[Dnsmasq-discuss] reducing DNS packet size for nameserver 127.0.0.1 to 1280

[Dominik Derigs]

Hey Justin,

On Tue, 2022-01-04 at 17:34 +0800, Justin wrote:
> Recently i see lots of logs in dnsmasq:
> reducing DNS packet size for nameserver 127.0.0.1 to 1280
> almost one per minute
> 
> my conf:
> [...]
> server=127.0.0.1#5353

once per minute sounds like this is happening all the time
(dnsmasq doesn't warn for one minute if it happened once).

You should either increase the EDNS buffer size on the server
running at 127.0.0.1#5353 or add the config line

edns-packet-max=1280

to your config to adhere to the limit.

Furthermore, What server is running on port 5353 of your machine?

I suggest reading this discussion, Pi-hole runs dnsmasq at its
heart and everything is directly applicable to your situation:

https://discourse.pi-hole.net/t/dnsmasq-warn-reducing-dns-packet-size/51803

Maximum packet sizes for some commonly used server are here

https://discourse.pi-hole.net/t/dnsmasq-warn-reducing-dns-packet-size/51803/31

Best,
Dominik