Re: [DNSOP] New draft for ALIAS/ANAME type

Tony Finch <dot@dotat.at> Mon, 03 April 2017 12:11 UTC

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Date: Mon, 3 Apr 2017 13:10:58 +0100
From: Tony Finch <dot@dotat.at>
To: Peter van Dijk <peter.van.dijk@powerdns.com>
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Subject: Re: [DNSOP] New draft for ALIAS/ANAME type
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Peter van Dijk <peter.van.dijk@powerdns.com> wrote:
> On 31 Mar 2017, at 12:10, Tony Finch wrote:
> >
> > Does the more ambitious version use the NSEC rdata format so that you can
> > have different target names for different alias RR types?
>
> I got this question some time ago when I was working on ALIAS for PowerDNS.
> Back then I said no, as nobody showed me an actual use case for it and I did
> not like the extra complexity. Today I feel the same way and the upcoming
> draft does not have type bitmaps currently.

That's probably sensible :-)

The vague idea I had was ALIAS A AAAA for your web hosting provider and
ALIAS MX TXT for your mail hosting provider. But the latter isn't actually
very useful, since MX and SPF records have built-in indirection, and TXT
is also used for other purposes (domain authorization, quite frequently in
my experience), and it doesn't cover DKIM or MUA SRV records. And other
scenarios stub their toes in similar ways, e.g. for SIP there's a mess of
SRV records plus NAPTR, and a NAPTR RRset can cover multiple unrelated
protocols and providers.

So I think my conclusion is that ALIAS is both unnecessary and unhelpful
for RRtypes other than A and AAAA.

Tony.
-- 
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