Apex domains cannot have CNAME records.
Question and response
Question
dig 130-190.45.238.178.in-addr.arpa. NS
Answer
130-190.45.238.178.in-addr.arpa. 5 NS nsc.hlubina.com.
130-190.45.238.178.in-addr.arpa. 5 NS nsb.hlubina.com.
130-190.45.238.178.in-addr.arpa. 5 NS nsa.hlubina.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0