Airdns.org DDNS IPv4/IPv6 flaw

[2Cents 7]

Hello,

I've tried searching the forums for anything similar to the behavior I'm noticing but it seems no one has experienced / posted about this, or maybe I missed it.

The issue: Selected IP layer is IPv4, xxxx_airdns.org is currently returning IPv4 via dig which is great but when connecting to it, IPv6 is used.

Expectation: Airdns.org DDNS service should adhere to the selected IP layer (IPv4, IPv6 or IPv4+IPv6) and only create the relevant A and/or AAAA records.

I spent several hours yesterday troubleshooting the router's iptables/nat script, which I know works 100%, only to realize that using the DDNS hostname was the culprit. As soon as I switched my connecting device to use the IPv4 address did it start working!
 

➜  ~ dig xxxx.airdns.org

; <<>> DiG 9.10.6 <<>> xxxx.airdns.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 40918
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;xxxx.airdns.org.		IN	A

;; ANSWER SECTION:
xxxx.airdns.org.	15	IN	A	37.46.199.87

;; Query time: 2 msec
;; SERVER: 10.10.10.1#53(10.10.10.1)
;; WHEN: Sat Feb 14 12:43:35 +04 2026
;; MSG SIZE  rcvd: 61

➜  ~ telnet xxxx.airdns.org 12345
Trying 2a00:dd0:aaaa:X:XXX:XXXX:XXXX:XXXX...

[Tech Jedi Alex 1524]

 

42 minutes ago, 2Cents said:

Expectation: Airdns.org DDNS service should adhere to the selected IP layer (IPv4, IPv6 or IPv4+IPv6) and only create the relevant A and/or AAAA records.

This expectation stems from a misunderstanding on how the Port Forwarding feature works.

DDNS is set to your exit server's IP addresses, which is both v4 and v6, and you have no power over that setting. The IP layer selection only controls on which layer the port is opened.
When resolving, A and AAAA is resolved, AAAA chosen due to Happy Eyeballs, so connected via AAAA, but since the port is only open on v4, you get a timeout.

[Staff 10458]

@2Cents

Hello!

When a fully qualified domain name (FQDN) has both A (IPv4) and AAAA (IPv6) records, different tools may return or use different addresses when they ask for resolution because they follow different resolution and selection logic. For example, telnet calls the OS resolver which in turn prefers IPv6 or IPv4 according to /etc/gai.conf in Linux; in many distributions by default IPv6 is preferred over IPv4, but you can customize this behavior. 
 

Quote

Airdns.org DDNS service should adhere to the selected IP layer (IPv4, IPv6 or IPv4+IPv6) and only create the relevant A and/or AAAA records.

We don't think so. Different philosophy. The selected protocol (v4 or v6) is available for ports anyway and you can customize your system preferences.

Kind regards
 

[2Cents 7]

35 minutes ago, Tech Jedi Alex said:

This expectation stems from a misunderstanding on how the Port Forwarding feature works.

DDNS is set to your exit server's IP addresses, which is both v4 and v6, and you have no power over that setting. The IP layer selection only controls on which layer the port is opened.
When resolving, A and AAAA is resolved, AAAA chosen due to Happy Eyeballs, so connected via AAAA, but since the port is only open on v4, you get a timeout.

Appreciate the enlightenment.
 

32 minutes ago, Staff said:

When a fully qualified domain name (FQDN) has both A (IPv4) and AAAA (IPv6) records, different tools may return or use different addresses when they ask for resolution because they follow different resolution and selection logic. For example, telnet calls the OS resolver which in turn prefers IPv6 or IPv4 according to /etc/gai.conf in Linux; in many distributions by default IPv6 is preferred over IPv4, but you can customize this behavior. 
 
We don't think so. Different philosophy. The selected protocol (v4 or v6) is available for ports anyway and you can customize your system preferences.

My thoughts exactly, unfortunately it's not possible to customize Apple devices to prefer ipv4 over ipv6. Wouldn't it be beneficial to maybe add a new option to select what records to return for scenarios like this?

Either way, I think adding this key detail to the Ports page (yellow section) would be beneficial to users.