It can be anything! An apex, subdomain, or even a URL.

Results for*.blockmine.us

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-01-28T05:21:12.02	2020-01-25T00:00:00	2021-01-24T12:00:00	*.blockmine.us	*.blockmine.us	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2020-01-28T05:21:12.02	2020-01-25T00:00:00	2021-01-24T12:00:00	*.blockmine.us	*.blockmine.us	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2020-01-25T20:40:15.541	2020-01-25T00:00:00	2021-01-24T12:00:00	*.blockmine.us	*.blockmine.us	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2020-01-25T20:40:15.541	2020-01-25T00:00:00	2021-01-24T12:00:00	*.blockmine.us	*.blockmine.us	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1