Yup, you’re correct. But in common usage, it would be weird to refer to example.com as a subdomain. Depending on the context, it would also be weird to refer to

Yup, you’re correct. But in common usage, it would be weird to refer to example.com as a subdomain. Depending on the context, it would also be weird to refer to foo.example.com as a domain instead of a subdomain. If somebody asked me what domain you’re using and you said “com”, you would technically have answered accurately but they’d be confused.