[Pdns-users] Newbie question on using multiple forwarders

[Thomas Mieslinger]

Hi John,


On 5/12/21 12:50 AM, John Von Essen via Pdns-users wrote:
> [ Lots of Background info deleted ]
>
> My question is for a random server in Dublin, hitting pdns-recursor on localhost with those 3 forwarders, how is the traffic distributed? Does it go to the first one listed, and then only if the first one doesn’t respond, it tries the next?

In my experience, pdns-recursor versions from 4.3.x spread the load
evenly over all listed forwarders. I don't know exactly how they behave
if the forwarders have diverging latency.

Before, the first forwarder listed got practically all requests.

> I ask because I did a stress test with a similar setup and I saw that approx 60-70% of requests went to the IP of the first forwarder listed, then 30% to the second. I was expecting 100% traffic to the first.

Sidenote: Your performance might not be as good as Quad1/8/9 because the
caches of your recursors are not well filled. Some software exist to
keep the caches of recursor warm. Also the new "refetch" feature in 4.5
will help.

Thomas