Forwarders working differently on bind9.8 & bind9.11

[Matus UHLAR - fantomas]

>On Tue, Sep 19, 2023 at 7:28 AM Prashasti Arora <prashastistudies at gmail.com>
>wrote:
>
>> I have configured a new zone to forward certain queries to my application
>> on 2 VMs (One local and the other in my network) through a specific port. I
>> have 2 similar setups - they are identical, except that one uses bind9.8
>> and the other uses bind9.11. Configuration is also identical for both.
>>
>> On the first setup (using bind9.8): the traffic I send gets distributed
>> uniformly.
>> On the second setup (using bind9.11): the traffic gets distributed barely.
>> 99% of the traffic is sent to one VM.

BIND wants to get responses as soon as possible, thus it queries servers who 
respond fastest.

BIND keeps track of how fast servers are responding, and which server 
responds faster, will get queries more often.

Time to time, BIND re-checks other servers to see if they perform better, 
because that can change over time.

What is the problem?

>> I have verified that forwarding is working correctly on both, the issue is
>> not with the application because both VMs on each setup can handle traffic
>> individually, the firewall is not blocking the queries, and the
>> configuration is correct.
>>
>> This is the zone:
>>
>> zone "example.com" IN {
>> type forward;
>> forwarders { 127.0.0.1 port xxx; a.b.c.d port xxx; };
>> forward only;
>> };
>>
>>
>> Please share any other possible solutions.

On 19.09.23 08:25, Bob Harold wrote:
>Note that the 'forwarders' line, from the BIND 9.11 manual:  "There may be
>one or more forwarders, and they are queried in turn until the list is
>exhausted
>or an answer is found."  So the first one will get all the traffic, the
>second is just a backup to be used if the first fails.
>If you expect that to do load balancing, it will not.  Try a real load
>balancer, or 'dnsdist'.

I think this behaviour changed to the one I described above a long time ago.  
Perhaps after BIND 9.8


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