PT0-002 Reconnaissance and Enumeration Practice Question
A penetration tester is tasked with performing active reconnaissance on an internal network. The tester wants to identify live hosts and their open ports efficiently while minimizing noise. Which Nmap scan type should be used first to quickly discover which hosts are online?
⚠ Common exam trap
Candidates often choose full port scans (-sS or -sT) for initial discovery, overlooking that -sn is specifically designed for low-noise host discovery.
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
✓
nmap -sn 192.168.1.0/24
The `-sn` flag (ping scan) sends ICMP echo requests, TCP SYN to port 443, TCP ACK to port 80, and ICMP timestamp requests by default to determine if hosts are online without performing port scans. This minimizes network noise and quickly identifies live hosts on the subnet, which is the first step in active reconnaissance before deeper scanning.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
nmap -sS -sV 192.168.1.0/24
Why it's wrong here
This combines SYN scan and version detection, which is too noisy for initial discovery.
- ✗
nmap -A 192.168.1.0/24
Why it's wrong here
Aggressive scan includes OS detection, version detection, and scripts, which is noisy.
- ✓
nmap -sn 192.168.1.0/24
Why this is correct
Correct. Ping sweep quickly identifies live hosts.
- ✗
nmap -sT 192.168.1.0/24
Why it's wrong here
TCP connect scan is slower and more detectable.
Visual reference
Go deeper
Related to this question
Learn chapter
Advanced Nmap: Scripting Engine (NSE)
Key term
Nmap
Nmap is a network scanning tool used to discover hosts, services, and operating systems on a computer network.
Key term
Active reconnaissance
Active reconnaissance is the process of directly interacting with a target system or network to gather information, often through scanning and probing.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PT0-003 practice question is part of Courseiva's free CompTIA 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 PT0-003 exam.