Apex domains cannot have CNAME records.
Question and response
Question
dig epserv.ru. NS
Answer
epserv.ru. 5 NS marty.ns.cloudflare.com.
epserv.ru. 5 NS alla.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0