Apex domains cannot have CNAME records.
Question and response
Question
dig haeahn.com. NS
Answer
haeahn.com. 3 NS ns.gabia.co.kr.
haeahn.com. 3 NS ns.gabia.net.
haeahn.com. 3 NS ns1.gabia.co.kr.
Authority
The response has no authority records.
Additional
ns.gabia.co.kr. 3 A 43.201.170.100
ns.gabia.net. 3 A 121.78.117.39
ns.gabia.net. 3 A 211.234.124.90
ns1.gabia.co.kr. 3 A 20.200.205.248
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0