[Samba] Join AD fails DNS update

[Dr. Lars Hanke]

Thanks Rowland, this gives a more comprehensive view.

> The problem is probably that you are only searching on port 389, try
> this search:
> ldbsearch -LLL -x -h localhost -p 3268 -b "DC=example,DC=com" -s sub -D
> "CN=Administrator,CN=Users,DC=example,DC=com" -w <ADpassword>

The syntax looks like ldapsearch instead of ldbsearch, but yes this 
search returns the DNS entries maintained by the AD DC. It does not 
contain any entry for a machine calles samba4, i.e. the error that it 
cannot be added since it exists already is wrong, remember:

client 172.16.6.242#40938: updating zone 'ad.microsult.de/NONE': update 
unsuccessful: samba4.ad.microsult.de/A: 'RRset exists (value dependent)' 
prerequisite not satisfied (NXRRSET)

Still the only entity about the joined machine is:

ldapsearch -LLL -x -h localhost -p 3268 -b "DC=ad,DC=microsult,DC=de" -s 
sub -D "CN=Administrator,CN=Users,DC=ad,DC=microsult,DC=de" -W | grep -i 
samba4 | grep ^dn:
Enter LDAP Password:
dn: CN=samba4,CN=Computers,DC=ad,DC=microsult,DC=de

The process logging the error is named, but it claims to propagate an 
error from within samba_dlz. Too tired to dig into the code tonight ...

... and we learned that the DNS records except root servers are not 
stored in sam.ldb. However, a construct like:

for f in `find / -type f -name '*.ldb'`; do echo File: $f; ldbsearch 
--url="$f" | grep -i samba | grep ^dn: ; done

showed it's in

private/sam.ldb.d/DC=DOMAINDNSZONES,DC=AD,DC=MICROSULT,DC=DE.ldb

but no, there's no trace of any machine called samba4 in it.

Cheers,
  - lars.