Ict Qas May11

8/6/2019 Ict Qas May11

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Introduction to ICT Resources - QAs

MAHAN COMPUTER SERVICES (I) LIMITED, NEW DELHIFor student use only Page 1

PC Assembly and Operation

What is a Computer motherboard?

A motherboard is also known as Logic board, Main board, Printed Circuit board or System board. It is

the actual heart of the PC. It is made up of Chip Sets known as Glue Chips. It holds Processor, Memory,

Expansion slots and connects directly or indirectly to every part of the PC.

What are Motherboard Components?

It contains the following key components:

1. A microprocessor "socket" which defines what kind of central processing unit the motherboard uses.

2. A chipset which forms the computer's logic system. It is usually composed of two parts called bridges

(a "north" bridge and its opposite, "south" bridge), which connects the CPU to the rest of the system;

3. A Basic Input/output System (BIOS) chip which controls the most basic function of a computer, and

how to repair it;

4. A real-time clock which is a battery-operated chip which maintains the system's time, and other

basic functions.

The motherboard also has slots or ports for the attachment of various peripherals or support

system/hardware. There is an Accelerated Graphics Port, which is used exclusively for video cards;Integrated Drive Electronics, which provides the interfaces for the hard disk drives; Memory or RAM

cards; and Peripheral Component Interconnect (PCI), which provides electronic connections for video

capture cards and network cards, among others.

How to clear Computer Motherboard CMOS password?

To clear Computer Motherboard CMOS password we will do these steps. Since CMOS is a special chip

with its own battery, the best way to clear out a CMOS chip is to disconnect it from its power supply.

To clear the CMOS password you just remove the CMOS Battery or else you can also use a jumper

setting.

What is cache memory on Motherboard?

Cache memory is a small high-speed memory. It is used for temporary storage of data & information

between the main memory and the CPU (center processing unit). The cache memory is only in RAM.

Explain the difference between RAM and ROM?

RAM: Read / Write memory, High Speed, Volatile Memory. ROM: Read only memory, Low Speed, Non

Volatile Memory.

RAM- Random Access memory it is a Volatile Memory

volatile mean= when power is off data is loss ok

ROM- read only memory it is a non-volatile memory

it is read only memory we don't write this memory only read

What is an uninterruptable power supply?

An uninterruptable power supply (or UPS) is essentially a back-up battery for your computer or other

electronics system in the event of a power failure (blackout) or other electrical line problems. In the

occurrence of a blackout, for example, your computer would continue to draw power from the UPS

thus allowing you to save your work and shutdown your system properly without data loss or

interruption of service.


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What are the types of uninterruptable power supplies?

The common type is AC/AC, where the energy source is the AC line (120VAC or 240 VAC), and the

output is the same voltage through an inverter. The more efficient type is AC/DC, where the UPS

delivers the DC voltages needed by the system.

What is meant by 'On-line' and Off-line' UPS?

There are two basic types of UPS in modern use. The first, known as 'Off-line', passes through incoming

mains power to the output sockets while the supply is good. It monitors the line constantly for a major

voltage drop that signifies power failure. It then switches on it's inverter (the part that produces output

alternating current from it's inverter) and supplies output power from the battery or batteries until the

mains voltage has been restored and is stable for a period of time. There is by definition a momentary

power loss during switchover, but typically of around five milliseconds, which is insignificant to most

loads. According to how much you pay for your UPS, you may get some conditioning of the mains

power that is passed through under normal conditions, and you may get a genuine sine-wave output as

opposed to the square-wave or trapezoidal wave that you will find on the cheaper products.

The second type is known as an 'On-line' design because it's inverter is 'on-line' permanently. In this

design, all the incoming power is always converted to direct current, which both tops up the batteries

and feeds the inverter. The inverter is constantly producing fresh alternating current to supply the load.

When the mains goes off, the batteries are still holding up the incoming DC supply to the inverter, so

the load continues to be supplied with absolutely no break whatsoever. The inverter is a constant-duty

inverter, so this costs a little more. In any reputable on-line UPS, there is also a fail-safe mechanism

known as a 'Static Bypass' which on detecting failure in the inverter will throw the load on the mercy of

the mains supply, rather than letting it drop altogether. This design inherently cleans the supply by

virtue of reducing it to DC, then reconverting it to fresh AC.

What is BOOTING?

In computing, booting (also known as "booting up") is a bootstrapping process that starts operating

systems when the user turns on a computer system. A boot sequence is the initial set of operations

that the computer performs when power is switched on. The bootloader typically loads the main

operating system for the computer.

Restarting a computer or its operating system software. It is of two types

(1) Cold booting: when the computer is started after having been switched off.

(2) Warm booting: when the operating system alone is restarted (without being switched off) after a

system crash or 'freeze.' Both types of booting clear out (for the time being) the bugs, bombs, memory

conflicts, and other idiosyncrasies of the operating system.

What is Bootstrap loaderAlso known as bootstrapping or boot loader, a bootstrap loader is a program that resides in the

computers EPROM, ROM, or other non-volatile memory that automatically executed by the processor

when the computer is turned on? The bootstrap loader reads the hard disk drives boot sector to

continue the process of loading the computers operating system. The term boostrap comes from the

old phrase "Pull yourself up by your bootstraps."

