Apex domains cannot have CNAME records.
Question and response
Question
dig i-shn.net. NS
Answer
i-shn.net. 5 NS ns-1368.awsdns-43.org.
i-shn.net. 5 NS ns-1965.awsdns-53.co.uk.
i-shn.net. 5 NS ns-80.awsdns-10.com.
i-shn.net. 5 NS ns-712.awsdns-25.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0