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

Results for*.s16.co

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2021-02-20T20:25:46.824	2021-02-15T00:00:00	2022-02-15T23:59:59	s16.co	*.s16.co	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2021-02-20T20:25:46.824	2021-02-15T00:00:00	2022-02-15T23:59:59	s16.co	*.s16.co	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2021-02-15T19:08:55.413	2021-02-15T00:00:00	2022-02-15T23:59:59	s16.co	*.s16.co	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2021-02-15T19:08:55.413	2021-02-15T00:00:00	2022-02-15T23:59:59	s16.co	*.s16.co	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1