Apex domains cannot have CNAME records.
Question and response
Question
dig cloud.nospamproxy.com. NS
Answer
cloud.nospamproxy.com. 4 NS ns-1462.awsdns-54.org.
cloud.nospamproxy.com. 4 NS ns-933.awsdns-52.net.
cloud.nospamproxy.com. 4 NS ns-482.awsdns-60.com.
cloud.nospamproxy.com. 4 NS ns-1816.awsdns-35.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0