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

Results forbeta.letsbranch.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2018-07-31T06:10:19.402	2018-07-31T05:10:19	2018-10-29T05:10:19	beta.letsbranch.com	beta.letsbranch.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-07-31T06:10:19.058	2018-07-31T05:10:19	2018-10-29T05:10:19	beta.letsbranch.com	beta.letsbranch.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-07-31T06:03:09.641	2018-07-31T05:03:09	2018-10-29T05:03:09	beta.letsbranch.com	beta.letsbranch.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-07-31T06:03:09.476	2018-07-31T05:03:09	2018-10-29T05:03:09	beta.letsbranch.com	beta.letsbranch.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-07-19T15:56:39.58	2018-07-19T14:56:39	2018-10-17T14:56:39	beta.letsbranch.com	beta.letsbranch.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-07-19T15:56:39.325	2018-07-19T14:56:39	2018-10-17T14:56:39	beta.letsbranch.com	beta.letsbranch.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3