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

Results fordeveloper.smart.press

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2019-12-19T03:09:03.718	2019-12-19T02:09:03	2020-03-18T02:09:03	developer.smart.press	developer.smart.press	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-12-19T03:09:03.546	2019-12-19T02:09:03	2020-03-18T02:09:03	developer.smart.press	developer.smart.press	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-10-10T23:48:21.235	2019-10-10T22:48:21	2020-01-08T22:48:21	developer.smart.press	developer.smart.press	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-10-10T23:48:21.069	2019-10-10T22:48:21	2020-01-08T22:48:21	developer.smart.press	developer.smart.press	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-06-13T16:08:14.343	2019-05-25T00:00:00	2020-06-25T12:00:00	*.smart.press	*.smart.press	C=US, O=Amazon, OU=Server CA 1B, CN=Amazon
2019-05-25T06:06:25.108	2019-05-25T00:00:00	2020-06-25T12:00:00	*.smart.press	*.smart.press	C=US, O=Amazon, OU=Server CA 1B, CN=Amazon
2019-05-25T06:06:25.1	2019-05-25T00:00:00	2020-06-25T12:00:00	*.smart.press	*.smart.press	C=US, O=Amazon, OU=Server CA 1B, CN=Amazon