[Samba] After upgrade to 4.9.4, internal DNS no longer working

[L.P.H. van Belle]

Hai Viktor, 
 
Yes, i did keep that in mind that it was an upgrade, that exact why im responding. ;-)
 
If in the base  /etc/hostname, /etc/nsswitch.conf and /etc/resolv.conf or systemd  cointains wrong settings, you might inherit these. 
So it might be that a previous samba was accepting these settings, but a latest samba not. 
Or a previous systemd version accepted these and a newer not.. 
 
Setting : DNSStubListener=No in /etc/systemd/resolved.conf. 
is correct also, yes, its what you preffer, i mask the needed services. 
 
>hostname is DC1, confirmed by hostnamectl, resolv.conf has just two entries: nameserver (own IP), and search samdom.example.com. Same as it is now, so this all works. 
Just that because it works, that does not tell you if its correct. 
 
 
I dont expect that this problem is a samba problem, because we would have seen moch more messages. 
i still say, the upgrade problem is due your setup.  ( sorry ) 
 
Now, if you going to upgrade, i suggest review you setup closely. 
And keep Rowland and my advice in mind. 
 
 
Greetz, 
 
Louis