Quick Answer
The answer is the SMTP VRFY command, which is the correct choice because it directly queries an SMTP server to verify whether a specific mailbox or user exists on that system. When an attacker or security analyst sends a VRFY request followed by a username, the server responds with a success code if the user is valid or a failure code if not, effectively enabling user enumeration by testing a list of potential usernames. On the Certified Ethical Hacker CEH exam, this question tests your understanding of SMTP reconnaissance techniques, often appearing in the footprinting and enumeration domain alongside the EXPN command, which expands mailing lists. A common trap is confusing VRFY with RCPT TO, but remember that VRFY is a server-side verification command, while RCPT TO is used during mail delivery. For a quick memory tip, think “VRFY = Verify Real Folks, Yo”—it checks if the user is real before you even send an email.
This CEH practice question tests your understanding of enumeration and system hacking. 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 analyst wants to enumerate all users from an SMTP server. Which of the following SMTP commands can be used for user enumeration?
DATA
Why wrong: DATA starts the email body.
MAIL FROM
Why wrong: MAIL FROM specifies the sender.
HELO
Why wrong: HELO identifies the client to the server.
VRFY
VRFY checks if a mailbox exists, allowing enumeration.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
VRFY
Option B is correct. The SMTP VRFY command is used to verify if a user exists on the server, enabling user enumeration.
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.
DATA
Why it's wrong here
DATA starts the email body.
MAIL FROM
Why it's wrong here
MAIL FROM specifies the sender.
HELO
Why it's wrong here
HELO identifies the client to the server.
VRFY
Why this is correct
VRFY checks if a mailbox exists, allowing enumeration.
Related concept
Read the scenario before looking for a memorised answer.
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
Enumeration and System Hacking — This question tests Enumeration and System Hacking — Read the scenario before looking for a memorised answer..
The correct answer is: VRFY — Option B is correct. The SMTP VRFY command is used to verify if a user exists on the server, enabling user enumeration.
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.
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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