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

Results forplex.local.barbrick.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2019-12-04T06:36:00.162	2019-12-04T05:35:59	2020-03-03T05:35:59	plex.local.barbrick.com	plex.local.barbrick.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-12-04T06:36:00.017	2019-12-04T05:35:59	2020-03-03T05:35:59	plex.local.barbrick.com	plex.local.barbrick.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-12-04T06:28:12.229	2019-12-04T05:28:11	2020-03-03T05:28:11	plex.local.barbrick.com	plex.local.barbrick.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-12-04T06:28:12.073	2019-12-04T05:28:11	2020-03-03T05:28:11	plex.local.barbrick.com	plex.local.barbrick.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-12-04T05:20:24.427	2019-12-04T04:20:24	2020-03-03T04:20:24	plex.local.barbrick.com	plex.local.barbrick.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-12-04T05:20:24.314	2019-12-04T04:20:24	2020-03-03T04:20:24	plex.local.barbrick.com	plex.local.barbrick.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-12-04T04:43:30.264	2019-12-04T03:43:29	2020-03-03T03:43:29	plex.local.barbrick.com	plex.local.barbrick.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-12-04T04:43:29.817	2019-12-04T03:43:29	2020-03-03T03:43:29	plex.local.barbrick.com	plex.local.barbrick.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3