[dnsdist] Some statistics I would like to have

Remi Gacogne remi.gacogne at powerdns.com
Tue Jun 13 08:23:26 UTC 2023

Hi Stéphane,

On 12/06/2023 14:44, Stephane Bortzmeyer via dnsdist wrote:
> I'm wondering about the average number of DNS queries per DoT/DoH
> connection (to see if the setup "cost" is amortized over enough
> requests). I do not find something like that in the output of
> dumpStats (I have the number of queries but not the number of
> connections). Any idea?

You should be able to find what you are looking for in the output of 

> Also, the Web interface tells me:
> Average response time: [...] DoT 357.45 ms, DoH 531.12 ms
> I assumed, may be wrongly, that this response time depended on the
> time required to fetch the response and so was the same for DoT and
> DoH. Why not?

The response time is computed from the moment we received the query from 
the client until after the response has been sent, so while this is 
usually indeed pretty much equal to the time required to fetch the 
response, it also records the time needed for internal processing, there 
might be some differences between protocols.
But more importantly, dnsdist forwards queries received over DoH using 
UDP, while queries received over DoT are forwarded over TCP, unless the 
backend has been configured as TCP-only, DoT or DoH. So it might be why 
you are seeing a difference, although this usually tends to be the other 
way around with DoH being faster than DoT because DNS servers have 
historically been optimized for UDP.

Remi Gacogne
PowerDNS.COM BV - https://www.powerdns.com/

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