Apex domains cannot have CNAME records.
Question and response
Question
dig d355vbv4nfva9o.cloudfront.net. NS
Answer
d355vbv4nfva9o.cloudfront.net. 2 NS ns-1542.awsdns-00.co.uk.
d355vbv4nfva9o.cloudfront.net. 2 NS ns-1310.awsdns-35.org.
d355vbv4nfva9o.cloudfront.net. 2 NS ns-366.awsdns-45.com.
d355vbv4nfva9o.cloudfront.net. 2 NS ns-929.awsdns-52.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0