Apex domains cannot have CNAME records.
Question and response
Question
dig nhn-techorus.com. NS
Answer
nhn-techorus.com. 5 NS ns-788.awsdns-34.net.
nhn-techorus.com. 5 NS ns-1683.awsdns-18.co.uk.
nhn-techorus.com. 5 NS ns-405.awsdns-50.com.
nhn-techorus.com. 5 NS ns-1045.awsdns-02.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0