Andrew Brown writes:
> >>> "Broadcasting to what"? 
> >>
> >>To the local net.
> >>
> >>You presumably get answers from the local routers and hosts if they
> >>know what the netmask is.
> >
> >Right, but if you have a CIDR network then the broadcast address is an
> >unknown... You could just send the ICMP to the gateway and hope it's
> >implemented (is it required by any standards?), but I don't think
> >relying on a broadcast is a good idea.
> 
> (jumping in over my head perhaps :)
> 
> what's wrong with broadcasting to 255.255.255.255?  at a least
> configured gatewway should answer, no?

Broadcasts are done, in the end, to the ethernet broadcast address. In
the end, that's all you need to know. If broadcasts didn't work before 
you were configured, DHCP and friends couldn't work at all.

.pm