- A
TCP SYN scan to common ports
Why wrong: SYN scan is for port scanning, not host discovery, and uses IP.
- B
Nmap ping sweep with -sn
Why wrong: Ping sweep uses ICMP or TCP probes at Layer 3, which may be blocked or require IP.
- C
arp-scan
arp-scan uses ARP (Layer 2) to discover hosts on the local subnet.
- D
SNMP walk
Why wrong: SNMP walk queries SNMP agents on known hosts, not host discovery.
Question 446 of 1,000
PT0-002 Practice Question: Information Gathering and Vulnerability Scanning
This PT0-002 practice question tests your understanding of information gathering and vulnerability scanning. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 performing internal network scanning and wants to identify live hosts on a local subnet without sending IP packets. Which method is most effective in a switched Ethernet environment?
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
✓
arp-scan
In a switched Ethernet environment, ARP (Address Resolution Protocol) operates at Layer 2 and does not require IP packets to discover hosts. The `arp-scan` tool sends ARP requests to the local broadcast MAC address, and live hosts respond with their MAC addresses, making it the most effective method for identifying live hosts without sending IP 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.
- ✗
TCP SYN scan to common ports
Why it's wrong here
SYN scan is for port scanning, not host discovery, and uses IP.
- ✗
Nmap ping sweep with -sn
- ✓
arp-scan
Why this is correct
arp-scan uses ARP (Layer 2) to discover hosts on the local subnet.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
SNMP walk
Why it's wrong here
SNMP walk queries SNMP agents on known hosts, not host discovery.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume Nmap's `-sn` ping sweep is the standard for host discovery, overlooking that it relies on IP-layer packets, whereas ARP operates at Layer 2 and is the only method that avoids IP packets entirely on a local subnet.
Detailed technical explanation
How to think about this question
ARP operates at Layer 2 of the OSI model, using broadcast frames (destination MAC FF:FF:FF:FF:FF:FF) to resolve IP addresses to MAC addresses. In a switched network, ARP requests are flooded to all ports, and only the host with the matching IP responds, making it reliable for host discovery. A subtle behavior is that ARP-scan can also detect hosts that are firewalled or have no IP stack running, as long as they have an IP configured and respond to ARP.
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.
Visual reference
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
What to study next
Got this wrong? Here's your next step.
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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: arp-scan — In a switched Ethernet environment, ARP (Address Resolution Protocol) operates at Layer 2 and does not require IP packets to discover hosts. The `arp-scan` tool sends ARP requests to the local broadcast MAC address, and live hosts respond with their MAC addresses, making it the most effective method for identifying live hosts without sending IP 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.
About these practice questions
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Last reviewed: Jul 4, 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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