[Samba] samba_kcc issue after joining the domain as a DC

[Alex]

Hello,

I'm  trying  to  promote samba4 as a 3rd DC in Windows 2008 R2 AD domain (to get
rid  of  Windows  Servers in future). It's joined well, but failing on samba_kcc
run (it's happened when I launched samba after joining the domain, so for
debugging purposes I then started samba_kcc manually):
# /usr/local/samba/sbin/samba_kcc
Traceback (most recent call last):
  File "/usr/local/samba/lib64/python3.6/site-packages/samba/kcc/kcc_utils.py", line 87, in load_nc
    scope=ldb.SCOPE_BASE, attrs=attrs)
_ldb.LdbError: (32, 'No such Base DN: DC=DomainDnsZones,DC=domain,DC=com')
...
  File "/usr/local/samba/lib64/python3.6/site-packages/samba/kcc/kcc_utils.py", line 92, in load_nc
    (self.nc_dnstr, estr))
samba.kcc.kcc_utils.KCCError: Unable to find naming context (DC=DomainDnsZones,DC=domain,DC=com) - (No such Base DN: DC=DomainDnsZones,DC=domain,DC=com)

I joined the domain with the following command:
samba-tool domain join domain.com DC -k yes --dns-backend NONE --server=vm-dc1.domain.com

vm-dc1 does have the mentioned context b/c it's a domain naming master.
Wondering why samba tries to find it - it's not a domain naming master..

Any ideas are highly appreciated!

-- 
Best regards,
Alex