Default Domain Name Linux. Host name is generally put in the etchostname file. Thankfully its still only one line - just using the resolvectl.
Thus resulting in a domain with local extension. Add below line in etcsysconfignetwork. Edit your hostname not FQDN in etchostname file.
I was looking for a solution to this issue for Ubuntu Focal 2004 as my local domain was not appending to hostnames.
A hostname show or set the systems host name b domainname show or set the systems NISYP domain name c dnsdomainname show the systems DNS domain name d nisdomainname show or set systems NISYP domain name e ypdomainname show or set the systems NISYP domain name. Setting a default domain name allows users to log in with only their user name not specifying the domain name which would be required for users outside the primary domain. Thus resulting in a domain with local extension. ABoth Linux UNIX comes with the following utilities to display hostname domain name.