Re: transparent addrsel policy adjustment for outbound TE

[Thomas Narten <narten@us.ibm.com>]

Pekka Savola <pekkas@netcore.fi> writes:

> >> This doesn't really help with inbound TE though.  (One could add similar 
> >> function the site's authoritative DNS server, and unmodified resolvers 
> >> might comply with that policy, but caching DNS servers would mess this up.)
> >> 
> >
> > why?
> > i agree that the expressed policy has to be quite stable, i mean, the cache 
> > will introduce certain inertia, and changing the preferences may take some 
> > time, but at least you can express some preferences about which addresses the 
> > site preffers for incoming communications...

> The problem is that DNS caches in the middle will cache both IP_1 and 
> IP_2, but lose the "preference" which is conveyed by the weighted 
> address ordering, because from the DNS cache perspective IP_1 and IP_2 
> are equivalent.

> So this only works if there are no DNS caches in the middle, AFAICS.

I'm not following something here. Could you elaborate? Caching doesn't
mess things up in the DNS, unless one is using kludgery that is known
to be inconsistent with the basic DNS architecture.

Thomas