Apex domains cannot have CNAME records.
Question and response
Question
dig sip.everywan.net. NS
Answer
sip.everywan.net. 5 NS ns2.dnsfacil.com.
sip.everywan.net. 5 NS ns1.dnsfacil.com.
Authority
The response has no authority records.
Additional
ns1.dnsfacil.com. 4 A 217.150.212.10
ns2.dnsfacil.com. 4 A 51.15.253.221
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0