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

Results forhostmaster.odakyapi.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2021-05-19T04:16:28.662	2021-05-19T03:16:28	2021-08-17T03:16:28	hostmaster.odakyapi.com	hostmaster.odakyapi.com	C=US, O=Let's Encrypt, CN=R3
2021-05-19T04:16:28.525	2021-05-19T03:16:28	2021-08-17T03:16:28	hostmaster.odakyapi.com	hostmaster.odakyapi.com	C=US, O=Let's Encrypt, CN=R3
2020-09-21T11:15:21.021	2020-09-21T10:15:20	2020-12-20T10:15:20	smartgardener.com.au	*.odakyapi.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-09-21T11:15:20.787	2020-09-21T10:15:20	2020-12-20T10:15:20	smartgardener.com.au	*.odakyapi.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-07-23T11:15:28.668	2020-07-23T10:15:28	2020-10-21T10:15:28	odakyapi.com	*.odakyapi.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-07-23T11:15:28.405	2020-07-23T10:15:28	2020-10-21T10:15:28	odakyapi.com	*.odakyapi.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3