ISC2 CC Network Security Practice Question
A security analyst detects a large number of incomplete TCP connection requests (SYN segments) directed at a server. This is indicative of which type of attack?
⚠ Common exam trap
Watch out — candidates often confuse volumetric floods (ICMP/UDP) with protocol-level exhaustion attacks; candidates may pick 'ICMP flood' simply because it is a flood, missing that the question specifies incomplete TCP connection requests (SYN segments).
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
A SYN flood exploits the TCP three-way handshake by sending numerous SYN packets with spoofed source addresses, leaving the server with half-open connections that exhaust its backlog queue. The server responds with SYN-ACK to unreachable hosts and waits for the final ACK that never arrives, consuming resources until legitimate connections are refused. This matches the scenario of many incomplete TCP connection requests.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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ICMP flood
Why it's wrong here
An ICMP flood consists of echo request or reply packets, which carry no TCP headers or SYN flags. The stem's half-open TCP connections point to SYN flood activity. ICMP flood would be correct if the traffic observed were ping packets saturating the link.
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UDP flood
Why it's wrong here
A UDP flood sends connectionless datagrams; UDP has no handshake, so no SYN segments exist. The stem's incomplete TCP handshakes indicate SYN flood behaviour. UDP flood would be correct if the analyst observed high volumes of unsolicited UDP packets to random ports.
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Smurf attack
Why it's wrong here
A Smurf attack floods a victim with ICMP echo replies by spoofing its address to a broadcast subnet, so it produces ICMP traffic, not TCP SYN segments. It would be the answer if the stem described amplified ICMP replies from many hosts.
- ✓
SYN flood
Why this is correct
A SYN flood exploits the TCP three-way handshake by sending numerous SYN segments without completing the final ACK, exhausting the server's half-open connection table. This matches the stem's observation of many incomplete TCP connection requests.
Visual reference
Go deeper
Related to this question
Key term
Denial-of-service
A Denial-of-service (DoS) attack is an attempt to make a computer, network, or online service unavailable to its intended users by overwhelming it with fake traffic or requests.
Key term
TCP
TCP is a connection-oriented transport layer protocol that ensures reliable, ordered, and error-checked delivery of data between applications over IP networks.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISC2 exam blueprint
This CC practice question is part of Courseiva's free ISC2 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 CC exam.