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Number

SRM Institute of Science and Technology College of

Set - D
Engineering and Technology
School of Computing
SRM Nagar, Kattankulathur – 603203, Chengalpattu District,
Tamil Nadu
Academic Year: 2024-25 (Odd)

Test: FLJ1 Date: 23-08-2024

Course Code & Title: 21CSC302J - Computer Networks Duration: 100 Minutes
Year & Sem: III Year / V Sem Max. Marks: 50
Course Articulation Matrix:
Course
PO1 PO2 PO3 PO4 PO5 PO6 PO7 PO8 PO9 PO10 PO11 PO12
Outcome
CO1 3 - - - 3 - - - - - - 3
3 - - 2 - - - - - - - 3
CO2

Note: CO1 – To understand and apply the basic knowledge of networking in communication
CO2 – To construct the network using addressing schemes

Part – A (10 x 1 = 10 Marks)

Instructions:
1) Answer ALL questions.
2) The duration for answering part A is 15 minutes (this sheet will be collected after 15 minutes).
3) Encircle the correct answer (if more than one is the right answer encircle appropriately)
Question Marks BL CO PO PI Code

You are a member of a club that deals with computer 1 1 1 1 1.6.1

networks. The club has to take a project to build a MAN.
Where would this project likely take place?
o Country
o University or college
o Home
o Small Building
The main advantages of a star network are: 1 1 1 1 1.6.1
o Low cost to set up and manage
o Easy to implement
o Requires additional hardware
o Process data very fast
o Can store more data than other networks
Which one of the following technology is used by a typical 1 1 1 1 1.6.1
circuit switching protocol?
o Datagram Packets
o Virtual circuit
o Time division
o Frequency division
In the layer hierarchy, as the data packet moves from the 1 1 1 1 1.6.1
upper to the lower layers, headers are ___________
o Added
o Removed
o Rearranged
o Modified
An organization is setting up a network in a densely 1 2 1 1 1.6.1
populated urban area where physical cabling is challenging
due to the existing infrastructure and potential disruptions.
The network needs to provide connectivity over short
distances and be resilient to environmental factors. Which
types of media are more suitable for this urban setting?

o Fiber Optic Cable

o Coaxial Cable
o Wireless Radio Waves
o Microwave Transmission

You have an IP address of 172.16.13.5 with a 1 3 2 4 2.1.2

255.255.255.128 subnet mask. What is your class of address,
network address and broadcast address?
o Class A, 172.16.13.0 , 172.16.13.127
o Class B, 172.16.13.0 , 172.16.13.127
o Class B, 172.16.13.0 , 172.16.13.255
o Class B, 172.16.0.0 , 172.16.255.255
How many possible addresses per network are there in a class 1 1 2 1 1.6.1
C of an IPv4 address?
o 65536
o 128
o 256
o 2097152
How does supernetting improve routing efficiency in large 1 1 2 2 2.6.3
networks?
o By decreasing the total number of IP addresses used
o By increasing the number of routes in the routing
table
o By reducing the number of routing table entries
required
o By providing more security for internal network
traffic
What is the broadcast address for the network 10.10.10.0 with 1 3 2 1 1.6.1
a subnet mask of 255.255.255.128?
o 10.10.10.127
o 10.10.10.128
o 10.10.10.254
o 10.10.10.255
You are given the IP Address of 193.103.20.0 /24 and need 1 3 2 1 1.6.1
50 Subnets. How many hosts per network and what is the
total number of networks do you get once subnetted?
o 20 Hosts and 50 Subnets
o 2 Hosts and 64 Subnets
o 4 Hosts and 50 Subnets
o 6 Hosts and 64 Subnets
 Register
Number

SRM Institute of Science and Technology Set - D

College of Engineering and Technology
School of Computing
SRM Nagar, Kattankulathur – 603203, Chengalpattu District, Tamil Nadu
Academic Year: 2024-25 (Odd)

Test: FLJ1 Date: 23-08-2024

Course Code & Title: 21CSC302J - Computer Networks Duration: 100 Minutes
Year & Sem: III Year / V Sem Max. Marks: 50

Part – B
(4 x 5 = 20 Marks)
Instructions: Answer ALL the questions
Q. No Question Ma BL CO PO PI
rks Cod
e
11 Describe a scenario where a MAN would be the most appropriate 5 2 1 1 1.6.1
type of network.

