Author Topic: A+ Essentials Cram Notes 220-801  (Read 12529 times)

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #30 on: April 07, 2014, 02:48:13 AM »
DNS stands for Domain Name System Server. DNS Server is the one responsible for converting the
Domain names to IP addresses.

NIC, Network Interface Card is the one that interfaces your PC to the LAN. NIC sits in your PC on
one of the slot available on the motherboard.

Attenuation: When signals are transmitted over long distance, there will be ohmic losses, which result in loosing the strength of the signals. This is known as attenuation. Amplification is opposite of attenuation.

Asynchronous serial communication uses Start bit/Data bits/Stop bit. A modem connecting to the
Internet is a typical asynchronous device. Synchronous communication uses clock signals to transfer
information. Does not use start/stop bits. Synchronous communication is normally used for high speed data transfers.

TCP/IP is the medium of transport when your are accessing the Internet.

ISDN:ISDN BRI (Basic Rate Interface) will have two B channels, each can carry data up to 64Kbps,
aggregating to 128 Kbps.

Peer-to-peer model is best suited when you need to share files and folders among others in your
office. If the number of networked computers becomes very large or if the security of data is very
important, Client-Server model is recommended.

The SPDF - Sony/Phillips Digital Interface is designed to transfer digital signals between devices
without degrading the signal by converting it to analog. This preserves the quality of the signal
delivered to digital recording and playback devices.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #31 on: April 07, 2014, 02:51:19 AM »
Wireless Networking

The generic standard that defines wireless LAN technologies is 802.11. Specifically, the following
standards exist:

a. 802.11: applies to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4 GHz band.
b. 802.11a: an extension to 802.11 that applies to wireless LANs and provides up to 54 Mbps in the
5GHz band.
c. 802.11b (initially referred to as 802.11 or Wi-Fi): an extension to 802.11 that applies to wireless
LAN and provides up to 11 Mbps transmission in the 2.4 GHz band.
d. 802.11g: applies to wireless LANs and provides 20+ Mbps in the 2.4 GHz band.

Bluetooth is widely used for communication between smart phones and other accessories or between PDAs and information kiosks. The typical coverage for Bluetooth devices is up to 30 feet. It can be used for personal area networking devices like keyboards and headphones.

SSID, short for service set identifier, a unique identifier attached to the header of packets sent over a WLAN. The SSID differentiates one WLAN from another, so all access points and all devices
attempting to connect to a specific WLAN must use the same SSID. WEP together with SSID,
provides basic protection for the wireless network.

WPA, short for Wi-Fi Protected Access, is a Wi-Fi standard that was designed to improve upon the
security features of WEP (Wired Equivalent Privacy). The technology is designed to work with
existing Wi-Fi products that have been enabled with WEP.

WEP, short for Wireless Equivalent Protection, is a security protocol designed to provide protection
equivalent to wired LANs. WPA is an improved security protocol compared to WEP.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #32 on: April 07, 2014, 02:52:52 AM »
9. Operating System

Windows 2000

Windows 2000 Operating systems support 5 different volume types:

1. Simple volumes
2. Spanned volumes
3. Striped volumes
4. Mirrored volumes
5. RAID-5 volumes

-A simple volume consists of a formatted disk on a single hard disk.
-A Spanned volume consists of disk space on more than one hard disk.
-A Striped volume has disk space on 2 or more disks. The disk spaces must be same on all disks.
Fastest disk access among all volume types. RAID level 0.
-A mirrored volume consists of a Simple volume that is mirrored in total, onto a second dynamic disk.
Provides highest level of fault tolerance. RAID level 1
-A RAID-5 volume consists of identical sized disk space located on three or more dynamic disks. Here any single disk failures can be recovered. RAID level 5

Note that Windows 2000 Professional doesn’t support Disk Mirroring, RAID-5 volumes, where as
other Windows 2000 Operating Systems (2000 Server, Advanced Server) support.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #33 on: April 07, 2014, 02:55:52 AM »
Windows XP

In Windows XP computer, you can use Start -> Windows Update to connect to the Microsoft site.
Windows Update is a catalog of items such as drivers, patches, the latest help files, and Internet
products that you can download to keep your computer up to date. You must be logged on as an
administrator or a member of the Administators group in order to access the Product Updates section of Windows Update for downloading help files.

