IP spoofing is the correct answer because the attacker is forging the source IP address of packets to impersonate the company's internal DNS server. By flooding the network with packets that appear to originate from a trusted internal server, the attacker can bypass security controls, launch reflection attacks, or cause denial of service. This directly matches the scenario where the source IP is falsified to match a legitimate internal host.
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.
✗
Smurf attack
Why it's wrong here
A Smurf attack uses ICMP echo requests with a spoofed source IP to cause a flood of replies to the victim, but the description here does not mention ICMP or amplification.
✓
IP spoofing
Why this is correct
IP spoofing involves forging the source IP address in packets to make them appear to come from a trusted source.
Related concept
Read the scenario before looking for a memorised answer.
✗
Man-in-the-middle
Why it's wrong here
A man-in-the-middle attack involves intercepting and possibly altering communications between two parties; the scenario describes a flood of packets, not interception.
✗
ARP poisoning
Why it's wrong here
ARP poisoning manipulates ARP tables to redirect traffic, not to flood the network with spoofed packets.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the distinction between IP spoofing and Smurf attacks, where candidates mistakenly choose Smurf because both involve spoofed source addresses, but Smurf specifically requires ICMP and broadcast amplification, not arbitrary packet flooding with a DNS server's IP.
Trap categories for this question
Scenario analysis trap
A man-in-the-middle attack involves intercepting and possibly altering communications between two parties; the scenario describes a flood of packets, not interception.
Detailed technical explanation
How to think about this question
IP spoofing exploits the lack of inherent authentication in the IP protocol (RFC 791), where the source address field can be arbitrarily set. In a flood scenario, the attacker may use spoofed packets to trigger a DNS amplification attack, sending queries with the victim's spoofed source IP to open DNS resolvers, which then flood the victim with large responses. Real-world mitigations include ingress/egress filtering (BCP 38) and uRPF (unicast Reverse Path Forwarding) to drop packets with source addresses that do not match the expected interface.
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: IP spoofing — IP spoofing is the correct answer because the attacker is forging the source IP address of packets to impersonate the company's internal DNS server. By flooding the network with packets that appear to originate from a trusted internal server, the attacker can bypass security controls, launch reflection attacks, or cause denial of service. This directly matches the scenario where the source IP is falsified to match a legitimate internal host.
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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