Apex domains cannot have CNAME records.
Question and response
Question
dig rubi-com.RU. NS
Answer
rubi-com.RU. 5 NS ns2.rubi-com.RU.
rubi-com.RU. 5 NS ns1.rubi-com.RU.
Authority
The response has no authority records.
Additional
ns1.rubi-com.ru. 5 A 134.19.151.186
ns2.rubi-com.ru. 5 A 134.19.151.187
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0