1. watchNS/ayu-net.com/unbound

CNAMEがキャッシュにある状態で、unboundキャッシュにMXを問い合わせると、

$ dig -t mx ayu-net.com @127.0.0.2 

; <<>> DiG 9.9.5-3ubuntu0.13-Ubuntu <<>> -t mx ayu-net.com @127.0.0.2
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11453
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
;; QUESTION SECTION:
;ayu-net.com.                   IN      MX

;; ANSWER SECTION:
ayu-net.com.            280     IN      CNAME   blog-01.livedoor.jp.

;; AUTHORITY SECTION:
livedoor.jp.            2680    IN      SOA     ns1.naver.jp. domain.linecorp.com. 2017021400 10800 3600 604800 3600

;; Query time: 5 msec
;; SERVER: 127.0.0.2#53(127.0.0.2)
;; WHEN: Sun Feb 19 22:16:20 JST 2017
;; MSG SIZE  rcvd: 135

2. キャッシュからCNAMEが消えたら

$ dig -t mx ayu-net.com @127.0.0.2 

; <<>> DiG 9.9.5-3ubuntu0.13-Ubuntu <<>> -t mx ayu-net.com @127.0.0.2
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 932
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
;; QUESTION SECTION:
;ayu-net.com.                   IN      MX

;; ANSWER SECTION:
ayu-net.com.            1200    IN      CNAME   blog-01.livedoor.jp.

;; AUTHORITY SECTION:
livedoor.jp.            2385    IN      SOA     ns1.naver.jp. domain.linecorp.com. 2017021400 10800 3600 604800 3600

;; Query time: 156 msec
;; SERVER: 127.0.0.2#53(127.0.0.2)
;; WHEN: Sun Feb 19 22:21:15 JST 2017
;; MSG SIZE  rcvd: 135

3. CNAME があると

$ dig -t a ayu-net.com 

; <<>> DiG 9.9.5-3ubuntu0.13-Ubuntu <<>> -t a ayu-net.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3417
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
;; QUESTION SECTION:
;ayu-net.com.                   IN      A

;; ANSWER SECTION:
ayu-net.com.            1199    IN      CNAME   blog-01.livedoor.jp.
blog-01.livedoor.jp.    3600    IN      A       125.6.190.6

;; Query time: 173 msec
;; SERVER: 127.0.0.2#53(127.0.0.2)
;; WHEN: Sun Feb 19 23:20:39 JST 2017
;; MSG SIZE  rcvd: 89

NSを欲しいのにCNAMEが返ってくる。（乗取り成功かい）

$ dig -t ns ayu-net.com 

; <<>> DiG 9.9.5-3ubuntu0.13-Ubuntu <<>> -t ns ayu-net.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 52026
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1

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

;; ANSWER SECTION:
ayu-net.com.            1193    IN      CNAME   blog-01.livedoor.jp.

;; AUTHORITY SECTION:
livedoor.jp.            3593    IN      SOA     ns1.naver.jp. domain.linecorp.com. 2017021400 10800 3600 604800 3600

;; Query time: 0 msec
;; SERVER: 127.0.0.2#53(127.0.0.2)
;; WHEN: Sun Feb 19 23:20:45 JST 2017
;; MSG SIZE  rcvd: 135