Apex domains cannot have CNAME records.
Question and response
Question
dig d3brdux51izex1.cloudfront.net. NS
Answer
d3brdux51izex1.cloudfront.net. 4 NS ns-589.awsdns-09.net.
d3brdux51izex1.cloudfront.net. 4 NS ns-1660.awsdns-15.co.uk.
d3brdux51izex1.cloudfront.net. 4 NS ns-323.awsdns-40.com.
d3brdux51izex1.cloudfront.net. 4 NS ns-1303.awsdns-34.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0