DNS problem: SERVFAIL looking up A

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My domain is: pipedproxy-yyz.kavin.rocks

I ran this command: certbot

It produced this output:

Saving debug log to /var/log/letsencrypt/letsencrypt.log

Which names would you like to activate HTTPS for?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1: pipedapi.kavin.rocks
2: pipedproxy-yyz.kavin.rocks
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Select the appropriate numbers separated by commas and/or spaces, or leave input
blank to select all options shown (Enter 'c' to cancel): 2
Requesting a certificate for pipedproxy-yyz.kavin.rocks

Certbot failed to authenticate some domains (authenticator: nginx). The Certificate Authority reported these problems:
  Domain: pipedproxy-yyz.kavin.rocks
  Type:   dns
  Detail: DNS problem: SERVFAIL looking up A for pipedproxy-yyz.kavin.rocks - the domain's nameservers may be malfunctioning; no valid AAAA records found for pipedproxy-yyz.kavin.rocks

Hint: The Certificate Authority failed to verify the temporary nginx configuration changes made by Certbot. Ensure the listed domains point to this nginx server and that it is accessible from the internet.

Some challenges have failed.
Ask for help or search for solutions at https://community.letsencrypt.org. See the logfile /var/log/letsencrypt/letsencrypt.log or re-run Certbot with -v for more details.

My web server is (include version):
nginx 1.16.1
The operating system my web server runs on is (include version):
Alpine Linux 3.15

I can login to a root shell on my machine (yes or no, or I don't know):

I'm using a control panel to manage my site (no, or provide the name and version of the control panel):

The version of my client is (e.g. output of certbot --version or certbot-auto --version if you're using Certbot):
certbot 1.22.0

dig A pipedproxy-yyz.kavin.rocks @

; <<>> DiG 9.16.24 <<>> A pipedproxy-yyz.kavin.rocks @
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41078
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

; EDNS: version: 0, flags:; udp: 512
;pipedproxy-yyz.kavin.rocks.    IN      A

pipedproxy-yyz.kavin.rocks. 300 IN      A

;; Query time: 20 msec
;; WHEN: Wed Jan 26 19:10:00 UTC 2022
;; MSG SIZE  rcvd: 71

I can confirm this error at https://unboundtest.com/m/A/pipedproxy-yyz.kavin.rocks/HTR3Y6UY

Which is a test site using the same DNS resolver library (Unbound) with almost exactly the same configuration as the Let's Encrypt validation servers.

However, it's logging, while being very verbose, is very hard to understand. Almost impossible if you'd ask me. I think the relevant message here is "NSEC RRset for the referral proved not a delegation point", but I'm not sure a) what it means and b) if it's actually an error or not?


Is this an issue on Cloudflare's end in that case? Oddly enough, I have other subdomains/hostnames on the same domain, which all work. Example: https://unboundtest.com/m/A/pipedproxy-bom.kavin.rocks/LIWCKYTX

I'm not sure. I'm not even sure what the message means I'm afraid.


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