Apex domains cannot have CNAME records.
Question and response
Question
dig send-mail4.xyz. NS
Answer
send-mail4.xyz. 5 NS ns72.domaincontrol.com.
send-mail4.xyz. 5 NS ns71.domaincontrol.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0