The boot loader has been replaced in computers that have an Extensible Firmware Interface (EFI). The

boot loader is now part of the EFI BIOS.

Difference Between AT and ATX


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AT boards were much bigger compared to ATX boards. This results in some drives overlapping the

boards inside the case which meant that in order to replace the board, you would need to take

everything out. This is very inconvenient for personal computers, thus the ATX boards were made

narrower by almost 4 inches to ensure that there is no overlap.

Another shortcoming of the AT system is in the ports at the back. AT boards only had the most minimal

amount connectors in order to maintain compatibility with AT cases. If you like more connectors, you

would need to add flying leads to unused expansion slots. ATX cases allowed manufacturers to produce

their own custom back plates to suit their motherboards. This allowed most ports to be integrated to

the board and moved up, making it much less of an effort to install a new motherboard and even frees

up some of the expansion slots taken up by the ports.

ATX boards also introduced the soft off capability. Prior to ATX, the power switch was directly

connected to the power supply and the computer cannot turn itself off. ATX cases moved the switch to

the motherboard. Computers then had the ability to turn itself on or off depending on its

programming. You would no longer need to wait for the computer to safely shutdown before turning it

off. It also paved the way for the additional features like WOL (Wake On Lan) that allows computers to

be turned on remotely via its network adapter.

What is a Microprocessor?

A microprocessor is a digital electronic component with miniaturized transistors on a single

semiconductor integrated circuit. One or more micro processors typically serve as a central processing

unit in a computer system.

What is BIOS?

Short for Basic Input-Output System; this is a chip (or set of chips) in your computer that controls how

your computer communicates with some of the basic hardware components in your system, such as

the keyboard, floppy drive, and hard disk. In newer computers, the BIOS is also what supports Plug-&-

Play. A buggy or incompatible BIOS is a common cause of problems encountered when upgrading to a

new version of Windows.

If the BIOS detect an Hardware-Error, the BIOS gives out a special Error Message and/or special beep-

tones.

How can I reset CMOS / BIOS settings?

If your computer is having issues booting, has errors during boot, after adding hardware is running into

issues, or you're having other abnormal system behaviors that cannot be resolved though any other

method it may be necessary to reset the CMOS settings or load the default or fail-safe defaults as

explained below.

Load / Reset defaults

1. Enter CMOS setup.2. In CMOS setup look for an option to reset the CMOS values to the default setting or an option

to load the fail-safe defaults. With many CMOS setup screens there will be a function key to do

this; for example, the F5, F6, F9, F11, or F12 key like shown in the picture to the right. Other

setups may actually list an option that you can arrow over to using the arrow keys and press

Enter.

3. When found and selected you'll likely be asked if you're sure you wish to load the defaultspress Y for yes or arrow to the yes option.

4. Once the default values have been set make sure to Save and Exit and not just exit.


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What is the difference between BIOS and CMOS?

Often the BIOS and CMOS can be confused because instructions may either indicate to enter the BIOS

Setup or the CMOS Setup. Although the setup for BIOS / CMOS is the same, the BIOS and CMOS on the

motherboard are not.

If you have already read the above BIOS and CMOS definition links you should now know that the BIOS

and CMOS are two different components on the motherboard. The BIOS on the motherboard containsthe instructions on how the computer boots and is only modified or updated with BIOS updates, the

CMOS is powered by a CMOS battery and contains your system settings and is modified and changed

by entering the CMOS Setup.

Although the setup is often referred to as the BIOS and CMOS setup, we suggest you only refer to the

setup as "CMOS Setup" as it is more appropriate. Computer Hope often refers to the setup as BIOS and

CMOS Setup to help users who are looking for one instead of the other.

What is backup? Difference between Physical Backups and Logical Backups

A backup is a copy of data from your database that can be used to reconstruct that data. Backups can

be divided into physical backups and logical backups.

Physical backups are backups of the physical files used in storing and recovering your database, such as

data files, control files, and archived redo logs. Ultimately, every physical backup is a copy of files

storing database information to some other location, whether on disk or some offline storage such as

tape.

Logical backups contain logical data (for example, tables or stored procedures) exported from a

database with an Oracle export utility and stored in a binary file, for later re-importing into a database

using the corresponding Oracle import utility.

What are the different types of backup?

You can choose from three different backup methods. Most backup strategies use a combination of

two or three of these methods.

Full Backup

A complete set of all files you wish to back up. Think of this as your 'reference set'. You only need

perform a full backup occasionally. Provides a complete copy of all your data; makes it easy to locate

files which need restoring. Takes a long time and the most space on backup media; redundant backups

created, as most files remain static.

Incremental Backup

A backup of those files which have changed since the last backup of any type.Uses the lease time and

space as only those files changed since the last backup are copied; lets you back up multiple versions of

the same file. Makes the job of restoring files fiddly, as you have to reinstall the last full backup first,

then all subsequent incremental backups in the correct order; also makes it hard to locate a particularfile in the backup set.

Differential Backup

A backup of those files which have changes since the last full backup. Should be performed at regular

intervals. Takes up less time and space than a full backup; provides for more efficient restoration than

incremental backups. Redundant information stored, because each backup stores much of the same

information plus the latest information added or created since the last full backup. Subsequent

differential backups take longer and longer as more files are changed.


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Installation of Windows XP operating System

The best way install Windows XP is to do a clean install. It is not difficult to perform a clean installation.

