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

Reindl Harald h.reindl at thelounge.net
Mon Dec 16 20:10:39 UTC 2019

Am 16.12.19 um 20:13 schrieb Roberto Carna:
> 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

it's not unusual behavior these days that a client asks both nameservers
and takes the answer of the faster one

that avoid large delays in case of timeouts when the asked one is down

More information about the bind-users mailing list