168.2.1 AND 10.1.1.2, BUT IS UNABLE TO PING 168.4.1.WHAT IS TH...

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.