Internet Technologies
Chapter 1: Introduction to Internet
1.1 Internet
The Internet is a global system of interconnected computer networks that use the standard Internet
protocol suite (often called TCP/IP, although not all applications use TCP) to serve billions of users
worldwide.
It is a network of networks that consists of millions of private, public, academic, business, and
government networks, of local to global scope, that are linked by a broad array of electronic, wireless and
optical networking technologies. The Internet carries an extensive range of information resources and
services, such as the inter-linked hypertext documents of the World Wide Web (WWW) and the
infrastructure to support email.
1.2 Computer Networks
A computer network is the infrastructure that allows two or more computers (called hosts) to
communicate with each other.
A network can be defined as a group of computers and other devices connected in some ways so
Definition
as to be able to exchange data. -Each of the devices on the network can be thought of as a node;
each node has a unique address.
A computer network, often simply referred to as a network, is a collection of hardware
components and computers interconnected by communication channels that allow sharing of
resources and information.
The network achieves this by providing a set of rules for communication, called protocols, which should
be observed by all participating hosts.
A communications protocol is a set of rules for exchanging information over a network
The need for a protocol should be obvious: it allows different computers from different vendors and with
different operating characteristics to ‘speak the same language’.
1.2.1. Properties of Computer Networks:
a) Facilitate communications. Using a network, people can communicate efficiently and easily via
email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.
b) Permit sharing of files, data, and other types of information. In a network environment, authorized
users may access data and information stored on other computers on the network. The capability of
providing access to data and information on shared storage devices is an important feature of many
networks.
c) Share network and computing resources. In a networked environment, each computer on a network
may access and use resources provided by devices on the network, such as printing a document on a
shared network printer. Distributed computing uses computing resources across a network to
accomplish tasks.
Chapter 1: Introduction to Internet Page 1
, d) May be insecure. A computer network may be used by computer hackers to deploy computer viruses
or computer worms on devices connected to the network, or to prevent these devices from normally
accessing the network (denial of service).
e) May be difficult to set up. A complex computer network may be difficult to set up. It may also be
very costly to set up an effective computer network in a large organization or company.
1.2.3. Why Networks
a) Load Sharing: Both the program and data are transmitted to a remote computer to equalize the load
between the two facilities.
b) Message Service: A network can be used to handle interpersonal message transmissions. This type of
service can also be used for educational services and conference activities. However, it is not an
important motivation for a network of scientific computers.
c) Data Sharing: The program is sent to a remote computer where a large data base exists. This type of
operation will be particularly useful where data files are too large to be duplicated economically
d) Program Sharing
e) Remote Service
1.2.4. Network Terminologies
1) Intranet: An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web
browsers and file transfer applications, that is under the control of a single administrative entity. That
administrative entity closes the intranet to all but specific, authorized users. Most commonly, an
intranet is the internal network of an organization. A large intranet will typically have at least one
web server to provide users with organizational information.
2) Extranet: An Extranet is a computer network used outside the intranet. An extranet is a computer
network that allows controlled access from the outside, for specific business or educational purposes.
In a business-to-business context, an extranet can be viewed as an extension of an organization's
intranet that is extended to users outside the organization, usually partners, vendors and suppliers, in
isolation from all other Internet users.
3) Local area network: A local area Network (LAN) is a network that connects computers and devices in
a limited geographical area such as home, school, computer laboratory, office building, or closely
positioned group of buildings. Each computer or device on the network is a node.
4) Wide area network: A wide area Network (WAN) is a computer network that covers a large
geographic area such as a city, country, or spans even intercontinental distances, using a
communications channel that combines many types of media such as telephone lines, cables, and air
waves. A WAN often uses transmission facilities provided by common carriers, such as telephone
companies.
5) Enterprise private network: An enterprise private network is a network built by an enterprise to
interconnect various company sites, e.g., production sites, head offices, remote offices, shops, in order
to share computer resources.
6) Virtual private network: A virtual private network (VPN) is a computer network in which some of the
links between nodes are carried by open connections or virtual circuits in some larger network (e.g.,
the Internet) instead of by physical wires. The data link layer protocols of the virtual network are said
to be tunneled through the larger network when this is the case. One common application is secure
communications through the public Internet, but a VPN need not have explicit security features, such
Chapter 1: Introduction to Internet Page 2
Chapter 1: Introduction to Internet
1.1 Internet
The Internet is a global system of interconnected computer networks that use the standard Internet
protocol suite (often called TCP/IP, although not all applications use TCP) to serve billions of users
worldwide.
