200-201 Security Monitoring Practice Question
Which OSI layer is targeted by a TCP SYN flood attack?
⚠ Common exam trap
Cisco often tests the distinction between the layer where the vulnerability exists (Layer 4, TCP) versus the layer where the packet is encapsulated (Layer 3, IP), leading candidates to mistakenly choose Layer 3 because the attack uses IP packets.
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
✓
Layer 4 - Transport
A TCP SYN flood attack targets the Transport layer (Layer 4) because it exploits the TCP three-way handshake mechanism. The attacker sends a high volume of SYN packets with spoofed source IP addresses, causing the server to allocate resources for half-open connections that never complete, exhausting its connection queue.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Layer 7 - Application
Why it's wrong here
Application layer attacks target protocols like HTTP, not TCP handshake.
- ✓
Layer 4 - Transport
Why this is correct
TCP is at the Transport layer, so a SYN flood targets Layer 4.
- ✗
Layer 3 - Network
Why it's wrong here
IP is at Layer 3, but the attack is on TCP, which is Layer 4.
- ✗
Layer 2 - Data Link
Why it's wrong here
SYN flood is a TCP attack, not a Layer 2 attack.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-201 practice question is part of Courseiva's free Cisco 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 200-201 exam.