Apex domains cannot have CNAME records.
Question and response
Question
dig gov-ncloud.com. NS
Answer
gov-ncloud.com. 2 NS ns1.naver.com.
gov-ncloud.com. 2 NS ns2.naver.com.
Authority
The response has no authority records.
Additional
ns1.naver.com. 2 A 61.247.220.6
ns2.naver.com. 2 A 61.247.221.6
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0