It is a network of networks that consists of millions of private, public, academic, business, and
government networks, of local to global scope, that are linked by a broad array of electronic, wireless and
optical networking technologies. The Internet carries an extensive range of information resources and
services, such as the inter-linked hypertext documents of the World Wide Web (WWW) and the
infrastructure to support email.
1.2 Computer Networks
A computer network is the infrastructure that allows two or more computers (called hosts) to
communicate with each other.
A network can be defined as a group of computers and other devices connected in some ways so
Definition
as to be able to exchange data. -Each of the devices on the network can be thought of as a node;
each node has a unique address.
A computer network, often simply referred to as a network, is a collection of hardware
components and computers interconnected by communication channels that allow sharing of
resources and information.
The network achieves this by providing a set of rules for communication, called protocols, which should
be observed by all participating hosts.
A communications protocol is a set of rules for exchanging information over a network
The need for a protocol should be obvious: it allows different computers from different vendors and with
different operating characteristics to ‘speak the same language’.
1.2.1. Properties of Computer Networks:
a) Facilitate communications. Using a network, people can communicate efficiently and easily via
email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.
b) Permit sharing of files, data, and other types of information. In a network environment, authorized
users may access data and information stored on other computers on the network. The capability of
providing access to data and information on shared storage devices is an important feature of many
networks.
c) Share network and computing resources. In a networked environment, each computer on a network
may access and use resources provided by devices on the network, such as printing a document on a
shared network printer. Distributed computing uses computing resources across a network to
accomplish tasks.
Chapter 1: Introduction to Internet Page 1
, d) May be insecure. A computer network may be used by computer hackers to deploy computer viruses
or computer worms on devices connected to the network, or to prevent these devices from normally
accessing the network (denial of service).
e) May be difficult to set up. A complex computer network may be difficult to set up. It may also be
very costly to set up an effective computer network in a large organization or company.
1.2.3. Why Networks
a) Load Sharing: Both the program and data are transmitted to a remote computer to equalize the load
between the two facilities.
b) Message Service: A network can be used to handle interpersonal message transmissions. This type of
service can also be used for educational services and conference activities. However, it is not an
important motivation for a network of scientific computers.
c) Data Sharing: The program is sent to a remote computer where a large data base exists. This type of
operation will be particularly useful where data files are too large to be duplicated economically
d) Program Sharing
e) Remote Service
1.2.4. Network Terminologies
1) Intranet: An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web
browsers and file transfer applications, that is under the control of a single administrative entity. That
administrative entity closes the intranet to all but specific, authorized users. Most commonly, an
intranet is the internal network of an organization. A large intranet will typically have at least one
web server to provide users with organizational information.
2) Extranet: An Extranet is a computer network used outside the intranet. An extranet is a computer
network that allows controlled access from the outside, for specific business or educational purposes.
In a business-to-business context, an extranet can be viewed as an extension of an organization's
intranet that is extended to users outside the organization, usually partners, vendors and suppliers, in
isolation from all other Internet users.
3) Local area network: A local area Network (LAN) is a network that connects computers and devices in
a limited geographical area such as home, school, computer laboratory, office building, or closely
positioned group of buildings. Each computer or device on the network is a node.
4) Wide area network: A wide area Network (WAN) is a computer network that covers a large
geographic area such as a city, country, or spans even intercontinental distances, using a
communications channel that combines many types of media such as telephone lines, cables, and air
waves. A WAN often uses transmission facilities provided by common carriers, such as telephone
companies.
5) Enterprise private network: An enterprise private network is a network built by an enterprise to
interconnect various company sites, e.g., production sites, head offices, remote offices, shops, in order
to share computer resources.
6) Virtual private network: A virtual private network (VPN) is a computer network in which some of the
links between nodes are carried by open connections or virtual circuits in some larger network (e.g.,
the Internet) instead of by physical wires. The data link layer protocols of the virtual network are said
to be tunneled through the larger network when this is the case. One common application is secure
communications through the public Internet, but a VPN need not have explicit security features, such
Chapter 1: Introduction to Internet Page 2
