CCNP Questions

If a router has more than one route to the same IP prefix, the best path is the one with the shortest AS_PATH (assuming other BGP attributes are equal).

If a router has more than one route to the same IP prefix, the best path is the one with the highest LOCAL_PREF (assuming the WEIGHT attribute for the routes is equal).

Unicast IP packets are forwarded based on the destination IP address. Multicast packets are forward based on the source IP address. If a multicast packet is received on the interface used to send a unicast packet back to the source, the multicast packet is forwarded to multicast neighbors. If the multicast packet is received on an interface that would not be used to send a unicast IP packet back to the source, the packet is discarded.

OSPF databases on routers in the same area must be identical. If route summarization was allowed within an area, some routers would have specific routes and some routers would have summary routes for routes in the area. If this were allowed, the databases for the area would never agree

By default, all routes are advertised into all OSPF areas. This includes interarea OSPF routes and external routes that have been injected into OSPF. By default, IS-IS does not advertise interarea or external routes into an area, but injects a default route.

Using multiple protocols is modular and allows changes to one protocol without affecting the others. For example, if the addressing protocol is dependent on the delivery protocol, changes to one would imply changes need to be made to the other.

Routing moves a letter or telephone call to the access layer (as in a street or telephone exchange). Switching makes the final delivery. A switching decision is made on the part of the address that is not used in routing (as in the street number or last four digits of a phone number).

Classless routing protocols advertise subnet mask information along with the network prefixes. Classful routing protocols do not. Therefore, for a classful protocol, all subnets for the major network number being used must be the same length. Also, classful protocol cannot support discontiguous networks prefixes.