Re: [DNSOP] abandoning ANAME and standardizing CNAME at apex

Colm MacCárthaigh <colm@allcosts.net> Mon, 25 June 2018 14:25 UTC

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From: =?UTF-8?Q?Colm_MacC=C3=A1rthaigh?= <colm@allcosts.net>
Date: Mon, 25 Jun 2018 07:25:07 -0700
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To: Tony Finch <dot@dotat.at>
Cc: Ray Bellis <ray@bellis.me.uk>, IETF DNSOP WG <dnsop@ietf.org>
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Subject: Re: [DNSOP] abandoning ANAME and standardizing CNAME at apex
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On Mon, Jun 25, 2018 at 7:02 AM, Tony Finch <dot@dotat.at>; wrote:

> > Even that though requires that the authoritative server be capable of
> > waiting for an asynchronously retrieved value before it can respond.
> >
> > For some authoritative servers that might require a substantial redesign.
>
> That isn't required if the ANAME target records are fetched/updated by an
> out-of-band provisioning process. A server will want to do it this way if
> its query rate is bigger than the number of ANAME targetss divided by
> their TTLs.
>

A challenge with that is that many people now use geographic or latency
based DNS routing based on the resolver IP address or EDNS-client-subnet.
That's one of the reasons why Route53's ALIAS works only for targets that
Route53 is authoritative for.

-- 
Colm