forwarder selection logic by bind9

Matus UHLAR - fantomas uhlar at fantomas.sk
Sun Nov 11 14:06:08 UTC 2018


On 10.11.18 15:59, József Lázár wrote:
>I'm wondering what the selection logic in bind for forwarders. I tried to
>look for this information in the official documentation but couldn't find
>it. Could you please describe it for me briefly?
>
>Actually, the scenario is that I have two DNS servers and I'm using bind to
>forward only the incoming DNS requests and if the "primary" one is failed
>for a short period of time then the bind will try to use the "secondary"
>one, but when the "primary" comes back, then it doesn't try to connect to
>it at all, only if the connection breaks for the "secondary" server.
>
>Is there any way to configure this logic somehow? 

No. BIND technically choses server that responds faster. If one of servers
doesn't respond (it's down), BIND uses the another one. However, time to
time, BIND rechecks the other server(s) to see if situation has changed.

BIND does not differ between servers as primary and secondary.

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Matus UHLAR - fantomas, uhlar at fantomas.sk ; http://www.fantomas.sk/
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