CEH Scanning Networks and Enumeration Practice Question
During an internal penetration test, you are tasked with enumerating services on a target server. You run a full TCP port scan and find that ports 22 (SSH), 80 (HTTP), and 443 (HTTPS) are open. You then perform version detection on these ports. Which additional enumeration step would provide the most valuable information for identifying potential vulnerabilities?
⚠ Common exam trap
EC-Council often tests the misconception that SNMP, DNS zone transfers, or NetBIOS enumeration are universally applicable, but the trap here is that these techniques only work when the corresponding services are actually running and accessible — the question explicitly limits open ports to 22, 80, and 443, so only banner grabbing on those ports is directly actionable.
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
✓
Perform banner grabbing on port 22 to identify the SSH version.
Banner grabbing on port 22 (SSH) is the most valuable next step because it directly identifies the SSH server version (e.g., OpenSSH 7.4). Knowing the exact version allows you to cross-reference known vulnerabilities (CVEs) for that specific SSH implementation, which is a common high-risk attack vector during internal penetration tests. While version detection already identified the service, banner grabbing can reveal additional details like patch levels or configuration quirks that version detection might miss.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Perform banner grabbing on port 22 to identify the SSH version.
Why this is correct
Banner grabbing on port 22, typically used for SSH, is a fundamental reconnaissance technique. By connecting to the port and observing the initial response, an attacker can identify the specific SSH server software and its version number. This version information is crucial for cross-referencing against public vulnerability databases (e.g., CVEs) to discover known exploits, potentially leading to unauthorized access or privilege escalation if an outdated or misconfigured version is in use.
- ✗
Perform SNMP enumeration to gather system information.
Why it's wrong here
Performing SNMP enumeration is inappropriate without prior indication of the service running, as SNMP typically operates over UDP port 161. While it can yield extensive system information, blindly attempting it on a generic server during an internal penetration test is inefficient and unlikely to succeed unless a port scan specifically identifies UDP 161 as open and responsive. The absence of an open SNMP port makes this an ineffective initial enumeration strategy.
- ✗
Attempt a DNS zone transfer from the server.
Why it's wrong here
Attempting a DNS zone transfer is a technique specifically designed to extract comprehensive DNS records from a DNS server, not a general web server. This method is only viable if the target server is configured as an authoritative DNS server and permits zone transfers, which is not indicated here. Applying this technique to a non-DNS server would yield no useful information and is a misapplication of the reconnaissance method.
- ✗
Enumerate NetBIOS names using `nbtstat`.
Why it's wrong here
Enumerating NetBIOS names using `nbtstat` is primarily relevant for identifying Windows-based systems and their shared resources. NetBIOS services typically communicate over UDP ports 137 and 138, and TCP port 139. Without specific information suggesting a Windows host or these ports being open, attempting NetBIOS enumeration is generally ineffective and a poor use of time during initial reconnaissance on an unknown server.
Go deeper
Related to this question
About these practice questions
This CEH question is part of Courseiva's 870-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
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.