How does a Cisco router handle broadcasts heard through multiple paths?
A. A Cisco router does not forward a broadcast which has a hop count of zero. A Cisco router forwards a broadcast that has a non-zero hop count but only if it heard that broadcast on the interface that it considers as the best choice to reach the source of the broadcast. The only exception to this rule is the broadcast to the StreetTalk service. Broadcasts are only ever forwarded if they are received on the interface that is, in that router opinion, the best interface to reach the source. This does not allow the router to forward multiple copies of the same broadcast. In this diagram, when the server sends a broadcast, cisco1 and cisco2 each forward the broadcast from the top Ethernet to the middle Ethernet because they know that the best path to the server is through the top Ethernet. Cisco3 sees both of these broadcasts and forwards them to the bottom Ethernet because it knows that the best path to the server is through the middle Ethernet. This clause comes into play when cisco2 see