XP Professional supports multiple processors, multiple monitors (up to 9), Group Policy, Encrypting
File System, Dynamic Disks, IIS, a built in backup program, and advanced networking capabilities
(such as IPSec.) All of these features are missing from XP Home Edition. Another important
distinction between the two versions is that XP Home Edition cannot join a Windows NT/2000/2003
domain.

Windows XP Operating System comes in the following flavours:

a. Windows XP Home: The basic XP OS intended for home users,
b. Windows XP Professional: The XP OS intended for business users,
c. Windows XP Media Center Edition: Windows Media Center provides a large-font, remotely
accessible interface ("10-foot user interface") for television viewing on the computer as well as
recording and playback, a TV guide, DVD playback, video playback, photo viewing, and music
playback.
d. Windows XP Table PC: This edition is intended for specially-designed notebook/laptop computers
called tablet PCs. Windows XP Tablet PC Edition is compatible with a pen-sensitive screen,
supporting handwritten notes and portrait-oriented screens.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #34 on: April 07, 2014, 02:59:51 AM »
Boot process (F8) in Windows XP desk top bring up the following options:

* Safe Mode: This option uses a minimal set of device drivers and services to start Windows. The
drivers loaded with Safe Mode include mouse, monitor, keyboard, hard drive, and standard video
driver.
* Safe Mode with Networking: This option uses a minimal set of device drivers and services to start
Windows together with the drivers that you must have to load networking.
* Safe Mode with Command Prompt: This option is the same as Safe mode, except that Cmd.exe starts instead of Windows Explorer.
* Enable VGA Mode: This option starts Windows in 640 x 480 mode by using the current video driver (not Vga.sys). This mode is useful if the display is configured for a setting that the monitor cannot display.
Note Safe mode and Safe mode with Networking load the Vga.sys driver instead.
* Last Known Good Configuration: This option starts Windows by using the previous good
configuration.
* Directory Service Restore Mode: This mode is valid only for Windows-based domain controllers.
This mode performs a directory service repair.
* Debugging Mode: This option turns on debug mode in Windows. Debugging information can be sent across a serial cable to another computer that is running a debugger. This mode is configured to use COM2.
* Enable Boot Logging: This option turns on logging when the computer is started with any of the
Safe Boot options except Last Known Good Configuration. The Boot Logging text is recorded in the
Ntbtlog.txt file in the %SystemRoot% folder.
* Starts Windows Normally: This option starts Windows in its normal mode.
* Reboot: This option restarts the computer.
* Return to OS Choices Menu: On a computer that is configured to starting to more than one operating system, this option returns to the Boot menu.

You can configure support for multiple displays on your Windows XP computer. This is done through
the use of Control Panel -> Display -> Settings. A Windows XP computer can support up to ten display monitors at the same time. Use additional video cards as required.

The Device Manager (It can be accessed using Add/Remove Hardware in XP) lists all the hardwaredevices installed on your system. You can also update any existing drivers, as well as change the hardware settings. You use Add/Remove Hardware to install new hardware. Accessibility options are primarily used to configure the keyboard, display, and mouse options on a computer to accommodate the users who are physically handicapped. The Add/ Remove Programs is used to install/uninstall 3rd party software. This is also used for installing/uninstalling Windows XP optional components.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #35 on: April 07, 2014, 03:01:29 AM »
Features supported by XP:

On readable/writable disks, Microsoft Windows XP Professional supports the NTFS file system and
three file allocation table (FAT) file systems: FAT12, FAT16, and FAT32. On CDROM and DVD
media, Windows XP Professional supports two file systems: Compact Disc File System (CDFS) and
Universal Disk Format (UDF).

While installing XP, if you have a standard desktop PC that uses integrated drive electronics (IDE)
disk drives, then these will be detected during setup. If, however, you use SCSI disks or have
Redundant Array of Independent Disk (RAID) storage systems, you will see, shortly after the reboot, the following line of text displayed at the bottom of the screen:
“Press F6 if you need to install a third party SCSI or RAID driver...”

