Consider the network depicted in the figure below. The IP addresses and MAC addresses of individual interfaces are as denoted in the figure.

Suppose that the sender host PC-B with the IP address 10.10.30.1 wants to send an IP datagram to the receiver host PC-A with IP address 10.10.10.1. Answer the following questions.

a) What is the source MAC address of the frame when it leaves the router R1? 

b) What is the destination MAC address of the frame when it leaves the router R1? 

c) Suppose now that the host PC-A wants to reply to host PC-B. What is the destination MAC address of the frame when it leaves the PC-A? What is the destination MAC address of the frame when it leaves the router R1? 
 

PC-A PC-A 10.10.10.1 AA: AA: AA: AA: AA: AA Interface E1 10.10.10.250 CC:CC:CC:CC:CC:CC E1 R1 E2 Interface E2 10.10.20.2 Interface E3 10.10.20.1 EE:EE:EE:EE:EE:EE E3 R2 DD:DD:DD:DD:DD:DD PC-B 10.10.30.1 BB: BB: BB: BB: BB: BB E4 Interface E4 10.10.30.250 HH:HH:HH:HH:HH:HH PC-B