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

Results forgoogleauthenticatation.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2019-07-30T23:44:23.186	2019-07-30T22:44:22	2019-10-28T22:44:22	googleauthenticatation.com	googleauthenticatation.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-07-30T23:44:22.557	2019-07-30T22:44:22	2019-10-28T22:44:22	googleauthenticatation.com	googleauthenticatation.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-07-30T21:23:25.87	2019-07-30T20:23:24	2019-10-28T20:23:24	googleauthenticatation.com	googleauthenticatation.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-07-30T21:23:24.725	2019-07-30T20:23:24	2019-10-28T20:23:24	googleauthenticatation.com	googleauthenticatation.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3