Apex domains cannot have CNAME records.
Question and response
Question
dig snapfirewall.com. NS
Answer
snapfirewall.com. 5 NS ns-694.awsdns-22.net.
snapfirewall.com. 5 NS ns-594.awsdns-10.net.
snapfirewall.com. 5 NS ns-215.awsdns-26.com.
snapfirewall.com. 5 NS ns-771.awsdns-32.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0