Apex domains cannot have CNAME records.
Question and response
Question
dig ekby.gr. NS
Answer
ekby.gr. 5 NS ns1.otenet.gr.
ekby.gr. 5 NS ns2.otenet.gr.
Authority
The response has no authority records.
Additional
ns1.otenet.gr. 5 A 195.170.0.2
ns2.otenet.gr. 5 A 195.170.2.1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0