The answer is `nmap -sV --top-ports 100 target`. This command is the most appropriate because the `--top-ports 100` option restricts the scan to only the 100 most frequently open ports, which directly minimizes network traffic and scan time by avoiding the overhead of scanning all 65,535 ports or a large arbitrary range. On the CompTIA PenTest+ PT0-002 exam, this question tests your understanding of efficient reconnaissance—specifically how to balance thoroughness with stealth and speed. A common trap is choosing a full port scan or a large range like `-p 1-1000`, which generates far more packets and takes longer; the key insight is that `--top-ports` uses a statistically derived list of the most common ports, making it the most efficient choice. For a memory tip, think “Top 100, time well-spent”—the `--top-ports` flag is your go-to for a fast, low-traffic sweep that still catches the high-value targets.
PT0-002 Practice Question: Information Gathering and Vulnerability Scanning
This PT0-002 practice question tests your understanding of information gathering and vulnerability scanning. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A penetration tester is using Nmap to scan a target web server. The tester only wants to see which of the top 100 ports are open, but wants to minimize network traffic and time. Which Nmap command is most appropriate?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
nmap -sV --top-ports 100 target
Option D is correct because `--top-ports 100` instructs Nmap to scan only the 100 most commonly open ports, which minimizes network traffic and time compared to scanning all ports or a large range. The `-sV` flag enables version detection, which is not strictly required but is commonly used in information gathering; however, the key factor for minimizing traffic and time is the `--top-ports` option, which uses a statistically derived list to reduce scan scope.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 -p- target
Why it's wrong here
-p- scans all ports, creating more traffic and taking longer.
✗
nmap -sT -p 1-100 target
Why it's wrong here
Scans ports 1-100 numerically, missing common ports like 443, 3306, etc. that are above 100.
✗
nmap -sC -p 1-1000 target
Why it's wrong here
Scans 1000 ports, more than needed, and runs default scripts, increasing traffic.
✓
nmap -sV --top-ports 100 target
Why this is correct
--top-ports 100 scans the most frequently open ports, minimizing traffic and time while focusing on likely candidates.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse `-p 1-100` (first 100 ports numerically) with `--top-ports 100` (most commonly open ports), leading them to choose option B, which misses high-numbered common ports like 443 (HTTPS) or 8080 (HTTP-alt).
Detailed technical explanation
How to think about this question
Nmap's `--top-ports` option uses a frequency table compiled from millions of scans to select the most commonly open ports (e.g., 80, 443, 22, 21), rather than a sequential range. This approach drastically reduces scan time because it avoids scanning thousands of rarely open ports, and the underlying scan type defaults to `-sS` (SYN stealth scan) when run as root, which is faster and less intrusive than a connect scan. In real-world assessments, using `--top-ports 100` with `-sV` balances speed with service identification, but for pure port discovery, `--top-ports 100` alone suffices.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this PT0-002 question in full detail.
Information Gathering and Vulnerability Scanning — This question tests Information Gathering and Vulnerability Scanning — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: nmap -sV --top-ports 100 target — Option D is correct because `--top-ports 100` instructs Nmap to scan only the 100 most commonly open ports, which minimizes network traffic and time compared to scanning all ports or a large range. The `-sV` flag enables version detection, which is not strictly required but is commonly used in information gathering; however, the key factor for minimizing traffic and time is the `--top-ports` option, which uses a statistically derived list to reduce scan scope.
What should I do if I get this PT0-002 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This PT0-002 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 PT0-002 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.