What is poisoned reverse in RIP?

Poisoned reverse is a specific technique employed within the Routing Information Protocol (RIP) to prevent routing loops and improve stability within a network. This method involves advertising a route with an infinite metric—typically represented with the value 16 in RIP—to indicate that a route is no longer reachable. By signaling other routers that the route is invalid when it is learned from them, it effectively prevents them from continuing to use that route. This process helps in maintaining accurate and updated routing tables without creating the potential for routing loops, which can lead to inefficient routing decisions and network congestion.

The other options, while related to routing in some capacity, do not correctly describe the function of poisoned reverse. For example, increasing routing efficiency could refer to various strategies but does not define the concept of poisoned reverse specifically. Enhancing packet security involves different protocols and methods not directly associated with RIP. Doubling the update frequency of routes is a separate concept linked to how often routing information is exchanged but does not align with the definition of poisoned reverse. Thus, the focus on advertising an unreachable route with an infinite metric accurately captures the essence of poisoned reverse within the context of RIP.