Apex domains cannot have CNAME records.
Question and response
Question
dig atel.su. NS
Answer
atel.su. 2 NS ns1.beget.ru.
atel.su. 2 NS ns2.beget.ru.
atel.su. 2 NS ns1.beget.pro.
atel.su. 2 NS ns1.beget.com.
atel.su. 2 NS ns2.beget.com.
atel.su. 2 NS ns2.beget.pro.
Authority
The response has no authority records.
Additional
ns1.beget.ru. 2 A 5.101.159.11
ns1.beget.com. 2 A 5.101.159.11
ns1.beget.pro. 2 A 5.101.159.11
ns2.beget.ru. 2 A 185.50.27.12
ns2.beget.com. 2 A 185.50.27.12
ns2.beget.pro. 2 A 185.50.27.12
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0