ARPANET was the first wide-area packet switching network developed in the late 1960s under the U.S. Defense Department to connect research computers and allow for more effective communication. It served as the basis for the modern Internet and implemented the TCP/IP protocol. A computer network connects computers together to share resources, data, and applications over various connection types. Key network components include network interface cards, servers, routers, bridges, hubs, switches, and gateways. Modern computer technologies that utilize networks include artificial intelligence, data science, the Internet of Things, blockchain, and edge computing.

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Computer Network History
 18th Centuries: Watt's Steam Engine, Optical Telegraph, The Lightning Rod.
 19th Centuries: Telegraph in 1837, Telephone in 1876, Electric Battery in 1800,
Camera in 1888, Typewriter in 1867.
 20th Centuries: Radio, Television, The Personal Computer, Information
Gathering, Processing and Distribution.
 21st Centuries: Satellites, Fiber Optics, Internet.
ARPANET
Advance Research Project Agency 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 networks to implement the TCP/IP protocol suit.
ARPANET was created to make it easier for people to access computers, improve computer
equipment, and to have more effective communication method for the military.
An arm of the U.S. Defense department funded the development of the ARPANET in the late
1960s. Its initial purpose was to link computers at Pentagon-funded research institutions over
telephone lines.
Computer Network
A computer network is a group of computers linked to each other that enables the computer
to communicate with another computer and share their resources, data, and applications.
The most common resource shared today is connection to the internet. A computer network
can be categorized by their size. A computer network is mainly of four types:
1. LAN (Local Area Network): Upto1 Kilometer Distance
2. PAN (Personal Area Network): Up to 10 Meter Distance
3. MAN (Metropolitan Area Network): 10 Kilometer Distance
4. WAN (Wide Area Network): work up to a state or country
Goals of Computer Network
 Sharing Resources: from one Computer to another Computer over a network.
 Performance: by measuring the speed of data transmission with number of users,
connectivity and the software used.

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 Reliability: makes easy to use an alternative source for data communication in case
of hardware failure or connectivity issues
 Scalability: increases the system performance by adding more processors
 Security: is the main characteristics of Computer network where you can take
necessary steps for protecting your data from unauthorized access
 Flexible Access: Files can be accessed from any computer in the network. The project
can be begun on one computer and finished on another. Other goals include
Distribution of processing functions, Centralized management, and allocation of
network resources, Compatibility of dissimilar equipment and software, Good
network performance, Scalability, Saving money, Access to remote information,
Person to person communication, etc.
Application of Computer Network
 Business Applications
 Communication Medium
 E-commerce
 Home Applications
 Electronic commerce
 Mobile Users
Network Hardware and Software
1. Hardware equipment: NIC, Server, Client, Peers, Transmission, Medium, Router,
Bridge, Hub, Switches, Gateway, Repeaters
2. Software: Network Operating System, Protocols Switches(TCP/IP, OSI)
3. Cables and Connectors: Twisted Pair Cable, Coaxial Cable, Fiber-Optic Cable
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.
Purpose of NIC:
 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).
 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.

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Types of NIC cards:
1. 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)
2. External network card: in desktop and laptops that do not have an internal NIC,
external NICs are used. External network cards are of two types: wireless and 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
of accessing a wireless signal.
Server: A server is a computer or system that provides resources, data, services, or programs
to other computers, known as clients, over a network. In theory, whenever computers share
resources with client machines they are considered servers. Some example of server tasks:
email, file sharing, website hosting, network management, database, custom application.
Router: A router is a networking device that forwards data packets between computer
networks. Routers perform the traffic directing functions on the Internet. When a data packet
comes in on one of the lines, the router reads the network address information in the packet
header to determine the ultimate destination.
Bridge: A network bridge is a computer networking device that creates a single, aggregate
network from multiple communication networks or network segments. This function is called
network bridging.
Hub: A hub is a physical layer networking device which is used to connect multiple devices
in a network. They are generally used to connect computers in a LAN. A hub has many ports
in it. A computer which intends to be connected to the network is plugged in to one of these
ports.
Hub can detect only physical PC but can’t detect Mac Address.
Switch: A switch is a device in a computer network that connects other devices together. ...
Switches manage the flow of data across a network by transmitting a received network packet
only to the one or more devices for which the packet is intended.
A switch keeps a record of the MAC (Media Access Control) address of all the devices
connected to it.
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. It allows computers within the local network to send and receive data over the
Internet.

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Repeater: A repeater is an electronic device that receives a signal and retransmits it.
Repeaters are used to extend transmissions so that the signal can cover longer distances or be
received on the other side of an obstruction.
An important point to be noted about repeaters is that they do not amplify the signal. When
the signal becomes weak, they copy the signal bit by bit and regenerate it at the original
strength. It is a 2 port device.
Network Operating System: NOS is one of the important types of operating system.
Network operating system runs on a server and gives the server the capability to manage data,
users, groups, security, application and other networking functions. The basic purpose of the
network operating system is to allow shared file and printer access among multiple computers
in a network, typically a local area network (LAN), a private network or to other network.
Some example of network operating systems include Microsoft windows server 2003,
Microsoft windows server 2008, UNIX, Linux, Mac OS X, Novell Netware and BSD.
Advantage
 Centralized servers are highly stable.
 Security is server managed.
 Upgradation of new technologies and hardware can be easily integrated into the
system.
 It is possible to remote access to servers from different locations and types of systems.
Disadvantage
 High cost of buying and running a server
 Dependency on a central location for most operations.
 Regular maintenance and updates are required.
Twisted pair cable:
Modern Computer Technologies:
 Artificial Intelligence: Artificial intelligence (AI) is the technology used for
equipping computer systems with the ability to make decisions like humans.
 Data Science: Data scientists examine which questions need answering and where to
find the related data. They have business acumen and analytical skills as well as the
ability to mine, clean, and present data. Businesses use data scientists to source,
manage, and analyze large amounts of unstructured data.
 Internet of Things: The Internet of Things (IoT) describes the network of physical
objects—“things”—that are embedded with sensors, software, and other technologies
for the purpose of connecting and exchanging data with other devices and systems
over the internet.
 Blockchain: Blockchain technology can be used to create a permanent, public,
transparent ledger system for compiling data on sales, tracking digital use and
payments to content creators, such as wireless users or musicians.

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 Robotic Process Automation (RPA): Robotic process automation (RPA) is a
software technology that makes it easy to build, deploy, and manage
software robots that emulate human actions interacting with digital systems and
software.
 Virtual Reality: Essentially, it's used as a training aid to help measure athletic
performance and analyses technique.
 Edge Computing: Edge computing optimizes Internet devices and web applications
by bringing computing closer to the source of the data. This minimizes the need for
long distance communications between client and server, which reduces latency and
bandwidth usage.
 Intelligent apps: Intelligent apps save users' time and money also on a certain level.
These apps are powered by AI and machine learning, which understand users'
behavior, and based on that, it suggests the action the user should take. This
functionality can save users' time, and also it stops them from making a wrong
decision.