Apex domains cannot have CNAME records.
Question and response
Question
dig sloth1688.online. NS
Answer
sloth1688.online. 5 NS henry.ns.cloudflare.com.
sloth1688.online. 5 NS marissa.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0