Connecting Multiple Branch Offices in a City - MANs enable

access to the same network in multiple locations. In a LAN, users
can only access the network in one location. In a MAN,
organizations with LANs in the same municipality, such as
different office buildings, can extend their network to those areas.
Community network access. Government entities might
configure a MAN to provide public network connectivity to users.
One example is when municipalities offer free, public Wi-Fi to
city residents via wireless MAN technology.
Smart city connectivity. MANs provide and enable connectivity
in smart cities. They provide features like intelligent
transportation systems, IoT deployment, smart grids and other city
services.
12 What is the structure of an IPv4 address, and how are the 32 bits 5 1 1 1 1.7.1
divided into octets?

• The IPv4 addresses are unique and universal.

• An IPv4 address is 32 bits long.
– The address space of IPv4 is 232 (4,294,967,296)
– Notation.
• Binary notation
• Dotted-decimal notation
 Structure of IPv4 Address:

 Total Bits: 32 bits

 Division: 4 octets (each octet consists of 8 bits)
 Format: Each octet is typically represented as a decimal
number separated by dots.

 Octets:

 Each octet is an 8-bit segment of the IPv4 address.

 In decimal form, each octet ranges from 0 to 255.
 The four octets are separated by dots in the standard
 dotted-decimal notation.

Example:

13 Explain calculating the number of subnets and hosts per subnet 5 3 2 1 1.4.1
given an IP address and subnet mask. For example, with an IP
address of 192.168.1.0 and a subnet mask of 255.255.255.192.

Answer:

1. Understanding the Subnet Mask

The subnet mask 255.255.255.192 can be converted into

binary to understand how many bits are used for the network
and subnet portions.

 Decimal to Binary:
o 255 = 11111111
o 255 = 11111111
o 255 = 11111111
o 192 = 11000000

So, the subnet mask in binary is:

11111111.11111111.11111111.11000000.

CIDR Notation: The subnet mask 255.255.255.192

corresponds to a /26 prefix (26 bits for network + subnet).

2. Calculating the Number of Subnets

To find the number of subnets, we need to determine how many

bits are used for the subnetting beyond the original classful
network.

 Classful Network: 192.168.1.0 is a Class C address,

which originally uses a /24 prefix (24 bits for the
network portion).
 Subnet Bits:
o Subnet Mask: /26
o Number of subnet bits = 26 - 24 = 2 bits

 Number of Subnets:
o Use the formula 2n , where n is the number of
subnet bits.
o 22 = 4 subnets

3. Calculating the Number of Hosts per Subnet

To find the number of hosts per subnet:

 Subnet Bits:
o The subnet mask /26 means that 26 bits are used
 for the network and subnet portion, leaving
32−26=6 bits for host addresses.

 Number of Hosts:
o Use the formula 2h−2, where h is the number of
host bits. The subtraction of 2 accounts for the
network address and the broadcast address.
o 26−2=64−2=62 hosts per subnet

Summary

Given the IP address 192.168.1.0 and the subnet mask

255.255.255.192:

 Number of Subnets: 4
 Number of Hosts per Subnet: 62

Network Broadcast Usable IP Range

Subnet Address Address
Number
Subnet 1 192.168.1.0 192.168.1.63 192.168.1.1 to
192.168.1.62
Subnet 2 192.168.1.64 192.168.1.127 192.168.1.65 to
192.168.1.126
Subnet 3 192.168.1.128 192.168.1.191 192.168.1.129 to
192.168.1.190
Subnet 4 192.168.1.192 192.168.1.255 192.168.1.193 to
192.168.1.254
14 Write short notes on different network devices. 5 1 2 1 1.4.1

Different network devices - Hub, Repeaters, Switch, Bridge,

Gateways, Router, Firewall.

1. Router:

 Function: Routers are devices that connect multiple

networks and direct data packets between them. They
operate at the Network layer (Layer 3) of the OSI model.
 Use: Routers determine the best path for data to travel
from the source to the destination across different
networks, such as from a home network to the internet.

2. Switch:

 Function: A switch operates at the Data Link layer (Layer

2) and connects multiple devices within the same
network. It uses MAC addresses to forward data only to
the specific device that needs it.
 Use: Switches are used to create a network by connecting
devices like computers, printers, and servers in a local
area network (LAN).

3. Hub:

 Function: Hubs are basic networking devices that operate

at the Physical layer (Layer 1) of the OSI model. They
broadcast incoming data packets to all devices connected
 to it.
 Use: Hubs are largely obsolete, but they were used to
connect multiple Ethernet devices in a network, often
leading to network inefficiencies due to unnecessary data
transmissions.

