watchAAAA/gitbook.comについて、ここに記述してください。

$ dig -t aaaa cdn.gitbook.com @ns1.gitbook.me.

; <<>> DiG 9.11.1 <<>> -t aaaa cdn.gitbook.com @ns1.gitbook.me.
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60579
;; flags: qr rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;cdn.gitbook.com.               IN      AAAA

;; ANSWER SECTION:
cdn.gitbook.com.        3600    IN      A       128.199.158.79

;; Query time: 218 msec
;; SERVER: 107.170.136.67#53(107.170.136.67)
;; WHEN: Tue Jun 13 17:00:08 JST 2017
;; MSG SIZE  rcvd: 64

query type AAAAの問い合わせにAを答えてくる。

$ dnsq 28 cdn.gitbook.com ns1.gitbook.me
28 cdn.gitbook.com:
64 bytes, 1+1+0+0 records, response, noerror
query: 28 cdn.gitbook.com
answer: cdn.gitbook.com 3600 A 128.199.158.79

BIND 9.11.1 は

$ dig -t aaaa cdn.gitbook.com @127.0.0.1

; <<>> DiG 9.11.1 <<>> -t aaaa cdn.gitbook.com @127.0.0.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 7582
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: d63deaa516020b1cf52967fd593f9fc9f0b49fc1fb32fd4f (good)
;; QUESTION SECTION:
;cdn.gitbook.com.               IN      AAAA

;; Query time: 390 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Tue Jun 13 17:18:17 JST 2017
;; MSG SIZE  rcvd: 72