Apex domains cannot have CNAME records.
Question and response
Question
dig cfdns.biz. NS
Answer
cfdns.biz. 4 NS ns4.cfdns.biz.
cfdns.biz. 4 NS ns1.cfdns.biz.
cfdns.biz. 4 NS ns2.cfdns.biz.
cfdns.biz. 4 NS ns3.cfdns.biz.
Authority
The response has no authority records.
Additional
ns1.cfdns.biz. 4 A 199.73.82.7
ns2.cfdns.biz. 4 A 199.73.83.7
ns3.cfdns.biz. 4 A 204.138.102.7
ns4.cfdns.biz. 4 A 192.188.176.7
ns1.cfdns.biz. 4 AAAA 2620:1f:8000:0:0:0:0:7
ns2.cfdns.biz. 4 AAAA 2620:1f:8002:0:0:0:0:7
ns3.cfdns.biz. 4 AAAA 2620:1f:8004:0:0:0:0:7
ns4.cfdns.biz. 4 AAAA 2620:1f:8006:0:0:0:0:7
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0