Before you perform the installation I recommend that you check Windows XP Compatibility List to

ensure that your hardware is supported by XP. If your hardware is not on the compatibility list you can

check your hardware manufactures website to download the drivers for Windows XP. Save all thenecessary drivers onto floppy disks or CD before you start the installation.

All versions of Windows XP CD are bootable. In order to boot from CD/DVD-ROM you need to set the

boot sequence. Look for the boot sequence under your BIOS setup and make sure that the first boot

device is set to CD/DVD-ROM. You can then perform the following steps to install Windows XP:

Step 1 - Start your PC and place your Windows XP CD in your CD/DVD-ROM drive. Your PC should

automatically detect the CD and you will get a message saying "Press any key to boot from CD". Soon as

computer starts booting from the CD your will get the following screen:

Step 2 - At this stage it will ask you to press F6 if you want to install a third party Raid or SCSI driver. If

you are using a an IDE Hard Drive then you do not need to press F6. If you are using a SCSI or SATA Harddrive then you must press F6 otherwise Windows will not detect your Hard Drive during the

installation. Please make sure you have the Raid drivers on a floppy disk. Normally the drivers are

supplied on a CD which you can copy to a floppy disk ready to be installed. If you are not sure how to

do this then please read your motherboard manuals for more information.

Step 3 - Press S to specify that you want to install additional device.

Step 4 - You will be asked to insert the floppy disk with the Raid or SCSI drivers. Press enter after you

have inserted the disk.

Step 5 - You will see a list of Raid drivers for your HDD. Select the correct driver for your device and

press enter.

Step 6 - You will then get a Windows XP Professional Setup screen. You have the option to do a new

Windows install, Repair previous install or quit. Since we are doing a new install we just press Enter to

continue.

Step 7 - You will be presented with the End User Licensing Agreement. Press F8 to accept and continue

Step 8 - This step is very important. Here we will create the partition where Windows will be installed.

If you have a brand new unformatted drive you will get a screen similar to below. In our case the drive

size is 8190MB. We can choose to install Windows in this drive without creating a partition, hence use

the entire size of the drive. If you wish to do this you can just press enter and Windows will

automatically partition and format the drive as one large drive.

However for this demonstration I will create two partitions. The first partition will be 6000MB (C: drive)

and second partition would be 2180MB (E: drive). By creating two partitions we can have one which

stores Windows and Applications and the other which stores our data. So in the future if anything goes

wrong with our Windows install such as virus or spyware we can re-install Windows on C: drive and our

data on E: drive will not be touched. Please note you can choose whatever size partition youre like. For

example if you have 500GB hard drive you can have two partitions of 250GB each.

Press C to create a partition.


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Step 8 - Windows will show the total size of the hard drive and ask you how much you want to allocate

for the partition you are about to create. I will choose 6000MB. You will then get the screen below.

Notice it shows C: Partition 1 followed by the size 6000 MB. This indicates the partition has been

created. We still have an unpartitioned space of 2189MB. Next highlight the unpartitioned space by

pressing down the arrow key. Then press C to create another partition. You will see the total space

available for the new partition. Just choose all the space left over, in our case 2180MB.

Step 9 - Now you will see both partition listed. Partition 1 (C: Drive) 6000MB and Partition 2 (E: Drive)

2180MB. You will also have 8MB of unpartitioned space. Don't worry about that. Just leave it how it is.

Windows normally has some unpartitioned space. You might wonder what happened to D: drive.

Windows has automatically allocated D: drive to CD/DVD-ROM.

Select Partition 1 (C: Drive) and press Enter.

Step 10 - Choose format the partition using NTFS file system. This is the recommended file system. If

the hard drive has been formatted before then you can choose quick NTFS format. We chose NTFS

because it offers many security features, supports larger drive size, and bigger size files.

Windows will now start formatting drive C: and start copying setup files as shown on the two imagesbelow:

Step 11 - After the setup has completed copying the files the computer will restart. Leave the XP CD in

the drive but this time DO NOT press any key when the message "Press any key to boot from CD" is

displayed. In few seconds setup will continue. Windows XP Setup wizard will guide you through the

setup process of gathering information about your computer.

Step 12 - Choose your region and language.

Step 13 - Type in your name and organization.

Step 14 - Enter your product key.

Step 15 - Name the computer, and enter an Administrator password. Don't forget to write down your

Administrator password.

Step 16 - Enter the correct date, time and choose your time zone.

Step 17 - For the network setting choose typical and press next.

Step 18 - Choose workgroup or domain name. If you are not a member of a domain then leave the

default settings and press next. Windows will restart again and adjust the display.

Step 19 - Finally Windows will start and present you with a Welcome screen. Click next to continue.

Step 20 - Choose 'help protect my PC by turning on automatic updates now' and press next.

Step 21 - Will this computer connect to the internet directly, or through a network? If you are

connected to a router or LAN then choose: 'Yes, this computer will connect through a local area

network or home network'. If you have dial up modem choose: 'No, this computer will connect directly

to the internet'. Then click next.


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Step 22 - Ready to activate Windows? Choose yes if you wish to active Windows over the internet now.

Choose no if you want to activate Windows at a later stage.

Step 23 - Add users that will sign on to this computer and click next.