4. Bridge:

 Function: A bridge operates at the Data Link layer (Layer

2) and is used to divide a large network into smaller
segments or to connect two LANs that use the same
protocol.
 Use: Bridges help reduce network traffic by filtering and
forwarding data based on MAC addresses.

5.Firewall:

 Function: Firewalls are security devices that monitor and

control incoming and outgoing network traffic based on
predetermined security rules. They can operate at various
layers of the OSI model, typically at the Network layer
(Layer 3) and Transport layer (Layer 4).
 Use: Firewalls protect networks from unauthorized
access, cyber attacks, and malicious traffic.

6. Gateway:

 Function: A gateway is a network device that connects

two different networks that use different protocols. It
operates at various layers of the OSI model, depending on
its functionality.
 Use: Gateways are used to translate and forward data
between different network systems, such as between an
enterprise network and the internet.

7. Repeater:

 Function: A repeater operates at the Physical layer (Layer

1) and is used to amplify or regenerate signals to extend
the range of a network.
 Use: Repeaters are used in both wired and wireless
networks to ensure that signals remain strong over long
distances.

Part – C
(2 x 10 = 20 Marks)
Instructions: Answer ANY TWO questions
Q. No. Question Mar B CO PO PI Code
ks L
15 A rural area with limited infrastructure requires connectivity to the 10 3 1 1 1.6.1
internet. Discuss the various types of unguided media that could be
used to provide internet access to this remote location. Consider
their physical characteristics, performance metrics, and typical
applications. Which type would be the most suitable for this
scenario, and why?
 Answer:
When providing internet connectivity to a rural area with
limited infrastructure, unguided media (wireless
communication methods) are often the most practical
solution due to their ability to cover large distances without the
need for physical cables.

1. Satellite Communication:

 Physical Characteristics: Satellite communication involves

transmitting signals to and from satellites orbiting the Earth.
The ground stations (satellite dishes) communicate with
these satellites, which then relay the signals back to Earth.
 Performance Metrics:
o Bandwidth: Varies depending on the service
provider, typically ranging from 1 Mbps to 100 Mbps
for consumer services.
o Latency: High latency, usually between 500 ms to
600 ms, due to the long distance signals must travel.
o Reliability: Generally reliable but can be affected by
weather conditions (rain fade) and potential line-of-
sight issues.
 Typical Applications: Ideal for remote and rural areas
where other forms of connectivity are unavailable. Used for
internet access, broadcasting, and military applications.
 Suitability: Satellite communication is highly suitable for
very remote areas where other options are not feasible.

2. Infrared (IR) communication

Physical Characteristics:

 Wavelength Range: Infrared waves have wavelengths

between approximately 700 nanometers (nm) and 1
millimeter (mm), lying just outside the visible spectrum.
 Transmission Medium: Infrared communication uses
infrared light, which travels through the air but is blocked by
physical obstacles like walls or furniture. The signal is
typically direct and line-of-sight.

Performance Metrics:

 Data Rate: Infrared communication can support a wide range

of data rates, from a few kilobits per second (Kbps) to several
gigabits per second (Gbps) in high-speed applications. For
instance, IrDA (Infrared Data Association) standards support
data rates up to 4 Mbps.
  Range: Typical ranges for infrared communication are
relatively short, usually up to 5-10 meters. High-power
systems may extend this range slightly, but it’s generally
limited compared to other wireless technologies.
 Latency: Infrared communication provides low latency, often
in the range of milliseconds, making it suitable for real-time
applications.
 Reliability: The reliability of infrared communication is high
within its operational range. However, it is sensitive to
obstructions and requires a direct line of sight between the
transmitter and receiver.

Typical Applications:

 Remote Controls: One of the most common uses of infrared

technology is in remote controls for consumer electronics,
such as TVs, DVD players, and air conditioners. The devices
use infrared signals to send commands from the remote to
the controlled device.

Advantages:

 Security: Infrared communication is more secure than many

other wireless technologies because it requires a direct line
of sight, making it difficult to intercept the signal without
being in the direct path.
 Low Interference: Infrared is less susceptible to radio
frequency interference, which can be beneficial in
environments with high RF noise.

