external-dns is responding to questions for AAAA/MX with A records

[iliana]

Discovered while using host:

$ host recovery.sys.oxide.test 192.168.1.20
Using domain server:
Name: 192.168.1.20
Address: 192.168.1.20#53
Aliases:

recovery.sys.oxide.test has address 192.168.1.22
recovery.sys.oxide.test has address 192.168.1.23
recovery.sys.oxide.test has address 192.168.1.24
recovery.sys.oxide.test has address 192.168.1.22
recovery.sys.oxide.test has address 192.168.1.23
recovery.sys.oxide.test has address 192.168.1.24
recovery.sys.oxide.test has address 192.168.1.22
recovery.sys.oxide.test has address 192.168.1.23
recovery.sys.oxide.test has address 192.168.1.24

host sends queries for A, AAAA, and MX records by default.

$ dig @192.168.1.20 recovery.sys.oxide.test -t A

; <<>> DiG 9.18.14 <<>> @192.168.1.20 recovery.sys.oxide.test -t A
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 50534
;; flags: qr rd; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;recovery.sys.oxide.test.       IN      A

;; ANSWER SECTION:
recovery.sys.oxide.test. 0      IN      A       192.168.1.22
recovery.sys.oxide.test. 0      IN      A       192.168.1.23
recovery.sys.oxide.test. 0      IN      A       192.168.1.24

;; Query time: 0 msec
;; SERVER: 192.168.1.20#53(192.168.1.20) (UDP)
;; WHEN: Wed Oct 11 18:14:14 UTC 2023
;; MSG SIZE  rcvd: 89


$ dig @192.168.1.20 recovery.sys.oxide.test -t AAAA

; <<>> DiG 9.18.14 <<>> @192.168.1.20 recovery.sys.oxide.test -t AAAA
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 44245
;; flags: qr rd; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;recovery.sys.oxide.test.       IN      AAAA

;; ANSWER SECTION:
recovery.sys.oxide.test. 0      IN      A       192.168.1.22
recovery.sys.oxide.test. 0      IN      A       192.168.1.23
recovery.sys.oxide.test. 0      IN      A       192.168.1.24

;; Query time: 0 msec
;; SERVER: 192.168.1.20#53(192.168.1.20) (UDP)
;; WHEN: Wed Oct 11 18:14:16 UTC 2023
;; MSG SIZE  rcvd: 89


$ dig @192.168.1.20 recovery.sys.oxide.test -t CNAME

; <<>> DiG 9.18.14 <<>> @192.168.1.20 recovery.sys.oxide.test -t CNAME
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 52989
;; flags: qr rd; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;recovery.sys.oxide.test.       IN      CNAME

;; ANSWER SECTION:
recovery.sys.oxide.test. 0      IN      A       192.168.1.22
recovery.sys.oxide.test. 0      IN      A       192.168.1.23
recovery.sys.oxide.test. 0      IN      A       192.168.1.24

;; Query time: 3 msec
;; SERVER: 192.168.1.20#53(192.168.1.20) (UDP)
;; WHEN: Wed Oct 11 18:14:17 UTC 2023
;; MSG SIZE  rcvd: 89


$ dig @192.168.1.20 recovery.sys.oxide.test -t MX

; <<>> DiG 9.18.14 <<>> @192.168.1.20 recovery.sys.oxide.test -t MX
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1632
;; flags: qr rd; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;recovery.sys.oxide.test.       IN      MX

;; ANSWER SECTION:
recovery.sys.oxide.test. 0      IN      A       192.168.1.22
recovery.sys.oxide.test. 0      IN      A       192.168.1.23
recovery.sys.oxide.test. 0      IN      A       192.168.1.24

;; Query time: 0 msec
;; SERVER: 192.168.1.20#53(192.168.1.20) (UDP)
;; WHEN: Wed Oct 11 18:14:18 UTC 2023
;; MSG SIZE  rcvd: 89

Correct behavior would be to send a response with 0 answer records (but not set the status to NXDOMAIN).

[davepacheco]

I think this is the same issue as #4051.

[iliana]

It is indeed!

[iliana]

Well. There is a subtle difference, actually. I will elaborate a bit over there.

[davepacheco]

I think given #4051 (comment), this is a dup of #4051 (but please reopen if I've misunderstood!)