DNS queries go to primary and secondary DNS servers at the same time

Matus UHLAR - fantomas uhlar at fantomas.sk
Mon Dec 16 20:01:52 UTC 2019

On 16.12.19 16:13, Roberto Carna wrote:
>I have a primary and a secondary BIND9 DNS servers, working as master /
>slave with zone transfers between them.
>I have several Linux machines (desktops and servers) with Debian and Mint.
>I've realized, using TCPDUMP at DNS1 and DNS2, that all DNS queries from
>Linux machines go to both DNS1 and DNS2 BIND servers at the same time.
>In all Linux machines we have setup the DNS resolution using
>nameserver IP_dns1
>nameserver IP_dns2
>But when the from Linux clients I execute:
>$ host <some_fqdn>
>I can see UDP traffic arriving to DNS1 and DNS2 at the same time.

maybe modified version of the "host" command?

>What can be the problem ? Because I expect only DNS traffic going to DNS1
>because it is before DNS2 in /etc/resolv.conf.

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