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From: "Carlos E. R." <robin_listas@es.invalid>
Newsgroups: comp.os.linux.misc
Subject: Re: Linux advocacy
Date: Tue, 20 May 2025 11:46:44 +0200
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On 2025-05-20 10:36, Nuno Silva wrote:
> On 2025-05-20, Marc Haber wrote:


> 
> Maybe what's missing here for some of the affected people is configuring
> address lookup to prefer IPv4 if they're using nameservers that return
> AAAA records?
> 
> (Just a wild guess, but fitting enough that it's probably a good idea to
> drop this here:)
> 
>      news://news.gmane.io/m3msju6x5x.fsf@lugabout.jhcloos.org
> 
> Although I'm not sure, from the gai.conf online manual page, that just
> the mentioned line is sufficient, given it's said to disable the
> "default table". I didn't test this myself.

I knew and did the trick in the past, but I have forgotten, so I asked 
chatgpt:

Method 1: Edit /etc/gai.conf to prefer IPv4

The /etc/gai.conf file is used by the GNU C Library (glibc) to influence 
address selection when a hostname resolves to multiple addresses (e.g., 
both A and AAAA records).

     Open the file in a text editor as root:

sudo nano /etc/gai.conf

Find the following line (it’s usually commented out):

#precedence ::ffff:0:0/96  100

Uncomment the line by removing the #:

     precedence ::ffff:0:0/96  100

     This tells the system to prefer IPv4-mapped addresses over IPv6.

     Save and exit the editor.

This change takes effect immediately for new processes that use glibc’s 
getaddrinfo() function.

Method 2: Disable IPv6 (not recommended unless necessary)

(skip)

Verify Preference

You can test the preference with getent:

getent ahosts example.com

The top address should be IPv4 if the change worked.



-- 
Cheers,
        Carlos E.R.