Apex domains cannot have CNAME records.
Question and response
Question
dig restream.rt.ru. NS
Answer
restream.rt.ru. 5 NS ns7.restream.rt.ru.
restream.rt.ru. 5 NS ns2.restream.rt.ru.
restream.rt.ru. 5 NS ns6.restream.rt.ru.
restream.rt.ru. 5 NS ns4.restream.rt.ru.
restream.rt.ru. 5 NS ns5.restream.rt.ru.
restream.rt.ru. 5 NS ns3.restream.rt.ru.
restream.rt.ru. 5 NS ns1.restream.rt.ru.
Authority
The response has no authority records.
Additional
ns1.restream.rt.ru. 5 A 188.254.12.121
ns2.restream.rt.ru. 5 A 188.254.13.121
ns3.restream.rt.ru. 5 A 95.167.22.94
ns4.restream.rt.ru. 5 A 188.254.13.61
ns5.restream.rt.ru. 5 A 95.167.22.46
ns6.restream.rt.ru. 5 A 188.254.13.195
ns7.restream.rt.ru. 5 A 188.254.12.138
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0