ccTLD/au/netについて、ここに記述してください。

$ dnsq ns net.au a.au
{{{
2 net.au:
264 bytes, 1+0+4+8 records, response, noerror
query: 2 net.au
authority: net.au 86400 NS x.au
authority: net.au 86400 NS w.au
authority: net.au 86400 NS z.au
authority: net.au 86400 NS y.au
additional: w.au 86400 A 37.209.192.5
additional: w.au 86400 AAAA 2001:dcd:1::5
additional: x.au 86400 A 37.209.194.5
additional: x.au 86400 AAAA 2001:dcd:2::5
additional: y.au 86400 A 37.209.196.5
additional: y.au 86400 AAAA 2001:dcd:3::5
additional: z.au 86400 A 37.209.198.5
additional: z.au 86400 AAAA 2001:dcd:4::5
}}}

ここのadditionalはglueではないので、
別途x.auなどのAを求める必要がある。

慎重なリゾルバーであれば、auのNSを得たときにglueではなくて、Aレコードを求めているはず。

$ dnsq ns aridns.net.au x.au
{{{
2 aridns.net.au:
302 bytes, 1+0+4+8 records, response, noerror
query: 2 aridns.net.au
authority: aridns.net.au 14400 NS ari.beta.aridns.net.au
authority: aridns.net.au 14400 NS ari.alpha.aridns.net.au
authority: aridns.net.au 14400 NS ari.gamma.aridns.net.au
authority: aridns.net.au 14400 NS ari.delta.aridns.net.au
additional: ari.beta.aridns.net.au 14400 A 37.209.194.2
additional: ari.beta.aridns.net.au 14400 AAAA 2001:dcd:2::2
additional: ari.alpha.aridns.net.au 14400 A 37.209.192.2
additional: ari.alpha.aridns.net.au 14400 AAAA 2001:dcd:1::2
additional: ari.delta.aridns.net.au 14400 A 37.209.198.2
additional: ari.delta.aridns.net.au 14400 AAAA 2001:dcd:4::2
additional: ari.gamma.aridns.net.au 14400 A 37.209.196.2
additional: ari.gamma.aridns.net.au 14400 AAAA 2001:dcd:3::2
}}}

$ dnsq ns beta.aridns.net.au ari.beta.aridns.net.au
{{{
2 beta.aridns.net.au:
105 bytes, 1+0+1+0 records, response, authoritative, noerror
query: 2 beta.aridns.net.au
authority: aridns.net.au 900 SOA ari.alpha.aridns.net.au support.ariservices.com 1413306155 1800 300 1814400 1800
}}}