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200-201 Practice Question: During network intrusion analysis, an analyst…
During network intrusion analysis, an analyst observes a TCP connection with the SYN flag set but no subsequent ACK. This pattern is indicative of:
⚠ Common exam trap
Cisco often tests the distinction between a normal three-way handshake and an incomplete handshake pattern, where candidates mistakenly think any SYN packet indicates a legitimate connection attempt rather than recognizing the missing ACK as the hallmark of a SYN flood.
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 attack
A SYN flood attack is a type of denial-of-service (DoS) attack where the attacker sends a high volume of TCP SYN packets to a target server but never completes the three-way handshake by sending the final ACK. This leaves the server with half-open connections, consuming resources and potentially exhausting the connection backlog, which prevents legitimate clients from establishing connections.
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 attack
Why this is correct
Incomplete SYN handshakes are a sign of SYN flood.
- ✗
DNS resolution
Why it's wrong here
DNS mostly uses UDP, not TCP with SYN.
- ✗
Normal three-way handshake
Why it's wrong here
Normal handshake includes ACK after SYN.
- ✗
ICMP echo request
Why it's wrong here
ICMP does not use TCP flags.
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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.