Step 24 - You will get a Thank you screen to confirm setup is complete. Click finish.

Step 25 - Log in, to your PC for the first time.

Step 26 - You now need to check the device manager to confirm that all the drivers has been loaded or

if there are any conflicts. From the start menu select Start -> Settings -> Control Panel. Click on the

System icon and then from the System Properties window select the Hardware tab, then click on

Device Manager.

If there are any yellow exclamation mark "!" next to any of the listed device, it means that no drivers or

incorrect drivers has been loaded for that device. In our case we have a Video Controller (VGA card)

which has no drivers installed.

Your hardware should come with manufacturer supplied drivers. You need to install these drivers usingthe automatic setup program provided by the manufacturer or you need to manually install these

drivers. If you do not have the drivers, check the manufacturers website to download them.

To install a driver manually use the following procedure:

(a) From the device manager double click on the device containing the exclamation mark.

(b) This would open a device properties window.

(c) Click on the Driver tab.

(d) Click Update Driver button. The Wizard for updating device driver pops up as shown below:

How to Installing a New Printer in Windows XP

When installing a new printer with the Add Printer Wizard, you can choose between adding a local

printer (one that's directly cabled to your computer through one of the ports) or a network printer (a

printer that's connected to your network with an Ethernet connection, just as your computer is

connected to the LAN).

To install a new local printer with the Add Printer Wizard, follow these steps:

1. Click the Start button on the Windows taskbar and then click Control Panel on the right side of the

Start menu.

2. Click the Printers and Other Hardware hyperlink if the Control Panel window is in Category View.

Otherwise, double-click the Printers and Faxes icon if the Control Panel window is in Classic View.

3. Click the Add a Printer hyperlink in the Printers and Other Hardware window to start the Add Printer

Wizard and then click the Next button, or press Enter to advance to the Local Printer or Printer

Connection dialog box.


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4. Make sure that the Add Printer Wizard selects the Local Printer radio button, and the Automatically

Detect and Install my Plug and Play Printer check box beneath this radio button before you click the

Next button.

5. If the wizard is unable to detect your printer in the New Printer Detection dialog box, click Next to

install the printer manually.

6. Select the port for the printer to use in the Use the Following Port drop-down list box in the Select a

Printer Port dialog box and then click the Next button.

7. Click the manufacturer and the model of the printer in the Manufacturers and Printers list boxes,

respectively, of the Install Printer Software dialog box.

If you have a disk with the software for the printer, put it into your floppy or CD-ROM drive and then

click the Have Disk button: Select the drive that contains this disk in the Copy Manufacturer's Files

drop-down list box and then click OK.

8. Click the Next button to advance to the Name Your Printer dialog box.

If you want, edit the name for the printer in the Printer Name text box. If you want to make the printer

that you're installing the default printer that is automatically used whenever you print from Windows

or from within a Windows program, leave the Yes radio button selected beneath the heading, Do you

want your Windows-based programs to use this printer as the default printer?

9. Click the Next button to advance to the Printer Sharing dialog box.

If you want to share this printer with other users on the network, click the Share Name radio button

and then, if you want, edit the share name (this is the name that the other users on the network see

when they go to select this printer for printing their documents) that the wizard gives the printer in the

Share Name text box.

10. To print a test page from your newly installed printer, click the Yes radio button selected beneath

the heading, would you like to print a test page? in the Print Test Page dialog box.

11. Click the Next button to advance to the Completing the Add Printer Wizard dialog box, where you

can review the settings for your new printer before you click the Finish button or press Enter to finish

installing the new printer.

What is difference between FAT and NTFS?

NTFS

1. NTFS stands for New Technology File System2. There are three categories in NTFS file System3. NTFS 4.0 - NT O/S4. NTFS 5.0 - 2000 O/S5. NTFS 6.0 - 2003O/S6. In NTFS Up-to File Level Security is available


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7. Compression Option is available8. Encryption Option is available9. Disk Quota Option is Available10.NTFS Supported By only Limited Microsoft Based Operating System11.Allows access local to w2k, w2k3, XP, win NT4 with SP4 & later may get access for some file.12.Maximum size of partition is 2 Terabytes & more.13.Maximum File size is up to 16TB.14.File & folder Encryption is possible only in NTFS.

FAT 32

1. Fat stands for File Allocation Table2. There are two categories in Fat File System3. Fat 164. Fat 325. In Fat Up To Folder Level Security is available6. Compression Option is not available7. Encryption Option is not available8. Disk Quota Option is not Available9. FAT is Supported By All Of The Microsoft Based Operating System10.Fat 32 Allows access to win 95, 98, win millenium, win2k, xp on local partition.11.Maximum size of partition is up to 2 TB.12.Maximum File size is up to 4 GB.13.File & folder Encryption is not possible


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Utilities

What is the Windows Disk Defragmenter and what is its function?

The Disk Defragmenter is a software utility that has been included in almost every Microsoft operating

system, from MS-DOS 6.0 through Windows XP (with the exception of Windows NT). It's purpose is to

optimize access time and restore continuity to a fragmented file system. It does this by locating

separated fragments of files and programs and restoring them to continuous sequences. The purpose

of Disk optimization is to optimize the time it takes to read and write files to/from the disk by

minimizing head travel time and maximizing the transfer rate.

