Re: [DNSOP] Eric Rescorla's No Objection on draft-ietf-dnsop-attrleaf-13: (with COMMENT)

Dave Crocker <> Wed, 10 October 2018 20:18 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id E6F401277CC; Wed, 10 Oct 2018 13:18:45 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.491
X-Spam-Status: No, score=-2.491 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001, T_DKIM_INVALID=0.01] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=fail (1024-bit key) reason="fail (message has been altered)"
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id o58kHC4tYdxC; Wed, 10 Oct 2018 13:18:44 -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 B3EE51277C8; Wed, 10 Oct 2018 13:18:44 -0700 (PDT)
Received: from [] ([]) (authenticated bits=0) by (8.14.4/8.14.4/Debian-4.1ubuntu1) with ESMTP id w9AKJ5KU009426 (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 10 Oct 2018 13:19:06 -0700
DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple;; s=default; t=1539202747; bh=v2zdU9rRBcEveyCr5TW86rV1uF5p0P/RqlH0BiDtzgk=; h=From:Subject:To:Cc:References:Date:In-Reply-To:From; b=QMh93+sTJ7TPO/HlN2AcB6MJu8VhJTj98/Jcd3ZmLae9VWfv1g7ay65mtYpuZ7WBd 9sKjRxJuXbXKZv2/WCj0xlL9lVczjCXfRXAZD/t5ZHK8PmV1+KXN0liycAtQyF3R/j Ngl9wWK5ULwYNw3yys907UURzlg3fxPKhEHJwabk=
From: Dave Crocker <>
To: Eric Rescorla <>, The IESG <>
Cc:,, Benno Overeinder <>,, Tim Wicinski <>
References: <>
Message-ID: <>
Date: Wed, 10 Oct 2018 16:18:47 -0400
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1
MIME-Version: 1.0
In-Reply-To: <>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Archived-At: <>
Subject: Re: [DNSOP] Eric Rescorla's No Objection on draft-ietf-dnsop-attrleaf-13: (with COMMENT)
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: IETF DNSOP WG mailing list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Wed, 10 Oct 2018 20:18:46 -0000


On 10/9/2018 7:23 PM, Eric Rescorla wrote:
>>       However some services have defined an operational convention, which
>>       applies to DNS leaf nodes that are under a DNS branch having one or
>>       more reserved node names, each beginning with an _underscore.  The
>>       underscored naming construct defines a semantic scope for DNS record
>>       types that are associated with the parent domain, above the
>>       underscored branch.  This specification explores the nature of this
> This text is a bit hard to parse for the layman. Here's my attempted
> rewrite, which captures what I think this means.
> Conventionally, this construct associates data with the parent domain,
> with the underscored label instead denoting the type of the data.
> I'm not sure if that helps, but perhaps something along these lines?

Yeah, this has been an oddly challenging bit of text to formulate.  Perhaps:

      However some services use an operational convention for defining 
specific interpretations of an RRset, by locating the records in a DNS 
branch, under the parent domain to which the RRset actually applies. 
The top of this subordinate branch is defined by a naming convention 
that uses a reserved node name, which begins with an _underscore.

> S 1.1.
>>    1.1.  Underscore Scoping
>>       As an alternative to defining a new RR type, some DNS service
>>       enhancements call for using an existing resource record type, but
>>       specify a restricted scope for its occurrence.  Scope is meant as a
> I think I get why you are saying "scope" here, but it's kind of not
> that good fit with the programming concepts of scope as I am familiar
> with.

    So I took your concern as an excuse to review the CS definition and 
find that I still think its application here is appropriate...  And it 
has not seemed to cause confusion for others.

> S 2.
>>                          +----------------------------+
>>                           Examples of Underscored Names
>>       Only global underscored names are registered in the IANA Underscore
>>       Global table.
> so just for clarify, in the examples above, only _service[1-4] and
> _authority would need to be registered?

Yes.  (And I've added a sentence noting that point, for clarity. Thanks.)


Dave Crocker
Brandenburg InternetWorking

Dave Crocker
Brandenburg InternetWorking