Apex domains cannot have CNAME records.
Question and response
Question
dig APNIC.NET. NS
Answer
apnic.net. 5 NS ns1.apnic.net.
apnic.net. 5 NS ns4.apnic.net.
apnic.net. 5 NS ns2.apnic.net.
apnic.net. 5 NS apnic.authdns.ripe.net.
Authority
The response has no authority records.
Additional
ns1.apnic.net. 5 A 203.119.42.53
ns2.apnic.net. 5 A 203.119.95.53
ns4.apnic.net. 5 A 202.12.31.53
ns1.apnic.net. 5 AAAA 2001:dd8:e:0:0:0:0:53
ns2.apnic.net. 5 AAAA 2001:ddd:0:0:0:0:0:53
ns4.apnic.net. 5 AAAA 2001:dd8:12:0:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0