SECTION 4 Computer Networks a) describe a modem and its purpose; b) state the difference between analogue data and digital data; c) describe the need for conversion between analogue and digital data; d) identify the advantages and disadvantages of using common network environments such as the Internet; e) describe what is meant by the terms user id and password, stating their purpose and use; f) identify a variety of methods of communication such as fax, e-mail, bulletin boards, and tele/video conferencing; g) define the terms Local Area Network (LAN) and Wide Area Network (WAN); h) describe the difference between LANs and WANs, identifying their main characteristics; i) describe the characteristics and purpose of common network environments, such as intranets and the Internet; j) discuss the problems of confidentiality of data, including problems surrounding common network environments; k) identify the need for encryption and authentication techniques when using common network environments such as the Internet.
THE INTERNET - DEFINITIONS
Internet: a vast computer network linking smaller computer networks worldwide.
Username: a unique sequence of characters used to identify a user and allow access to a computer system, computer network or online account.
Password: a secret word or expression used by authorized persons to prove their right to access information, files etc...
DIFFERENT WAYS OF COMMUNICATING USING THE INTERNET
Email: it can be used to send messages from one computer to another (one username to another)
IM (Instant Messaging): allows people people to exchange text or video/audio messages from many different places in the world.
Social networks: allows people to share information and pictures (and then people commenting on these) from anywhere in the world.
Conference calls: used to have video/audio conversations with people who may be all around the world. This is usually a default option of many IM companies/brands.
Blog: web pages which allow users to make entries/journals on a wide range of topics and these can easily be accessed by typing the name of site on any browser (Google, Yahoo...).
LANs and WANs
LAN- Local Area Network
Used for: Small areas, for example a school (a building)
Types of LAN:
*WLAN: Wireless Local Area Network- this means it does not need any wires to function.
*Ethernet LAN:
Ethernet is a family of computer networking technologies for local area networks (LANs)
WAN- Wide Area Network
Used for: bigger areas, connects computers which are far away (it may cover a whole street, or a government building; which is usually bigger…)
File system software: A file system (or filesystem) is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device(s) which contain it.
5 applications that are network aware
1) Web browser: to look for certain information on various sites all over the net.
2) Email client: account which allows the user to send, and receive, messages.
3) Videoconference program: (such as Skype) to allow users to communicate audiovisually with other users around the world.
4) DNS (Domain Name System): it translates domain names meaningful to humans into the numerical identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide.
5) Anti-virus: used to prevent viruses to access a personal computer, by having access to the files and; eventually, invading an entire network.
Intranets and Encryption
1) An intranet is a private network based on internet standards but only available within the business or other organization. It’s different to the internet in the sense that it cannot be accessed by anyone who’s not a part of the business. Also, it’s not directly connected to the internet, however, some intranets allow access. If a school has an intranet, it may use it in the following ways: to upload room changes, examination timetables, sports teams and results, revision guides and homework tasks. These can be shared between teachers and students.
2) An intranet is only available within a business or an organisation. An extranet allows authorised outsiders to access the extranets.
3) EDI: (stands for Electronic Data Interchange) allows data to be exchanged and is a special way to transfer business documents, such as orders and invoices.
e-commerce: it's the term given to the buying and selling of goods and services throught the internet and, particularly, the WWW (World Wide Web).
encryption: to put data into a special computer code to prevent other people from accessing the specific data.
Assignments
QUESTIONS
What's a modem?
A modem is an electronic device that converts a computer's digital signals into specific frequencies to travel over telephone or cable television lines.
What does it do?
Its job is to encode digital information, and also demodulate such a carrier signal to decode the transmitted information.
HOW TO CONNECT TO THE INTERNET VIA...
1) Dial up: it is a type of Internet connectivity that operates through a standard telephone line.
2)ISDN: it is a network technology that supports digital transfer of simultaneous voice and data traffic.
3)ADSL: uses existing copper pair phone line wiring in conjunction with special hardware on the switch and user ends of the line.
What is a network? A network is a group of interconnected systems.
What is a computer network? It's the interconnection of various computer components/peripherals. Uses: *File sharing *Printer sharing *Communication and colaboration *Organization
Advantages:
*It's a lot easier to access (you can access your bank account from your computer without needing to actually go to the bank
*The process is a lot faster
Disadvantages:
*Loss of interaction with other people.
Homework
Workstation: It's a computer of individual use that is faster and more efficient and capable than a personal computer.
1000Gb Switches: A device for connecting multiple devices in a network with 1000 GB of capacity.
File server: In the client model, a file server is a computer responsible for the central storage and management of data files so that other computers on the same network can access the files.
Firewall (web cache):A firewall is software or hardware that checks information coming from the Internet or a network, and then either blocks it or allows it to pass through to your computer. It protects the resources of private networks from other networks.
Cat5e cable: A cable that supports 1 GB.
Tape drive: Stores comptuer data (from the network) on a magnetic tape.