Computer operating systems divvy up space on their hard drives into tiny segments of bytes called

"Clusters," with the actual byte-size based on varying factors. Typically a cluster on a Windows

computer will range from 4096 to 8192 bytes in size.

A cluster represents the smallest continuous amount of disk space on which any file can be stored, in

part or in whole. The default cluster size in Windows 98/ME/2000/XP is only 4096 bytes, depending on

the Operating System and hard drive capacity (in Windows 9x). Often, a file is much too large to fit on

only one cluster and must occupy many clusters when saved to disk. Each cluster has a code to identifythe filename of the data it contains, so that when the file is needed it is assembled by polling the hard

disk for all clusters containing the assigned code for that file.

Note that the Windows Disk Defragmenter requires at least 15% free space to move files around as it

reassembles them into contiguous sections. Even with the minimum recommended 15% free space the

defragmenter may not be able to reassemble huge files that have become fragmented, and you may

have to start deleting files or programs to free up some more space. You can start by running the

Windows Cleanup Tool to remove temporary files and empty your Recycle Bin. It is found at: Start >

Programs > Accessories > System Tools > Disk Cleanup.

What is a Computer Firewall? There types.

A Firewallis a computer program that monitors the flow of information from the Internet to yourcomputer. There are two different types of firewall available for you to use - Hardware Firewalls and

Software Firewalls.

Hardware Firewall:

A Hardware Firewallis a physical piece of equipment that sits between the Internet and your

computer. An example of a hardware firewall is a broadband router, a common form of Internet

connection. The benefit of using a hardware firewall, is that it has the ability to protect multiple

computer systems that are connected to it at the same time. This makes it an effective firewall for use

in businesses that have multiple computers connected to the Internet, as well as in homes that have

more than one computer system.

Software Firewall:Software Firewalls work in the same way as a hardware firewall, by monitoring and blocking

information that comes to your computer via the Internet, however software firewalls must be

installed as a program on your computer. These software firewalls can either be installed from a

computer disk that you have purchased, or downloaded over the Internet. Software firewalls are the

most common type of firewall. Programs such as Norton 360, Norton Internet Security, ESET Smart

Security, and Kaspersky Internet Security all have a firewall bundled within them.

What are the Benefits of a firewall?


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Firewalls protect private local area networks from hostile intrusion from the Internet. Consequently,

many LANs are now connected to the Internet where Internet connectivity would otherwise have been

too great a risk.

Firewalls allow network administrators to offer access to specific types of Internet services to selected

LAN users. This selectivity is an essential part of any information management program, and involves

not only protecting private information assets, but also knowing who has access to what. Privileges canbe granted according to job description and need rather than on an all-or-nothing basis.

What is IP spoofing?

Many firewalls examine the source IP addresses of packets to determine if they are legitimate. A

firewall may be instructed to allow traffic through if it comes from a specific trusted host. A malicious

cracker would then try to gain entry by "spoofing" the source IP address of packets sent to the firewall.

If the firewall thought that the packets originated from a trusted host, it may let them through unless

other criteria failed to be met. Of course the cracker would need to know a good deal about the

firewall's rule base to exploit this kind of weakness. This reinforces the principle that technology alone

will not solve all security problems. Responsible management of information is essential. One of

Courtney's laws sums it up: "There are management solutions to technical problems, but no technical

solutions to management problems".

An effective measure against IP spoofing is the use of a Virtual Private Network (VPN) protocol such as

IPSec. This methodology involves encryption of the data in the packet as well as the source address.

The VPN software or firmware decrypts the packet and the source address and performs a checksum. If

either the data or the source address have been tampered with, the packet will be dropped. Without

access to the encryption keys, a potential intruder would be unable to penetrate the firewall.

What is High-Level Formatting?

After low-level formatting is complete, we have a disk with tracks and sectors--but nothing written on

them. High-level formatting is the process of writing the file system structures on the disk that let the

disk be used for storing programs and data. If you are using DOS, for example, the DOS FORMAT

command performs this work, writing such structures as the master boot record and file allocationtables to the disk. High-level formatting is done after the hard disk has been partitioned, even if only

one partition is to be used. See here for a full description of DOS structures, also used for Windows 3.x

and Windows 9x systems.

The distinction between high-level formatting and low-level formatting is important. It is not necessary

to low-level format a disk to erase it: a high-level format will suffice for most purposes; by wiping out

the control structures and writing new ones, the old information is lost and the disk appears as new.

(Much of the old data is still on the disk, but the access paths to it have been wiped out.) Under some

circumstances a high-level format won't fix problems with the hard disk and a zero-fill utility may be

necessary.

Different operating systems use different high-level format programs, because they use different filesystems. However, the low-level format, which is the real place where tracks and sectors are recorded,

is the same.

What is Low-Level Formatting?

Low-level formatting is the process of outlining the positions of the tracks and sectors on the hard disk,

and writing the control structures that define where the tracks and sectors are. This is often called a

"true" formatting operation, because it really creates the physical format that defines where the data is

stored on the disk. The first time that a low-level format ("LLF") is performed on a hard disk, the disk's

platters start out empty. That's the last time the platters will be empty for the life of the drive. If an LLF


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is done on a disk with data on it already, the data is permanently erased (save heroic data recovery

measures which are sometimes possible).

