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Archive for October, 2010

Fire walls


Free standing, uses it’s own hardware

Costs more

Multiple computer use

Little impact on computer performance


Availible as 3rd party software, cost varies

Included in Windows XP

Only protects the computer it is on

Uses the CPU, can slow computer speeds

Wireless network stuff

The domain is the bigger network, a work group is a smaller group within the domain, information can be shared between only these computers.

SSID – Service Set Identifier

The default wireless network name so that wireless devices can detect other devices in a wireless network, it must be manually entered when the SSID broadcast has been disabled on the wireless router or access point.

MAC address filtering

A security technique in which only identified MAC addresses can connect to a wireless network, used on wireless LAN’s

WEP – Wired Equivalent Privacy

First generation security for wireless, crap, it is easy to break it’s encryption making it pretty much useless.

WPA – Wi-Fi Protected Access

2nd generation of WEP, has much stronger encryption


A security layer for wireless systems, once it was made an official standard WPA2 was released

WPA2 – Wi-Fi protected access 2

The improved version of WPA which uses the entire 802.11i standard and provides goverment grade security. It can be enabled in two versions:

Personal – Password authentication

Enterprise – Server authentication

LEAP – Lightweight extensible Authentiation Protocol

CISCO’s wireless security, addresses weaknesses in WEP and WPA

WTLS – Wireless Transport Layer Security

Security for mobile devices which uses a smaller amount of bandwidth. Uses WAP (Wireless Applications Protocol)

 Hub – receives data, sends to all ports

Switch – Sends to intended port, more sophisticated than a bridge

Routers – Connects entire networks to each other e.g. internet

WAP – Wireless Access Points, Uses radio waves to connect wireless devices to the network

Printer and scanner hazards

Weight read instructions for two or three man lifting

Clothes that may shift it, from desks for example or shoes that don’t protect your feet if something drop on them

Jewelery that may drop into slots or scratch flatbeds

Heat from being turned on may remain for hours after being turned off

Packaging that should be removed


Serial attached SCSI (sas)

Point to point

Can take 65535 devices

No terminators

SATA (old)

Half duplex- Info goes one way at a time

Consumer market

1-2m cables

SCSI (new)

Full duplex- Info goes both ways at the same time

Better error handling

Critical server applications

10m cables

Laptops and portable devices


Blue tooth

Short range

Eliminates the need for cables between devices

Operates at 2.4 to 2.485 GHz

Low power, low cost and small size

Use adaptive frequency hopping AFH

Vers. 1.2 up to 1.2Mbps

Vers. 2.0 + EDR up to 3 Mbps

vers. 3.0 + HS up to 24Mbps


Short range

Operates in the lowest light frequency, usu between 100GHz-1000THz (terahertz)

Has to be aligned with the device so the light signal isn’t blocked

Cellular WAN

Two ranges about 800 MHz and about 1900 MHz

Wi-Fi (Wireless Fidelity)

Connection distance 300 feet

Easy to access for network connectivity


Faster than dial-up slower than cable and DSL

Ideal for rural and remote internet users

Faster to download than upload

Weather can screw with the connection.

Laptop servicing

Replacing parts

CRU – Customer replaceable units, parts a customer can replace

FRU – Field replaceable unit, parts only a field technician


You may need a new laptop battery if

It shuts off immediately when AC is removed

Battery is leaking

Battery over heats

Battery wont hold a charge

Look for the largest capacity battery when buying

Docking stations

Lets you connect PCI cards, addtional hard drives optical drives and floppy drives

Usually made for each specific laptop so you have to buy the one made for your laptop

Storage devices

External USB hard drive

Firewire hard drive

BD/DVD/CD burner

Additional RAM

SODIMM usually used for laptops

Read manual to check what can be changed before beginning

Preventive maintainence

Clean regularly

Perform hard drive maintainance, disk clean ups and disk defragmenter

Update software

Stopping ‘system slow down’

The two main tools by windows.

Disk clean up and disk defrag

There are much better tools availible free on the internet but they are usually time trials.

cmd stuff

Change drives by typing the drive letter and a : followed by the enter key

backing up:  xcopy f:\*.* /e

cd\ – Takes you directly to the root eg c:

dir /? – Lists the attributes

/ – Is a switch

tree – shows every file and folder in the system

cls – Clear screen

cd – Change directory

md – Make directory

rd – Remove directory

cd.. – Change directory to parent

cd. – Change to the current directory

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