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 is investigating a network anomaly. The analyst notices that the company's web server is receiving a large number of TCP SYN packets from random source IP addresses, all destined for port 80. The web server is responding with SYN-ACK packets, but the connections are never completed. This is causing the server's connection table to fill up, degrading performance for legitimate users. Which type of attack is being described?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "never"
Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
Why wrong: Ping of death involves sending an oversized or malformed ICMP packet to cause a buffer overflow. It does not target TCP connections.
B
Smurf attack
Why wrong: A Smurf attack uses ICMP echo requests with a spoofed source IP broadcast to a network, causing many replies to flood the victim. This does not involve TCP SYN packets.
C
SYN flood
A SYN flood sends many TCP SYN packets with spoofed IPs, never completing the handshake, exhausting server resources. This matches the description.
D
DNS amplification
Why wrong: DNS amplification uses small DNS queries with a spoofed source IP to cause large responses directed at the victim. It uses UDP, not TCP SYN.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
SYN flood
The attack described is a SYN flood, a type of denial-of-service (DoS) attack that exploits the TCP three-way handshake. The attacker sends a high volume of TCP SYN packets with spoofed source IP addresses to the server's port 80. The server responds with SYN-ACK packets to each spoofed source and waits for the final ACK, which never arrives, causing the server's half-open connection table (backlog queue) to fill up and exhaust resources, degrading performance for legitimate users.
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.
✗
Ping of death
Why it's wrong here
Ping of death involves sending an oversized or malformed ICMP packet to cause a buffer overflow. It does not target TCP connections.
✗
Smurf attack
Why it's wrong here
A Smurf attack uses ICMP echo requests with a spoofed source IP broadcast to a network, causing many replies to flood the victim. This does not involve TCP SYN packets.
✓
SYN flood
Why this is correct
A SYN flood sends many TCP SYN packets with spoofed IPs, never completing the handshake, exhausting server resources. This matches the description.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
DNS amplification
Why it's wrong here
DNS amplification uses small DNS queries with a spoofed source IP to cause large responses directed at the victim. It uses UDP, not TCP SYN.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse a SYN flood with a Smurf attack or DNS amplification because all three are volumetric DoS attacks, but the key differentiator is the protocol and mechanism: SYN flood uses TCP SYN packets targeting the three-way handshake, while Smurf uses ICMP and DNS amplification uses UDP.
Detailed technical explanation
How to think about this question
In a SYN flood, the attacker often randomizes the source IP addresses to avoid detection and to ensure the server's SYN-ACK responses go to non-existent hosts, preventing the final ACK. The server's backlog queue has a limited size (e.g., net.ipv4.tcp_max_syn_backlog in Linux, default 1024), and once full, the server drops new connection requests. Modern mitigations include SYN cookies (RFC 4987), which encode connection state in the SYN-ACK sequence number, allowing the server to avoid maintaining state until the handshake completes.
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: SYN flood — The attack described is a SYN flood, a type of denial-of-service (DoS) attack that exploits the TCP three-way handshake. The attacker sends a high volume of TCP SYN packets with spoofed source IP addresses to the server's port 80. The server responds with SYN-ACK packets to each spoofed source and waits for the final ACK, which never arrives, causing the server's half-open connection table (backlog queue) to fill up and exhaust resources, degrading performance for legitimate users.
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.
Are there clue words in this question I should notice?
Yes — watch for: "never". Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
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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