If you've explored other areas of this material describing hard disks, you have learned that modern

hard disks are much more precisely designed and built, and much more complicated than older disks.

Older disks had the same number of sectors per track, and did not use dedicated controllers. It was

necessary for the external controller to do the low-level format, and quite easy to describe thegeometry of the drive to the controller so it could do the LLF. Newer disks use many complex internal

structures, including zoned bit recording to put more sectors on the outer tracks than the inner ones,

and embedded servo data to control the head actuator. They also transparently map out bad sectors.

Due to this complexity, all modern hard disks are low-level formatted at the factory for the life of the

drive. There's no way for the PC to do an LLF on a modern IDE/ATA or SCSI hard disk, and there's no

reason to try to do so.

Older drives needed to be re-low-level-formatted occasionally because of the thermal expansion

problems associated with using stepper motor actuators. Over time, the tracks on the platters would

move relative to where the heads expected them to be, and errors would result. These could be

corrected by doing a low-level format, rewriting the tracks in the new positions that the stepper motor

moved the heads to. This is totally unnecessary with modern voice-coil-actuated hard disks.


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Networking Concepts

What do you mean by data communication?

Ans: It is the exchange of data between two devices via some form of transmission medium such as

wire cable. The communicating system must be part of a communication system made up of a

combination of hardware and software. The effectiveness of a data communication system depends on

three fundamental characteristics: delivery, accuracy and timeliness.

What is a network?

Ans: It is a set of devices connected by communication links. A node can be a computer or any other

device capable of sending and/or receiving data generated by other nodes on the network.

What is distributed processing?

Ans: It is a strategy in which services provided by the network reside at multiple sites.

What is point to point connection?

Ans:It provides a dedicated link between two devices. The entire capacity of the link is reserved for

transmission between the two devices

e.g. when we change the TV channels by remote control we establish a point to point connectionbetween remote control and TV control system.

What is multipoint connection?

Ans: In multipoint connection more than two specific devices share a single link.

Here the capacity of the channel is shared either separately or temporally.

What is a topology?

Ans: Topology of a network is defined as the geometric representation of the relationship of all the

links and linking devices (node) to one another.Four basic topologies are star, bus, ring and mesh.

Star Here each device has a dedicated point to point link only to a central controller called hub.

Bus -It is multipoint. One long cable acts as a backbone to link all the devices in the network.

Ring -Here each device has a dedicated point to point connection only with the two devices on eitherside of it.

Mesh -Here every device has a dedicated point to point link to every other device.

Define LAN, MAN and WAN.

Ans: LAN- A local area network (LAN) is a privately owned and links the devices in a single office,

building or campus.

It allows resources to be shared between personal computers and work stations.

MAN- A metropolitan-area network (MAN) spreads over an entire city.

It may be wholly owned and operated by a private company, eg local telephone company.

WAN A wide area network (WAN) provides long distance transmission of data, voice, image and video

information over large geographic areas that comprise a country, a continent or even whole world.

What is a protocol?

Ans: It is a set of rules that governs data communication. A protocol defines what is communicated,

how it is communicated, and when it is communicated. The key elements of protocol are syntax,

semantics and timing.

What is TCP/IP protocol model?

Ans: It is a five layered model which provides guidelines for the development of universally compatible

networking protocols.

The five layers are physical, data link, network, transport and application.


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Describe the functions of five layers?

Ans: Physical- It transmits raw bits over a medium. It provides mechanical and electrical specification.

Data link- It organizes bits into frames. It provides hop to hop delivery.

Network-It moves the packets from source to destination.It provide internetworking.

Transport-It provides reliable process to process message delivery and error recovery.

Application-It allows ti access to network resources.

What is ISO-OSI model?

Ans: Open Systems Interconnection or OSI model was designed by the International Organization for

Standardization (ISO) .It is a seven layer model. It is a theoretical model designed to show how a

protocol stack should be implemented.

It defines two extra layers in addition to TCP/IP model.

Session -It was designed to establish, maintain, and synchronize the interaction between

communicating system.

Presentation-It was designed to handle the syntax and semantics of the information exchanged

between the two systems. It was designed for data translation, encryption, decryption, and

compression.

What is switching?Ans: Switching in data communication is of three types

Circuit switching

Packet switching

Message switching

What are the different transmission media?

Ans: The transmission media is broadly categorized into two types

i)Guided media(wired)

i)Unguided media(wireless)

What are the different Guided Media?

Ans: The media which provides a conduct from one device to another is called a guided media. Theseinclude twisted pair cable, coaxial cable, and fiber-optic cable.

Describe about the different Guided Medias.

Ans: Twisted pair cable consists of two insulated cupper wires twisted together. It is used in telephone

line for voice and data communications.

Coaxial cable has the following layers: a metallic rod-shaped inner conductor, an insulator covering the

rod, a metallic outer conductor (shield), an insulator covering the shield, and a plastic cover.Coaxial

cable can carry signals of higher frequency ranges than twisted-pair cable.

Coaxial cable is used in cable TV networks and Ethernet LANs.Fiber-optic cables are composed of a

glass or plastic inner core surrounded by cladding, all encased in an outer jacket.Fiber-optic cables carry

data signals in the form of light. The signal is propagated along the inner core by reflection. Its features

are noise resistance, low attenuation, and high bandwidth capabilities.It is used in backbone networks, cable TV nerworks, and fast Ethernet networks.

