Refer to the exhibit. The network setup is running the RIP routing protocol.
Which two events will occur following link failure between R2 and R3? (Choose two.)
A. R2 will advertise network 192.168.2.0/27 with a hop count of 16 to R1.
B. R2 will not send any advertisements and will remove route 192.168.2.0/27 from its routing table.
D. After communication fails and after the hold-down timer expires, R1 will remove the 192.168.2.0/27 route from its routing table.
C. R1 will reply to R2 with the advertisement for network 192.168.2.0/27 with a hop count of 16.
E. R3 will not accept any further updates from R2, due to the split-horizon loop prevention mechanism.
A and C
POISON REVERSE:
The poison reverse rule overwrites split horizon rule. For example, if router B receives a route poisoning of network 4 from router C then router B will send an update back to router C (which breaks the split horizon rule) with the same poisoned hop count of 16. This ensures all the routers in the domain receive the poisoned route update.
Notice that every router performs poison reverse when learning about a downed network. In the above example, router A also performs poison reverse when learning about the downed network from B.
I think BP is right.
A. R2 will advertise network 192.168.2.0/27 with a hop count of 16 to R1.
D. After communication fails and after the hold-down timer expires, R1 will remove the 192.168.2.0/27 route from its routing table. – Flush time 60 second after hold down timer expires.
This is not true due to split horizon
C. R1 will reply to R2 with the advertisement for network 192.168.2.0/27 with a hop count of 16.
Agreed.
Actually after further investigation, AC is correct.
When router A has learnt a route from router B, it advertises the route back to B with a metric of 16 (unreachable). This ensures that B is never under the impression that A has a different way of getting to the same destination. This technique is known as “split horizon with poison reverse.
https://www.metaswitch.com/knowledge-center/reference/what-is-routing-information-protocol-rip
An augmented version of Split Horizon is the addition of the Poisoned Reverse mechanism, resulting in Split Horizon with Poisoned Reverse. This principle states that a network should always be explicitly advertised as unreachable over the interface that is used to reach that network. This version of Split Horizon is stronger than its basic version: Instead of simply not advertising the route back toward its next hop, silently hoping the next hop has never considered us a possible backup for this path, we explicitly force the next-hop router to avoid and ignore us when choosing the best path to the network. ___While more effective, it is not implemented in the Cisco RIPv2.___
________________________________________________
So – C for cisco incorect