Pressing F6 will start a dialog that allows you to configure and install the drivers for your SCSI or
other disk subsystem controllers. This option is usually used on server platforms that use largecapacity, high-speed, fault-tolerant disk subsystems. For most PCs, however, you won't need to use this option.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #36 on: April 07, 2014, 03:03:06 AM »
Windows Vista:

Certain versions of Windows Vista uses BitLocker Drive Encription. BitLocker Drive Encryption is a
full disk encryption feature included with the Ultimate and Enterprise editions of Microsoft's Windows Vista and Windows 7 desktop operating systems.

In order for BitLocker to operate, the hard disk requires at least two NTFS-formatted volumes: one for the operating system (usually C:) and another with a minimum size of 100MB from which the
operating system boots. BitLocker requires the boot volume to remain unencrypted, so the boot should not be used to store confidential information.

Windows Sidebar is a pane on the side of the Microsoft Windows Vista desktop where you can keep your gadgets organized and always available. Gadgets are mini programs that give you information at a glance and provide access to frequently used tools. Windows Sidebar helps you to organize your gadgets. The Windows sidebar is also available in Windows 7 Operating System.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #37 on: April 07, 2014, 03:06:04 AM »
Aero Interface

Windows Vista and Windows 7 feature a user interface termed as Aero by Microsoft. This is the
default interface used by Vista. Aero interface is characterized by the following features:

1.Glass-like translucent design
2.Dynamic windows: When you minimize a window, it animates to its place on the taskbar, so it's
easier to find when you need it.
3.High dots-per-inch (dpi) support: Windows Aero supports high-resolution monitors, so you can get a laptop or flat-screen monitor that's smaller in size but shows visually richer, displaying highresolution, easy-to-read images.
4.Live taskbar thumbnails: In Windows Aero, live taskbar thumbnail images display the actual
contents of both windows that are currently open and those that are minimized in the taskbar. When you rest your mouse pointer on a tile on the taskbar, you'll see the "live" contents of that window without having to bring it to the foreground.

Other features include Windows Flip 3D, and smooth scrolling desktop.

Windows Vista Home Basic, Vista Home Premium, and Vista Starter provide only limited support for
EFS (Encrypted File System), whereas Vista Business, and Vista Ultimate provide full support for
EFS.
Upgrade to Windows Vista Ultimate

You can upgrade to Windows Vista Ultimate from Windows XP Home, XP Professional, XP Media
Center, and XP Tablet PC, Windows 2000 Professional can't be upgraded to Windows Vista directly.

The following reserved characters can't be used in Windows file names:

< (less than)
> (greater than)
: (colon)
" (double quote)
/ (forward slash)
\ (backslash)
| (vertical bar or pipe)
? (question mark)
* (asterisk)

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #38 on: April 07, 2014, 03:21:42 AM »
10. Computers

PDA: Handheld PCs are also referred to as Personal Digital Assistants (PDAs).

Laptops:

- Nickel Cadmium battery is not environmentally friendly and not as efficient as Nickel / Metalhydride
or Lithium Ion. Nickel / Metal hydride, though environmentally friendly, not as efficient as Lithium
Ion. Lithium Ion battery is environmentally friendly and very efficient.
- Passive matrix displays are most commonly used and cheaper than Active matrix displays. Also,
passive matrix displays consume less power. However, the advantages of active matrix display are that they can handle faster screen image transition, and display is clearly viewable, even from slant angles.
- Laptops most widely use PCMCIA cards, also referred to as PC cards.
Normally, desktop processors consume higher power compared to laptop processors. Laptop
processors are optimized for lesser power consumption, so that the heat produced is also less. This is to take care of poor ventilation conditions in a laptop computer.

General PC error codes and probable causes:

100-199 : System board failures
200-299 : Memory failures
300-399 : Key board failures
400-499 : Monochrome video problems
500-599 : Color video problems
600-699 : Floppy disk errors
1700-1799: Hard disk problems.

