PT0-002 Reconnaissance and Enumeration Practice Question
A penetration tester is using Nmap to identify the operating system of a target host. Which Nmap option should be used to enable OS detection?
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
✓
-O
The -O option enables OS detection in Nmap.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
-sV
Why it's wrong here
-sV is incorrect because it invokes version detection, which probes open ports to identify the exact software and version running on those services. Although version detection can sometimes hint at the underlying OS, it is not a genuine OS fingerprinting technique and does not perform the packet-level analysis necessary to determine the operating system. Therefore, -sV would not be the correct choice when the explicit goal is OS detection.
- ✓
-O
Why this is correct
-O is the correct answer because it is the dedicated Nmap flag for operating system detection. This option works by sending specially crafted TCP and UDP probes to the target and comparing the responses against Nmap's large database of OS fingerprints, thereby identifying the likely operating system. It is the precise, purpose-built switch for this task, unlike broader or unrelated flags.
- ✗
-sC
Why it's wrong here
-sC is wrong because it enables Nmap's default script suite, which runs a collection of common NSE scripts against the target to gather additional service, vulnerability, or misconfiguration information. It does not perform OS detection at all; OS fingerprinting requires the -O switch or the --osscan-guess option. Thus, selecting -sC for operating system identification reflects a misunderstanding of what script scanning actually does.
- ✗
-A
Why it's wrong here
-A is incorrect because it is an aggregate flag that turns on many features at once: OS detection (-O), version detection (-sV), script scanning (-sC), and traceroute. While including OS detection as part of its bundle, it is not the *specific* option for OS detection and also triggers unrelated scans that may be noisy, slow, or undesired. The question asks for the specific option, so -A would not be the precise or minimal answer.
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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.