Limitations:

 Short Range: Infrared communication is generally limited to

short distances, which can be a constraint for applications
requiring long-range connectivity.
 Line-of-Sight Requirement: The need for a clear line of sight
between the transmitter and receiver limits the usability in
environments with obstacles or where direct alignment is
challenging.
 Environmental Sensitivity: Infrared signals can be
disrupted by strong ambient light, such as sunlight, and by
physical obstructions, which can degrade the signal quality.

3. Microwave Links:

 Physical Characteristics: Microwave communication

involves the use of high-frequency radio waves to transmit
data between two fixed points, typically using line-of-sight
antennas.
 Performance Metrics:
o Bandwidth: Capable of high data rates, often in the
range of 50 Mbps to several Gbps, depending on the
frequency and technology used.
o Latency: Very low latency, often under 1 ms, as
signals travel directly between the two points.
o Reliability: Highly reliable over short to medium
distances (up to 50 km), but requires a clear line of
sight between antennas. Can be affected by weather
 conditions, especially rain.
 Typical Applications: Used for point-to-point
communication, including backhaul for cellular networks,
connecting remote offices, and providing internet access to
rural areas.
 Suitability: Microwave links are suitable if there are clear
line-of-sight paths between the rural area and a nearby
internet access point.

4. Wi-Fi and WiMAX:

 Physical Characteristics: Wi-Fi is a short-range wireless

technology that can be extended over larger areas using
directional antennas. WiMAX is a longer-range wireless
broadband technology that can cover distances up to 50 km.
 Performance Metrics:
o Bandwidth: Wi-Fi typically offers speeds up to 1
Gbps for modern standards, while WiMAX can
provide speeds ranging from 1 Mbps to 70 Mbps.
o Latency: Low latency, generally around 10 ms to 50
ms for both Wi-Fi and WiMAX.
o Reliability: Wi-Fi is reliable over short distances,
while WiMAX is reliable over longer distances but can
be influenced by terrain and obstacles.
 Typical Applications: Wi-Fi is commonly used for local area
networking, while WiMAX is used for wireless broadband in
rural and urban areas.
 Suitability: WiMAX could be suitable for providing internet
access to rural areas, especially if cellular networks are
unavailable. However, the infrastructure required might be a
limiting factor.

Most Suitable Option:

Satellite Communication would likely be the most suitable option

for providing internet access to a rural area with limited
infrastructure. The key reasons include:

 Coverage: Satellite communication can provide coverage

virtually anywhere on Earth, making it ideal for remote and
isolated areas where other technologies might not reach.
 Ease of Deployment: Unlike terrestrial technologies that
require the installation of towers, antennas, or cables,
satellite services can be deployed with just a satellite dish and
modem.
 Availability: Satellite internet is available in most regions
globally, including areas without any other form of internet
connectivity.

Limitations: The main drawbacks of satellite communication are

the higher latency and potential weather-related disruptions.
However, for basic internet access in remote areas, these are often
acceptable trade-offs.
16 i. Identify the layers that work together to ensure reliable 5 3 1 1 1.6.1
communication between devices on the same network
segment. Explain in brief.
Answer:
5 3 2 1 1.7.1
To ensure reliable communication between devices on the same
network segment, the following layers of the OSI (Open Systems
Interconnection) model work together:

1. Data Link Layer (Layer 2):

 Function: The Data Link layer is responsible for node-to-

node communication and ensures that data is transmitted
across a physical link reliably. It packages raw bits from the
Physical layer into frames, adds a header and trailer, and
manages error detection and correction.
 Key Protocols: Ethernet, Wi-Fi (IEEE 802.11), and MAC
(Media Access Control).
 Reliability Mechanisms:
o Error Detection: The Data Link layer uses
mechanisms like Cyclic Redundancy Check (CRC) to
detect errors in the transmitted frames.
o Flow Control: Manages the rate of data transmission
to prevent overwhelming the receiving device.
o Frame Synchronization: Ensures that the frames are
properly synchronized between the sender and
receiver.

