I have joined a Samba server 4.9.5 to a Microsoft SBS 2011 server, i.e. a Windows Server 2008 R2. That worked, but only if I made the replication of the DNS reverse zone Windows 2000 compatible. However, Samba now cannot replicate the DNS. Before I changed the replication typ of the reverse zone, I received error 9003, 'WERR_DNS_ERROR_RCODE_NAME_ERROR' when trying to join. Unfortunately, only afterwards did I see https://wiki.samba.org/index.php/Samba_AD_DC_Troubleshooting#DNS what I should have done. Can I do this now after the join? What happens if I change the legacy DNS zones to the modern locations? Is the DNS preserved? Can I join the Samba server again afterwards or can I join the same machine only once? Would it be better if I reinstalled the Samba server? On the Windows server, I only have to delete it from the Domain Controllers structure, right? The replication error messages in /var/log/samba/log.samba: [2020/03/27 11:07:29.302958, 0] ../lib/util/util_runcmd.c:327(samba_runcmd_io_handler) /usr/sbin/samba_dnsupdate: ; TSIG error with server: tsig verify failure [2020/03/27 11:07:29.306816, 0] ../lib/util/util_runcmd.c:327(samba_runcmd_io_handler) /usr/sbin/samba_dnsupdate: update failed: REFUSED [2020/03/27 11:07:29.332424, 0] ../source4/dsdb/dns/dns_update.c:330(dnsupdate_nameupdate_done) ../source4/dsdb/dns/dns_update.c:330: Failed DNS update - with error code 1