Re: RFC3484 problem: scoping with site-locals/ULAs

[Havard Eidnes <he@uninett.no>]

> So I have a dumb question.
>
> Why not:
> 	- use a DNS lookup that asks for all records (including A, MX, and  
>         AAAA)

Because you can't do this with a single DNS query.  The "ANY" query
type will return all the records/record types cached for a given name,
but there is no guarantee that the cache has been filled with all the
information available on the authoritative name servers for the given
name.  Individual RRsets (name+type) can have different TTLs, so even
if the cache was filled with all the information initially, a caching
name server can't guarantee that will always be the case at a later
time.

That's a minor detail, though -- one or two DNS queries doesn't make
much of a difference.

> 	- open both a v4 and a v6 connection simultaneously
> 	- accept the first to successfully open and shut down all others

I think that the TCP connect operations are typically synchronous at
the user/kernel interface.  Doing several connection attempts in
parallel is therefore at best problematical.  Using pthreads could
possibly be a workaround, but mandating use of pthreads for all
applications for using the C library is, I think, not acceptable.

Regards,

- Håvard