Re: [DNSOP] DNSOP Call for Adoption - draft-west-let-localhost-be-localhost

"John Levine" <> Wed, 13 September 2017 02:15 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 092FD13292A for <>; Tue, 12 Sep 2017 19:15:55 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.9
X-Spam-Status: No, score=-1.9 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id jcO7Uu2MPUcc for <>; Tue, 12 Sep 2017 19:15:53 -0700 (PDT)
Received: from ( [IPv6:2001:470:1f06:1126::2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id EBE61126C19 for <>; Tue, 12 Sep 2017 19:15:52 -0700 (PDT)
Received: (qmail 27447 invoked by uid 125); 13 Sep 2017 02:15:51 -0000
Received: from unknown ( by with QMQP; 13 Sep 2017 02:15:51 -0000
Date: Wed, 13 Sep 2017 02:15:29 -0000
Message-ID: <20170913021529.2540.qmail@ary.lan>
From: John Levine <>
In-Reply-To: <>
X-Headerized: yes
Mime-Version: 1.0
Content-type: text/plain; charset="utf-8"
Content-transfer-encoding: 8bit
Archived-At: <>
Subject: Re: [DNSOP] DNSOP Call for Adoption - draft-west-let-localhost-be-localhost
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: IETF DNSOP WG mailing list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Wed, 13 Sep 2017 02:15:55 -0000

In article <> you write:
>Since we are doing a draft/RFC on what localhost is and is not, I 
>suggest we put some text in there banning (MUST NOT) the practice of 
>having localhost entries (at least those pointing to in 
>auth zones. If there is agreement on this I am happy to contribute text. 
>This may mean having to say we are updating RFC 1912.

Believe it or not, there are real non-loopback localhost domain names,

I agree that localhost.<foo> pointing to loopback is generally asking
for trouble, but I am not at this point sufficiently confident that it
is never ever a good idea to say MUST NOT rather than SHOULD NOT.  I
can for example imagine ways that might make some kinds of debugging