It can be anything! An apex, subdomain, or even a URL.
Domain Name: katy.undefined.aiDomain Status: No Object Found>>> Last update of WHOIS database: 2024-09-21T11:46:56.417Z <<<
Domain Name: katy.undefined.ai
Domain Status: No Object Found
>>> Last update of WHOIS database: 2024-09-21T11:46:56.417Z <<<