Apex domains cannot have CNAME records.
Question and response
Question
dig nc. NS
Answer
nc. 5 NS ns1.nc.
nc. 5 NS ns2.nc.
nc. 5 NS any-ns1.nc.
nc. 5 NS nc.cctld.authdns.ripe.net.
Authority
The response has no authority records.
Additional
ns1.nc. 136370 A 202.87.129.16
ns2.nc. 136370 A 202.87.129.17
any-ns1.nc. 136370 A 114.69.222.1
ns1.nc. 136370 AAAA 2404:2200:10:1000:0:0:53:1
ns2.nc. 136370 AAAA 2404:2200:10:1000:0:0:53:2
any-ns1.nc. 136370 AAAA 2001:500:14:8000:7245:de00:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0