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