Apex domains cannot have CNAME records.
Question and response
Question
dig vsi.RU. NS
Answer
vsi.RU. 5 NS ns.rt.RU.
vsi.RU. 5 NS ns.vsi.RU.
Authority
The response has no authority records.
Additional
ns.vsi.RU. 5 A 80.82.32.9
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0