Some of the frequently encountered error codes and their corresponding error messages are given
below:

Error Code                                     Error Message

161                                                CMOS battery failure: Replace the CMOS battery
164                                                Memory size error : If the error occurs after memory
                                                      upgrade, run SETUP program.
201                                                Memory test failed : RAM chips failed, one or more may
                                                      need to be replace.
301                                                Keyboard error: You may have to check the key board

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #39 on: April 07, 2014, 03:26:48 AM »
11. Motherboard

Given below are important bus types and their characteristics:

Bus Type          Data bus           width        Speed Bandwidth      Comments

ISA                   16-bit               8.3MHz           15.9MBPS             Use jumpers to configure
EISA                 32-bit               8.3MHz           31.8MB              Backward compatible with ISA, uses
                                                                                                 software/ jumpers for configuration
VESA or
VL bus             32-bit                33MHz           127.2MBPS          Backward compatible with ISA cards
PCI                  32-bit                33MHz           127.2MBPS          Supports Plug and Play
64-bit PCI        64-bit                66MHz           508.6MBPS          Supports Plug and Play
PCMCIA           32-bit                 33MHz                                     Used in laptops, also know as PC card
AGP                 32-bit               Speedof                                     Processor Used in video cards

Common Buses and their Max Bandwidth

         Common Buses                                     Max Bandwidth
                PCI                                                    132 M B/s
                AGP                                                    8X 2,100 MB/s
               PCI Express 1x                                   250 [500]* MB/s
               PCI Express 2x                                   500 [1000]* MB/s
               PCI Express 4x                                   1000 [2000]* MB/s
               PCI Express 8x                                   2000 [4000]* MB/s
               PCI Express 16x                                 4000 [8000]* MB/s
               PCI Express 32x                                 8000 [16000]* MB/s
               IDE (ATA100)                                        100 MB/s
               IDE (ATA133)                                        133 MB/s
               SATA                                                     150 MB/s
              Gigabit Ethernet                                    125 MB/s
              IEEE1394B[Firewire]                             100 MB/s
« Last Edit: April 07, 2014, 03:35:59 AM by Vijayb »

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #40 on: April 07, 2014, 03:37:55 AM »
PCI

PCIe busses for 3x and 5x are not available. Since PCI Express is a serial based technology, data can be sent over the bus in two directions at once. Normal PCI is Parallel, and as such all data goes in one direction around the loop. Each 1x lane in PCI Express can transmit in both directions at once. In the table the first number is the bandwidth in one direction and the second number is the combined bandwidth in both directions. Also please note that in PCI Express bandwidth is not shared the same way as in PCI, so there is less congestion on the bus.

Firewire

A standard FireWire connection will support 100,200 and 400 Mbps. The important features of
IEEE1394 (also known as FireWire 400) are:

1. 100 Mbit/s, 200Mbit/s, and 400Mbit/s supported.
2. Works without control, devices communicate peer-to-peer.
3. Cable up to 4.5 m.
4. Up to 63 devices supported.
5. Power supply to external devices is 1.25A/12V (max.).
6. The only computer bus used in digital video cameras

The IEEE 1394b specification supports data rates up to 400 Mbit/s in half-duplex mode, and even
higher in full duplex. It can support optical connections up to 100 metres in length.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #41 on: April 07, 2014, 03:41:30 AM »
SCSI Types:

SCSI Type                              Transfer speed                                        Bus

SCSI-1                                     5MBPS                                                 8 bit bus
Fast Wide SCSI                       20MBPS                                               16 bit bus
Wide Ultra SCSI                      40MBPS                                                16 bit bus
Ultra2 SCSI                             40MBPS                                                 8 bit bus
Wide Ultra2 SCSI                    80MBPS                                                16 bit bus
Ultra3 SCSI or Ultra 160         160MBPS                                               16 bit bus
Ultra320                                 320 MBPS                                               16 bit bus

SCSI ID - 0=bootable drive, 7=controller, 1-6=any other devices
Wide-Ultra SCSI - 16 devices, 0=bootable drive, 15=controller

Each device in a SCSI chain need to have unique ID. For a 16-bit Wide SCSI, there are 16 possible
SCSI Ids, 0-15. A standard 8-bit SCSI can support only 8 devices (including SCSI card), the Ids
allowed are 0-7.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #42 on: April 07, 2014, 04:25:36 AM »
SCSI bus termination:

If the termination is not done, a SCSI devices on the bus will not function properly. This is due to
reflection of the signals at the end of the bus. To prevent this, both ends of the SCSI bus need to be terminated. If one end of the SCSI bus is terminated, you may find intermittent problems. Never
terminate the bus at a device connected in between.

