Apex domains cannot have CNAME records.
Question and response
Question
dig gigas.com. NS
Answer
gigas.com. 5 NS ns02.gigas.com.
gigas.com. 5 NS ns01.gigas.com.
Authority
The response has no authority records.
Additional
ns01.gigas.com. 5 A 146.255.99.195
ns02.gigas.com. 5 A 199.89.52.35
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0