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

Results forgroup5.tworksystem.org

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-05-26T07:32:58.887	2020-05-26T06:32:58	2020-08-24T06:32:58	tworksystem.org	*.tworksystem.org	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-05-26T07:32:58.703	2020-05-26T06:32:58	2020-08-24T06:32:58	tworksystem.org	*.tworksystem.org	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-09-22T03:16:13.537	2018-09-22T02:16:12	2018-12-21T02:16:12	group5.tworksystem.org	group5.tworksystem.org	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-09-22T03:16:12.84	2018-09-22T02:16:12	2018-12-21T02:16:12	group5.tworksystem.org	group5.tworksystem.org	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-07-24T03:35:54.871	2018-07-24T02:35:54	2018-10-22T02:35:54	group5.tworksystem.org	group5.tworksystem.org	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-07-24T03:35:54.637	2018-07-24T02:35:54	2018-10-22T02:35:54	group5.tworksystem.org	group5.tworksystem.org	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3