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

Results forwww.opensourcecommunitysummit.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2019-07-13T23:04:26.011	2019-07-13T22:04:25	2019-10-11T22:04:25	www.poly-cases.com	www.opensourcecommunitysummit.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-07-13T23:04:25.019	2019-07-13T22:04:25	2019-10-11T22:04:25	www.poly-cases.com	www.opensourcecommunitysummit.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-07-02T21:39:17.266	2019-07-02T20:39:16	2019-09-30T20:39:16	architectural-designs.com	www.opensourcecommunitysummit.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-07-02T21:39:16.396	2019-07-02T20:39:16	2019-09-30T20:39:16	architectural-designs.com	www.opensourcecommunitysummit.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-06-09T10:31:53.528	2019-06-09T09:31:52	2019-09-07T09:31:52	opensourcecommunitysummit.com	www.opensourcecommunitysummit.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-06-09T10:31:52.702	2019-06-09T09:31:52	2019-09-07T09:31:52	opensourcecommunitysummit.com	www.opensourcecommunitysummit.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3