It can be anything! An apex, subdomain, or even a URL.
Domain Name: webmail.sai.cxDomain Status: No Object Found>>> Last update of WHOIS database: 2024-09-22T05:25:49.012Z <<<
Domain Name: webmail.sai.cx
Domain Status: No Object Found
>>> Last update of WHOIS database: 2024-09-22T05:25:49.012Z <<<