Apex domains cannot have CNAME records.
Question and response
Question
dig cfdns.info. NS
Answer
cfdns.info. 3 NS ns1.cfdns.info.
cfdns.info. 3 NS ns2.cfdns.info.
cfdns.info. 3 NS ns3.cfdns.info.
cfdns.info. 3 NS ns4.cfdns.info.
Authority
The response has no authority records.
Additional
ns1.cfdns.info. 3 A 199.73.82.8
ns2.cfdns.info. 3 A 199.73.83.8
ns3.cfdns.info. 3 A 204.138.102.8
ns4.cfdns.info. 3 A 192.188.176.8
ns1.cfdns.info. 3 AAAA 2620:1f:8000:0:0:0:0:8
ns2.cfdns.info. 3 AAAA 2620:1f:8002:0:0:0:0:8
ns3.cfdns.info. 3 AAAA 2620:1f:8004:0:0:0:0:8
ns4.cfdns.info. 3 AAAA 2620:1f:8006:0:0:0:0:8
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0