[Samba] Does DomainCompatibilityMode still work for NT4 domain joins in Windows 10?

[David Whitney]

Greetings!

I have a brand new Windows 10 Pro box, Version 1703, Build 15063.1155, and
made the two registry mods (DNSNameResolutionRequired and
DomainCompatibilityMode) to enable it to join an old-style NT4 Samba domain
(Version 4.3). However, I note that the dialog for joining a domain within
Windows 10 now specifically says to "Join an Active Directory Domain," and
no attempt to join the domain has succeeded. In all cases, the domain name
I provide is not found.

I began to observe a slight delay from the time I would provide the domain
name and receive the failure message, which led me to believe the DNS
lookup is still occurring. I added the name of my DC to both the local
HOSTS file and even the LMHOSTS file on the W10 box, neither to any avail.

I am suspecting now that this most recent build of Windows has quietly
turned off the last vestige of NT4 domain-join support by now ignoring
minimally the DomainCompatibilityMode setting. I was wondering if any other
users with a very recent Windows 10 Pro build might have experienced the
same issue. I have not yet undertaken a network trace to see if the W10 box
is querying DNS for the conspicuous "_ldap..." style AD domain record.

Also, I was wondering why logon for a domain-joined W10 box against an NT4
Samba domain requires the max SMB level to be NT1. My understanding was
that Samba started supporting 3.11 with 4.3.

Many thanks for your attention and consideration. Anyone with additional
information or insight on this would be appreciated!

-David