Apex domains cannot have CNAME records.
Question and response
Question
dig MINDBOX.ru. NS
Answer
MINDBOX.ru. 5 NS ns2.yandexcloud.net.
MINDBOX.ru. 5 NS ns2.edgedns.co.
MINDBOX.ru. 5 NS ns1.edgedns.co.
MINDBOX.ru. 5 NS ns1.yandexcloud.net.
Authority
The response has no authority records.
Additional
ns1.edgedns.co. 5 A 37.9.39.39
ns2.edgedns.co. 5 A 37.9.39.40
ns1.edgedns.co. 5 AAAA 2a11:27c0:1020:0:0:0:0:1039
ns2.edgedns.co. 5 AAAA 2a11:27c0:1020:0:0:0:0:1040
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0