forwarder selection logic by bind9

József Lázár jozsef.gabor.lazar at gmail.com
Mon Nov 19 09:11:11 UTC 2018


Did you have a chance to look at my email below? Thanks again, Joe

On Tue, 13 Nov 2018 at 10:42, József Lázár <jozsef.gabor.lazar at gmail.com>
wrote:

> Ok, I see. However, could you please specify this "time to time" period?
> Does it depends of the dns traffic which the bind receives?
> I've tried the following scenario:
> Configured two dns forwarders, both of them worked at the beginning. After
> one minute I turned off the first dns forwarder and after an another minute
> I restarted it.
> Then I sent one dns request to bind in every 1,5 second for over one hour,
> but the first dns server didn't receive any request after the restart.
>
> Thanks, Joe
>
> On Sun, 11 Nov 2018 at 15:06, Matus UHLAR - fantomas <uhlar at fantomas.sk>
> wrote:
>
>> 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.
>>
>> --
>> Matus UHLAR - fantomas, uhlar at fantomas.sk ; http://www.fantomas.sk/
>> Warning: I wish NOT to receive e-mail advertising to this address.
>> Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
>> They that can give up essential liberty to obtain a little temporary
>> safety deserve neither liberty nor safety. -- Benjamin Franklin, 1759
>> _______________________________________________
>> Please visit https://lists.isc.org/mailman/listinfo/bind-users to
>> unsubscribe from this list
>>
>> bind-users mailing list
>> bind-users at lists.isc.org
>> https://lists.isc.org/mailman/listinfo/bind-users
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.isc.org/pipermail/bind-users/attachments/20181119/e283161e/attachment.html>


More information about the bind-users mailing list