What do you mean by wireless communication?

Ans: Unguided media transport electromagnetic waves without using a physical conductor. This type of

communication is referred as wireless communication.

Here signals are broadcaster through air and thus available to anyone who has a device to receive it.


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What do you mean by switching?

Ans: It is a method in which communication devices are connected to one another efficiently.

A switch is intermediary hardware or software that links devices together temporarily.

What are the switching methods?

Ans: There are three fundamental switching methods: circuit switching, packet switching,

And message switching.In circuit switching, a direct physical connection between two devices is createdby space division switches, time division switches or both.

In packet switching data is transmitted using a packet switched network. Packet switched network is a

network in which data are transmitted in independent units called packets.

What are the duties of data link layer?

Ans: Data link layer is responsible for carrying packets from one hop (computer or router) to the next.

The duties of data link layer include packetizing, adderssing, error control, flow control, medium access

control.

What is IP address?

Ans: The internet address (IP address) is 32bits that uniquely and universally defines a host or router on

the internet.The portion of the IP address that identifies the network is called netid. The portion of the IP address

that identifies the host or router on the network is called hostid.

What are the advantages of fiber optics cable ?

Ans: The advantages of fiber optics cable over twisted pair cable are Noise resistance-As they use light

so external noise is not a factor. Less signal attenuation-fiber optics transmission distance is

significantly greater than that of other guided media.Higher bandwidth-It can support higher

bandwidth.

What are the disadvantages of fiber optics cable?

Ans: The disadvantages of fiber optics cable over twisted pair cable are

Cost-It is expensive Installation/maintenance-Any roughness or cracking defuses light and alters thesignal Fragility-It is more fragile.

What is FDDI?

Ans: It is high performance fiber optic token ring LAN running at 100Mbps over distance up 1000

stations. FDDI access is limited by time. A FDDI cabling consists of two fiber rings.

i)one transmitting clockwise

ii)one transmitting counterclockwise

What is Repeaters?

Ans: A receiver receives a signal before it becomes too weak or corrupted,r egenerates the original bit

pattern, and puts the refreshed copy back onto the link.It operates on phycal layer of OSI model.

What is Bridges?

Ans: They divide large network into smaller components. They can relay frames between two originally

separated LANs. They provide security through partitioning traffic. They operate on phycal and data

link layer of OSI model.

What is Router?

Ans: Router relay packets among multiple interconnected networks.They receive packet from one

connected network and pass it to another network.They have access to network layer addresses and


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Define IP ?

Ans: Internetwork protocol (IP) is the transmission mechanism used by TCP/IP protocol.It is an

unreliable and connectionless datagram protocol.It provides no error checking and tracking.

What do you mean by client server model ?

Ans: In client server model ,the client runs a program to request a service and the server runs a

program to provide the service.These two programs communicate with each other. One serverprogram can provide services to many client programs.

What are the information that a computer attached to a TCP/IP internet must possesses ?

Ans: Each computer attached to TCP/IP must possesses the following information

Its IP addesss

Its subnet mask

The IP addesss of the router.

The Ip address of the name server.

What is Hypertext Transfer Protocol(HTTP) ?

Ans: It is the main protocol used to access data on the World Wide Web .the protol transfers data in

the form of plain text,hypertext,audio,video,and so on. It is so called because its efficiency allows itsuse in a hypertext environment where there are rapid jumps from one document to another.

What is URL ?

Ans: It is a standard for specifying any kind of information on the World Wide Web.

What Is MAC?

Definition: Media Access Control (MAC) technology provides unique identification and access control

for computers on an Internet Protocol (IP) network. In wireless networking, MAC is the radio control

protocol on the wireless network adapter. Media Access Control works at the lower sublayer of the

data link layer (Layer 2) of the OSI model.

MAC Addresses

Media Access Control assigns a unique number to each IP network adapter called theMAC address. A

MAC address is 48 bits long. The MAC address is commonly written as a sequence of 12 hexadecimal

digits as follows:

48-3F-0A-91-00-BC

MAC addresses are uniquely set by the network adapter manufacturer and are sometimes called

physical addresses. The first six hexadecimal digits of the address correspond to a manufacturer's

unique identifier, while the last six digits correspond to the device's serial number. MAC addresses mapto logical IP addresses through the Address Resolution Protocol (ARP).

What Is a MAC Address?

The MAC address is a unique value associated with a network adapter. MAC addresses are also known

as hardware addresses or physical addresses. They uniquely identify an adapter on a LAN.

MAC addresses are 12-digit hexadecimal numbers (48 bits in length). By convention, MAC addresses

are usually written in one of the following two formats:


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MM:MM:MM:SS:SS:SS

MM-MM-MM-SS-SS-SS

The first half of a MAC address contains the ID number of the adapter manufacturer. These IDs are

regulated by an Internet standards body (see sidebar). The second half of a MAC address represents

the serial number assigned to the adapter by the manufacturer. In the example,00:A0:C9:14:C8:29

The prefix

00A0C9

indicates the manufacturer is Intel Corporation.

Why MAC Addresses?

Recall that TCP/IP and other mainstream networking architectures generally adopt the OSI model. In

this model, network functionality is subdivided into layers. MAC addresses function at the data link

layer (layer 2 in the OSI model). They allow computers to uniquely identify themselves on a network at

this relatively low level.

