Apex domains cannot have CNAME records.
Question and response
Question
dig ns1.hyperhosting.gr. NS
Answer
ns1.hyperhosting.gr. 5 NS ns2.hyperhosting.gr.
ns1.hyperhosting.gr. 5 NS ns1.hyperhosting.gr.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0