[getdns-api] EDNS maximum UDP payload size defaults to 512

[Shumon Huque]

On Mon, Sep 22, 2014 at 1:50 PM, Shumon Huque <shuque at gmail.com> wrote:

>
> The 1280 magic number comes from the IPv6 minimum MTU. To avoid IPv6
> fragmentation, we'd need to specify a number somewhat below 1280 to account
> for UDP header (8 bytes) and any likely encapsulation/extension headers.
> BIND appears to use a value of 1232 for this purpose.
>

Apologies for following up to my own message. I realized later that the
1232 value is the result of subtracting the length of the IPv6 header (40)
and the UDP header (8) from 1280. That leaves a max UDP payload size of
1232.

--Shumon
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