Apex domains cannot have CNAME records.
Question and response
Question
dig astranet.ru. NS
Answer
astranet.ru. 5 NS ns2.astranet.ru.
astranet.ru. 5 NS ns1.astranet.ru.
Authority
The response has no authority records.
Additional
ns1.ASTRANET.RU. 5 A 178.34.168.30
ns2.ASTRANET.RU. 5 A 178.34.168.31
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0