The correct answer is a ping sweep using ICMP echo requests, as this technique sends a single Type 8 packet to each potential host and listens for a Type 0 echo reply, making it the most efficient method for live host discovery with minimal network overhead. Unlike a full port scan, which probes multiple ports and generates significant traffic, a ping sweep for host discovery relies on the fundamental ICMP protocol to quickly map active devices without overwhelming the network or triggering intrusion detection systems. On the Certified Ethical Hacker CEH exam, this concept tests your understanding of reconnaissance phases and traffic efficiency, often appearing in questions that contrast ping sweeps with ARP scans or TCP SYN scans. A common trap is assuming a full port scan is always better, but remember that a ping sweep is the stealthiest first step for host discovery. Memory tip: think “one ping, one reply” for ICMP Type 8 and Type 0—the simplest path to live hosts.
CEH Footprinting, Reconnaissance and Scanning Practice Question
This CEH practice question tests your understanding of footprinting, reconnaissance and 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 security analyst wants to identify all live hosts on a network without generating excessive traffic. Which of the following techniques is MOST appropriate for this purpose?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Ping sweep using ICMP echo requests
A ping sweep using ICMP Echo Requests (Type 8) is the most efficient method to identify live hosts on a network because it sends a single packet per target and listens for ICMP Echo Replies (Type 0). This generates minimal traffic compared to full port scans, making it ideal for initial reconnaissance without overwhelming the network or triggering intrusion detection systems.
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.
✗
Banner grabbing with Netcat
Why it's wrong here
Banner grabbing is used to identify services on open ports, not to discover live hosts. It requires prior knowledge of open ports.
✗
Full TCP connect scan on all ports
Why it's wrong here
A full TCP connect scan on all ports generates much more traffic and is not efficient for simply identifying live hosts.
✗
UDP scan on common ports
Why it's wrong here
UDP scanning is slower and less reliable for host discovery, and it generates more traffic than a ping sweep.
✓
Ping sweep using ICMP echo requests
Why this is correct
Ping sweep sends ICMP echo requests to multiple IPs; replies indicate live hosts. It is efficient and low-traffic.
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 often confuse host discovery with service discovery, choosing a port-based scan (like TCP connect or UDP) because they think 'scanning' always involves ports, but the question explicitly asks for identifying live hosts with minimal traffic, which is the textbook purpose of a ping sweep.
Detailed technical explanation
How to think about this question
Under the hood, ICMP Echo Requests are processed at the network layer (IP) without involving transport-layer ports, so a single packet can determine host liveness even if firewalls block TCP/UDP scans. In real-world scenarios, many administrators block ICMP at the perimeter, so a ping sweep may fail against hardened networks, requiring alternative techniques like ARP scans (local subnet) or TCP SYN pings on common ports (e.g., 80, 443) to bypass ICMP filtering while still keeping traffic low.
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: Ping sweep using ICMP echo requests — A ping sweep using ICMP Echo Requests (Type 8) is the most efficient method to identify live hosts on a network because it sends a single packet per target and listens for ICMP Echo Replies (Type 0). This generates minimal traffic compared to full port scans, making it ideal for initial reconnaissance without overwhelming the network or triggering intrusion detection systems.
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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