Apex domains cannot have CNAME records.
Question and response
Question
dig 24unix.net. NS
Answer
24unix.net. 5 NS ns2.24unix.net.
24unix.net. 5 NS ns1.24unix.net.
24unix.net. 5 NS ns3.24unix.net.
Authority
The response has no authority records.
Additional
ns1.24unix.net. 5 A 202.61.245.65
ns2.24unix.net. 5 A 37.120.185.117
ns3.24unix.net. 5 A 91.132.147.24
ns1.24unix.net. 5 AAAA 2a03:4000:53:1bc:b83e:85ff:fe09:f8d0
ns2.24unix.net. 5 AAAA 2a03:4000:f:5e2:a80c:2dff:fed1:e109
ns3.24unix.net. 5 AAAA 2a03:4000:37:76:7481:40ff:fed9:c040
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0