Apex domains cannot have CNAME records.
Question and response
Question
dig central01.net. NS
Answer
central01.net. 5 NS ns1.central01.net.
central01.net. 5 NS ns2.central01.net.
Authority
The response has no authority records.
Additional
ns1.central01.net. 5 A 138.204.100.5
ns2.central01.net. 5 A 138.204.100.5
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0