Apex domains cannot have CNAME records.
Question and response
Question
dig plutoweb.io. NS
Answer
plutoweb.io. 5 NS ns2.world4you.at.
plutoweb.io. 5 NS ns1.world4you.at.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0