DNS obscurities/"skipping update"

[sokai]

🙋‍♂️️ Hi, can someone help me to find the cause (and resolution) for a strange DNS/IP problem?

Insights/Background

• ddns-updater: v2.9.0 (@NixOS)
• Records: 9 DDNS domains configured ( ipv4 only)
  • 8x @
  • 1x (1st-level) subdomain
• Split DNS by RESOLVER_ADDRESS

👉️ start-up logs

Logs

Apr 19 10:20:25 HOST systemd[1]: Stopped DDNS-updater service.
Apr 19 10:20:26 HOST systemd[1]: Started DDNS-updater service.
Apr 19 10:20:26 HOST ddns-updater[107931]: ========================================
Apr 19 10:20:26 HOST ddns-updater[107931]: ========================================
Apr 19 10:20:26 HOST ddns-updater[107931]: ============= ddns-updater =============
Apr 19 10:20:26 HOST ddns-updater[107931]: ========================================
Apr 19 10:20:26 HOST ddns-updater[107931]: =========== Made with ❤️ by ============
Apr 19 10:20:26 HOST ddns-updater[107931]: ======= https://github.com/qdm12 =======
Apr 19 10:20:26 HOST ddns-updater[107931]: ========================================
Apr 19 10:20:26 HOST ddns-updater[107931]: ========================================
Apr 19 10:20:26 HOST ddns-updater[107931]: Running version unknown built on an unknown date (commit unknown)
Apr 19 10:20:26 HOST ddns-updater[107931]: 🔧 Need help? ☕ Discussion? https://github.com/qdm12/ddns-updater/discussions/new/choose
Apr 19 10:20:26 HOST ddns-updater[107931]: 🐛 Bug? ✨ New feature? https://github.com/qdm12/ddns-updater/issues/new/choose
Apr 19 10:20:26 HOST ddns-updater[107931]: 💻 Email? quentin.mcgaw@gmail.com
Apr 19 10:20:26 HOST ddns-updater[107931]: 💰 Help me? https://www.paypal.me/qmcgaw https://github.com/sponsors/qdm12
Apr 19 10:20:26 HOST ddns-updater[107931]: 2025-04-19T12:20:26+02:00 INFO Settings summary:
Apr 19 10:20:26 HOST ddns-updater[107931]: ├── HTTP client
Apr 19 10:20:26 HOST ddns-updater[107931]: |   └── Timeout: 20s
Apr 19 10:20:26 HOST ddns-updater[107931]: ├── Update
Apr 19 10:20:26 HOST ddns-updater[107931]: |   ├── Period: 10m0s
Apr 19 10:20:26 HOST ddns-updater[107931]: |   └── Cooldown: 5m0s
Apr 19 10:20:26 HOST ddns-updater[107931]: ├── Public IP fetching
Apr 19 10:20:26 HOST ddns-updater[107931]: |   ├── HTTP enabled: yes
Apr 19 10:20:26 HOST ddns-updater[107931]: |   ├── HTTP IP providers
Apr 19 10:20:26 HOST ddns-updater[107931]: |   |   └── all
Apr 19 10:20:26 HOST ddns-updater[107931]: |   ├── HTTP IPv4 providers
Apr 19 10:20:26 HOST ddns-updater[107931]: |   |   └── all
Apr 19 10:20:26 HOST ddns-updater[107931]: |   ├── HTTP IPv6 providers
Apr 19 10:20:26 HOST ddns-updater[107931]: |   |   └── all
Apr 19 10:20:26 HOST ddns-updater[107931]: |   ├── DNS enabled: yes
Apr 19 10:20:26 HOST ddns-updater[107931]: |   ├── DNS timeout: 3s
Apr 19 10:20:26 HOST ddns-updater[107931]: |   └── DNS over TLS providers
Apr 19 10:20:26 HOST ddns-updater[107931]: |       └── all
Apr 19 10:20:26 HOST ddns-updater[107931]: ├── Resolver
Apr 19 10:20:26 HOST ddns-updater[107931]: |   ├── Address: 202.61.251.9:53
Apr 19 10:20:26 HOST ddns-updater[107931]: |   └── Timeout: 5s
Apr 19 10:20:26 HOST ddns-updater[107931]: ├── Server
Apr 19 10:20:26 HOST ddns-updater[107931]: |   ├── Listening address: :8000
Apr 19 10:20:26 HOST ddns-updater[107931]: |   └── Root URL: /
Apr 19 10:20:26 HOST ddns-updater[107931]: ├── Health
Apr 19 10:20:26 HOST ddns-updater[107931]: |   └── Server is disabled
Apr 19 10:20:26 HOST ddns-updater[107931]: ├── Paths
Apr 19 10:20:26 HOST ddns-updater[107931]: |   ├── Data directory: /var/lib/ddns-updater
Apr 19 10:20:26 HOST ddns-updater[107931]: |   ├── Config file: /var/lib/ddns-updater/config.json
Apr 19 10:20:26 HOST ddns-updater[107931]: |   └── Umask: system default
Apr 19 10:20:26 HOST ddns-updater[107931]: ├── Backup: disabled
Apr 19 10:20:26 HOST ddns-updater[107931]: └── Logger
Apr 19 10:20:26 HOST ddns-updater[107931]:     ├── Level: debug
Apr 19 10:20:26 HOST ddns-updater[107931]:     └── Caller: hidden
Apr 19 10:20:26 HOST ddns-updater[107931]: 2025-04-19T12:20:26+02:00 INFO reading JSON config from environment variable CONFIG
Apr 19 10:20:26 HOST ddns-updater[107931]: 2025-04-19T12:20:26+02:00 DEBUG config read: {REDACTED}
Apr 19 10:20:26 HOST ddns-updater[107931]: 2025-04-19T12:20:26+02:00 INFO Found 9 settings to update records
Apr 19 10:20:27 HOST ddns-updater[107931]: 2025-04-19T12:20:27+02:00 INFO Reading history from database: domain REDACT.ED owner @ ipv4
[…]
Apr 19 10:20:27 HOST ddns-updater[107931]: 2025-04-19T12:20:27+02:00 INFO [http server] http server listening on [::]:8000
Apr 19 10:20:27 HOST ddns-updater[107931]: 2025-04-19T12:20:27+02:00 INFO [backup] disabled
Apr 19 10:20:27 HOST ddns-updater[107931]: 2025-04-19T12:20:27+02:00 DEBUG configured to fetch IP: v4 or v6: false, v4: true, v6: false
Apr 19 10:20:27 HOST ddns-updater[107931]: 2025-04-19T12:20:27+02:00 DEBUG your public IP address are: v4 or v6: invalid IP, v4: 80.XX.XX.XX, v6: invalid IP
Apr 19 10:20:27 HOST ddns-updater[107931]: 2025-04-19T12:20:27+02:00 DEBUG ipv4 address of REDACT.ED is 80.XX.XX.XX and your ipv4 address is 80.XX.XX.XX, skipping update
[…]
Apr 19 10:30:27 HOST ddns-updater[107931]: 2025-04-19T12:30:27+02:00 DEBUG configured to fetch IP: v4 or v6: false, v4: true, v6: false
Apr 19 10:30:27 HOST ddns-updater[107931]: 2025-04-19T12:30:27+02:00 DEBUG your public IP address are: v4 or v6: invalid IP, v4: 80.XX.XX.XX, v6: invalid IP
Apr 19 10:30:27 HOST ddns-updater[107931]: 2025-04-19T12:30:27+02:00 DEBUG ipv4 address of REDACT.ED is 80.XX.XX.XX and your ipv4 address is 80.XX.XX.XX, skipping update
[…]

