Apex domains cannot have CNAME records.
Question and response
Question
dig inserra.net. NS
Answer
inserra.net. 5 NS ns-118.awsdns-14.com.
inserra.net. 5 NS ns-1693.awsdns-19.co.uk.
inserra.net. 5 NS ns-345.awsdns-43.com.
inserra.net. 5 NS ns-1908.awsdns-46.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0