Re: [dnsext] Some thoughts on the updated aliasing draft

[Paul Vixie <[e-mail]>]

> Date: 27 Mar 2011 19:25:12 -0000
> From: "John Levine" <[e-mail]>
> 
> It seems to me that we can divide applications into two groups.  In one
> group, the client uses the name to find a server, but the name never
> appears in the data stream or only appears as a comment.  This includes
> FTP, SSH, POP, and IMAP.  Something like BNAME would be adequate to make
> names look the same to users.  I'd say these applications don't know
> what their names are.
> 
> In the other group, the domain name appears in the data stream, and
> the server does something with it beyond resolving it to an A or AAAA
> record.  The standard examples are SMTP and HTTP.  These apps do know
> what their names are, and the only alternatives I see are a great deal
> of manual provisioning, or else they learn how to check the DNS to see
> whether a hitherto unknown name in the data stream is an alias of a
> canonical name that it does know.  So, yeah, the applications will
> eventually have to change.
> 
> From the point of view of DNS design, I'd want something that returns
> an appropriate A or AAAA for the first group, and offers a
> straightforward way for the second group to see what's an alias of
> what.
> 
> For a transition, it's still possible to configure the second group
> manually, but it'd be a lot easier if they got smarter so people
> didn't have to do so.

these would be, in the parlance used when this topic was first introduced,
"second class names".  they can't be used as the target of MX or NS RRs,
and they won't work for services whose servers have not been upgraded.

if we're allowed to produce second class names as our answer to the problem
then this is news to me but it massively simplifies the work.  and we will
have the burden of explaining to all of the IDN people that these "second
class names" will have precisely zero value for the first few years and
very little value for the first few decades.  and, making them believe us.