I use unbound as local caching server.
When query goes from my local unbound to provider with “OPT UDPsize=512” - there is no any response from provider. I tried to set different values for “edns-buffer-size” but it does not helped.
I found that unbound tries to send queries with this option. After several attempts it send queries without this option and that it gets response from the provider. This leads to the significant delay in resolving.
Is there and way to make unbound send queries without this option?
This is example from tcpdump: