[Dnsmasq-discuss] Further thoughts/questions on failover
michael at kmaclub.com
Thu Sep 2 17:44:48 UTC 2021
On 9/2/21 6:58 AM, Kevin Tedder wrote:
> You just need to update the /etc/resolv.conf file on each of your clients to
> point them at both DNS's.
> nameserver 192.168.1.2
> nameserver 192.168.1.3
> The client will now ask both DNS servers. It will get a response even if one
> of them is off-line.
This is generally platform specific. Not all resolvers treat things
equally. Some will only query one and if it times out, then will go
to the other. This can cause big delays in DNS resolution and ends up
feeling like your whole network is slow. Others query both and take the
fastest response, so it is hit or miss based on your client platforms.
Additionally, if the dnsmasq instance is ONLY doing DNS service, this
can work fairly well. Keep the hosts file replicated and either server
can hand out the same data. Obviously the cache will be different for
each so you loose some effectiveness, but the client never really knows.
However, if you are running DHCP and dnsmasq is updating/maintaining a
list of host names of your local clients in the leases file, then only
one of the dnsmasq instances is going to know about those. In this
instance, I think makes more sense to ensure you have one really robust
dnsmasq system than having two that don't respond the same.
I think both have valid use cases and it just depends on what works best
for your scenario.
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