Forwarding via different external networks

[Dave Warren]

On Sat, Aug 27, 2016, at 11:32, Paul Kosinski wrote:
> So my question is, is it possible to configure my forwarding BIND to
> have a primary and *secondary* path for sending out DNS queries? As far
> as I can tell, the "query-source address" option in named.conf only
> allows one outbound interface to be (implicitly) specified, and I don't
> want to leave the outbound interface unspecified as that would defeat
> monitoring and logging on the specific interface. The "forwarders"
> option *does* allow multiple DNS servers to be specified, but that
> doesn't help if the network path is down.
> 
> P.S. I suppose I might try something with policy routing, but that was
> already a nightmare to set up, since I use DSL vs cable based on the
> source and type (e.g. HTTP, SSH) of the traffic rather than the more
> common destination.

Since you're forwarding anyway, why not forward to a pair of public
servers, 8.8.8.8 and 8.8.4.4, or 4.2.2.1 and 4.2.2.2, and then use youe
routing table or other technique to route traffic for each destination
IP?

However, since you run BIND, why bother with forwarding queries at all,
I would recommend just resolving without forwarders, in which case BIND
doesn't need any particular connection and whatever else you use to
failover from the primary to the secondary would automatically ensure
BIND resolves too.