Apex domains cannot have CNAME records.
Question and response
Question
dig METAPLAST-RUS.RU. NS
Answer
metaplast-rus.ru. 4 NS mario.ns.cloudflare.com.
metaplast-rus.ru. 4 NS sara.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0