Table of Contents
Notes
Assignments
Homework
Notes
SECTION 4
Computer Networks
a) describe a modem and its purpose;
b) state the difference between analogue data and digital data;
c) describe the need for conversion between analogue and digital data;
d) identify the advantages and disadvantages of using common network environments such as the Internet;
e) describe what is meant by the terms user id and password, stating their purpose and use;
f) identify a variety of methods of communication such as fax, e-mail, bulletin boards, and
tele/video conferencing;
g) define the terms Local Area Network (LAN) and Wide Area Network (WAN);
h) describe the difference between LANs and WANs, identifying their main characteristics;
i) describe the characteristics and purpose of common network environments, such as intranets and the Internet;
j) discuss the problems of confidentiality of data, including problems surrounding common network environments;
k) identify the need for encryption and authentication techniques when using common network environments such as the Internet.
THE INTERNET - DEFINITIONS
Internet: a vast computer network linking smaller computer networks worldwide.
Username: a unique sequence of characters used to identify a user and allow access to a computer system, computer network or online account.
Password: a secret word or expression used by authorized persons to prove their right to access information, files etc...
DIFFERENT WAYS OF COMMUNICATING USING THE INTERNET
Email: it can be used to send messages from one computer to another (one username to another)
IM (Instant Messaging): allows people people to exchange text or video/audio messages from many different places in the world.
Social networks: allows people to share information and pictures (and then people commenting on these) from anywhere in the world.
Conference calls: used to have video/audio conversations with people who may be all around the world. This is usually a default option of many IM companies/brands.
Blog: web pages which allow users to make entries/journals on a wide range of topics and these can easily be accessed by typing the name of site on any browser (Google, Yahoo...).
LANs and WANs
LAN- Local Area Network
Used for: Small areas, for example a school (a building)
Types of LAN:
*WLAN: Wireless Local Area Network- this means it does not need any wires to function.
*Ethernet LAN:
Ethernet is a family of computer networking technologies for local area networks (LANs)
WAN- Wide Area Network
Used for: bigger areas, connects computers which are far away (it may cover a whole street, or a government building; which is usually bigger…)
Hardware required on a network:
File server:
is a computer attached to a network that has the primary purpose of providing a location for shared disk access
Print server:
is a device that connects printers to client computers over a network
Hub/switch:
is a computer networking device that connects network segments
Router/USB modem:
is a device that forwards data packets between computer networks, creating an overlay internetwork
Workstation:
is a high-end microcomputer designed for technical or scientific applications.
Network cable:
are used to connect one network device to other or to connect two or more computers to share printer, scanner etc.
Network card:
is a computer hardware component that connects a computer to a computer network.
Software required to operate on a network
File system software: A file system (or filesystem) is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device(s) which contain it.
5 applications that are network aware
1) Web browser: to look for certain information on various sites all over the net.
2) Email client: account which allows the user to send, and receive, messages.
3) Videoconference program: (such as Skype) to allow users to communicate audiovisually with other users around the world.
4) DNS (Domain Name System): it translates domain names meaningful to humans into the numerical identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide.
5) Anti-virus: used to prevent viruses to access a personal computer, by having access to the files and; eventually, invading an entire network.
Intranets and Encryption
1) An intranet is a private network based on internet standards but only available within the business or other organization. It’s different to the internet in the sense that it cannot be accessed by anyone who’s not a part of the business. Also, it’s not directly connected to the internet, however, some intranets allow access. If a school has an intranet, it may use it in the following ways: to upload room changes, examination timetables, sports teams and results, revision guides and homework tasks. These can be shared between teachers and students.
2) An intranet is only available within a business or an organisation. An extranet allows authorised outsiders to access the extranets.
3) EDI: (stands for Electronic Data Interchange) allows data to be exchanged and is a special way to transfer business documents, such as orders and invoices.
e-commerce: it's the term given to the buying and selling of goods and services throught the internet and, particularly, the WWW (World Wide Web).
encryption: to put data into a special computer code to prevent other people from accessing the specific data.
Assignments
QUESTIONS
What's a modem?
A modem is an electronic device that converts a computer's digital signals into specific frequencies to travel over telephone or cable television lines.
What does it do?
Its job is to encode digital information, and also demodulate such a carrier signal to decode the transmitted information.
HOW TO CONNECT TO THE INTERNET VIA...
1) Dial up: it is a type of Internet connectivity that operates through a standard telephone line.
2)ISDN: it
is a network technology that supports digital transfer of simultaneous voice and data traffic.
3)ADSL:
uses existing copper pair phone line wiring in conjunction with special hardware on the switch and user ends of the line.
What is a network? A network is a group of interconnected systems.
What is a computer network? It's the interconnection of various computer components/peripherals.
Uses:
*File sharing
*Printer sharing
*Communication and colaboration
*Organization
Advantages:
*It's a lot easier to access (you can access your bank account from your computer without needing to actually go to the bank
*The process is a lot faster
Disadvantages:
*Loss of interaction with other people.
Homework
- Workstation: It's a computer of individual use that is faster and more efficient and capable than a personal computer.
- 1000Gb Switches: A device for connecting multiple devices in a network with 1000 GB of capacity.
- File server: In the client model, a file server is a computer responsible for the central storage and management of data files so that other computers on the same network can access the files.
- Firewall (web cache):A firewall is software or hardware that checks information coming from the Internet or a network, and then either blocks it or allows it to pass through to your computer. It protects the resources of private networks from other networks.
- Cat5e cable: A cable that supports 1 GB.
.Tape drive: Stores comptuer data (from the network) on a magnetic tape.