CEH Footprinting, Reconnaissance and Scanning Practice Question
This CEH practice question tests your understanding of footprinting, reconnaissance and scanning. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 security team wants to identify all live hosts on a large, Class B private IP network (172.16.0.0/16) as quickly as possible while minimizing network load. Which tool and technique should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Masscan with --ping to send ICMP echo requests across the /16 range
Masscan is designed for high-speed scanning and can send ICMP echo requests across a /16 range (65,536 IPs) in seconds, far faster than Nmap or hping3, while its --ping mode minimizes network load by using stateless packet transmission. This makes it the optimal choice for quickly identifying live hosts on a large private network without overwhelming the network.
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.
✓
Masscan with --ping to send ICMP echo requests across the /16 range
Why this is correct
Masscan can send ICMP echo requests at very high rates, making it ideal for fast host discovery on large networks.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use theHarvester to query DNS records for the domain
Why it's wrong here
theHarvester is for passive OSINT, not active host discovery on a private network.
✗
Nmap with -sn (ping sweep) on all 65536 IPs
Why it's wrong here
Nmap's ping sweep is relatively slow for such a large range; Masscan is much faster.
✗
hping3 with --icmp on each IP sequentially
Why it's wrong here
hping3 is not designed for large-scale scanning; sequential scanning would be extremely slow.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume Nmap's -sn is the fastest option because it is the most commonly used ping sweep tool, but they overlook Masscan's specialized design for ultra-high-speed scanning across large ranges, which is explicitly tested in CEH questions about minimizing time and network load.
Detailed technical explanation
How to think about this question
Masscan uses a custom TCP/IP stack and asynchronous, stateless packet transmission, allowing it to send packets at rates exceeding 10 million packets per second on appropriate hardware, whereas Nmap's -sn uses a synchronous, stateful method that waits for responses before sending the next probe. The --ping flag in Masscan specifically sends ICMP echo requests (Type 8) and listens for echo replies (Type 0), but it can also be configured to use SYN or ARP probes for faster results on local networks. In real-world scenarios, Masscan is often used for internet-wide scanning (e.g., scanning the entire IPv4 address space), but its speed must be balanced with network policy compliance to avoid triggering intrusion detection systems.
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 practitioner preparing for the CEH exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Footprinting, Reconnaissance and Scanning — This question tests Footprinting, Reconnaissance and Scanning — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Masscan with --ping to send ICMP echo requests across the /16 range — Masscan is designed for high-speed scanning and can send ICMP echo requests across a /16 range (65,536 IPs) in seconds, far faster than Nmap or hping3, while its --ping mode minimizes network load by using stateless packet transmission. This makes it the optimal choice for quickly identifying live hosts on a large private network without overwhelming the network.
What should I do if I get this CEH 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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Question Discussion
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