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

Results fortest-adminer.conflabs.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-06-19T16:29:10.725	2020-06-19T15:29:10	2020-09-17T15:29:10	test-adminer.conflabs.com	test-adminer.conflabs.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-06-19T16:29:10.47	2020-06-19T15:29:10	2020-09-17T15:29:10	test-adminer.conflabs.com	test-adminer.conflabs.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-04-20T17:33:11.459	2020-04-20T16:33:11	2020-07-19T16:33:11	test-adminer.conflabs.com	test-adminer.conflabs.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-04-20T17:33:11.246	2020-04-20T16:33:11	2020-07-19T16:33:11	test-adminer.conflabs.com	test-adminer.conflabs.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3