[Samba] Join AD fails DNS update

[Lars Hanke]

I made some substantial progress in finding out what is happening. 
tcpdump was my friend. I always thought the update was internal to the 
the DC, but it is actually a matter of the client talking to the DNS.

The prerequisite, which is considered not satisfied, is:

samba4.ad.microsult.de CNAME NONE 0 0

which means (RFC 2136, 2.4.3) that the said CNAME must not exist.

This makes sense, and it should not exist. I'll try to reproduce this 
using nsupdate. By now samba 3.6.6 seems to do everything right, but the 
DLZ answers wrong, i.e. if there is a bug, it seems to be on the samba4 
side.

Regards,
  - lars.