Apex domains cannot have CNAME records.
Question and response
Question
dig eks.uz. NS
Answer
eks.uz. 5 NS dns2.yandex.net.
eks.uz. 5 NS dns1.yandex.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0