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

Results forbinaryoptionsspain.com.o71.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-11-18T01:49:34.381	2020-11-18T00:49:34	2021-02-16T00:49:34	binaryoptionsspain.com.o71.com	binaryoptionsspain.com.o71.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-11-18T01:49:34.164	2020-11-18T00:49:34	2021-02-16T00:49:34	binaryoptionsspain.com.o71.com	binaryoptionsspain.com.o71.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-09-19T11:37:43.772	2020-09-19T10:37:43	2020-12-18T10:37:43	binaryoptionsspain.com.o71.com	binaryoptionsspain.com.o71.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-09-19T11:37:43.552	2020-09-19T10:37:43	2020-12-18T10:37:43	binaryoptionsspain.com.o71.com	binaryoptionsspain.com.o71.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3