[dnsdist] Backend Questions

[Klaus Darilion]

Hello!

We use dnsdist with 1 single backend server (PDNS). So if this backend is overloaded, dnsdist will detect the backend as DOWN. Hence, the only server for this backend pool down. How will dnsdist behave if all servers for a backend pool are down? Will it stop senden queries to the backend, or will it still send queries to the DOWN server as there is no UP server available?

So it may be useful to disable healthchecks completely. How can this be done?


My current config is a few years old tested with dnsdist 1.3. These days, dnsdist was faster when I added the listen port multiple times, and also add the single backend server multiple times, to have more receiver threads. For example:
-- Open the same socket multiple times. This allows better load distribution
-- over all cores. Note: 1. setLocal(), dann addLocal()!
setLocal("192.174.68.96:53", { reusePort=true, tcpFastOpenSize=100 })
addLocal("192.174.68.96:53", { reusePort=true, tcpFastOpenSize=100 })

-- Define the Backend Server Pools. Define them multiple times to have multiple receiver threads
-- handling the responses from the Backend.
newServer{address='127.0.0.1:14001',name='pdns_1'}               -- this is the PowerDNS server
newServer{address='127.0.0.1:14001',name='pdns_2'}               -- this is the PowerDNS server


Is it still (dnsdist 1.6/1.7) useful/necessary to add listenSockets and Backendserver multiple times to improve performance?

Thanks
Klaus


--
Klaus Darilion, Head of Operations
nic.at GmbH, Jakob-Haringer-Straße 8/V
5020 Salzburg, Austria
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