Network security: Restrict NTLM: NTLM authentication in this domain

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.

If you select "Disabled" or do not configure this policy setting, the domain controller will allow all NTLM pass-through authentication requests within the domain.

If you select "Deny for domain accounts to domain servers" the domain controller will deny all NTLM authentication logon attempts to all servers in the domain that are using domain accounts and return an NTLM blocked error unless the server name is on the exception list in the "Network security: Restrict NTLM: Add server exceptions for NTLM authentication in this domain" policy setting.

If you select "Deny for domain account" the domain controller will deny all NTLM authentication logon attempts from domain accounts and return an NTLM blocked error unless the server name is on the exception list in the "Network security: Restrict NTLM: Add server exceptions for NTLM authentication in this domain" policy setting.

If you select "Deny for domain servers" the domain controller will deny NTLM authentication requests to all servers in the domain and return an NTLM blocked error unless the server name is on the exception list in the "Network security: Restrict NTLM: Add server exceptions for NTLM authentication in this domain" policy setting.

If you select "Deny all," the domain controller will deny all NTLM pass-through authentication requests from its servers and for its accounts and return an NTLM blocked error unless the server name is on the exception list in the "Network security: Restrict NTLM: Add server exceptions for NTLM authentication in this domain" policy setting.

This policy is supported on at least Windows Server 2008 R2.

Note: Block events are recorded on this computer in the "NTLMBlock" Log located under the Applications and Services Log/Microsoft/Windows/Security-NTLM.