[dnsdist] DoT/TCP model question

[Remi Gacogne]

Hi Kevin,

On 1/15/21 1:37 PM, dbgong--- via dnsdist wrote:
> In the DoT and TCP model,  dnsdist only issue a TCP query to the
> backend server. And there is no way to configure it to send a UDP
> query to the backend server. Is this a feature or a bug?

Forwarding queries received over TCP and DoT to the backend over TCP is
a design choice. We might at some point implement the ability to decide
whether you want queries forwarded over UDP or TCP, regardless of the
incoming protocol, but it goes with a lot of surprises and headaches
regarding EDNS payload size and truncation, at the very least.

We made a different choice for DoH based on the fact that at the moment
DoH client are always regular clients, with up-to-date implementations,
but even that proved to be painful as well.


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