USB (Universal Serial Bus):

- USB supports up to 127 devices simultaneously.
- USB enables you to daisy chain up to 127 USB devices. A USB hub is used for this purpose.
Also, USB devices can be plugged in without turning on/off power. i.e, USB devices are hot
swappable.

USB 2.0

The important features of USB 2.0 are given below:

1. 1.5 Mbit/s 12Mbit/s 480Mbit/s supported.
2. USB controller is required to control the bus and data transfer.
3. Cable up to 5 m.
4. Up to 127 devices supported.
5. Power supply to external devices is 500 mA/5V (max).
6.Full compatibility with USB 1.1 devices.

To achieve proper USB connectivity six basic system elements must be present

1) Support from the BIOS
2) Support from the Operating System
3) Physical USB ports
4) A USB Device
5) The correct USB cable for the device
6) Drivers either from the OS and/or the peripheral maker
USB 2.0 has a raw data rate at 480Mbps, and it is rated 40 times faster than its predecessorinterface, USB 1.1, which has 12Mbps max speed.

External Serial Advanced Technology Attachment or eSATA is an external interface for SATA
technologies. It is faster compared to USB 2.0 or PATA technologies, and suitable for backing up large amounts of data using external hard drive.

Even though eSATA is part of the SATA interface specifications, it uses a very different physical
connector from the internal SATA connectors. The reason for this is to better shield the high speed
serial lines used to transfer the signals from EMI protection. It also provides a 2m overall cable length compared to the 1m for internal cables. As a result the, the two cable types can not be used interchangeably.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #43 on: April 07, 2014, 04:27:04 AM »
Speeds achievable by different technologies

* USB 1.1 – 15 Mbps
* FireWire (1394a) – 400 Mbps
* USB 2.0 – 480 Mbps
* FireWire 800 (1394b) – 800 Mpbs
* SATA 1.5 – 1.5 Gbps
* SATA 3.0 – 3.0 Gbps

System board connectors of a PC:

1. 9-pin male connector on system board is serial and usually COM 1 (mouse)
2. 25-pin male connector on system board is serial and usually COM 2 (modem)
3. 25-pin female connector on system board is parallel and usually LPT 1 (printer)
Northbridge Southbridge Chipset

The Northbridge chipset controls communications between the CPU, memory, PCI and AGP busses.
The Southbridge actually uses the PCI bus to handle the I/O ports, USB and the IDE controller.

Real Time Clock:
The Complementary Metal-Oxide Semiconductor (CMOS) allows the computer to store the Real Time
Clock (RTC)and other device information even after the computer is switched off and on. This is
achieved by using a battery back, just for CMOS.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #44 on: April 07, 2014, 04:29:27 AM »
12. Security

Windows Vista\Windows 7 Security Center secures a PC by alerting when security software is out of date or when your security settings should be strengthened. The Security Center also displays your firewall settings and automatic updates are enabled or not.

Software is considered malware (malicious software) based on how the software is intended to be
used. Malware includes computer viruses, worms, trojan horses, spyware, dishonest adware, and othermalicious and unwanted software

1. A boot sector virus stays resident by infecting the boot sector of the computer
2. A Master boot record (MBR) virus infect the first physical sector of all affected disks
3. File viruses either replace or attach themselves to executable files, and most commonly found virus.
4. Macro virus attaches itself to documents in the form of macros.
5. Memory viruses are viruses that execute and stay resident in memory. Trojan Horse is an example of memory virus.

A trojon is not a virus. The principal variation between a Trojan horse, or Trojan, and a virus is that
Trojans don’t spread themselves. Trojan horses disguise themselves as valuable and useful software available for download on the internet. Trojan may work as a client software on your computer communicating with the Trojan server over the Internet.

Note that script files may include viruses hidden inside. Therefore, it is not wise to open any script fileattachments such as file.scr or file.bat etc.