forwarders used in order or based on RTT ?

Warren Kumari warren at
Mon Oct 19 15:37:58 UTC 2020

On Mon, Oct 19, 2020 at 11:26 AM Victoria Risk <vicky at> wrote:
> The ARM was updated in 9.16.6.  Sorry it took us so long!
> from
> Forwarders are typically used when an administrator does not wish for
> all the servers at a given site to interact directly with the rest of
> the Internet. For example, a common scenario is when multiple internal
> DNS servers are behind an Internet firewall. Servers behind the firewall
> forward their requests to the server with external access, which queries
> Internet DNS servers on the internal servers' behalf.
> Another scenario (largely now superseded by Response Policy Zones) is to
> send queries first to a custom server for RBL processing before
> forwarding them to the wider Internet.
> There may be one or more forwarders in a given setup. The order in which
> the forwarders are listed in ``named.conf`` does not determine the
> sequence in which they are queried; rather, ``named`` uses the response
> times from previous queries to select the server that is likely to
> respond the most quickly. A server that has not yet been queried is
> given an initial small random response time to ensure that it is tried
> at least once. Dynamic adjustment of the recorded response times ensures
> that all forwarders are queried, even those with slower response times.
> This permits changes in behavior based on server responsiveness.

Awesome, thank you -- that's clean and easy to understand.

> Vicky
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I don't think the execution is relevant when it was obviously a bad
idea in the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair
of pants.

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