Re: Which takes priority, ipv4, or ipv6?

[Richmond <dnomhcir@gmx.com>]

Jeremy Ardley <jeremy@ardley.org> writes:

> On 27/3/23 19:48, Richmond wrote:
>>
>> So how is the preference determined? It seems to be determined by the
>> DNS, but why or how do I tell for example with host -v?
>
> When you as a DNS about a hostname it can return an A record and/or an
> AAAA record.
>
> The A record is IPv4 and the AAAA record is IPv6
>
> When you get both it is then up to your application to choose IPv4 or
> IPv6 for the connection.
>
> If either fails the application will then try the other before finally
> failing.
>
> You need a DNS that can return A and AAAA records, and an application
> that can use either.
>
> I have noticed in my debian LAN that utilities such as ssh prefer IPv6
> and if that is not possible will use IPv4

Both DNS return AAAA records. I am not sure why this choice of DNS
should make a difference.

host -v ip6.me |grep AAAA
			IN	AAAA
	9306	IN	AAAA	2001:4838:0:1b::201
host -v ip6.me 8.8.8.8|grep AAAA
			IN	AAAA
	10800	IN	AAAA	2001:4838:0:1b::201
host -v ip6.me 79.79.79.78|grep AAAA
			IN	AAAA
	300	IN	AAAA	2001:4838:0:1b::201