Apex domains cannot have CNAME records.
Question and response
Question
dig sproducers.com. NS
Answer
sproducers.com. 3 NS pns73.cloudns.com.
sproducers.com. 3 NS pns72.cloudns.net.
sproducers.com. 3 NS ns71.cloudns.net.
sproducers.com. 3 NS ns74.cloudns.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0