Subject: Re: Last Call: draft-cheshire-dnsext-multicastdns (Multicast DNS) to Informational RFC

From: Dave Thaler <[email-masked]>
Date: Mon, 30 Nov 2009 20:08:45 +0000

The biggest problem I have with this document is among those pointed out by Wouter:
> * The rule that .local names MUST be sent to mdns(port 5353). I feel 
>   this is a little too strong, there are sites out there that have set ups 
>   with .local in their unicast DNS. Propose: SHOULD. 

As stated above, it's already a somewhat common practice to use .local 
in *private* DNS namespaces (e.g., corporate networks), whether we like 
it or not, and the current text in the mdns draft section 3 is incompatible
with this (i.e., it proposes to break them).

The current practice is cited in many places including:
http://tools.ietf.org/html/draft-kato-dnsop-local-zones-00 
> While it has yet been described in a RFC, .local is used to provide a
> local subspace of the DNS tree.  Formal delegation process has not been
> completed for this TLD.  In spite of this informal status, .local has
> been used in many installations regardless of the awareness of the
> users.

http://en.wikipedia.org/wiki/Top-level_domain 
> The top-level pseudo domain local is required by the Zeroconf protocol. 
> It is also used by many organizations internally, which may become a 
> problem for those users as Zeroconf becomes more popular.

And there's lots of places people have complained about this conflict
with mdns, such as:

http://lists.apple.com/archives/Macnetworkprog/2004/Oct/msg00089.html 
http://www.markwilson.co.uk/blog/2007/11/managing-simultaneous-access-to-resources-from-both-internal-and-external-dns-namespaces.htm 
http://www.macosxhints.com/article.php?story=20040806232315819 
etc

-Dave