Quick Answer
Masscan is the correct choice because it is purpose-built for fast live host discovery across a large IP range, such as the 10.0.0.0/8 subnet, by leveraging asynchronous transmission and raw sockets to send SYN probes at rates exceeding 10 million packets per second. Unlike slower tools like Nmap, which use sequential scanning, Masscan’s high-speed packet injection allows it to probe all 16.7 million addresses in a /8 range in just a few minutes, making it the best tool for rapid reconnaissance. On the Certified Ethical Hacker CEH exam, this question tests your understanding of scanning methodology and tool specialization—common traps include choosing Nmap for its popularity or Angry IP Scanner for its simplicity, but Masscan is the only option designed for massive scale. A helpful memory tip: think “Masscan = Massive scan,” as its name directly reflects its ability to handle massive IP ranges at blistering speeds.
This CEH practice question tests your understanding of footprinting, reconnaissance and 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.
Which of the following tools would be BEST to use for identifying all live hosts in a large IP range (e.g., 10.0.0.0/8) quickly?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Masscan
Masscan is optimized for speed and can scan large ranges quickly.
OpenVAS
Why wrong: OpenVAS is a vulnerability scanner, not designed for rapid host discovery.
Nmap with -sL flag
Why wrong: -sL is a list scan that does not send packets, so it cannot identify live hosts.
hping3
Why wrong: hping3 is useful for custom packet crafting but is slower for large ranges.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Masscan
Masscan is the best choice because it is designed for high-speed scanning across large IP ranges, capable of transmitting packets at rates exceeding 10 million packets per second. It uses asynchronous transmission and raw sockets to quickly identify live hosts by sending SYN probes and analyzing responses, making it ideal for scanning a /8 subnet (16.7 million addresses) in minutes.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Masscan
Why this is correct
Masscan is optimized for speed and can scan large ranges quickly.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
OpenVAS
Why it's wrong here
OpenVAS is a vulnerability scanner, not designed for rapid host discovery.
Nmap with -sL flag
Why it's wrong here
-sL is a list scan that does not send packets, so it cannot identify live hosts.
hping3
Why it's wrong here
hping3 is useful for custom packet crafting but is slower for large ranges.
Common exam traps
EC-Council often tests the distinction between scanning speed and functionality, where candidates mistakenly choose Nmap (a versatile tool) for large-range host discovery without recognizing that its default scanning modes are too slow for a /8 subnet, whereas Masscan is purpose-built for speed.
Detailed technical explanation
Masscan operates by sending SYN packets to random ports (default port 80) and uses a custom TCP/IP stack to handle responses asynchronously, allowing it to scan the entire IPv4 internet in under 5 minutes under optimal conditions. It supports output formats compatible with Nmap, enabling further analysis of discovered hosts. In real-world scenarios, penetration testers use Masscan for initial reconnaissance to quickly map large internal networks (e.g., 10.0.0.0/8) before performing detailed scans with tools like Nmap.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Footprinting, Reconnaissance and Scanning — study guide chapter
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FAQ
Footprinting, Reconnaissance and Scanning — This question tests Footprinting, Reconnaissance and Scanning — Read the scenario before looking for a memorised answer..
The correct answer is: Masscan — Masscan is the best choice because it is designed for high-speed scanning across large IP ranges, capable of transmitting packets at rates exceeding 10 million packets per second. It uses asynchronous transmission and raw sockets to quickly identify live hosts by sending SYN probes and analyzing responses, making it ideal for scanning a /8 subnet (16.7 million addresses) in minutes.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Read the scenario before looking for a memorised answer.
About these practice questions
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. 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?
mediumWhy A: 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.
Last reviewed: Jun 30, 2026
This CEH practice question is part of Courseiva's free EC-Council 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 CEH exam.
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