ARPANET was the first wide-area packet switching network developed in the late 1960s under the US Advanced Research Projects Agency (ARPA). It served as the basis for today's internet and initially linked computers located at Pentagon-funded research institutions over telephone lines. A computer network connects computers together to allow for sharing of resources like files, printers or internet access. There are several types of computer networks including local area networks (LANs), personal area networks (PANs), metropolitan area networks (MANs), and wide area networks (WANs). Key components of computer networks include hardware like network interface cards (NICs), cables, routers, switches and software.

1. CITY UNIVERSITY
Computer Network Assignment No. 1
SEPTEMBER 5, 2021
MD SAYLAB
ID. 1834902547
Department of Computer Science & Engineering

2. What is ARPANET?
Advance research project network (ARPANET) was the network that becomes the
basis for the internet. Based on a concept first published in 1967, ARPANET was
developed under the direction of the U.S Advance research project agency (ARPA).
ARPANET was the first wide area packet switching network with distributed control
and one of the first network to implement the TCP/IP protocol suit. ARPANET was
created to make it easier for people to access computer, improve computer
equipment, and to have more effective communication method for the military. An
arm of the US defense department funded the development of the ARPANET in the
late 1990s. its initial purpose was to link computers at pentagon funded research
institutions over telephone lines.
What is computer network?
A computer network is a set of computers connected together for the purpose of
sharing resources. The most common resource shared today is connection to the
internet. Other shared resource can include a printer or a file server. The internet
itself can be considered a computer network.
There are four types of computer networks: -
1. Local Area Network (LAN)
2. Personal Area Network (PAN)
3. Metropolitan Area Network (MAN)
4. Wide Area Network (WAN)
LAN: A local area network (LAN) is a collection of devices connected together in
one physical location, such as a building, office or home. A LAN can be small or
large, ranging from a home network with one user to an enterprise network with
thousands of users and devices in an office or school.
PAN: A personal area network (PAN) connects electronic devices within a user’s
immediate area. The size of a PAN ranges from a few centimeters to a few meters.
PANs can also connect laptops, tablets, printers, keywords and other computerized
devices. PAN network connections can either be wired or wireless.
MAN: A metropolitan area network is a computer network that interconnectors
users with computer resources in a geographic region of the size of a metropolitan
area.
WAN: A wide area network is a telecommunication network that extends over a
large geographic area for the primary purpose of computer networking. Wide area
networks are often established with leased telecommunication circuit.

3. Goals of computer network: -
1. Sharing resources from one computer to another computer over a network
2. Performance by measuring the speed of data transmission with number of
users, connectivity and the software used
3. Reliability makes easy to use an alternative source for data communication in
case of hardware failure or connectivity issues.
4. Scalability increase the system performance by adding more processors
5. Security is the main characteristics of computer network where you can take
necessary steps for protecting your data from unauthorized access.
6. Flexible access – Files can be accessed from any computer in the network. The
project can be begun on one computer and finished on another.
Application of computer network: -
1. Business Application
2. Communication Medium
3. E-Commerce
4. Home Application
5. Electronic commerce
6. Mobile User
Network hardware & software: -
There are three components of computer network
1. Hardware Equipment’s
2. Software
3. Cables and Connectors
What is NIC?
A network interface card (NIC) is a hardware component without which a computer
cannot be connected over a network. It is a circuit board installed in a computer that
provides a dedicated network connection to the computer. It is also called network
interface controller, network adapter or LAN adapter.
Why is NIC used?
• NIC allows both wired and wireless communications.
• NIC allows communications between computers connected via local area
network (LAN) as well as communications over large-scale network through
Internet Protocol (IP).

