Networking

Question 0

Mainframe

Answer 0

• This is a very large computer, which may be connected to hundreds of terminals, many of which may be dumb terminals with no processing power.
• Most of the processing will be done by the mainframe processor, which shares its time between the terminals - a multi-access system.

Question 1

Nodes and Channels

Answer 1

• Networked computers can exchange data and messages.
• Each computer on the network is called a station, terminal or node.
• They can be connected by different means e.g. by cable, which could be wire (most common is UTP - Unshielded Twisted Pair) or optical fibre or radio (wireless) links.
• The means of connection is the communications channel.

Question 2

Types of Network

Answer 2

• LAN - Local Area Network commonly using UTP wire cable (perhaps with optical fibre) or wireless.
• WAN - Wide Area Network - may use public communication channels e.g. telephone lines - wire, optical fibre, microwave.
• Intranet - private network which may be local or covering a wider area, using same protocols (TCP/IP) as the Internet. Secure intranets are much less expensive to build and manage than private networks based on other protocols.
• Client Server Network has dedicated servers, which provide facilities such as file serving, print serving, web serving or mail serving for the client machines - the other stations on the network.
• Peer to Peer Network is similar to the client server network but each station usually deals with its own storage.

Question 3

File, Print and Web Servers

Answer 3

• A File Server, in the client/server model, 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.
• A Web Server is a program often running on a dedicated computer, which uses the web protocol, HTTP, to serve out files that form Web pages to Web users (whose computers contain HTTP clients - web browser programs). Every computer on the Internet that hosts a Web site must have a Web server program.
• A Print Server is a program, a network device, or computer that manages print requests and makes printer queue status information available to users.

Question 4

Network topologies

Answer 4

Network topologies can be Bus, Star, Tree, Mesh, and Ring etc.
Consequences of channel and node failure need to be known.

Question 5

Network hardware

Answer 5

• A network interface card (NIC) is an electronic card fitted to a computer. It provides a dedicated full-time connection to a network and has a unique
  hardware address.
• A hub is common connection point for segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.
• A switch actually reads the destination address (the hardware address of the NIC) on each packet and then forwards the packet to the correct port on the switch.
• A router is connected between networks, commonly two LANs or WANs. A router keeps tables of the states of the networks it is connected to and uses these to decide which way to send each information packet.

Question 6

Trends in Networks

Answer 6

• Bandwidth in computer networks, means the same as data transfer rate - the amount of data that can be carried from one point to another in a given time usually expressed in bits (of data) per second (bps) or bytes per second (Bps). Network bandwidth is steadily increasing.
• Wireless networks are becoming more popular.

Question 7

Which 3 Acts in British Law cover Misuse of Networks?

Answer 7

1. Misuse of Computers Act
2. Data Protection Act
3. Copyright, Designs and Patents Act

Question 8

Misuse of Computers Act

Answer 8

• Makes hacking (attempting to access to computer data without authorisation) a criminal offence.
• Writing or wilful distribution of viruses made illegal.

Question 9

Data Protection Act

Answer 9

• Protects personal data
• Principles include:
  
  • Data controllers who use personal data must register
  • Data must be processed lawfully
  • Data must be accurate
  • Subjects have right to find out what data is held about them only and have it corrected if wrong
  • If subject can show that they have suffered because data was wrong s/he can take legal action for compensation
• Exemptions include National Security

Question 10

Copyright, Designs and Patents Act

Answer 10

• Gives the creators rights to control ways their material can be copied or distributed.
• Computer programs and pages on websites (text, pictures etc.) are protected.