Apex domains cannot have CNAME records.
Question and response
Question
dig ratm.ru. NS
Answer
ratm.ru. 5 NS ns2.ratm.ru.
ratm.ru. 5 NS ns.ratm.ru.
ratm.ru. 5 NS ns4.ratm.ru.
ratm.ru. 5 NS ns3.ratm.ru.
Authority
The response has no authority records.
Additional
ns.ratm.ru. 5 A 95.170.129.134
ns2.ratm.ru. 5 A 37.193.119.40
ns3.ratm.ru. 5 A 185.135.80.183
ns4.ratm.ru. 5 A 185.135.82.159
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0