CEH Enumeration and System Hacking Practice Question
A penetration tester runs `nbtstat -A 192.168.1.10` on a Windows machine. The output reveals the NetBIOS name table and shows a <20> entry. What does this indicate?
⚠ Common exam trap
It's easy for candidates to confuse the <20> entry with a general 'server' role, but the CEH exam specifically tests the mapping of NetBIOS suffixes to services, where <20> uniquely identifies the File Server Service, not a domain controller or workstation.
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
✓
The target is a file server
The <20> entry in the NetBIOS name table indicates that the target machine is running the File Server service, which is a NetBIOS service type for file sharing. The `nbtstat -A` command queries the remote NetBIOS name table, and the <20> hex code specifically maps to the 'File Server Service' (also known as the 'Server' service) in the NetBIOS naming convention, as defined in RFC 1001/1002. This service is essential for SMB-based file sharing, making the target a file server.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The target is a printer
Why it's wrong here
The presence of specific NetBIOS suffixes in `nbtstat -a` output is key to identifying a device's role. Printers typically register a <07> suffix, indicating a print server service, or sometimes a <21> for a Remote Access Service, which some network-attached printers might utilize for management. The absence of these particular entries, and the presence of a <20> suffix instead, definitively rules out the target being primarily identified as a network printer.
- ✓
The target is a file server
Why this is correct
The NetBIOS suffix <20> (hexadecimal) is specifically registered by a computer running the Server service, which is fundamentally responsible for sharing files and printers over the network. When `nbtstat -a` reveals a <20> entry for a target IP address, it strongly indicates that the machine is configured to act as a file server, making its shared resources available to other network clients. This is the definitive indicator for a file server role.
- ✗
The target is a domain controller
Why it's wrong here
Domain controllers register distinct NetBIOS names to advertise their critical roles within an Active Directory environment. A <1C> entry signifies a Domain Group Name, representing the domain itself, while a <1B> entry indicates the Domain Master Browser, responsible for maintaining the list of network resources. The absence of these specific and essential entries in the `nbtstat` output means the target is not functioning as a domain controller.
- ✗
The target is a workstation
Why it's wrong here
A standard Windows workstation typically registers a <00> (workstation service) entry along with its unique computer name in its NetBIOS name table. While a workstation can also run the Server service and thus display a <20> entry, the primary indicator for a generic workstation is often the <00> suffix. However, the explicit presence of <20> points more specifically to a server role, rather than just a basic workstation.
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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.