REFER TO THE EXHIBIT. A PING BETWEEN THE SERIAL INTERFACES OF R1 A...

10. Refer to the exhibit. A ping between the serial interfaces of R1 and R2 is successful, but a ping between their FastEthernet

interfaces fails. What is the reason for this problem?

The FastEthernet interface of R1 is disabled.

One of the default routes is configured incorrectly.

A routing protocol is not configured on both routers.

The default gateway has not been configured on both routers.