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

Results forhostmaster.37.vc

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2022-11-22T18:05:55.278	2022-11-22T17:05:54	2023-02-20T17:05:53	37.vc	*.37.vc	C=US, O=Let's Encrypt, CN=E1
2022-11-22T18:05:54.574	2022-11-22T17:05:54	2023-02-20T17:05:53	37.vc	*.37.vc	C=US, O=Let's Encrypt, CN=E1
2022-08-24T17:20:05.788	2022-08-24T16:20:05	2022-11-22T16:20:04	37.vc	*.37.vc	C=US, O=Let's Encrypt, CN=E1
2022-08-24T17:20:05.607	2022-08-24T16:20:05	2022-11-22T16:20:04	37.vc	*.37.vc	C=US, O=Let's Encrypt, CN=E1
2021-02-13T17:56:13.542	2021-02-13T16:56:13	2021-05-14T16:56:13	hostmaster.37.vc	hostmaster.37.vc	C=US, O=Let's Encrypt, CN=R3
2021-02-13T17:56:13.415	2021-02-13T16:56:13	2021-05-14T16:56:13	hostmaster.37.vc	hostmaster.37.vc	C=US, O=Let's Encrypt, CN=R3