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

Results foraccess.plexlink.net

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2022-07-09T10:12:06.857	2022-07-09T09:12:06	2022-10-07T09:12:05	activation.nolimitdata.net	access.plexlink.net	C=US, O=Let's Encrypt, CN=R3
2022-07-09T10:12:06.133	2022-07-09T09:12:06	2022-10-07T09:12:05	activation.nolimitdata.net	access.plexlink.net	C=US, O=Let's Encrypt, CN=R3
2022-05-10T11:11:19.008	2022-05-10T10:11:18	2022-08-08T10:11:17	activation.nolimitdata.net	access.plexlink.net	C=US, O=Let's Encrypt, CN=R3
2022-05-10T11:11:18.711	2022-05-10T10:11:18	2022-08-08T10:11:17	activation.nolimitdata.net	access.plexlink.net	C=US, O=Let's Encrypt, CN=R3
2022-03-11T12:10:31.196	2022-03-11T11:10:30	2022-06-09T11:10:29	activation.nolimitdata.net	access.plexlink.net	C=US, O=Let's Encrypt, CN=R3
2022-03-11T12:10:31.002	2022-03-11T11:10:30	2022-06-09T11:10:29	activation.nolimitdata.net	access.plexlink.net	C=US, O=Let's Encrypt, CN=R3