Apex domains cannot have CNAME records.
Question and response
Question
dig mailspike.net. NS
Answer
mailspike.net. 2 NS ns11.mailspike.net.
mailspike.net. 2 NS ns12.mailspike.net.
mailspike.net. 2 NS ns13.mailspike.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0