4. • NIC is both a physical layer and a data link layer device, i.e., it provides the
necessary hardware circuitry so that the physical layer processes and some
data link layer processes can run on it.
NIC cards are of two types –
1. Internal Network Card
2. External Network Card
Internal Network Card:
In internal networks cards, motherboard has a slot for the network card where it can
be inserted. It requires network cables to provide network access. Internal network
cards are of two types. The first type uses Peripheral Component Interconnect (PCI)
connection, while the second type uses Industry Standard Architecture (ISA).
External Network Card:
In desktop and laptop that do not have an internal NIC, external NICs are used.
External network cards are two types:
1. Wireless
2. USB based.
Wireless network card needs to be inserted into the motherboard; however, no
network cable is required to connect to the network. They are useful while traveling
or accessing a wireless signal.
What is Server?
A server is a computer program or device that provides a service to another computer
program and its user also known as the client. In data center, the physical computer
that a server program runs on is also frequently referred to as a server. That machine
might be a dedicated server or it might be used for other purposes.
What is Clint?
In computing, a client is a piece of computer hardware or software that accesses a
service made available by a server as part of the client server model of computer
networks. The server is often on another computer system in which case the client
accesses the service by way of network.
What is peer?
In networking a peer is a node that provides the same functionality as another. For
example, two desktop PCs in a network are peers. A desktop PC and a server are not
peers as they perform different operations.

5. What is Transmission?
Transmission mode means transferring of data between two devices. It is also
known as communication mode. Buses and networks are designed to allow
communication to occur between individual devices that are interconnected.
What is medium?
Communication medium refers to the physical channel through which data is sent
and received.
The speed of data transmission or data rate depends upon the type of medium being
used in the network. There are basically two types of networks:
1. Wired network
2. Wireless network
What is Router?
A router received and sends data on computer networks. Routers are sometimes
confused with network hubs, modems or network switches. However, routers can
combine the functions of these components and connect with these devices, to
improve internet access or help create business networks.
What is bridge?
A network bridge is computer networking device that creates a single aggregate
network from multiple communication networks or network segments. Routing allows
multiple networks to communicate independently and yet remain separate whereas
bridging connected two separate networks as if they were a single network.
What is HUB?
A network hub is a device that allows multiple computers to communicated with each
other over network. It has several Ethernet ports that are used to connect two or
more network devices together. While switches send incoming data to a specific port,
hubs broadcast all incoming data to all active ports.
What is Switch?
A switch is device in a computer network that connects other devices together.
Multiple data cables are plugged into a switch to enable communication between
different networked devices. A device that also operates at these higher layers is
known as a multilayer switch.

6. What is gateway?
a gateway is a hardware device that acts as a gate between two networks. It may be
a router, firewall, server or other device that enables traffic to flow in and out of the
network.
What is Repeater?
Repeaters are network devices operating at physical layer of the OSI model that
amplify or regenerate an incoming signal before retransmitting it. They are
incorporated in networks to expand its coverage area. They are also known as signal
boosters.
IP: An internet protocol address is a numerical label assigned to each device
connected to a computer network that uses the internet protocol for communication.
An IP address server two main function:
1. Host or network interface identification
2. Location addressing
What is Twisted Pair Cable?
Twisted-pair cable is a type of cabling that is used for telephone communications and
most modern Ethernet networks. A pair of wires forms a circuit that can transmit
data. The pairs are twisted to provide protection against crosstalk, the noise
generated by adjacent pairs.
There are two types of twisted pair cable: -
3. Unshielded Twisted-Pair Cable (UTP)
4. Shielded Twisted-Pair Cable (STP)
What is Coaxial Cable?
A coaxial cable is a type of shielded and insulated copper cable that is used in
computer networks and to deliver cable TV services to end users. It was first
commercially implemented in the early 1940s and is used for both baseband and
broadband data communication services.
What is Fiber Optic Cable?
A fiber optic cable is a network cable that contains strands of glass fibers inside an
insulated casing. They're designed for long-distance, high-performance data
networking, and telecommunications. Fiber optic cables support much of the
world's internet, cable television, and telephone systems.

7. It has three parts:
Core: It is a central tube as shown in the diagram. It is of skinny size and made up
of the optically transparent dielectric medium. It carries the light from the transmitter
to the receiver. The diameter of the core varies from 5um to 100um.
Cladding: it is the outer optical material surrounding the core. Its reflective index is
lower than the core. It helps to keep the light within the core as it uses the
phenomena of total internal reflection.
Jacket: As the bare fiber is easily broken, fiber optic cable jacket is needed to provide
protection for the shielding and conductors within the cable. The cable jacket is the
first line of moisture, mechanical, flame and chemical defense for a fiber cable.