A. They establish routes that will never go down.
B. The keep routing tables small.
C. They require a great deal of CPU power.
D. The allow connectivity to remote networks that are not in the routing table.
E. They direct traffic from the Internet into corporate networks.

A. Information learned from one source is not distributed back to that source.
B. Routing updates from the poisoned source are ignored until a holddown timer expires.
C. Failed routes are advertised with infinite metrics.
D. New routing updates are ignored until the network has converged.
E. A route is marked as unavailable when its time-to-live is exceeded.