Apex domains cannot have CNAME records.
Question and response
Question
dig sta.211.ru. NS
Answer
sta.211.ru. 5 NS ns2.211.ru.
sta.211.ru. 5 NS ns.211.ru.
sta.211.ru. 5 NS ns4.211.ru.
Authority
The response has no authority records.
Additional
ns.211.ru. 5 A 193.238.131.195
ns2.211.ru. 5 A 89.189.191.224
ns4.211.ru. 5 A 80.67.208.71
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0