2. Physical Layer (Layer 1):

 Function: The Physical layer is responsible for the

transmission of raw bitstreams over a physical medium. It
deals with the physical connection between devices and the
electrical, optical, or radio signals used to transmit data.
 Key Components: Network cables, switches, hubs, wireless
signals.
 Reliability Mechanisms:
o Signal Encoding: Converts data into signals that can
be transmitted over the physical medium.
o Bit Synchronization: Ensures that the sender and
receiver are in sync at the bit level to correctly
interpret the signals.
o Transmission Medium: The quality and type of
transmission medium (e.g., twisted-pair cable, fiber
optics, wireless) directly affect the reliability of
communication.

ii. Convert the following IP addresses from dotted-decimal

notation to binary notation. Additionally, identify the class and
the default subnet mask for each IP address:
a. 192.168.0.100
b. 172.31.255.255
c. 198.51.100.25
Answer:
 192.168.0.100:
 Binary: 11000000.10101000.00000000.01100100
 Class: C
 Default Subnet Mask: 255.255.255.0

 172.31.255.255:
 Binary: 10101100.00011111.11111111.11111111
  Class: B
 Default Subnet Mask: 255.255.0.0

 198.51.100.25:
 Binary: 11000110.00110011.01100100.00011001
 Class: C
 Default Subnet Mask: 255.255.255.0
17 Consider an IP address block of 172.16.0.0/16. Using VLSM, divide 10 3 2 1 1.6.1
this block into subnets to meet the following requirements:
Subnet 1: 100 hosts
Subnet 2: 50 hosts
Subnet 3: 20 hosts
Subnet 4: 10 hosts
List the subnet addresses, subnet masks and the range of usable IP
addresses for each subnet.
Answer:
To divide the IP address block 172.16.0.0/16 into subnets that
meet the specific requirements using Variable Length Subnet
Masking (VLSM), we can allocate the subnets from the largest to the
smallest, ensuring that each subnet has the necessary number of IP
addresses.
Step 1: Determine the required subnet sizes
(2h) - Nearest higher power of 2

 Subnet 1: 100 hosts →(27) Nearest higher power of 2 = 128

IP addresses.
 Subnet 2: 50 hosts → (26) = 64 IP addresses.
 Subnet 3: 20 hosts → (25) = 32 IP addresses.
 Subnet 4: 10 hosts → (24)= 16 IP addresses.

Step 2: Determine the subnet mask for each subnet

 Subnet 1: 128 IP addresses → Subnet mask /25

(255.255.255.128)i.e 255.255.255.10000000
 Subnet 2: 64 IP addresses → Subnet mask /26
(255.255.255.192) i.e 255.255.255.11000000
 Subnet 3: 32 IP addresses → Subnet mask /27
(255.255.255.224) i.e 255.255.255.11100000
 Subnet 4: 16 IP addresses → Subnet mask /28
(255.255.255.240) i.e 255.255.255.11110000

Step 3: Assign subnets from the available IP block

Starting from 172.16.0.0:

1. Subnet 1:
o Subnet Address: 172.16.0.0/25
o Subnet Mask: 255.255.255.128
o Usable IP Range: 172.16.0.1 - 172.16.0.126
o Broadcast Address: 172.16.0.127

2. Subnet 2:
o Subnet Address: 172.16.0.128/26
o Subnet Mask: 255.255.255.192
o Usable IP Range: 172.16.0.129 - 172.16.0.190
o Broadcast Address: 172.16.0.191
 3. Subnet 3:
o Subnet Address: 172.16.0.192/27
o Subnet Mask: 255.255.255.224
o Usable IP Range: 172.16.0.193 - 172.16.0.222
o Broadcast Address: 172.16.0.223

4. Subnet 4:
o Subnet Address: 172.16.0.224/28
o Subnet Mask: 255.255.255.240
o Usable IP Range: 172.16.0.225 - 172.16.0.238
o Broadcast Address: 172.16.0.239

Summary
Subnet Subnet Usable IP Broadcast
Subnet
Address Mask Range Address
172.16.0. 255.255.25 172.16.0.1 - 172.16.0.12
Subnet 1 0/25 5.128 172.16.0.126 7
172.16.0.129
172.16.0. 255.255.25 172.16.0.19
Subnet 2 128/26 5.192
-
1
172.16.0.190
172.16.0.193
172.16.0. 255.255.25 172.16.0.22
Subnet 3 192/27 5.224
-
3
172.16.0.222
172.16.0.225
172.16.0. 255.255.25 172.16.0.23
Subnet 4 224/28 5.240
-
9
172.16.0.238
These subnets are efficiently allocated to meet the given host
requirements while using VLSM.

Course Outcome (CO) and Bloom’s level (BL) Coverage in Questions

CO coverage BLOOM's Level

60%
50% 50%
50%
BL1 (Re-
40% membering)
27%
30%
BL3 (Apply)
20% 63%
BL2 (Under-
10% standing) 10%
0%
CO1 CO2