forwarder's behavior

Stephen John Smoogen smooge at
Tue Nov 10 17:49:38 UTC 2009

On Tue, Nov 10, 2009 at 2:28 AM, KyuMin Choi <qmin77 at> wrote:
> Hello ~ can anyone answer me below questions ?
>  # The server is RHEL5.4

This should be a bind-9.3.2 server but may be different due to local
updates. The bind version will be more important.

>  1. What is the timeout value if a forwarders server specified in
>  named.conf is down and how many retry
>  does it do ?

The forwarding code in bind-9.3 uses RTT I believe. This would then be
more about how many forwarders there are. If there are multiple then
the code uses a clock to figure out which ones are the fastest and
tries to use those first and slow ones later. If there is only one I
am not sure what happens without looking at the code. A poor guess on
my part would be that it uses the old 3 tries (1 sec, 3 sec 6 sec?)

>  2. If the client makes a query for same FQDN for the second times after
>  the forwarders server has comes back online,
>  does this query give up and does not bother asking the forwarders server
>  as the first query to the forwarders server previoursly timed out ?

I would guess it would depend on the number of forwarding servers in
the list. My guess is that if there are multiple ones (say A, B, and
C) and A doesn't answer during the testing period.. it would be the
last one tried in any future attempts. If there is only one.. I would
guess it would try again.

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Stephen J Smoogen.

Ah, but a man's reach should exceed his grasp. Or what's a heaven for?
-- Robert Browning

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