Moin!

On 2 Jun 2023, at 17:23, Jesus Cea wrote:

> Bind DNS server replies AAAA queries to "oauth-login.cloud.huawei.com" with 
> SERVFAIL and the logs shows: "Name huawei.com (SOA) not subdomain of zone 
> cloud.huawei.com". This is not an issue with AAAA, but with any query for a 
> register not present in the zone. This is not a BIND bug, it is a 
> misconfiguration in the "cloud.huawai.com" delegation.

The delegation is fine:

; <<>> DiG 9.18.15 <<>> +nocookie NS cloud.huawei.com @nsall.huawei.com.
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 23409
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 3, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;cloud.huawei.com.              IN      NS

;; AUTHORITY SECTION:
cloud.huawei.com.       600     IN      NS      ns4.dnsv5.com.
cloud.huawei.com.       600     IN      NS      ns3.dnsv5.com.
cloud.huawei.com.       600     IN      NS      gns1.huaweicloud-dns.org.

What is not fine is what the child zone thinks about itself:

; <<>> DiG 9.18.15 <<>> +nocookie NS cloud.huawei.com @gns1.huaweicloud-dns.org.
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 21797
;; flags: qr aa rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;cloud.huawei.com.              IN      NS

;; AUTHORITY SECTION:
huawei.com.             300     IN      SOA     gns1.huaweicloud-dns.org. 
hwclouds\.cs.huawei.com. 1 7200 900 1209600 300

My guess is that the reason the resolution is failing is a problem with either 
qname minimisation or trying to validate zone cuts. If you do regular old style 
just follow the delegation you get a correct answer (e.g do a dig +trace).

I agree that you should complain to Huawei, but the domain is certainly 
resolvable for most resolvers out there.

> Interestingly, 8.8.8.8, 1.1.1.1, 9.9.9.9 and most other open resolvers just 
> ignore (or not detect) the misconfiguration. Too bad, since then the issue 
> goes unresolved because "it works for me!".
>
> This is a common misconfiguration. Would be a public service that common and 
> popular open DNS resolvers care about it, since a proper SERVFAIL would 
> prompt a fast and trivial fix in the affected DNS configurations.

What would be the incentive for those public resolver or other resolvers to 
give back SERVFAIL? There users would no longer be able to get to the site and 
complain. To do something requires a concerted effort of all participants like 
we did with the DNS Flag days, but IMHO this misconfiguration is less severe 
than others we had flag days for.

So long
-Ralf
——-
Ralf Weber

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