Quick Answer
The answer is a UDP scan on three ports with service version detection. This command uses the -sU flag to perform a UDP scan, which is critical because UDP services like DNS (port 53) and SNMP (ports 161 and 162) do not respond with a standard handshake like TCP, making them harder to discover. The -sV flag then probes these open UDP ports to identify the exact service and version running, such as the specific DNS server software or SNMP agent version. On the Certified Ethical Hacker CEH exam, this question tests your ability to interpret Nmap flags in a real-world penetration testing scenario, where many students mistakenly assume -sV only works with TCP. A common trap is forgetting that UDP scans are slower and less reliable than TCP scans, so the version detection may be incomplete if the target drops UDP responses. Memory tip: think "UDP is Unreliable, so use -sV to Verify what's actually running."
This CEH practice question tests your understanding of malware, social engineering and network attacks. 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 uses the following command to scan a target: nmap -sU -sV -p 53,161,162 10.0.0.1. Which of the following BEST describes what this scan will accomplish?
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.
Full port scan of all 65535 UDP ports
Why wrong: Only the three specified ports are scanned, not all.
Ping sweep and OS detection on the target
Why wrong: No ping sweep (-sn) or OS detection (-O) flags.
UDP scan on three ports with service version detection
-sU = UDP scan, -sV = version detection, -p specifies the ports.
TCP SYN scan on ports 53, 161, 162 with version detection
Why wrong: -sU is UDP scan, not TCP.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
UDP scan on three ports with service version detection
-sU performs a UDP scan, -sV attempts service version detection on the specified UDP ports (53=DNS, 161=SNMP, 162=SNMP trap).
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.
Full port scan of all 65535 UDP ports
Why it's wrong here
Only the three specified ports are scanned, not all.
Ping sweep and OS detection on the target
Why it's wrong here
No ping sweep (-sn) or OS detection (-O) flags.
UDP scan on three ports with service version detection
Why this is correct
-sU = UDP scan, -sV = version detection, -p specifies the ports.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
TCP SYN scan on ports 53, 161, 162 with version detection
Common exam traps
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
Identify which CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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FAQ
Malware, Social Engineering and Network Attacks — This question tests Malware, Social Engineering and Network Attacks — Read the scenario before looking for a memorised answer..
The correct answer is: UDP scan on three ports with service version detection — -sU performs a UDP scan, -sV attempts service version detection on the specified UDP ports (53=DNS, 161=SNMP, 162=SNMP trap).
Identify which CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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.
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Last reviewed: Jun 21, 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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