Computer Communication & Networks
Sample Question Paper
Question # 1
a) How do the layers of the internet model correlate to the layers of the OSI
model? 03 marks
b) For n devices in a network, what is the number of cable links required for a
mesh, ring, bus, and star topology?
c) What are three criteria necessary for an effective and efficient network?
d) How does information get passed from one layer to the next in the Internet
e) What is the difference between network layer delivery and transport layer
f) What is the difference between a port address, a logical address, and a
g) Identify the five components of a data communications system?
Question # 2
Suppose the length of a 10Base5 cable is 2500m. If the speed of propagation in a thick
coaxial cable is 200,000,000 m/s, how long does it take for a bit to travel from the
beginning to the end of the network? Assume there are 10µs delays in the equipment.
Question # 3
1. Suppose a computer sends a packet at the transport layer to another computer
somewhere in the Internet. There is no process with the destination port address
running at the destination computer. What will happen?
2. An ISP has a block of 1024 addresses. It needs to divide the addresses among
1024 customers. Does it need subnetting? Explain your answer.
Question # 4
a) Which of the following are true regarding a network using a subnet mask of
255.255.248.0? (Choose three)
A. It corresponds to a Class A address with 13 bits borrowed.
B. It corresponds to a Class B address with 4 bits borrowed.
C. The network address of the last subnet will have 248 in the 3rd octet.
D. The first 21 bits make the host portion of the address.
E. This subnet mask allows for 16 total subnets to be created.
F. The subnetwork numbers will be in multiples of 8.
b) You work as network consultant. Your IIUI University, has a class C
network license. University wants you to subnet the network to provide a separate
subnet for each of its 5 departments. Each subnet must support at least 24 hosts.
Which network mask should you use?
c) The International Islamic University network has been divided into 5
separate departments as displayed below: (9 marks)
(5 Users) (3 users)
(6 Users) (8 Users)
Using a Class C IP network, which subnet mask will provide one useable subnet per
department while allowing enough host addresses for each department specified in the
A. 255.255.255.0 B. 255.255.255.192
C. 255.255.255.224 D. 255.255.255.240
E. 255.255.255.248 F. 255.255.255.252