Apex domains cannot have CNAME records.
Question and response
Question
dig d1vkrexmt9sd4l.cloudfront.net. NS
Answer
d1vkrexmt9sd4l.cloudfront.net. 5 NS ns-1899.awsdns-45.co.uk.
d1vkrexmt9sd4l.cloudfront.net. 5 NS ns-100.awsdns-12.com.
d1vkrexmt9sd4l.cloudfront.net. 5 NS ns-637.awsdns-15.net.
d1vkrexmt9sd4l.cloudfront.net. 5 NS ns-1207.awsdns-22.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0