200-201 Security Concepts Practice Question
A security analyst at a mid-sized company is reviewing a packet capture from the DMZ and notices a series of TCP SYN packets sent to multiple ports on a single internal web server, all originating from the same external IP address within a 3-second window. None of the SYN packets are followed by a completed three-way handshake. The analyst must classify this activity to determine the appropriate response. Which type of attack is most consistent with this traffic pattern?
⚠ Common exam trap
A common mix-up: candidates confuse a SYN flood with a port scan, because both send SYNs to multiple ports; however, a port scan typically completes or resets connections and aims to discover services, while a SYN flood deliberately leaves connections half-open to exhaust resources.
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 denial-of-service attack
The traffic pattern of many TCP SYN packets to multiple ports from a single source without completed handshakes is the hallmark of a SYN flood. This attack consumes server resources by leaving connections half-open, preventing legitimate users from establishing sessions. Recognizing this pattern allows the analyst to apply mitigations such as SYN cookies or rate limiting.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
UDP amplification attack
Why it's wrong here
A UDP amplification attack uses spoofed UDP requests to services like DNS or NTP to generate large responses toward a victim. The captured traffic here consists of TCP SYN packets, not UDP, and there is no evidence of amplification or spoofing. Therefore, this option does not fit the observed packet characteristics.
- ✓
SYN flood denial-of-service attack
Why this is correct
A SYN flood sends numerous TCP SYN packets to open ports without completing the three-way handshake, exhausting the server's connection backlog. The scenario describes exactly this: multiple SYNs to different ports from one source with no completed handshakes. This matches the classic half-open connection pattern used to deny service to legitimate users.
- ✗
ARP poisoning attack
Why it's wrong here
ARP poisoning involves sending forged ARP replies to associate an attacker's MAC address with a legitimate IP, enabling man-in-the-middle or denial-of-service on a local segment. The scenario describes external TCP SYN packets targeting a web server, not local ARP traffic. Thus, ARP poisoning is unrelated to the observed pattern.
- ✗
DNS tunneling attack
Why it's wrong here
DNS tunneling encodes data within DNS queries and responses to exfiltrate information or bypass controls. The traffic described is TCP SYN packets to multiple ports, which is not characteristic of DNS tunneling. DNS tunneling typically involves long or unusual DNS query strings and does not resemble a SYN flood.
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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.