Refer to the exhibit. Both routers are using the RIPv2 routing protocol and static routes are undefined. R1 can ping 192.168.2.1 and 10.1.1.2, but is unable to ping 192.168.4.1.

Refer to the exhibit. Both routers are using the RIPv2 routing protocol and static routes are undefined. R1 can ping 192.168.2.1 and 10.1.1.2, but is unable to ping 192.168.4.1. 

What is the reason for the ping failure?


The serial interface between two routers is down.
R2 is not forwarding the routing updates.
The 192.168.4.0 network is not included in the RIP configuration of R2.
RIPv1 needs to be configured.