Apex domains cannot have CNAME records.
Question and response
Question
dig networkguardpro.com. NS
Answer
networkguardpro.com. 1 NS ns-1168.awsdns-18.org.
networkguardpro.com. 1 NS ns-1293.awsdns-33.org.
networkguardpro.com. 1 NS ns-1183.awsdns-19.org.
networkguardpro.com. 1 NS ns-1552.awsdns-02.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0