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

Results forapi.flatroofingedinburgh.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2021-07-28T02:39:55.306	2021-07-28T01:39:55	2021-10-26T01:39:53	api.flatroofingedinburgh.com	api.flatroofingedinburgh.com	C=US, O=Let's Encrypt, CN=R3
2021-07-28T02:39:55.152	2021-07-28T01:39:55	2021-10-26T01:39:53	api.flatroofingedinburgh.com	api.flatroofingedinburgh.com	C=US, O=Let's Encrypt, CN=R3
2021-07-28T02:23:00.241	2021-07-28T01:22:59	2021-10-26T01:22:57	www.api.flatroofingedinburgh.com	www.api.flatroofingedinburgh.com	C=US, O=Let's Encrypt, CN=R3
2021-07-28T02:22:59.753	2021-07-28T01:22:59	2021-10-26T01:22:57	www.api.flatroofingedinburgh.com	www.api.flatroofingedinburgh.com	C=US, O=Let's Encrypt, CN=R3