Apex domains cannot have CNAME records.
Question and response
Question
dig cloudfloordns.com. NS
Answer
cloudfloordns.com. 5 NS ns1.g01.cfdns.net.
cloudfloordns.com. 5 NS ns2.g01.cfdns.biz.
cloudfloordns.com. 5 NS ns3.g01.cfdns.info.
cloudfloordns.com. 5 NS ns4.g01.cfdns.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0