Re: [Doh] Clarification for a newbie DoH implementor

Tony Finch <dot@dotat.at> Wed, 19 June 2019 16:05 UTC

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Date: Wed, 19 Jun 2019 17:05:01 +0100
From: Tony Finch <dot@dotat.at>
To: Mark Delany <d5e@xray.emu.st>
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Subject: Re: [Doh] Clarification for a newbie DoH implementor
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Mark Delany <d5e@xray.emu.st>; wrote:
>
> As we've discussed previously, it's pointless returning TC=1 to the stub as it
> will simply re-issue an identical query as far as the DoH server is concerned.

TC=1 implies that the client should retry using a different transport
that can handle larger messages. If your transport is not UDP, there
aren't any alternatives that can handle larger messages :-)

You *can* get TC=1 on TCP etc, because it is possible to create an RRset
that is larger than 65536 octets.

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>;  http://dotat.at/
the widest possible distribution of wealth