Computer Networks and Web Technologies

Question 1

What is Data Communication?

Answer 1

Data communication is the transmission of data and information between two or more computers.
Essential for:
Email, Voicemail, Facsimile, Telecommuting, Videoconferencing, Electronic Data Interchange (EDI), Online services such as e-commerce/internet banking, social media, E-learning, Global Positioning System (GPS), Use of the Internet.

Question 2

Why are networks used?

Answer 2

1. Transmit data and information to share files.
2. Resources such as disk drives, CD-ROm drives, modems or printers can be shared.
3. Programs (software): such as word processors, spreadsheets and databases can be shared.

Question 3

How is data transmitted to computers?

Answer 3

By:
Uploading - sending data from your computer to another computer on the network or the Internet.
Downloading - receiving data to your computer from another computer on the network or the Internet

Question 4

How are computers linked or configured?

Answer 4

1. Point-point: a direct link between two computers in a network.
2. Broadcast: using one computer to transmit data and information to serve the needs of several terminals or computers connected to it in a network.

Question 5

The types of networks

Answer 5

1. Large Area Network (LAN) - covers a small geographical area, usually connects computers, printers, etc.
   Eg. a set of computers in a high school.
2. Metropolitan Area Network - falls between LAN and WAN, connects computers over a relatively large ara like a city or a university campus.
3. Wide Area Network (WAN) - connects computers that are spread out over a large area like an island, a region in the Caribbean or across continents, the internet.
4. Mobile Networks: communications network spread out over a large geographical area connected wirelessly by transreceivers at fixed locations known as cell sites.

Question 6

What is a transceiver?

Answer 6

A two-way radio combination of a transmitter and receiver that transmits and receives radio wave signals.

Question 7

What are the basic LAN requirements?

Answer 7

1. Network cabling
2. Network card
3. A hub
4. File server
5. System software.

Question 8

What are the different LAN layouts (Topology)?

Answer 8

1. Star Network - all the nodes (computers) are connected to a central hub meaning each computer has its own connection to the network.
   Computer - HUB - Computer
   Computer
2. Bus network - all the nodes are in a line connected to each other.
   Computer - Computer - Computer - Computer
3. Ring network - unlike the bus, has no end line. The last node is connected to the first node forming a ring/loop.

                             Computer
     Computer                                   Computer
                             Computer

Question 9

What is a Stand alone computer

Answer 9

A computer that is not a part of a network.

• Disadvantages
  1. Cannot easily share large amounts of data with others.
  2. Data can only be transmitted by disk/modem which can be time consuming and unreliable.
• Advantages
  1. No need for network software licenses/network card.
  2. Security from users on other sites.

Question 10

What are the Wireless Technologies?

Answer 10

These technologies provide wireless connectivity using radio waves.
1. Bluetooth - to replace cables as it allow for the exchange of data over short distance among wireless and wired devices.
2. Wireless Fidelity - provides high speeds wireless access to a network or the Internet.
NB: Hotspots are public areas varying in size that offers internet access over a WLAN.

Question 11

What are Voiceband channels and Broadband channels?

Answer 11

Voiceband channels - can transmit data at a rate of 300 bits per second to 9,600 bps. The most popular form of transmitting data is via telephone line. Twisted pairs are used for this form of data transmission.

Broadband channels - transmit data at thousands of characters per second. Examples are coaxial cables and fibre optic cables.
One character = 8bits.

Question 12

What are the types of transmission media?

Answer 12

Wired (cabled) media - uses wires/cables to transmit data.
Eg.
1. Twisted pair/ethernet cable - commonly used in phone line/cables.
2. Coaxial cables - found on televisions, video and cable TV.
3. Fibre Optic cables - transmits signals at high speed over long distances, used by large telephone and telecommunications.

Wireless media - transmits data through the air.
Eg. Satellite, Microwave and Infrared.

Question 13

What direction can data be transmitted in?

Answer 13

1. Simplex - data can flow in only one directions
   Eg. Radio
2. Half-Duplex - data can flow in both directions but one way at a time.
   Eg. Walkie-talkie
3. Full Duplex or Duplex - data can be both sent and received at the same time.
   Eg. Modem connections.