Hi Bernd,
Quote Originally Posted by nntp-user View Post

when configure LAN via YaST I been ask for a hostname during the
configuration of a interface (LAN-Card).

And in the Hostname/DNS-Settings (one level above) I been asked for a
hostname and a domain name.

Why are there two locations to configure the hostname? And what is the
background for this double config? And last but not least: Should I
enter only a hostname or a FQDN in the interface settings?

the "upper-level" configuration (in the tab "Hostname / DNS") is for the actual *host name*, which is the "system level" name and each host can only have *one* of these. The per-interface configuration is about the IP-to-name Mapping (not saying "DNS" here on purpose), to properly generate /etc/hosts entries. It's even mentioned in the Yast help screen (thought not as explicitly for the variant on the DNS config screen)