Re: [Doh] [Ext] DNS over HTTP/3?

bert hubert <bert.hubert@powerdns.com> Mon, 19 November 2018 16:04 UTC

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Date: Mon, 19 Nov 2018 17:04:14 +0100
From: bert hubert <bert.hubert@powerdns.com>
To: Paul Hoffman <paul.hoffman@icann.org>
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Subject: Re: [Doh] [Ext] DNS over HTTP/3?
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On Mon, Nov 19, 2018 at 03:39:16PM +0000, Paul Hoffman wrote:
> > It does around 2 DNS queries per HTTPS connection on average dnsdist-doh
> > keeps open an HTTP/2 connection for 10 seconds if it becomes idle.
> 
> Thanks, that seems to be your problem.  Can the dnsdist DoH server package
> be configured to have an idle timeout that is more representative of
> typical browser use, such as on the order of minutes?

I have measured with timeout of 100 seconds and 300 seconds. In both cases,
the packets per query ratio drops to 12, from 22. This is still around 6
times more than UDP, and I now carry around hundreds of additional
filedescriptors. But ok.

> > My personal observation is that on a slightly bad network, turning off DoH
> > speeds up things massively and makes the web useable again.  This naively
> > makes sense, DoH uses way more packets and suffers from Head of Line
> > blocking, unlike plain DNS.
> 
> Is that still true with a server timeout that is not so short?

I will need to measure again. Linux can inject packet loss, so this should
be doable.

	Bert