[Samba] errors during samba_dnsupdate

[Daniel Betschart]

I joined a Samba server to a Windows 2003 server. As far as I can see,
replication works, but sometimes there are errors like this:

; TSIG error with server: tsig verify failure
Failed nsupdate: 2
update (nsupdate): SRV _ldap._tcp.Default-First-Site-
Name._sites.ForestDnsZones.domain.local server03.domain.local 389
Calling nsupdate for SRV _ldap._tcp.Default-First-Site-
Name._sites.ForestDnsZones.domain.local server03.domain.local 389 (add)
Successfully obtained Kerberos ticket to DNS / server03.domain.local as
server03 $
Outgoing update query:
;; - >> HEADER << - opcode: UPDATE, status: NOERROR, id: 0
;; flags :; ZONE: 0, PREREQ: 0, UPDATE: 0, ADDITIONAL: 0
;; UPDATE SECTION:
_ldap._tcp.Default-First-Site-Name._sites.ForestDnsZones.domain.local.
900 IN SRV 0 100 389 server03.domain.local.

If I do this with the --use-samba-tool option, this error looks like
this:

update (samba-tool): SRV _ldap._tcp.Default-First-Site-
Name._sites.ForestDnsZones.domain.local server03.domain.local 389
Calling samba-tool dns for SRV _ldap._tcp.Default-First-Site-
Name._sites.ForestDnsZones.domain.local server03.domain.local 389 (add)
Calling samba-tool dns add -k no -P ['192.168.21.22', 'domain.local',
'_ldap._tcp.Default-First-Site-Name._sites.ForestDnsZones',' SRV ','
server03.ham .local 389 0 100 ']
ERROR (runtime): uncaught exception - (9711,
'WERR_DNS_ERROR_RECORD_ALREADY_EXISTS')
  File "/usr/lib/python2.7/dist-packages/samba/netcmd/__init__.py",
line 177, in _run
    return self.run (* args, ** kwargs)
  File "/usr/lib/python2.7/dist-packages/samba/netcmd/dns.py", line
945, in run
    raise e
Failed 'samba-tool dns' based update of SRV _ldap._tcp.Default-First-
Site-Name._sites.ForestDnsZones.domain.local server03.domain.local 389

Are there such errors because the objects already does already exists
and can I therefore ignore this message?

For the time being, I don't want to change the Windows server, so the
question arises when exactly should I transfer the FSMO role to the
Samba server.

Daniel