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

Results for*.stackrow.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-04-02T20:03:18.668	2020-03-31T00:00:00	2021-04-01T12:00:00	stackrow.com	*.stackrow.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2020-04-02T20:03:18.668	2020-03-31T00:00:00	2021-04-01T12:00:00	stackrow.com	*.stackrow.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2020-03-31T09:15:32.084	2020-03-31T00:00:00	2021-04-01T12:00:00	stackrow.com	*.stackrow.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2020-03-31T09:15:32.084	2020-03-31T00:00:00	2021-04-01T12:00:00	stackrow.com	*.stackrow.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1