Routing Information Protocol (RIP)

Correct Answer: Configure passive interfaces on the specific routers

The most efficient method for preventing specific routers from receiving routing updates in a network using Routing Information Protocol (RIP) is to 'Configure passive interfaces on the specific routers'. This is because a passive interface in RIP is an interface that does not send routing updates, while it continues to listen to and process received RIP routing updates, which effectively prevents the router from sending out updates on that specific interface. 'Change the routers' RIP version', 'Configure RIP authentication' and 'Use hold-down timers' are not valid methods in this case. Changing the RIP version would not prevent updates from being sent, it would simply change the version of the routing protocol used. Configuring RIP authentication only adds security to the routing updates by requiring that each router in the network has the correct authentication to receive the updates. Lastly, hold-down timers merely control how often updates are sent and therefore does not prevent specific routers from receiving the updates.

Correct Answer: The route becomes invalid.

Routing Information Protocol (RIP) is a distance-vector routing protocol used in local and wide area networks. As per RIP specifications, the maximum hop count for a route is 15. If a route has a hop count of 16 or more, it is considered unreachable. That is why, if the hop count for a network route exceeds the maximum allowed in RIP, the route becomes invalid. The option stating 'The route metric resets to zero' is incorrect because in RIP, the hop count does not reset; instead, the route becomes invalid once it exceeds the maximum hop count. The option suggesting 'RIP switches to another routing protocol' is not correct since RIP does not have the functionality to switch to a different routing protocol automatically based on hop count metrics. Moreover, the claim that 'The network segment is reclassified as a supernetwork' is wrong as the classification of network segments is not dependent on RIP hop count but rather on the IP addressing scheme and subnetting in the network.

Correct Answer: RIP version mismatch

The best answer is 'RIP version mismatch'. RIP (Routing Information Protocol) routers use the same RIP version to communicate. If there's a mismatch, they won't be able to exchange updates. The other answers don't fit: 'Split horizon' is a method to prevent routing loops, not a cause for not receiving updates. The statement 'The route has exceeded the maximum hop count of 15' is not relevant here as it implies that the router could receive updates but the target is too far away. 'Triggered updates' is a mechanism that allows for faster propagation of network changes, it's not related to the inability of a router to receive updates.