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

Results for*.dyn.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2014-12-21T17:34:45.014	2013-10-22T12:00:01	2015-08-12T12:00:00	*.dyn.com	*.dyn.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert SHA2 High Assurance Server CA
2014-12-21T17:34:45.014	2013-10-22T12:00:01	2015-08-12T12:00:00	*.dyn.com	*.dyn.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert SHA2 High Assurance Server CA
2014-04-10T13:42:28.25	2013-10-22T12:00:01	2015-08-12T12:00:00	*.dyn.com	*.dyn.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert SHA2 High Assurance Server CA
2014-04-10T13:42:28.25	2013-10-22T12:00:01	2015-08-12T12:00:00	*.dyn.com	*.dyn.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert SHA2 High Assurance Server CA
2013-03-26T09:10:53.846	2012-06-04T00:00:00	2015-08-12T12:00:00	*.dyn.com	*.dyn.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert High Assurance CA-3
2013-03-26T09:10:53.846	2012-06-04T00:00:00	2015-08-12T12:00:00	*.dyn.com	*.dyn.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert High Assurance CA-3