200-201 Security Monitoring Practice Question
A security analyst is monitoring network traffic and notices a high volume of TCP SYN packets sent to various ports on a single host. Which type of attack is most likely occurring?
⚠ Common exam trap
The trap is that 'high volume of SYN packets' can sound like a SYN flood (DoS), but the key detail is 'to various ports on a single host' — that is reconnaissance (port scan), not a flood, and candidates who fixate on volume alone pick the wrong category.
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
✓
Port scan
A high volume of TCP SYN packets to various ports on a single host is the signature of a port scan, most commonly an SYN (half-open) scan using tools like Nmap with -sS. The scanner sends SYN to many ports and analyzes SYN-ACK (open) versus RST (closed) responses without completing the three-way handshake. This pattern of many SYNs to different ports on one target is the classic reconnaissance footprint.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
DNS amplification
Why it's wrong here
DNS amplification floods a victim with large DNS responses from open resolvers; it does not send TCP SYN packets to many ports. It is tempting because both are volumetric denial-of-service attacks, and would be correct where traffic shows spoofed DNS queries producing oversized replies.
- ✗
Smurf attack
Why it's wrong here
A Smurf attack floods a victim with ICMP echo replies via a spoofed broadcast address, so it produces ICMP traffic, not TCP SYN packets to many ports. It is tempting because Smurf also amplifies traffic toward one host, and would be correct where ICMP echo requests are broadcast to a network's directed broadcast address.
- ✓
Port scan
Why this is correct
A port scan sends TCP SYN packets to many ports on one host, seeking open services. The half-open SYN pattern, with no completed handshake, distinguishes scanning from a SYN flood, which targets a single port. This matches the stem's high-volume SYN traffic to various ports.
- ✗
ARP spoofing
Why it's wrong here
ARP spoofing sends forged ARP replies on the local subnet to redirect traffic; it generates no TCP SYN flood. It is tempting because both are network attacks, and would be correct where a host's MAC address is being impersonated to intercept or alter local traffic.
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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 Cisco exam blueprint
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.