A penetration tester is mapping a Windows-based internal network.

CEH v13 teaches that NetBIOS enumeration is a key technique for gathering information in Windows environments without raising alarms. Ports 137 and 139 indicate that NetBIOS Name Service (NBNS) and SMB services are active. The tool nbtstat -A <IP> retrieves valuable information including computer names, logged-in users, domain/workgroup membership, and system roles—all passively and without authentication. CEH emphasizes that querying NetBIOS is often overlooked by defenders and generates minimal noise, making it ideal for stealth enumeration. LDAP enumeration (Option A) requires directory access and tends to trigger logs. Psloggedon and pspasswd (Options B and D) involve active interaction and authentication attempts, which are far more detectable. nbtstat is the CEH-recommended tool for initial reconnaissance on Windows networks using NetBIOS and SMB, especially when quiet enumeration is required.