Apex domains cannot have CNAME records.
Question and response
Question
dig lgsmartplatform.com. NS
Answer
lgsmartplatform.com. 3 NS secns.lg.co.kr.
lgsmartplatform.com. 3 NS prmns.lg.co.kr.
Authority
The response has no authority records.
Additional
prmns.lg.co.kr. 3 A 165.243.5.15
secns.lg.co.kr. 3 A 27.122.242.230
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0