query-source for multiple interfaces

[Barry Margolin]

In article <e4iujv$242$1 at sf1.isc.org>,
 Mark Andrews <Mark_Andrews at isc.org> wrote:

> > In article <e4gd1a$4bm$1 at sf1.isc.org>,
> >  Mark Andrews <Mark_Andrews at isc.org> wrote:
> > 
> > > > In article <e4feh9$12k9$1 at sf1.isc.org>,
> > > >  Sam Wilson <Sam.Wilson at ed.ac.uk> wrote:
> > > > 
> > > > > Looking at the ARM the "query-source" option seems to be able to 
> > > > > specify
> >  
> > > > > only one address.  We are investigating anycast DNS on multihomed 
> > > > > servers.  It looks as though I can't use "query-source" to allow 
> > > > > queries
> >  
> > > > > to be sent from any address except the multicast address.  Is this 
> > > > > true 
> > > > > and is there any obvious workaround?  I've already thought of adding 
> > > > > a 
> > > > > second local /32 address that's specific to the box and sourcing the 
> > > > > queries from there, but that's getting rather messy.
> > > > 
> > > > If the anycast address is an alias IP, I don't think you need to do 
> > > > anything.  I think the OS will automatically default the source address 
> > > > to the primary IP of the outgoing interface rather than an alias.
> > > 
> > > 	Also it does not make sence to send queries from a anycast
> > > 	address as the replies are not guarenteed to go back to the
> > > 	correct instance.
> > 
> > That's his point -- he wants to PREVENT it from using the anycast 
> > address.  But he doesn't want to list all the other addresses 
> > explicitly, he was hoping for something like:
> > 
> > query-source address { !1.2.3.4; };
> > 
> > to mean "use any of the system's addresses except 1.2.3.4".
> > 
> 	Well he actually said "multicast" which a assummed was his
> 	way of saying "*".

Since he said they're setting up "anycast DNS on multihomed servers", 
the context led me to assume that "multicast" was a mistake (his brain 
merged pieces of "multihomed" and "anycast").

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
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