Apex domains cannot have CNAME records.
Question and response
Question
dig kakaowork.com. NS
Answer
kakaowork.com. 2 NS ns-545.awsdns-04.net.
kakaowork.com. 2 NS ns-1898.awsdns-45.co.uk.
kakaowork.com. 2 NS ns-205.awsdns-25.com.
kakaowork.com. 2 NS ns-1193.awsdns-21.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0