Networks

Question 1

Local area networks (LAN) - describe

Answer 1

Not over a large geographical area (e.g. in one building)
Typical LAN will consist of a number of computers and devices
Devices and computers will be connected to hubs or switches.
One of the hubs or switches will usually be connected to a router and modem to allow the LAN to connect to the internet

Question 2

LAN - Ads and Disads?

Answer 2

Advantages of Networking using LAN
The sharing of resources
Communication between users
Network administrator can control and monitor all aspects of the network
Disadvantages of Networking using LAN
Easier spread of viruses throughout the whole network
Increased security risk
If main server breaks down, usually the networks will no longer function.

Question 3

Different topologies

Answer 3

Star
Bus
Ring

Question 4

Wireless LANs (WLANs) - describe

Answer 4

Do not involve any wiring or cabling
Provide wireless network connection overs a short distance
They use radio or infrared signal’s instead of cables
Devices known as Access Points (APs) are used for a larger range
APs usually use spread spectrum technology (larger range)

Question 5

Wireless LANs (WLANs) - Ads and disads?

Answer 5

Advantages
All computers can access the same services and resources
No cabling is involved
The system is more flexible
Adding new computers and devices is very easy
Cost is reduced and safety is improved
Disadvantages
Security is an issue
Problems and interference can affect the signal
The data transfer is slow than in the wired LAN

Question 6

Wi-Fi - describe

Answer 6

Any system which allows you to connect to a network or computer through wireless communication
Examples :
o WLANs
o Tablets
o Laptop computers
o Peripheral devices such as printers

Question 7

Wi-Fi Hotspots - describe

Answer 7

Wi-Fi systems rely on AP (radio frequency technology) to enable the device to receive and send signals
Wi-Fi hotspots are places where you can access Wi-Fi (free or paid)
Hotspots are found in public places like Airports, hotels and cafés

Question 8

Bluetooth - describe

Answer 8

Bluetooth is an example of wireless personal area networking (WPAN) technology
Spread spectrum transmission (radio waves) is used to provide wireless links between to devices such as mobile phones and allow connection to the internet
A small home network can be created with this system

Used to transfer photos from camera to a mobile phone. It behaves like a mini-LAN

Question 9

Wide area networks - describe

Answer 9

WAN is formed by a number of LANs being connected together through a router or a modem e.g. the Internet is a WAN
Some companies set up Private WANs, it is expensive however it comes with a much enhanced security
It is common to use an Internet service provider (ISP) for connections to the internet and communicate via this network system
Additional hardware is needed for a WAN: Routers, modems and proxy servers

Question 10

Modems - describe

Answer 10

It stands for modulator demodulator.
Converts computer’s digital signals (modulates it) into analogue for transmission through telephone
lines.
Reverse this process- analogue signal from a telephone line into digital for a computer to process the data. (demodulates it)
The main use it to connect to computer networks over long distances using existing telephone lines.

Question 11

Network Hubs - describe

Answer 11

They are devices that can have multiple devices connected to them.
Main task is to receive data from different ports and send it to each device
The information will be received to the device whether its relevant, or not

Question 12

Switches - describe

Answer 12

More efficient than hubs in distributing data.
Each device has an access control media address MAC which identifies it uniquely
MAC is a number unique to each device connected to the network (like fingerprints)
Data sent will have a mac address which tells the source and receiving device.

Question 13

Bridges - describe

Answer 13

It connects 2 different types of networks together e.g. a bus and star network
It can only connect networks that use the same way for handling messages
They do this by changing the form of message to suite the different type of network

Question 14

Routers - describe

Answer 14

Acts like a bridge, yet can link between two or more networks
Makes decisions on messages being passed between the networks
Formats the messages making it suitable for the new network
Reads information about the message and decides where the message should go and the best route for it to get there
Used to provide a connection between a network and the internet
You need an ISP account to have access to the internet (internet server provider)

Question 15

HTTP Proxy Server - describe

Answer 15

Type of server that acts as a buffer between a WAN and a LAN.
Retrieves web pages and passes them onto the computer that made a request.
Stores any page retrieved on the server, which means that when a different computer requests the same page it would be available.
Speeds up the browsing process

Question 16

The Internet - describe

Answer 16

The Internet is a worldwide collection of networks.
It allows for web browsing, gaming, file sharing, video and email.
User can access by web browser.

