[Please explain how to get the answer]

Answer the following questions regarding IP address allocation and routing tables. Consider the network topology and IP configuration shown below. Determine the correct and complete entries for the forwarding information bases (i.e., routing tables) for routers R1 and R2. The router ports are named A and B as shown in the figure. Use the minimum number of necessary entries. You may assume that routers make the appropriate announcements towards the Internet.

128.119.86.132 128.119.86.129 128.119.86.133 128.119.86.135 R1 Interr 28.119.86.207 28.119.86.211 128.119.86.134 128.119.86.139 R2 128.119.86.136 23119 86 210 ooo 2 1 1 |101 0011 34 100ooll R1 R2 Prefix 1211a 86-135/32 | B 123 1a.86.192/27 B Port Port Prefix 23.4.7332 28-114 86 2828A