Re: [Resolverless-dns] Paper on Resolver-less DNS

Viktor Dukhovni <ietf-dane@dukhovni.org> Wed, 04 September 2019 14:50 UTC

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From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Subject: Re: [Resolverless-dns] Paper on Resolver-less DNS
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On Wed, Sep 04, 2019 at 03:51:55PM +0200, Erik Sy wrote:

> > What else could it mean?
> 
> Note, that the retrieval of a popular website requires on average
> connections to about 20 different hostnames. Thus, if the first
> connection to an average website provides you the DNS records for the
> remaining 19 hostnames then using resolver-less DNS can save up to 19
> traditional DNS lookups.

A more conservative "scope" for any such address hints would be to
limit them to just to the display of the current "location" (web
page).  When the browser navigates to a new page, any such cache
should be flushed.  This should include navigation via links on the
page.  Only the retrieval of resources needed to display the current
page would then make use any returned addresses.

Many users re-use existing tabs to navigate to new sites independent
of the one previously displayed in the tab.

Some of the concerns I have raised are ameliorated if the scope of
the returned addresses is limited to just the page being displayed.
That way, one perhaps gets faster loading of images, Javascript
(and advertisements, if not blocked).

That said, browsers do DNS lookups in parallel, and the user's
resolver will often already have the answers in its cache.  Is the
resulting reduction in latency really worth the added complexity
and potential risks?

-- 
	Viktor.