- A
SYN flood; enable TCP intercept or SYN cookies
The attack is a SYN flood. TCP intercept (or SYN cookies) allows the server to manage half-open connections and mitigate resource exhaustion.
- B
Ping flood; implement rate limiting
Why wrong: Ping floods use ICMP echo requests, not incomplete TCP connections.
- C
Smurf attack; disable IP-directed broadcasts
Why wrong: A Smurf attack sends ICMP echo requests to broadcast addresses with spoofed source IPs, causing amplification, not incomplete TCP handshakes.
- D
ARP poisoning; enable dynamic ARP inspection
Why wrong: ARP poisoning involves sending forged ARP replies to associate IPs with attacker MACs, not exhausting TCP resources.
Question 393 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 discovers that an attacker is sending large numbers of incomplete TCP connection requests to a server, causing the server to run out of resources and stop responding to legitimate requests. Which type of attack is this, and which mitigation should be implemented?
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
✓
SYN flood; enable TCP intercept or SYN cookies
This is a SYN flood attack, where the attacker sends a high volume of TCP SYN packets without completing the three-way handshake, exhausting the server's connection queue. Enabling TCP intercept (on Cisco devices) or SYN cookies (RFC 4987) allows the server to validate handshakes before allocating resources, mitigating the attack.
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.
- ✓
SYN flood; enable TCP intercept or SYN cookies
Why this is correct
The attack is a SYN flood. TCP intercept (or SYN cookies) allows the server to manage half-open connections and mitigate resource exhaustion.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Ping flood; implement rate limiting
When this WOULD be correct
A ping flood attack would be the correct answer if the question described an attacker sending a high volume of ICMP echo request packets to overwhelm a target's network bandwidth or CPU, and the mitigation would be implementing rate limiting on ICMP traffic.
- ✗
Smurf attack; disable IP-directed broadcasts
Why it's wrong here
A Smurf attack sends ICMP echo requests to broadcast addresses with spoofed source IPs, causing amplification, not incomplete TCP handshakes.
When this WOULD be correct
A Smurf attack would be correct if the question described an attacker sending ICMP echo requests to a network broadcast address, using a spoofed source IP of the victim, causing all hosts on the network to reply to the victim, overwhelming it with ICMP traffic.
- ✗
ARP poisoning; enable dynamic ARP inspection
Why it's wrong here
ARP poisoning involves sending forged ARP replies to associate IPs with attacker MACs, not exhausting TCP resources.
When this WOULD be correct
This option would be correct in a question describing an attacker sending forged ARP messages to associate their MAC address with the IP of a legitimate device, causing traffic interception or denial of service. The mitigation would be Dynamic ARP Inspection (DAI) to validate ARP packets.
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.
✓SYN flood; enable TCP intercept or SYN cookiesCorrect answer▾
Why this is correct
The attack is a SYN flood. TCP intercept (or SYN cookies) allows the server to manage half-open connections and mitigate resource exhaustion.
✗Ping flood; implement rate limitingWrong answer — click to see why▾
Why this is wrong here
The attack described involves incomplete TCP connection requests exhausting server resources, which is a SYN flood, not a ping flood. Ping floods use ICMP echo requests, not TCP connections, and rate limiting is a mitigation for ICMP-based floods, not for SYN floods.
★ When this WOULD be the correct answer
A ping flood attack would be the correct answer if the question described an attacker sending a high volume of ICMP echo request packets to overwhelm a target's network bandwidth or CPU, and the mitigation would be implementing rate limiting on ICMP traffic.
Why candidates choose this
Candidates may confuse 'flood' attacks and assume any overwhelming traffic is a ping flood, or they may not distinguish between TCP-based and ICMP-based attacks, leading them to choose a familiar mitigation like rate limiting.
✗Smurf attack; disable IP-directed broadcastsWrong answer — click to see why▾
Why this is wrong here
The question describes incomplete TCP connection requests exhausting server resources, which is a SYN flood, not a Smurf attack. A Smurf attack uses ICMP echo requests sent to a network's broadcast address with a spoofed source IP, causing amplification and targeting the victim with ICMP replies.
★ When this WOULD be the correct answer
A Smurf attack would be correct if the question described an attacker sending ICMP echo requests to a network broadcast address, using a spoofed source IP of the victim, causing all hosts on the network to reply to the victim, overwhelming it with ICMP traffic.
Why candidates choose this
Candidates may confuse any attack that consumes resources with a Smurf attack, especially if they remember that Smurf attacks cause resource exhaustion via amplification, but they overlook the specific protocol (ICMP vs. TCP) and the mechanism (broadcast vs. incomplete handshake).
✗ARP poisoning; enable dynamic ARP inspectionWrong answer — click to see why▾
Why this is wrong here
ARP poisoning targets the Address Resolution Protocol to intercept traffic on a local network, not to exhaust server resources via incomplete TCP connections. The described attack is a SYN flood, which exploits the TCP three-way handshake.
★ When this WOULD be the correct answer
This option would be correct in a question describing an attacker sending forged ARP messages to associate their MAC address with the IP of a legitimate device, causing traffic interception or denial of service. The mitigation would be Dynamic ARP Inspection (DAI) to validate ARP packets.
Why candidates choose this
Candidates may confuse network-layer attacks or think that any resource exhaustion attack involves poisoning, or they may recall ARP poisoning as a common attack without carefully matching the symptoms described.
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 confuse a SYN flood with a ping flood or Smurf attack because all involve flooding, but only SYN floods target the TCP three-way handshake state table.
Detailed technical explanation
How to think about this question
Under the hood, a SYN flood exploits the TCP backlog queue (typically 1024 entries on Linux) by sending spoofed SYN packets; the server responds with SYN-ACK and waits for an ACK that never arrives, eventually filling the queue. SYN cookies work by encoding connection state in the initial sequence number, allowing the server to avoid storing state until the handshake completes, as defined in RFC 4987. In real-world scenarios, attackers often use botnets to generate millions of SYN packets per second, overwhelming even large servers without mitigation.
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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
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: SYN flood; enable TCP intercept or SYN cookies — This is a SYN flood attack, where the attacker sends a high volume of TCP SYN packets without completing the three-way handshake, exhausting the server's connection queue. Enabling TCP intercept (on Cisco devices) or SYN cookies (RFC 4987) allows the server to validate handshakes before allocating resources, mitigating the attack.
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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