Apex domains cannot have CNAME records.
Question and response
Question
dig cerf.net. NS
Answer
cerf.net. 5 NS ns-west.cerf.net.
cerf.net. 5 NS ns-east.cerf.net.
Authority
The response has no authority records.
Additional
ns-east.cerf.net. 5 A 99.99.99.136
ns-west.cerf.net. 5 A 68.94.156.136
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0