It can be anything! An apex, subdomain, or even a URL.
Domain Name: www.rdap.whois.aiDomain Status: No Object Found>>> Last update of WHOIS database: 2024-09-20T13:33:22.866Z <<<
Domain Name: www.rdap.whois.ai
Domain Status: No Object Found
>>> Last update of WHOIS database: 2024-09-20T13:33:22.866Z <<<