[dns-operations] Unexpected truncation

Unbitrium unbitrium at unbitrium.co.uk
Sun Apr 3 21:22:17 UTC 2011

On 3 April 2011 18:41, George Barwood <george.barwood at blueyonder.co.uk> wrote:
> I think it's odd to truncate below 1460 bytes, which is where IP fragmentation starts, IIRC.
> I'd be interested in the reasoning here.

Semi-agreed, don't forget IPv6 :)

IPv6 specifies a minimum MTU that must be supported of 1280 (with a 40
byte IP header). I doubt there are any IPv4 networks which have
problems with packets this size, so this can probably be taken as a
baseline. (unfortunately there are people who have configured 1280 MTU
links "to make sure they don't have MTU problems")

Assuming their max packet size is 1169, if they are planning for a
worst case IPv6 network then that's still a lot of wiggle room they've
left themselves.

- Mike

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