DNS/glue/bind-9.14.0について、ここに記述してください。

$ rndc flush
WARNING: key file (/etc/rndc.key) exists, but using default configuration file (/etc/rndc.conf)

$ dig +norec -t ns com
...

$ dig -t ns com @127.0.0.1

; <<>> DiG 9.14.0 <<>> -t ns com @127.0.0.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 48004
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 13, AUTHORITY: 0, ADDITIONAL: 27

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
; COOKIE: 58ca49b6066b155a63de9f725ca21205d72650be664b4f09 (good)
;; QUESTION SECTION:
;com.                           IN      NS

;; ANSWER SECTION:
com.                    172799  IN      NS      g.gtld-servers.net.
com.                    172799  IN      NS      f.gtld-servers.net.
com.                    172799  IN      NS      b.gtld-servers.net.
com.                    172799  IN      NS      h.gtld-servers.net.
com.                    172799  IN      NS      l.gtld-servers.net.
com.                    172799  IN      NS      j.gtld-servers.net.
com.                    172799  IN      NS      a.gtld-servers.net.
com.                    172799  IN      NS      e.gtld-servers.net.
com.                    172799  IN      NS      m.gtld-servers.net.
com.                    172799  IN      NS      c.gtld-servers.net.
com.                    172799  IN      NS      d.gtld-servers.net.
com.                    172799  IN      NS      k.gtld-servers.net.
com.                    172799  IN      NS      i.gtld-servers.net.

;; ADDITIONAL SECTION:
a.gtld-servers.net.     172799  IN      A       192.5.6.30
b.gtld-servers.net.     172799  IN      A       192.33.14.30
c.gtld-servers.net.     172799  IN      A       192.26.92.30
d.gtld-servers.net.     172799  IN      A       192.31.80.30
e.gtld-servers.net.     172799  IN      A       192.12.94.30
f.gtld-servers.net.     172799  IN      A       192.35.51.30
g.gtld-servers.net.     172799  IN      A       192.42.93.30
h.gtld-servers.net.     172799  IN      A       192.54.112.30
i.gtld-servers.net.     172799  IN      A       192.43.172.30
j.gtld-servers.net.     172799  IN      A       192.48.79.30
k.gtld-servers.net.     172799  IN      A       192.52.178.30
l.gtld-servers.net.     172799  IN      A       192.41.162.30
m.gtld-servers.net.     172799  IN      A       192.55.83.30
a.gtld-servers.net.     172799  IN      AAAA    2001:503:a83e::2:30
b.gtld-servers.net.     172799  IN      AAAA    2001:503:231d::2:30
c.gtld-servers.net.     172799  IN      AAAA    2001:503:83eb::30
d.gtld-servers.net.     172799  IN      AAAA    2001:500:856e::30
e.gtld-servers.net.     172799  IN      AAAA    2001:502:1ca1::30
f.gtld-servers.net.     172799  IN      AAAA    2001:503:d414::30
g.gtld-servers.net.     172799  IN      AAAA    2001:503:eea3::30
h.gtld-servers.net.     172799  IN      AAAA    2001:502:8cc::30
i.gtld-servers.net.     172799  IN      AAAA    2001:503:39c1::30
j.gtld-servers.net.     172799  IN      AAAA    2001:502:7094::30
k.gtld-servers.net.     172799  IN      AAAA    2001:503:d2d::30
l.gtld-servers.net.     172799  IN      AAAA    2001:500:d937::30
m.gtld-servers.net.     172799  IN      AAAA    2001:501:b1f9::30

;; Query time: 561 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: 月  4月 01 22:28:37 JST 2019
;; MSG SIZE  rcvd: 856

1. キャッシュには

net, nstld.com ともになさそう。

$ dig +norec -t ns net @127.0.0.1

; <<>> DiG 9.14.0 <<>> +norec -t ns net @127.0.0.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 59945
;; flags: qr ra ad; QUERY: 1, ANSWER: 0, AUTHORITY: 13, ADDITIONAL: 27

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
; COOKIE: f8728b0040e41be98089d3a25ca21228294be848ae07de67 (good)
;; QUESTION SECTION:
;net.                           IN      NS

;; AUTHORITY SECTION:
.                       518365  IN      NS      j.root-servers.net.
.                       518365  IN      NS      g.root-servers.net.
.                       518365  IN      NS      d.root-servers.net.
.                       518365  IN      NS      i.root-servers.net.
.                       518365  IN      NS      a.root-servers.net.
.                       518365  IN      NS      k.root-servers.net.
.                       518365  IN      NS      e.root-servers.net.
.                       518365  IN      NS      m.root-servers.net.
.                       518365  IN      NS      c.root-servers.net.
.                       518365  IN      NS      f.root-servers.net.
.                       518365  IN      NS      h.root-servers.net.
.                       518365  IN      NS      b.root-servers.net.
.                       518365  IN      NS      l.root-servers.net.

;; ADDITIONAL SECTION:
a.root-servers.net.     518364  IN      A       198.41.0.4
...

$ dig +norec -t ns nstld.com @127.0.0.1

; <<>> DiG 9.14.0 <<>> +norec -t ns nstld.com @127.0.0.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 35971
;; flags: qr ra ad; QUERY: 1, ANSWER: 0, AUTHORITY: 13, ADDITIONAL: 27

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
; COOKIE: a1ec1692a2068f8a260cbbac5ca21263a87c8f2822e65f2e (good)
;; QUESTION SECTION:
;nstld.com.                     IN      NS

;; AUTHORITY SECTION:
com.                    172705  IN      NS      l.gtld-servers.net.
com.                    172705  IN      NS      g.gtld-servers.net.
com.                    172705  IN      NS      b.gtld-servers.net.
com.                    172705  IN      NS      c.gtld-servers.net.
com.                    172705  IN      NS      m.gtld-servers.net.
com.                    172705  IN      NS      k.gtld-servers.net.
com.                    172705  IN      NS      j.gtld-servers.net.
com.                    172705  IN      NS      e.gtld-servers.net.
com.                    172705  IN      NS      a.gtld-servers.net.
com.                    172705  IN      NS      f.gtld-servers.net.
com.                    172705  IN      NS      h.gtld-servers.net.
com.                    172705  IN      NS      d.gtld-servers.net.
com.                    172705  IN      NS      i.gtld-servers.net.

;; ADDITIONAL SECTION:
a.gtld-servers.net.     172705  IN      A       192.5.6.30
b.gtld-servers.net.     172705  IN      A       192.33.14.30
...