Apex domains cannot have CNAME records.
Question and response
Question
dig spamcontrol.gr. NS
Answer
spamcontrol.gr. 4 NS ns1.spamcontrol.gr.
spamcontrol.gr. 4 NS ns2.spamcontrol.gr.
Authority
The response has no authority records.
Additional
ns1.spamcontrol.gr. 4 A 185.23.88.13
ns2.spamcontrol.gr. 4 A 31.22.113.13
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0