Question 17

Websites - describe

Answer 17

Web is made up of millions of websites and web pages

Web pages are documents on a computer screen containing

Question 18

Uniform Resource Locator (URL) - describe

Answer 18

Web browsers use URLs to retrieve files.
They are standard way of locating on the internet
Standard form: 4 numbers e.g. 194.106.220.19
Also alphanumeric form: protcol://site address/path/filename
Where; Protocol is usually http
Site address consists of: computer name, domain name, domain type, and country code
Path is the web page
Filename is the item on the page

Question 19

ADSL modems - describe

Answer 19

Operate at 11,000 kilobits/sec.
Faster at downloading than uploading
They don’t tie up the line while accessing the internet

Question 20

Intranets - describe

Answer 20

It is an internal website that is setup internally for companies and can be accessed by employees for the purpose of standard documents or information and many items of information and data. They use internet protocols i.e. a browser

Question 21

Intranets - advantages

Answer 21

Safer and less chance of hacking
Possible to prevent employees from accessing unwanted sites
Companies ensure that info. available is specific to their needs
Easier to send sensitive messages that remain within a company

Question 22

User IDs - describe

Answer 22

To log on to a network, a user must type in a user ID
User ID assigns user privilege once user logs in
The top level privilege for a network is an administrator: Able to set passwords and delete files from server etc.
User privilege may only allow to access their own work area

Question 23

Passwords - describe

Answer 23

After typing in user ID, the user will be requested to type in their password.
Generally, it is a combination of letters and numbers
Passwords are shown as stars (***) so nobody overlooking can see it.
Many systems ask for password to be typed in twice as a verification check, in case of input errors
To help protect the system, user is has a finite number of attempts
If password is forgotten, administrator has to reset it
If password is forgotten on a website, it will be sent to your e-mail

Question 24

Encryption - describe

Answer 24

The conversion of data to code by encoding it
Done by using encryption software
Since data is encoded, it appears meaningless to a hacker
This technique does not prevent illegal access
Necessary to use decryption software to decode the data
Used to protect sensitive data e.g. banking details
Encryption keys are complex algorithms which makes codes almost unbreakable

Question 25

Describe authentication techniques

Answer 25

Biometric methods: finger print, retina scans, iris scans, face scans - using physical characteristics to authenticate access to systems
magnetic stripe cards

Question 26

Fax -describe

Answer 26

A system that scans documents electronically and converts them into a bit map image (a bit is a binary digit and is a 1 or a 0)
Then transmitted as a series of electrical signals through the telephone network
Receiving fax machine converts the electronic image and prints it out on paper
It is also possible to generate fax signals from a computer to allow documents to be sent to a fax machine
This saves printing out the document first and then passing it through the fax machine
Fax/modem software in the computer converts the image into a form fax machines can recognise

Question 27

Email - describe

Answer 27

A method for sending text and attachments from one computer to another over a network

Question 28

Email - ads and disads?

Answer 28

Advantages
Speed of sending and receiving replies is quick
Low cost (no stamps, paper etc.)
Not needing to leave home to send the mail
Disadvantages
Possibility of virus threats and hacking
Need for the email address to be correct
Inability to send bulky objects via emails
Don’t always get immediate response

Question 29

Video Conferencing - describe

Answer 29

This is a method of communication between people at 2 or more separate locations
It is done in real time and makes use of LAN, if internal, or WAN if through the internet.
Uses hardware like; webcam, microphones, speakers and monitors
It also uses special software like CODEC converts and compresses analogue data into digital data to send down digital lines.

How it works
Delegates at one end speak into a microphone and look into the webcam.
The other delegates can see them and hear them using speakers and monitors,
However there are several problems with these as the conference call often lags and quality is not always high. Also, as travelling tickets increase in price, terrorists can use this way of communicating with each other, increasing risk.

Question 30

VOIP - describe

Answer 30

VOIP (Voice over internet protocol) is a method used to talk to people over internet
VOIP converts sound (picked up by a microphone) into discrete digital packets that can be sent to a destination via internet
The biggest advantage is that it is free and can be used all over the world
The biggest disadvantage is that sound quality is usually bad.

Question 31

General security issues - describe

Answer 31

Identity and service theft
Viruses and malware
Spamming (sending junk mail)
Phishing attacks (the act of sending an email to a user falsely claiming to be an established legitimate enterprise in an attempt to scam user in different ways