Disable LLMNR and NBT-NS via Group Policy: 2026 Security Guide
LLMNR (Link-Local Multicast Name Resolution) and NBT-NS (NetBIOS Name Service) are legacy name resolution protocols that attackers exploit to capture credentials through poisoning attacks. When a Windows client can’t resolve a hostname via DNS, it falls back to broadcasting LLMNR and NBT-NS queries across the network — and attackers respond with malicious answers, capturing authentication attempts. Tools like Responder and Inveigh make this attack trivial, turning misconfigured name resolution into domain compromise. This guide shows how to disable LLMNR and NBT-NS via Group Policy, with registry paths, PowerShell verification, testing procedures, and complete rollback instructions for Windows 11 and Server 2025 environments. ...