[OpenWrt-Devel] RFC netifd: UCI parameter to sort name servers in resolv.conf.auto

Felix Fietkau nbd at nbd.name
Mon Sep 5 04:48:49 EDT 2016

On 2016-09-05 10:45, Hans Dedecker wrote:
> Hi Felix,
> Current implementation in netifd writes the dns servers into
> resolv.conf.auto file based on the order of the interfaces in the
> interface list which is alphabetical sorted. The resolver, in this
> case dnsmasq, reads the resolv.conf.auto file and queries the
> nameserver(s) in the order listed till it receives an answer.
> If you have multiple wan interfaces each receiving DNS server(s) via
> either DHCPv4/6 or PPP; there's no mechanism in place to influence the
> order of the dns servers in the resolv.conf.auto file (unless you
> would chose well thought interface names but which is not a
> transparent approach) .
> Possible use cases are :
> -Main and backup interfaces; priority needs to be given to the name
> server of the main interface only if these fail the dns servers of the
> backup interface can be queried.
> -Possibility to give priority to the IPv4 name servers above IPv6 name
> servers or vice versa in a dual stack scenario.
> We were thinking about adding an interface dnsmetric parameter (e.g.
> similar to interface metric for routes) which is used to sort the dns
> servers in the function  interface_write_resolv_conf.
> What is your opinion about this proposal ?
Makes sense to me, go for it.

- Felix
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