Which of these statements accurately identifies how Unicast Reverse Path Forwarding can be employed to prevent the use of malformed or forged IP sources addresses?
A.
It is applied only on the input interface of a router.
B.
It is applied only on the output interface of a router.
C.
It can be configured either on the input or output interface of a router.
D.
It cannot be configured on a router interface.
E.
It is configured under any routing protocol process.
Explanation:
Unicast RPF can be used in any "single-homed" environment where there is essentially only one access point out of the network; that is, one upstream connection. Networks having one access point offer the best example of symmetric routing, which means that the interface where a packet enters the network is also the best return path to the source of the IP packet. Unicast RPF is best used at the network perimeter for Internet, intranet, or extranet environments, or in ISP environments for customer network terminations.