Apex domains cannot have CNAME records.
Question and response
Question
dig dynamic.hinet.net. NS
Answer
dynamic.hinet.net. 4 NS ipdns2.hinet.net.
dynamic.hinet.net. 4 NS ipdns1.hinet.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0