Status

• Domain: REDACT.ED
  • Provider: netcup
• Current IP: 80.XX.XX.XX
• Last/Old IP: 80.XX.XX.YY
  • IP is set for REDACT.ED (as @)

👉️ DNS lookups

Local

[sokai@HOST:~]$ nslookup REDACT.ED.
Server:		10.1.0.1
Address:	10.1.0.1#53

Non-authoritative answer:
Name:	REDACT.ED
Address: 80.XX.XX.YY

Authorative

[sokai@HOST:~]$ nslookup REDACT.ED. 46.38.225.225
Server:		46.38.225.225
Address:	46.38.225.225#53

Non-authoritative answer:
Name:	REDACT.ED
Address: 80.XX.XX.YY

3rd party

[sokai@HOST:~]$ nslookup REDACT.ED. 9.9.9.9
Server:		9.9.9.9
Address:	9.9.9.9#53

Non-authoritative answer:
Name:	REDACT.ED
Address: 80.XX.XX.YY

[sokai@HOST:~]$ nslookup REDACT.ED. 202.61.251.9
Server:		202.61.251.9
Address:	202.61.251.9#53

Non-authoritative answer:
Name:	REDACT.ED
Address: 80.XX.XX.YY

Problem

• All DNS lookups (see above) show the old IP (80.XX.XX.YY) for the host REDACT.ED
• But ddns-updater believes (see start-up logs above) it has (set?) the correct IP 80.XX.XX.XX for the host REDACT.ED

Can someone maybe explain how/why ddns-updater has wrong IP information and isn't updating the domain/record?

I tried to change the RESOLVER_ADDRESS but couldn't find a clear answer. It seems (for me) ddns-updater is somehow caching the IP, instead of live requesting …(?)
I've also seen #891, discussion #894. Also #339, which I think does the same at Docker for RESOLVER_ADDRESS …

KR