Notes

Computer System
A collection of related components made up of two parts: hardware (physical equipment that you can touch) and software (programs installed on the computer)
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Computer Networks
This allows users to connect over distances. They allow file sharing, hardware sharing, and instant communication, making them a necessary tool for offices, schools, and homes all over the world.

It consists of several components, each of which is important to making the network function correctly as a whole.


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Workstations
These are known as desktop computers.


The computer you use at home or school would be called a this in a network
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Servers
*These can look like desktop computers; however, most do not look like your “normal” computer.
*They do not really need monitors, graphics and sound cards.
*What they really do need is hard drives.
*In most schools, when you save your work, you are saving to one of these.
*By doing this, you can access your school
work from any computer that is on your
school network.
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Modem
a device that enables computers to interpret data they receive from a network or send data in the proper form along a network
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Hub
This is sort of like a car radio. Every computer that has that section of network (like a radio station) can hear everything that is being transmitted.


All the computers that are connected to this receive all the information that goes through it.


Usually, if you have a this, you also have a router.
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Switch
This is more complex than a hub and works a lot like a two-way radio. In a room full of people, only the person holding the other radio can hear what is being said.
It keeps track of which computers are where, and when something comes in, it sends it only to that specific computer, not every computer on that section of the network.. It is more secure than a hub, andfaster than a hub, but not as powerful
as a router.
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Router
This works a lot like a telephone system. Each computer is given its own unique number by the this. When information comes into this device, it is then sent along to the correct number—or in this case, computer.
There are more options built into this than there are available to switches. This can have the equivalent phone options of call screening and caller ID. This is beyond a switch’s capabilities
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Peer to Peer Network
This is a type of network where the computers in the network share resources among each other.
Every computer on this network is equal; all the computers run the same networking software and file systems for sharing.
Printers, scanners, and other external devices are shared by the machine they are plugged into, otherwise known as managed by.
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Cons of Peer to Peer Networks
shared resources, such as printers, place a special demand on the computers in the network.
Due to the nature of this type of network, all of the computers on the network provide access to all of the machine’s resources. The down side of this is that you can unintentionally expose private files to all the other users on the network.
There is also no data security or protection from hackers, viruses, etc.
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Peer to Peer Operating Systems
Each of the workstations has an operating system that tells it how to store and share resources with the others.
The two software packages that we may use that allow this type of network are called
1. Appleshare (for MACs)
2. Windows for Workgroups (for PCs)
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Ethernet
A type of connection between computers that forms the basis of most LANs.
It serves as one of the main methods for connecting a computer or network to an Internet hub.

It has evolved into a much more sophisticated system that uses specialized cables that connect to a central hub or router in order to network several computers together.
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LAN
Stands for Local Area Network.
It is a group of computers that are linked together that share internet access, file access, applications, storage, and allows connected computers to share printers and scanners.
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WAN
This stands for Wide Area Networks.
It is a collection of regular local area networks that are all interconnected to form one giant network.
Oftentimes, schools and even large companies will operate a WAN on premises.
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Advantages of a WAN
Flexible access: School networks can be created for students to access files throughout the school district.


Networks speed up the file sharing and saving process.


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Disadvantages of a WAN
These are expensive to install: They save money over time, but they are expensive to set up at first.


They require maintenance of the network, which costs both money and time.
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Token Ring
standard specifies that computers and devices on the network share or pass a special signal in a unidirectional manner and in a preset order.
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Token Ring Issues
In order for these to work,
all computers must check for lost or duplicate tokens
All connected computers must “vote” a new leader to create a new token
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Client Server Operating Systems
This setup allows the network to centralize functions and applications in one or more file servers.
File servers become the “heart” of this system and provide access to files and resources, as well as providing security.
Workstations have access to the resources to files on the file servers.
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The most popular Client Server OS
Macintosh OSX
Microsoft Windows Server
Novell
UNIX
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Advantages of Client Server OS
This type of network makes it easy to install new technology and new elements.
The server can be accessed remotely, and you can have both MACs and PCs on a network.
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Disadvantages of Client Server OS
They depend on their servers. When they go down, the network will no longer work.
There is a hefty investment. It pays off in the long run, but it requires money to set it up.
Large networks will require dedicated staff to maintain this and to work out the “kinks” when problems arise.
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Hackers
Someone who finds access in a computer’s security system to break into another machine.
They usually collect information on the target computer and then try to find access into the computer system.
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Security Threats
Spam
Adware
Information Threats
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Spam
unwanted commercial e-mail

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Virus
This can cause your computer to slow down or even destroy your hard drive.

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Adaware
This is software that gets installed on the computer. It can cause annoying pop-ups or even steal information.
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Information Threats
hackers steal important information: client information, back account numbers, etc.
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Steps to protect yourself from Hackers

1. Install a firewall
2. Be aware and cautios on the net
3. Make sure that the network is password protected, especially if using a wireless network.
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Firewall
hardware and/or software that guards a private network by analyzing the information leaving and entering the network and then blocks unauthorized or suspicious content