The intention of a black-hole route is to draw traffic to a destination, only to discard it. You achieve it by creating a route to null0. For example, if you configured the following 'ip route 10.0.0.0 255.0.0.0 null0', and redistributed it into a routing protocol, all traffic for 10.0.0.0/255.0.0.0 woudl head to the router where they would get dropped.
If you do that, then the only thing that will do is to discard any packets for any destinations not known by the router (assuming it does not have a default route). However, the rest of the network does not learn of the route that is being black-holed.. you need to create a route to Nullo and tell the rest of the network about it.