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

[Roberto Carna]

Hi people,

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
/etc/resolv.conf:

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.

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

Thanks a lot !!!
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.isc.org/pipermail/bind-users/attachments/20191216/c99d22e0/attachment.htm>