Apex domains cannot have CNAME records.
Question and response
Question
dig aironet.RU. NS
Answer
aironet.RU. 5 NS ns2.aironet.RU.
aironet.RU. 5 NS ns.aironet.RU.
Authority
The response has no authority records.
Additional
ns.aironet.ru. 5 A 178.218.48.36
ns2.aironet.ru. 5 A 178.218.49.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0