CEH Enumeration and System Hacking Practice Question
A penetration tester is enumerating an SMTP server on port 25. They issue the command `VRFY root` and receive a 250 response, then `VRFY admin` also returns 250. What does this indicate about the SMTP server?
⚠ Common exam trap
Many candidates confuse the VRFY command's 250 success response with authentication success or syntax errors, when in fact it strictly indicates user existence on the server.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Both root and admin are valid email accounts on the server
The VRFY command is used to verify whether a specific user exists on an SMTP server. A 250 response code indicates that the user is valid and the mailbox exists. Since both `root` and `admin` returned 250, this confirms that both are valid email accounts on the server, making option A correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Both root and admin are valid email accounts on the server
Why this is correct
The 250 SMTP response code indicates that the requested mail action was successful and completed. In the context of the VRFY command, a 250 response explicitly confirms that the specified user, such as 'root' or 'admin', is a valid and existing account on the server. This direct confirmation of user existence is precisely what the penetration tester is looking for during enumeration, making both accounts valid.
- ✗
The SMTP server supports password authentication
Why it's wrong here
The VRFY command is designed solely to verify the existence of a mailbox or user on the SMTP server, not to facilitate or test authentication mechanisms. SMTP authentication, typically initiated with the AUTH command, involves a separate handshake where credentials are provided and validated. The successful VRFY responses provide no indication whatsoever that the server supports password-based login for these accounts, only that they exist.
- ✗
The command failed due to syntax errors
Why it's wrong here
An SMTP response code of 250 signifies a successful command execution, indicating that the server understood and processed the VRFY request without any syntax issues. If the command had failed due to syntax errors, the server would typically return a 500-series error code, such as 500 (Syntax error, command unrecognized) or 501 (Syntax error in parameters or arguments). The consistent 250 responses confirm proper command formatting and server understanding.
- ✗
The SMTP server has disabled user verification
Why it's wrong here
If the SMTP server had disabled user verification, the VRFY command would typically elicit a 550 response code (Mailbox unavailable or User not found) or a similar error indicating that the server does not permit such queries. The consistent 250 responses explicitly contradict the notion that user verification is disabled, as they confirm the successful verification of the specified accounts. A disabled VRFY command would actively prevent the confirmation of user existence.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.