Apex domains cannot have CNAME records.
Question and response
Question
dig unmsapp.com. NS
Answer
unmsapp.com. 5 NS ns-389.awsdns-48.com.
unmsapp.com. 5 NS ns-1906.awsdns-46.co.uk.
unmsapp.com. 5 NS ns-1209.awsdns-23.org.
unmsapp.com. 5 NS ns-861.awsdns-43.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0