Re: [DNSOP] [Ext] Re: Creating a registry for reserved labels.

Paul Hoffman <> Fri, 28 September 2018 20:20 UTC

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From: Paul Hoffman <>
To: Warren Kumari <>
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Thread-Topic: [Ext] Re: [DNSOP] Creating a registry for reserved labels.
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Date: Fri, 28 Sep 2018 20:20:29 +0000
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Subject: Re: [DNSOP] [Ext] Re: Creating a registry for reserved labels.
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On Sep 28, 2018, at 11:27 AM, Warren Kumari <> wrote:
> We are adding (at the IESG's request) this (thanks to Terry for the text):
> ------
> "The special labels defined here came after extensive IETF evaluation
> of alternative patterns and approaches in light of the desired
> behaviour (sections 2.1, 2.2) within the resolver and the applied
> testing methodology (section 4.3).  As one example, underscore
> prefixed names were rejected because a number of browsers / operating
> systems would not fetch them, as they were not viewed as valid
> "hostnames". Attention was paid to the consideration of local
> collisions and the reservation of Left Hand Side (LHS) labels of a
> domain name, and the impact upon zone operators who might desire to
> use a similarly constructed hostname for a purpose other than as
> documented here.  Therefore, it is important to note that the
> reservation of the labels in this manner is definitely not considered
> "best practice".
> -----
> to the KSK document. The registry creation document should contain some language explaining that this sort of thing is a poor design-pattern[0], and should be avoided unless there is a really good reason....

I agree that new document that I volunteered to edit (are there any offers of co-editors?) should have similar language. I fully disagree that it is a "poor design pattern". It has been shown over and over to work well.

> but, if people do things like this, having them documented is better than astonishment.

Yes, that's the reason for the registry.

--Paul Hoffman