A. It sends back the protocol received from a router as a posion pill, which stops the regular updates. the use of variable length subnet masks is permitted
B. It is information received from a router that can’t be sent back to the originating router.ripv2 supports claSSLess routing
C. It prevents regular update messages from reinstating a route that has just come up
D. It describes when a router sets the metric for a downed link to infinity