Apex domains cannot have CNAME records.
Question and response
Question
dig spf-report.com. NS
Answer
spf-report.com. 5 NS ns-1442.awsdns-52.org.
spf-report.com. 5 NS ns-1567.awsdns-03.co.uk.
spf-report.com. 5 NS ns-92.awsdns-11.com.
spf-report.com. 5 NS ns-588.awsdns-09.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0