200-201 Network Intrusion Analysis Practice Question
An analyst examines a PCAP and finds a series of UDP packets sent to multiple ports on a target. The target responds with ICMP 'Destination Unreachable (Port Unreachable)' messages for each port. What type of scan is being performed?
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
✓
UDP scan
UDP scan sends UDP packets to ports. When a port is closed, the target responds with an ICMP port unreachable message. Open or filtered ports may not respond.
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 scan
Why this is correct
UDP scan uses UDP packets; ICMP unreachable indicates closed port.
- ✗
SYN scan
Why it's wrong here
SYN scan uses TCP SYN packets.
- ✗
Xmas scan
Why it's wrong here
Xmas scan uses TCP packets with FIN, URG, PUSH flags.
- ✗
FIN scan
Why it's wrong here
FIN scan uses TCP FIN packets.
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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.