Apex domains cannot have CNAME records.
Question and response
Question
dig cfback.net. NS
Answer
cfback.net. 1 NS ns1.g01.cfdns.net.
cfback.net. 1 NS ns3.g01.cfdns.info.
cfback.net. 1 NS ns2.g01.cfdns.biz.
cfback.net. 1 NS ns4.g01.cfdns.co.uk.
Authority
The response has no authority records.
Additional
ns2.g01.cfdns.biz. 3 A 199.73.83.1
ns3.g01.cfdns.info. 3 A 204.138.102.1
ns4.g01.cfdns.co.uk. 3 A 192.188.176.1
ns2.g01.cfdns.biz. 3 AAAA 2620:1f:8002:0:0:0:0:1
ns3.g01.cfdns.info. 3 AAAA 2620:1f:8004:0:0:0:0:1
ns4.g01.cfdns.co.uk. 3 AAAA 2620:1f:8006:0:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0