Apex domains cannot have CNAME records.
Question and response
Question
dig imgsmail.ru. NS
Answer
imgsmail.ru. 5 NS ns1.mail.ru.
imgsmail.ru. 5 NS ns2.mail.ru.
Authority
The response has no authority records.
Additional
ns1.mail.ru. 4 A 217.69.139.112
ns2.mail.ru. 4 A 94.100.180.138
ns1.mail.ru. 4 AAAA 2a00:1148:db00:0:0:0:0:2
ns2.mail.ru. 4 AAAA 2a00:1148:db00:0:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0