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