Apex domains cannot have CNAME records.
Question and response
Question
dig svyaz-telekom.ru. NS
Answer
svyaz-telekom.ru. 4 NS ns2.svyaz-telekom.ru.
svyaz-telekom.ru. 4 NS ns1.svyaz-telekom.ru.
Authority
The response has no authority records.
Additional
ns1.svyaz-telekom.RU. 4 A 134.19.151.186
ns2.svyaz-telekom.RU. 4 A 134.19.151.187
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0