IM BORED

ActiveX – Technology created by Microsoft to control interactivity on web pages. If ActiveX is on a page, an applet or small program has to be downloaded to gain access to the full functionality. 


Java – Programming language that allows applets to run within a web browser. Examples of applets include a calculator or a counter.


JavaScript – Programming developed to interact with HTML source code to allow interactive websites. 



Attackers may use any of these tools to install a program on a computer.

 To prevent against these attacks,

 most browsers have settings that force the computer user to authorize

 the downloading or use of ActiveX,Java, or JavaScript

Common DoS attacks include the following:


Ping of death – A series of repeated, larger than normal pings that crash the receiving computer 


E-mail bomb – A large quantity of bulk e-mail that overwhelms the e-mail server preventing users from accessing it.



Here are some basic precautions to help protect against social engineering:


Never give out your password


Always ask for the ID of unknown persons


Restrict access of unexpected visitors


Escort all visitors


Never post your password in your work area


Lock your computer when you leave your desk


Do not let anyone follow you through a door that requires an access card



Application Protocols
Application layer protocols provide network services to user applications such as web browsers and e-mail programs. Explore some of the more common Internet protocols in Figure 2, the Application 

layer, to learn more about the protocols that operate in this layer.

Transport Protocols
Transport layer protocols provide end-to-end management of the data. One of the functions of these protocols is to divide the data into manageable segments for easier transport across the network. Explore each of the protocols in Figure 3, the Transport layer, to learn more about the protocols that operate in this layer.

Internet Protocols
Internet layer protocols operate in the third layer from the top in the TCP/IP model. These protocols are used to provide connectivity between hosts in the network. Explore each of the protocols in Figure 4, the Internet layer, to learn more about the protocols that operate in this layer.

Network Access Protocols
Network Access layer protocols describe the standards that hosts use to access the physical media. The IEEE 802.3 Ethernet standards and technologies, such as CSMA/CD and 10BASE-T are defined in this layer.

there are three types of different networks: LAN, WAN, WLAN

LAN:Stands for Local Area Network. A LAN describes connected devices under the same network, LAN’s are usually found in small offices, Schools and sometimes can be found at home.

Lan devices: Computers,printers, wireless, cables (media) switches, hub, router and severs.

WAN: stands for Wireless Area Network.  Are networks that connect LAN networks in different places and countries, for example, the internet is a massive WAN, the internet is made up of lots of connected LAN’s.

WLAN: Stands for Wireless local area network. Wireless devices connect to access points in specific areas. the range of a typical WLAN is around 30M indoors.

Peer to peer network: is a network where there is no administrator, it is all user contributed, and it cannot be shut down, like certain programmes such as youtube and limewire.

Bandwidth: Bandwidth is the amount of data that can be sent over a period of time. Bandwidth is usually measured in bits per second (bps).Imagine a motorway with cars on it, obviously the wider the motorway, the more cars can travel on it at one time, so therefore cars can get to their destinations quicker. So think of that, but in computer terms, the more bandwidth, the more information can be transferred within that period of time.

IP addressing: an IP address is used to identify your computer/device on a network. your computer gets an IP address when it first joins this network. Each device must have a unique address.

DHCP:Automatically gives a device an IP address automatically when it joins the network for the first time.

ICMP: (Internet Control Message Protocol) , is used by devices on a network to send error and control messages to computers and servers.

Hubs: is a device that extends the range on a network, it does this by recieving data on one port and then sending it to all other ports.

Bridges and Switches: this is were files are broken up into packets, then they are transmitted over a network, this allows for error checking and asier retransmission if the packet is lost or corrupted.

Routers: are devices the connect entire netowrks to eachother. Routers use use IP addressess to send frames (packets and address information)to eachother

WAP: (Wireless Access Points) Provide network access to wireless devices (laptops Iphones e.c.t)

Multipurpose devices: Are network devices that perform more than one function, it is cheaper and doenst take up as much room as buying seperate devices.

