nsd users - Jun 2021 - What is the selection order of forward-first NSs? sequential? random? IPv6 before/after IPv4?

On my server, I config

	cat /etc/resolv.conf
		nameserver 127.0.0.1

, where unbound 1.13.1 listens @

	server:
		interface: 127.0.0.1 at 53

if I set up forward-first in unbound config,

	forward-zone:
		name: "."
			forward-first: yes
			forward-addr: <server.1.ipv.6>
			forward-addr: <server.1.ipv.4>
			...
			forward-addr: <server.n.ipv.6>
			forward-addr: <server.n.ipv.4>

what's the order policy for those forward-addr's?

Is the forward-addr used randomly, or sequentially, selected from that list?

Is there any unbound preference for IPv4 vs IPv6 forward-addrs?
Does the preference respect /etc/gai.conf?

Hi pgnet(?),

I think you posted on the wrong mailing list :)
I'll reply here and include unbound-users also.

If you want to reply further please drop nsd-users and let us continue 
the discussion only on the unbound-users mailing list as to not generate 
noise here.

On 07/06/2021 21:31, PGNet Dev via nsd-users wrote:
> On my server, I config
> 
>  ????cat /etc/resolv.conf
>  ??????? nameserver 127.0.0.1
> 
> , where unbound 1.13.1 listens @
> 
>  ????server:
>  ??????? interface: 127.0.0.1 at 53
> 
> if I set up forward-first in unbound config,
> 
>  ????forward-zone:
>  ??????? name: "."
>  ??????????? forward-first: yes
>  ??????????? forward-addr: <server.1.ipv.6>
>  ??????????? forward-addr: <server.1.ipv.4>
>  ??????????? ...
>  ??????????? forward-addr: <server.n.ipv.6>
>  ??????????? forward-addr: <server.n.ipv.4>
>
> what's the order policy for those forward-addr's?
> 
> Is the forward-addr used randomly, or sequentially, selected from that 
> list?
Randomly between the fastest servers (in the <400ms band). Unbound will 
keep probing the other servers to keep updated metrics for them in case 
they become fast enough (<400ms). You can read more about it at 
https://www.nlnetlabs.nl/documentation/unbound/info-timeout/.
> 
> Is there any unbound preference for IPv4 vs IPv6 forward-addrs?
There are the 'prefer-ip4:' and 'prefer-ip6:' options if you
want to do
that.
> Does the preference respect /etc/gai.conf?
No.

Best regards,
-- George
> 
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