Re: [dbound] NXDomain (was: Re: [dmarc-ietf] Fwd: New Version Notification for draft-dcrocker-dns-perimeter-00.txt)

Dave Crocker <> Sat, 06 April 2019 21:15 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 5045C12006B for <>; Sat, 6 Apr 2019 14:15:03 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.701
X-Spam-Status: No, score=-2.701 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id w6ltMso5Kb3v for <>; Sat, 6 Apr 2019 14:15:01 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 775911200A0 for <>; Sat, 6 Apr 2019 14:15:01 -0700 (PDT)
Received: from [] ( []) (authenticated bits=0) by (8.14.4/8.14.4/Debian-4.1ubuntu1.1) with ESMTP id x36LGiAA013613 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT); Sat, 6 Apr 2019 14:16:45 -0700
DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple;; s=default; t=1554585405; bh=qu8h/bPv6fYl9sLEGrABd1TE+Pv1vtXi0AeXRcCJpJs=; h=Subject:To:References:From:Reply-To:Date:In-Reply-To:From; b=In3Ha2eZkizjo8jRntGsFtAKBMMqFAb8qdBZF39uvFt+/Mk1de0JN1kApABcoZyrY m6/Insdmk4erfKC/w0BnDPNDjxNm5WL4frZNbb+BecZOrIC2e0Itd3RgBDBqhsNbe3 COmTMHg1DEZHTGGDQMoV9VmqgCC6O1bIdG3CjOGc=
To: John Levine <>,
References: <20190406150918.9B9BC2011A23A4@ary.qy>
From: Dave Crocker <>
Organization: Brandenburg InternetWorking
Message-ID: <>
Date: Sat, 6 Apr 2019 14:14:51 -0700
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1
MIME-Version: 1.0
In-Reply-To: <20190406150918.9B9BC2011A23A4@ary.qy>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Archived-At: <>
Subject: Re: [dbound] NXDomain (was: Re: [dmarc-ietf] Fwd: New Version Notification for draft-dcrocker-dns-perimeter-00.txt)
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: DNS tree bounds <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Sat, 06 Apr 2019 21:15:03 -0000

On 4/6/2019 8:09 AM, John Levine wrote:
> In article <> you write:
>> My understanding is that it's likely careful use of a resolver library
>> can retrieve the Additional information.  Some calls won't get it;
>> others probably will.
> As I may have said one or two times before, this hack will require
> changes to DNS servers to return additional information that they
> don't return now, 

Since that statement is in the current draft, I'm not clear what insight 
is intended by your multiple repetitions of it here.

> changes to DNS caches to store and pass through
> additional information that they don't store or pass through now, and

Oh?  You are saying that caches do not cache an entire response.   I did 
not find references that support that. Please document.

> changes to DNS client libraries to retrieve the additional information
> that they don't retrieve now.  I will cheerfully bet any amount of
> money that none of these changes ever happen.

That does not match my understanding.  My understanding from a 
knowledgeable source is: "APIs such as those in libresolv that deal in 
raw packets do tend to make the entire packet available.  Others such as 
`getaddrinfo` do not."

Since you appear to be claiming otherwise, please explain.

Worse, I even found an RFC with multiple examples of Additional 
information in an NXDomain response:

    Negative Caching of DNS Queries (DNS NCACHE)

> Once again, please compare this proposal to my 2016 proposal that uses

If you wish to do the work of a careful audit of the differences and 
similarities, and pursue a pointed review of the similarities and 
differences, perhaps that will facilitate conversation.  It would 
certainly improve the tone.



Dave Crocker
Brandenburg InternetWorking