Note to self: If adding a Windows 8.1 computer to a SAMBA domain fails with the error “The specified domain either does not exist or could not be contacted” the following changes to the Registry might help:
Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\LanmanWorkstation\Parameters] ; Enable NT-Domain compatibility mode ; Default: ; [value not present] ; "DomainCompatibilityMode"=- "DomainCompatibilityMode"=dword:00000001 ; Disable required DNS name resolution ; Default: ; [value not present] ; "DNSNameResolutionRequired"=- "DNSNameResolutionRequired"=dword:00000000 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Netlogon\Parameters] ; Disable requirement of signed communication ; My Samba (3.0.33) works with signed communication enabled, so no need to disable it. ; Default: ; "RequireSignOrSeal"=dword:00000001 ; Disable the usage of strong keys ; Default: ; "RequireStrongKey"=dword:00000001 "RequireStrongKey"=dword:00000000
source: the answer from gigiga in the social.technet.microsoft.com forum.