Twisted pair (Media): is a type of copper cabling that is used for telephones.and most Ethernet networks. the twisted pair is designed to provide protection agaisnt crosstalk. (noise generated  by adjacent pairs of wires in the cable.

unsheilded Twisted Pairs: Cable that has two of four pairs of wires, this relies totally on cancellation effect, produced by the twisted wire pairs that limits signal caused by EMI (electromagnetic interface.)

Sheilded Twister pair: Each pair of wires is wrapped in a metalic foil, to better sheild the wires from noise.

Fiber Optic: a glass or plastic conductor that transmits information using light. Because it is made of either plastic or glass it is not affected by EMI. this means that fibre optic can deliver a clearer signals that are clearer, can go further and have greater bandwidth.

There are 5 LAN topoligies:

• bus
• ring
• star
• extended star
• mesh

Ethernet Standards: 802.11a, data rates of upto 54Mbps

802.11b, data rsates of upto 11Mbps

802.11g: maximum speeds of 54Mbps

802.11n, theoretical bandwidth of 540 Mbps

OSI Model: is a standard

Extended Star

A peer-to-peer network allows two or more PCs to pool their resources together. Individual resources like disk drives, CD-ROM drives, and even printers are transformed into shared, collective resources that are accessible from every PC.

Unlike client-server networks, where network information is stored on a centralized file server PC and made available to tens, hundreds, or thousands client PCs, the information stored across peer-to-peer networks is uniquely decentralized. Because peer-to-peer PCs have their own hard disk drives that are accessible by all computers, each PC acts as both a client (information requestor) and a server (information provider). In the diagram below, three peer-to-peer workstations are shown. Although not capable of handling the same amount of information flow that a client-server network might, all three computers can communicate directly with each other and share one another’s resources.

A peer-to-peer network can be built with either 10BaseT cabling and a hub or with a thin coax backbone. 10BaseT is best for small workgroups of 16 or fewer users that do not span long distances, or for workgroups that have one or more portable computers that may be disconnected from the network from time to time.

Bandwidth is a measure of the amount of data passing through a network at a given time. Things like huge images on web pages and needless questions posted to Usenet newsgroups waste bandwidth which could be better utilized for transferring information.

In computer networks, bandwidth is often used as a synonym for data transfer rate  the amount of data that can be carried from one point to another in a given time period usually a second. This kind of bandwidth is usually expressed in bits (of data) per second (bps). Occasionally, it’s expressed as bytes per second (Bps). A modem that works at 57,600 bps has twice the bandwidth of a modem that works at 28,800 bps. In general, a link with a high bandwidth is one that may be able to carry enough information to sustain the succession of images in a video presentation.

It should be remembered that a real communications path usually consists of a succession of links, each with its own bandwidth. If one of these is much slower than the rest, it is said to be a bandwidth bottleneck.

today i have learnt the difference between a ink jet print a laser printer and a dot matrix printer and there properties

• A ink jet printer can produce 2 – 8 pages per minute (ppm) and it is the slowest out of the 3 main printers and in the picture below it show’s the colours of inks. average cost is £45
• 
• A dot matrix printer has pins inside the printer that strikes the paper with ink on it and makes a dot and it does it so many times that it starts to make letters or numbers by making a load of dots and you can make anything with enough dots even a picture and it can print 2 – 10 . and can cost up to £5000
• 

A lazer printer uses a sort of roller that has toner on it and the printer puts the toner onto the roller and the roller pushes the toner onto the paper with extreme force and the toner gets pressed into the paper and can print 8 – 200 pages per min and the colours this uses are cyan, magenta, yellow and black.(C,M,Y,K) and costs up to £ 900

• The total cost of ownership of a printer is:
• initial purchase price
• cost of supplies, such as paper and toner
• price per page
• maintenance costs
• warranty costs
• the amount of material to be printed
• The expected lifetime of the printer

with laptop components they are easy to take out and replace because they are light and portable.But with desktop components its alot harder to take them out because they’re alot heavier and harder to replace.laptops can use other portable devices with laptops like docking stations but with a desktop you can and you cant. desktops you can use the common portable devices like memory stick, mouse and keyboards but they are not fully portable because you cant tkae the desktop with you. the motherboard on the laptop is much smaller than the desktop motherboard because the laptops components have to be more compact and also the laptops motherboard is proprietary.