unit 4 - networks

Modem

A device that converts a computer's digital signal into an analogue signal for transmission over an existing telephone line. 

Router

enables data packets to be routed between different networks. For example, it  can be used to connect a LAN to a WAN, however usually it has an internet cable plugged into it, and other cables that connect to computers on the LAN.

Hub

a hardware device that connects multiple computers or devices together; they’re mainly used to form a LAN with these devices. Its main task is to take any data packet (a group of data) that is received at its port and broadcast it to relevant computers in the network.

Switch

checks the data packet received and works out its destination address and sends the data to the appropriate computer only.

Bridge

a type of computer network device that connects with other LAN’s that use the same protocol.

Network Interface Card

This device is an internal device connected to the motherboard and allows a device such as a desktop PC to connect to a network. each of them is given a unique hardwired media access control (MAC) address.

LAN (local area network)

networks that are usually contained within a single building or small geographical location 

WAN (wide area network)

network that connects LANs over a large geographical area

WLAN (wireless local area network)

local area network accessed using radio wave connections

modem advantages

They can connect computers to networks from a long distance, operate  up to 100 Megabits* per second, they can be operate 24/7, ADSL modems allow telephone conversation and internet traffic to be proccessing at the sametime

modem disadvanatages

Modems are used just as an interface between LAN and the internet, Speed is slower than on a hub, It is expensive, a modem is not understood in the intermediate process.

how is a WAN formed?

one of the rubs or switches will usually be connected to a router and a modem to allow the LAN to connect to the internet

Local area network advantages

allows the sharing of resources, ease of communication between users, Allows centralized management of updates, backups and software installations, can secure its devices with the use of firewalls and antivirus software

local area network disadvantages

the network may not function correctly in case of hardware failure, they are more prone to attacks than standalone computers, if the main server breaks down in most cases the network no longer function, data accessing can be slow

wireless local area networks advantages

allow users to connect anywhere in the range of a wireless access point, they can be used in various indoor and outdoor environments making them highly flexible, printer access can be given to wireless devices

wireless local area network disadvantages

the strength of their signals can be affected by obstacles, speeds can be affected by high traffic areas, it can sustain interference from other devices which can affect performance and connectivity, can be vulnerable to security threats due to signal interception

wide area network advantages

provide the ability to connect geographically dispersed locations, offer flexibilty to scale up or scale down based on the organisation’s needs, administrators can monitor and manage the network infrastructure from a single location

wide area network disadvantages

setting up and maintaining a WAN can be more expensive than a WAAN, WANs are subject to the reliability and availability of external service providers

what is an advantage of a WLAN over a cable LAN

it allows the users to move around the area with their devices and remain connected, allows one or more people to connect their mobile devices.

data packet

a small chunk of data sent over a network. it containes both the actual data and control information such as destination address, source address and error checking bits

media access control address

a number that uniquely identifies a device when connected to a network

uses of wifi

Full-scale networks, When the data transfer rate is crucial, For uses where a higher range and better security are required.

uses of bluetooth

when transferring data between 2 or more devices that are very close together, when the speed of data transmission isnt crucial, for low bandwidth applications

differences and similarities of bluetooth and wifi

Wi-Fi offers much faster data transfer rates, better range and better security than Bluetooth. Bluetooth only allows up to 7 devices to be connected simultaneously whereas the number of devices connected to a wifi network depends on the routers used. Bluetooth uses key matching encryption whilst wifi used WPA and WEP

cloud computing

delivery of computer services over the internet. these services such as software and storage space, are housed in remote computers called servers.

cloud computing advantages

data will be secure if there is a fire etc, no need to buy expensive storage device, lower maintenance costs, all software is automatically upgraded, as long as internet access is available users can access data anywhere in the world, all data is automatically backed up

cloud computing disadvantages

internet access is required, download and upload speed can be affected by internet connection, hosting company can be targeted by online hackers, you have less control if the data is held by another company

how does routing work?

the computer splits the file into packetd and addresses them with the recipient’s IP address, these packets are then sent onto the network using cables or radio waves (wireless network). routers on the network incpsect each packet to find the destination address and decide the most efficient path the packet takes.

internet

network of interconnected networks

intranet

Usually private and are used to send information securely and safely.

Extranet

Private Intranet that also allows access by selected parties that reside outside of the organization.

Differences between the internet, intranet and extranet

The internet is a global network, whereas an intranet/extranet is a private network contained within an organization, Much information using internet is publicly available, whereas an intranet/extranet is not, The Internet is not owned solely by one person or organization, whereas the organization usually owns intranets/extranets.

How to protect your password:

Anti-spyware software can be run regularly to ensure that your information, including your password, is not passed to an unauthorized third-party user.

zero login

using facial features, user behavious, voice, movements etc as identification

biometric methods

physical characteristics of an indivual to identify them

magnetic stripes

personal and security data can be encoded on the magnetic stripe of a card and can be swiped through a reader to allow access

smart cards

contains a computer chip and when it is held near a reader, data can be transferred to allow the owner to be authenticated for access

physical token

verifying your identity with a physical device

electronic tokens

applications that users install on their hardware, such as smartphones.

Anti-malware Software

designed to protect devices against viruses and malicious software. It has 3 primary purposes: detect, prevent and remove malicious software. It is installed onto a computer system and will operate in the background.

Security measures

installing anti malware software scan all storage media to detect and destroy or quarantine malware, intalling firewalls ensures that software isn’t downloaded without your knowledge

what does quarantining files mean?

they are placed in a folder where they cannot interfere with other programs if the software suspects it and is unable to delete the malware or if it is actually malware

malware

short for malicious software and is designed to get into computers without the user’s consent and to damage or disrupt the computer

Electronic conferencing advantages

It is much easier to access important documents or bring in ‘experts’ at key parts of the conference, It is possible to hold conferences at short notice, Reduced travelling costs, Reduces the cost of taking people away from work for two or three days to travel

Electronic conferencing disadvantages

Potential time lag in responses/delays when talking, Images can jerk. Problems if the delegates live in different countries with large time zone differences, Requires IT knowledge to some extent.