Re: [hylafax-users] Clients with multiple IP addresses

["Jay R. Ashworth" <jra@baylink.com>]

On Wed, Jul 25, 2001 at 11:52:41AM -0600, Lee Howard wrote:
> At 01:34 PM 7/25/01 -0400, Jay R. Ashworth wrote:
> >On Wed, Jul 25, 2001 at 09:10:32AM -0600, Lee Howard wrote:
> ....
> >> My guess would be that you've misconfigured your DNS.
> >
> >No, I don't think so, Lee.
> >
> >He has a machine with more than one interface, and therefore, more than
> >one address.  He's using *names* in his hosts.hfaxd, and when HF does a
> >lookup to get an address, it's coming back with the wrong one, due to
> >DNS round-robin, as he suspected. 
> 
> So the DNS isn't misconfigured when "it's coming back with the wrong one"? :-)

Nope.  

:-)

He's connecting from a machine with two addresses.  If those both
happen, for some reason, to be on the same local network, or if there's
a router inbetween, then which one will be chosen by the client is
nondeterministic. 

When the *server* then dereferences all the symbolic names in it's
hosts.hfaxd file to get IP addresses against which to check (which is
stunningly inefficient, anyway, if the DNS server isn't on the same
box), it will get whichever roundrobin address is next to be served,
which may not be the same as the one the routing kernel on the client
chose to send the packet out.

Everything is working as designed, it's just that this is a
circumstance that the system wasn't designed for.

*I* would recommend against using DNS names in that file, *at least*
for multihomed clients.  It's a fairly uncommon situation, which is
probably why it hasn't come up in five years.  ;-)

Cheers,
-- jra
-- 
Jay R. Ashworth                                                jra@baylink.com
Member of the Technical Staff     Baylink                             RFC 2100
The Suncoast Freenet         The Things I Think
Tampa Bay, Florida        http://baylink.pitas.com             +1 727 804 5015

   "So easy to use, no wonder the Internet is going to hell!"
     -- me


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