Apex domains cannot have CNAME records.
Question and response
Question
dig shellit.org. NS
Answer
shellit.org. 3 NS sofia.ns.cloudflare.com.
shellit.org. 3 NS ian.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0