The graphic shows a network that is configured to use RIP routing protocol. Router2 detects that the link to Router1 has gone down. It then advertises the network for this link with a hop count metric of 16. Which routing loop prevention mechanism is in effect?

Route poisoning is the mechanism where a router advertises a failed route with an infinite metric (hop count 16 in RIP) to immediately inform other routers that the route is unreachable. This prevents routing loops by ensuring all routers know the route is bad. Split horizon (A) prevents sending updates back the way they came, error condition (B) is not a routing loop prevention mechanism, hold-down timer (C) waits before accepting changes, and count to infinity (E) is what routing loop prevention aims to avoid.