ray.bel...@nominet.org.uk wrote:
>
>> EDNS0 RFC restricts EDNS0 to 4096 bytes, number of implementations
>> will not send more even if client ask for it. Firewalls will
>> enforce this.
>
> RFC 2671 enforces no such limit - the strict limit is 65535, and §4.5.5
> has a hint that 4K might be a reasonable amount of state to maintain for
> fragment reassembly.
The text in RFC 2671, presented as a hint, could deal to similar issues
with the TCP transport for DNS (working to change SHOULD for MUST).
>
> I seem to recall that BIND, however, will not permit the EDNS0 buffer
> size to be configured above 4096. I'm not in a position to double check
> that right now, though.
>
>From BIND ARM 9.7.0
----------------------
edns-udp-size
Sets the advertised EDNS UDP buffer size in bytes to control the size
of packets received.
Valid values are 1024 to 4096 (values outside this range will be
silently adjusted)
----------------------
> Ray
>
>
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