Q: Can I use the passive-interface command to make sure only R4-e0/0 will advertise RIP?
A: You have a better way to solve this. Just follow the instructions and you may discover it. Also, you have some tools to help you make sure it is working.
Q: Do I need to filter the network 20.0.0.0 in or going out from R4?
A: Please refer to your text. The requirement is clear on the text.
