Viktor Dukhovni:
> > Another data point: by default, Postfix uses a 4096-byte buffer
> > when it calls the C library stub resolver, but it will repeat the
> > call with a larger buffer if the response has the 'truncated' flag
> > raised, and leaving it up to the library to switch to TCP as needed.
>
> It is largely a mistake to confuse the application's result buffer size
> passed to the DNS resolver (to allow the stub resolver to return larger
> result packets after TCP fallback) with any notion of the requested EDNS
> buffer size. The choice of EDNS (UDP!) buffer size is baked into the
> usual Unix stub resolver library, and is not configurable.
It is the size of the response that the library caller is willing
to receive, no less, no more. I have forgotten how libc signals to
the caller that it needs more space. If there's a better way than
looking at the 'truncated' flag, then educate me.
Wieyse
