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Date: Mon, 24 Dec 2018 21:06:17 -0500
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Subject: Re: DNS resolver patch

On Thu, Dec 06, 2018 at 07:46:02PM +0000, Laurent Bercot wrote:
> >The musl resolver should be able to handle a resolver returning NODATA.
> >That is popular for having a separate extranet infrastructure - your
> >extranet DNS only contains records for your local domain and returns
> >NODATA for requests outside that domain.
> 
> No, you are talking about servers containing data. The musl client
> (which is not a resolver, because it only performs recursive queries)
> should not contact those directly. It should contact a real resolver,
> a.k.a. cache, and the cache will contact the servers containing data.
> If the domain has been configured properly, the servers are never asked
> for data that are outside that domain.
> 
> It is the single most annoying, most bug-prone, and most confusing
> flaw of DNS to have "communication between the DNS client and the DNS
> cache" (recursive queries) and "communication between the DNS cache
> and the DNS server" (non-recursive queries) happen on the same port.
> I'd even take a different _protocol_ if it could stop people from
> misconfiguring DNS.
> 
> The default usage of BIND, which was "one single daemon is both a
> cache and a server and we entertain the confusion", did a lot of harm
> to the Internet. As your post illustrates, this harm pertains to this
> day.

I'm not sure what the relation to the confusion between querying an
authoritative server and a recursive server is here, but the quoted
interpretation of NODATA above is wrong independent of any such
confusion. NODATA does not indicate that the server you asked doesn't
know about the queried name. It indicates that that queried name
exists but has no records of the requested type.

Rich

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