- A
Perform an ARP scan using arp-scan from a connected workstation.
Why wrong: ARP scanning is an active technique that sends ARP requests to the network, which can be detected by security monitoring tools.
- B
Run Wireshark to capture traffic and analyze source IP addresses and TCP/IP stack signatures.
Wireshark (or similar tools) passively captures network traffic. Source IPs reveal active hosts, and analysis of TCP/IP parameters (e.g., TTL, window size) allows OS fingerprinting without sending any packets.
- C
Use Nmap with the -sn flag to perform a ping sweep of the subnet.
Why wrong: Nmap -sn (ping sweep) sends ICMP echo requests, TCP pings, or ARP probes, all of which are active scans that generate network traffic and may be detected.
- D
Initiate a DNS zone transfer request to the internal DNS servers.
Why wrong: A DNS zone transfer is an active query that requests all DNS records from a nameserver. It may be restricted and generates network traffic.
Quick Answer
The answer is to run Wireshark to capture traffic and analyze source IP addresses and TCP/IP stack signatures. This technique is correct because a network tap provides a read-only copy of all traffic, allowing for passive host discovery without injecting any packets that could trigger detection. By examining fields like TTL values, TCP window sizes, and IP ID patterns in captured frames, you can identify live hosts and fingerprint their operating systems entirely offline. On the CompTIA PenTest+ PT0-002 exam, this scenario tests your understanding of passive reconnaissance versus active scanning—a common trap is choosing ARP scans or Nmap ping sweeps, which send detectable packets. Remember the key distinction: if the requirement is zero network noise, you must rely solely on what the wire already carries. A useful memory tip is "Tap, don't zap"—the tap lets you listen without speaking, and Wireshark’s packet details reveal the OS through its digital handshake signature.
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 has been given access to a network tap on a client's internal network. The tester wants to perform initial reconnaissance by identifying all live hosts and their operating systems without sending any packets that could be detected. Which technique is most appropriate?
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
Run Wireshark to capture traffic and analyze source IP addresses and TCP/IP stack signatures.
Option B is correct because capturing traffic with Wireshark from a network tap is entirely passive—it never injects packets into the network. By analyzing source IP addresses and TCP/IP stack signatures (e.g., TTL values, window sizes, and IP ID patterns), the tester can identify live hosts and infer their operating systems without sending any detectable traffic. This aligns perfectly with the requirement to avoid sending any packets.
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.
- ✗
Perform an ARP scan using arp-scan from a connected workstation.
Why it's wrong here
ARP scanning is an active technique that sends ARP requests to the network, which can be detected by security monitoring tools.
- ✓
Run Wireshark to capture traffic and analyze source IP addresses and TCP/IP stack signatures.
- ✗
Use Nmap with the -sn flag to perform a ping sweep of the subnet.
- ✗
Initiate a DNS zone transfer request to the internal DNS servers.
Why it's wrong here
A DNS zone transfer is an active query that requests all DNS records from a nameserver. It may be restricted and generates network traffic.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume passive techniques like packet capture cannot identify operating systems, or they mistakenly think that ARP scans and ping sweeps are 'quiet' because they use low-level protocols, forgetting that any packet injection is detectable.
Detailed technical explanation
How to think about this question
Passive OS fingerprinting via packet capture relies on subtle differences in TCP/IP stack implementations, such as initial TTL values (e.g., 64 for Linux, 128 for Windows), TCP window size scaling, and the DF (Don't Fragment) flag behavior. A network tap provides a copy of all traffic without altering the flow, making it ideal for stealthy reconnaissance. In real-world engagements, this technique is often used to map internal networks without triggering alarms, especially in high-security environments where active scanning is prohibited.
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 security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Information Gathering and Vulnerability Scanning — study guide chapter
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FAQ
Questions learners often ask
What does this PT0-002 question test?
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: Run Wireshark to capture traffic and analyze source IP addresses and TCP/IP stack signatures. — Option B is correct because capturing traffic with Wireshark from a network tap is entirely passive—it never injects packets into the network. By analyzing source IP addresses and TCP/IP stack signatures (e.g., TTL values, window sizes, and IP ID patterns), the tester can identify live hosts and infer their operating systems without sending any detectable traffic. This aligns perfectly with the requirement to avoid sending any packets.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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.
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