Apex domains cannot have CNAME records.
Question and response
Question
dig flexline.ru. NS
Answer
flexline.ru. 5 NS ns5.flexline.ru.
flexline.ru. 5 NS ns4.flexline.ru.
Authority
The response has no authority records.
Additional
ns4.flexline.ru. 5 A 195.28.50.4
ns5.flexline.ru. 5 A 195.28.51.5
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0