watchNS/iana-servers.netについて、ここに記述してください。

$ dig -t ns iana-servers.net

; <<>> DiG 9.9.5-3ubuntu0.7-Ubuntu <<>> -t ns iana-servers.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4520
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
;; QUESTION SECTION:
;iana-servers.net.              IN      NS

;; ANSWER SECTION:
iana-servers.net.       1800    IN      NS      b.iana-servers.net.
iana-servers.net.       1800    IN      NS      a.iana-servers.net.
iana-servers.net.       1800    IN      NS      ns.icann.org.
iana-servers.net.       1800    IN      NS      c.iana-servers.net.

;; Query time: 187 msec
;; SERVER: 127.0.0.2#53(127.0.0.2)
;; WHEN: Fri Feb 12 20:52:36 JST 2016
;; MSG SIZE  rcvd: 119