Re: [dnssd] I-D Action: draft-ietf-dnssd-mdns-dns-interop-01.txt

[Douglas Otis <[e-mail]>]

On 7/4/15 5:23 PM, Andrew Sullivan wrote:
> Hi,
>
> On Sat, Jul 04, 2015 at 02:25:11PM -0700, [e-mail] wrote:
>> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>>  This draft is a work item of the Extensions for Scalable DNS Service Discovery  Working Group of the IETF.
>>
>>         Title           : On Interoperation of Labels Between mDNS and DNS
>>         Author          : Andrew Sullivan
>> 	Filename        : draft-ietf-dnssd-mdns-dns-interop-01.txt
>> 	Pages           : 10
>> 	Date            : 2015-07-04
> This draft attempts to deal with the issues that were raised to me
> about the previous versions.  In particular, it tries to de-emphasise
> the worry about system-wide resolvers (without dismissing it
> completely) and to emphasise the issue of actual administration
> policies in the public DNS.
Dear Andrew,

Why assume top level domains are always A-Labels?  A scheme
that visually conveys available services in list form for
user selection is not well served with A-labels.

Why not emphasize use of UTF-8 where possible to avoid
rather messy conversion issues and resulting visual
confusion.  

Your approach ignores two issues:

1) Dealing with look-alike spoofing can not depend upon
registrar regulation or conversion rules.

2) The size of a response accessed with a DNS wildcard may
lead to DDoS issues.

Publishing prophylactic wildcards destroys the utility of
the DNS-SD approach.  An incongruity of mixing A-Labels with
U-labels creates an unfriendly display of identifiers which
does not help limit the size of the list response.  The
listing approach can be made safe with use of HTTP rather
than DNS, or at the least DNS over QUIC.  Until an inter-op
document is more comprehensive, it is hard to see how this
improves upon the current situation.

DDoS and inadvertent disclosure issues are explained in:
https://tools.ietf.org/html/draft-otis-dnssd-mdns-xlink-06

Regards,
Douglas Otis