Quick Answer
The correct answer is SMB/RPC enumeration over port 445. This is because the `rpcclient` tool with the `-U '' -N` flags initiates a null session, allowing an unauthenticated connection to a Windows target over the Server Message Block (SMB) protocol. Once connected, commands like `enumdomusers` and `enumdomgroups` leverage Microsoft Remote Procedure Call (MS-RPC) functions to enumerate domain users and groups, with these RPC calls tunneled through SMB—by default over port 445 on modern systems. On the Certified Ethical Hacker CEH exam, this scenario tests your understanding of how legacy null session attacks still work against misconfigured systems, often appearing in questions about network service enumeration or footprinting. A common trap is confusing this with NetBIOS enumeration over port 139; remember that while both can carry SMB, port 445 is the direct SMB transport for modern Windows. Memory tip: think “SMB 445, RPC inside” to recall that the protocol is SMB, the service is RPC, and the port is 445.
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.
An attacker uses 'rpcclient -U '' -N 192.168.1.10' followed by 'enumdomusers' and 'enumdomgroups'. What type of enumeration is being performed, and which protocol does it rely on?
LDAP enumeration over port 389
Why wrong: LDAP uses ldapsearch or adfind, not rpcclient.
SMB/RPC enumeration over port 445
rpcclient uses MS-RPC over SMB, typically port 445.
NetBIOS enumeration over port 139
Why wrong: NetBIOS enumeration uses nbtstat, not rpcclient.
SNMP enumeration over port 161
Why wrong: SNMP enumeration uses snmpwalk or snmpget.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
SMB/RPC enumeration over port 445
The `rpcclient` tool with the `-U '' -N` flags performs a null session connection to a Windows system over the SMB protocol. The subsequent `enumdomusers` and `enumdomgroups` commands enumerate domain users and groups via MS-RPC (Remote Procedure Call) functions, which are transported over SMB. By default, modern Windows systems use SMB over port 445, making option B the correct choice.
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.
LDAP enumeration over port 389
Why it's wrong here
LDAP uses ldapsearch or adfind, not rpcclient.
SMB/RPC enumeration over port 445
Why this is correct
rpcclient uses MS-RPC over SMB, typically port 445.
Related concept
Read the scenario before looking for a memorised answer.
NetBIOS enumeration over port 139
Why it's wrong here
NetBIOS enumeration uses nbtstat, not rpcclient.
SNMP enumeration over port 161
Why it's wrong here
SNMP enumeration uses snmpwalk or snmpget.
Common exam traps
The trap here is that candidates confuse the underlying protocol (SMB/RPC on port 445) with the older NetBIOS session service (port 139), or mistakenly associate user/group enumeration solely with LDAP, not realizing that `rpcclient` uses MS-RPC over SMB.
Detailed technical explanation
Under the hood, `rpcclient` leverages the MSRPC (Microsoft Remote Procedure Call) protocol, which relies on the SMB transport for named pipe communication (e.g., `\pipe\samr` for security account manager queries). The `enumdomusers` command calls the `SamrEnumerateUsersInDomain` RPC function, which returns a list of user RIDs and names. In a real-world scenario, a successful null session (no credentials) on a misconfigured Windows system allows an attacker to map the entire domain user and group structure, often as a precursor to password spraying or privilege escalation.
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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Enumeration and System Hacking — study guide chapter
Learn the concepts, then practise the questions
Enumeration and System Hacking practice questions
Targeted practice on this topic area only
All CEH questions
1,010 questions across all exam domains
Certified Ethical Hacker CEH study guide
Full concept coverage aligned to exam objectives
CEH practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise CEH questions linked to Footprinting, Reconnaissance and Scanning.
Practise CEH questions linked to Enumeration and System Hacking.
Practise CEH questions linked to Malware, Social Engineering and Network Attacks.
Practise CEH questions linked to Web Application and Injection Attacks.
Practise CEH questions linked to Introduction to Ethical Hacking.
Practise CEH questions linked to Scanning Networks and Enumeration.
Practise CEH questions linked to Vulnerability Analysis and System Hacking.
Practise CEH questions linked to Advanced Topics: Wireless, Cloud, IoT, Cryptography.
Practise CEH questions linked to Footprinting and Reconnaissance.
Practise CEH questions linked to Network and Web Application Attacks.
Practise CEH questions linked to Wireless, IoT and Cloud Security.
Practise CEH questions linked to Cryptography and Malware Analysis.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
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: SMB/RPC enumeration over port 445 — The `rpcclient` tool with the `-U '' -N` flags performs a null session connection to a Windows system over the SMB protocol. The subsequent `enumdomusers` and `enumdomgroups` commands enumerate domain users and groups via MS-RPC (Remote Procedure Call) functions, which are transported over SMB. By default, modern Windows systems use SMB over port 445, making option B the correct choice.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 24, 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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.