Re: Proposed resolution: PTR queries for 254.169.in-addr.arpa

At 02:17 PM 4/24/2005, Rob Austein wrote:
>At Fri, 22 Apr 2005 21:14:42 -0700 (PDT), Bernard Aboba wrote:
> >
> > Here is a proposed resolution to the Issue:
> >
> > "Mapping from IPv4 addresses to host names is conventionally done
> > by issuing DNS queries for names of the form,
> > "x.x.x.x.in-addr.arpa." When used for link-local addresses, which
> > have significance only on the local link, it is inappropriate to
> > send such DNS queries beyond the local link.
> > DNS clients MUST NOT send unicast DNS queries for any name that
> > falls within the "254.169.in-addr.arpa." domain.
> >
> > Recursive name servers MUST NOT allow these queries to
> > escape the local scope.  Recursive name servers MAY reply
> > with RCODE 3, or they MAY silently discard the request.
> >
> > By default, recursive name server implementations SHOULD be
> > configured to act as if they were authoritative for an
> > empty 254.169.in-addr.arpa zone and return RCODE 3 for any
> > such query.  Implementations SHOULD allow this default to
> > be overridden.
>
>Er, s/SHOULD/MUST/ here.  Hard wiring this into a recursive name
>server with no way to override it is probably not wise.

Since the text said "configured to act" not "hard programmed to act" I took 
this to mean the default configuration file supplied with the name server 
implementation had it set that way, vs. programmed in as a default response.

To my thinking, a default config file shipping with the DNS server software 
that claims to be authoritative for 169.254/16 would meet the text above. 
The user is free to remove or change that default configuration. Indeed, 
the fact that the text talks about this as a default condition seems to 
imply the ability to change it.

Long way of saying that, at least to my reading, "hard wiring" was not 
implied, even with the SHOULD present. That said, if the text changed to 
"Implementations MUST allow this default to be overridden" I would still 
approve of the document.


> >                 Returning an RCODE 3 is the correct default
> > setting because it reduces the query load but also because if
> > the site administrator has not set up the reverse tree
> > corresponding to IPv4 Link-Local addresses in use,
> > returning RCODE 3 is in fact the correct answer."
>
>Other than the above, this seems ok.