Apex domains cannot have CNAME records.
Question and response
Question
dig ktcloud.com. NS
Answer
ktcloud.com. 4 NS ns2.kornet.net.
ktcloud.com. 4 NS ns.kornet.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0