The Network Security: Restrict NTLM: NTLM authentication in this domain setting should be configured correctly. This policy setting allows you to deny or allow NTLM authentication within a domain from this domain controller. This policy does not affect interactive logon to this domain controller. Fix: (1) GPO: Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options\Network Security: Restrict NTLM: NTLM authentication in this domain (2) KEY: HKLM\System\CurrentControlSet\Services\Netlogon\Parameters\RestrictNTLMInDomain