[dns-operations] DNS flag day 2020: Recommended EDNS buffer size discussion

Florian Weimer fweimer at redhat.com
Mon Sep 2 07:23:56 UTC 2019

* Jerry Lundström:

> Hi all,
> I have opened an issue that will serve as a public, open to all,
> discussion forum for what the recommended EDNS buffer size should be
> for DNS Flag Day 2020.
>   <https://github.com/dns-violations/dnsflagday/issues/125>
>> Please note that the exact recommended EDNS buffer sizes have not been agreed upon, the current ballpark around 1200 (1220, 1232, …) is to limit the risk of fragmentation in IPv6.
> Note that most of the text on dnsflagday.net mentions 1220 bytes.

I personally have used 1200 bytes, but I can switch to 1220 if that's
the consensus.  Previously, the consensus was that fragments were good
for the network (which I found rather odd).

> Please feel free to voice your opinion!

What about generating atomic fragments by default, to support stateless
IPv6 UDP service?  Or not generating atomic fragments under any
circumstances?  Would that be a separate discussion?


More information about the dns-operations mailing list