Andrew S. Tanenbaum Edition 5th Exercise 5 Question 33 (Page No. 492)

Question

A router has the following (CIDR) entries in its routing table:
 

Address/Mask	Next hop
135.46.56.0/22	Interface 0
135.46.60.0/22	Interface 1
192.53.40.0/23	Router 1
default	Router 2

For each of the following IP addresses, what does the router do if a packet with that
address arrives?
(a) 135.46.63.10
(b) 135.46.57.14
(c) 135.46.52.2
(d) 192.53.40.7
(e) 192.53.56.7

Answer 1

here longest Prefix Match will be done for forwarding

Entries in Router's table

10000111.00101110.00111000.00000000/22:  Interface 0

10000111.00101110.00111100.00000000/22:  Interface 1

11000000.00110101.00101000.00000000/23:  Router 1

Default:  Router 2

a. 10000111.00101110.00111111.00001010 it goes to interface 1

b. 10000111.00101110.00111001.00001110 it goes to interface 0

c. 10000111.00101110.00110100.00000010  it goes to router 2

d. 11000000.00110101.00101000.00000111 it goes to router 1

e. 11000000.00110101.00111000.00000111 it goes to router 2