Apex domains cannot have CNAME records.
Question and response
Question
dig quantumart.ru. NS
Answer
quantumart.ru. 5 NS ns02.qdns.ru.
quantumart.ru. 5 NS ns01.qdns.ru.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0