Apex domains cannot have CNAME records.
Question and response
Question
dig OS-CAR.RU. NS
Answer
OS-CAR.RU. 5 NS ns3.nic.RU.
OS-CAR.RU. 5 NS ns8.nic.RU.
OS-CAR.RU. 5 NS ns4.nic.RU.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0