MAC vs. IP Addressing

Whereas MAC addressing works at the data link layer, IP addressing functions at the network layer

(layer 3). It's a slight oversimplification, but one can think of IP addressing as supporting the software

implementation and MAC addresses as supporting the hardware implementation of the network stack.

The MAC address generally remains fixed and follows the network device, but the IP address changes

as the network device moves from one network to another.

IP networks maintain a mapping between the IP address of a device and its MAC address. This mapping

is known as the ARP cache or ARP table. ARP, the Address Resolution Protocol, supports the logic for

obtaining this mapping and keeping the cache up to date.

DHCP also usually relies on MAC addresses to manage the unique assignment of IP addresses to

devices.

How to Find and Change a MAC Address

Find a MAC Address in Windows

In Windows 95, Windows 98 and Windows ME, the winipcfg utility displays the computer's MAC

address. Use the ipconfig utility (with the /all option) in Windows NT and any newer versions of

Windows.

Both 'winipcfg' and 'ipconfig' may display multiple MAC addresses for one computer. One MAC address

exists for each installed network card. Additionally, Windows maintains one or more MAC addresses

that are not associated with hardware cards.

For example, Windows dial-up networking uses virtual MAC addresses to manage the phone

connection as if it were a network card. Some Windows VPN clients likewise have their own MAC

address. The MAC addresses of these "virtual" network adapters are the same length and format as

true hardware addresses.


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Changing a MAC Address To Work With Your ISP

Most Internet subscriptions allow the customer only a single IP address. The Internet Service Provider

(ISP) may assign one static (fixed) IP address to each customer. However, this approach is an inefficient

use of IP addresses that are currently in short supply. The ISP more commonly issues each customer

dynamic IP address that may change each time the customer connects to the Internet.

ISPs ensure each customer receives only one dynamic address using several methods.Dial-up and

many DSL services typically require the customer to log in with a username and password. Cable

modem services, on the other hand, do this by registering and tracking the MAC address of the device

that connects to the ISP.

The device whose MAC address is monitored by an ISP can be either the cable modem, a broadband

router, or the PC that hosts the Internet connection. The customer is free to build a network behind

this equipment, but the ISP expects the MAC address to match the registered value at all times.

Whenever a customer replaces that device, however, or changes the network adapter inside it, the

MAC address of this new equipment will no longer match the one registered at the ISP. The ISP will

often disable the customer's Internet connection for security (and billing) reasons.

MAC Addresses and Cable Modems

In addition to MAC addresses tracked by the ISP, some broadband modems also track the MAC address

of the host computer's network adapter within the home network. If you swap the computer

connected to the broadband modem, or change its network adapter, your cable Internet connection

may not function afterward.

In this case, MAC address cloning is not required. Resetting (including recycling power) on both the

cable modem and the host computer will automatically change the MAC address stored inside the

modem.

Changing MAC Addresses through the Operating System

Starting with Windows 2000, users can sometimes change their MAC address through the Windows My

Network Places interface. This procedure does not work for all network cards as it depends on a certain

level of software support built into the adapter driver.

In Linux and versions of Unix, the "ifconfig" also supports changing MAC addresses if the necessary

network card and driver support exists.

How Can I Get a MAC Address from an IP Address?

It is usually not possible for a person to get the MAC address of a computer from its IP address alone.

These two addresses originate from different sources. Simply stated, a computer's own hardwareconfiguration determines its MAC address while the configuration of the network it is connected to

determines its IP address.

However, computers connected to the same TCP/IP local network can determine each other's MAC

addresses. The technology called ARP - Address Resolution Protocol included with TCP/IP makes it

possible. Using ARP, each computer maintains a list of both IP and MAC addresses for each device it has

recently communicated with.


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Most computers allow you to see the list of IP and MAC addresses that ARP has collected there. In

Windows, Linux and other operating systems, the command line utility "arp" shows this information.

Using "arp," you can in fact determine the MAC address of some computers from their IP address. ARP

works only within the small group of computers on a local area network (LAN), though, not across the

Internet. ARP is intended for use by system administrators and is not generally useful as a way to track

down computers and people on the Internet.

What is an IP sub-network?

A single IP class A, B, or C network is further divided into a group of hosts to form an IP sub-network.

What is the use of sub-networks?

Sub-networks are created for manageability, performance, and security of hosts and networks and to

reduce network congestion.

Which RFC specifies IP subnetwork addressing?

RFC 950 specifies IP subnetwork addressing protocol.

How sub-networks are formed?

The host ID portion of an IP address is further divided into a sub-network ID part and a host ID part. Thesub-network ID is used to uniquely identify the different sub-networks within a network.

What is a subnet mask?

Subnet mask is a 4 byte (32 bit) number used to identify the sub-network ID and the host ID from an IP

address. All the hosts in a sub-network will have the same subnet mask. E.g. 255.255.255.0,

255.255.127.0, 255.255.0.0

How a host determines its subnet mask?

A host determines its subnet mask during the boot-up sequence either from a configuration file stored

in the local hard disk or from a server in the network using a network protocol like BOOTP, ICMP.

How is a subnet mask formed?For all the bits in the IP address which are used to represent the network ID, and the sub-network ID,

the corresponding bits in the subnet mask will be one. For all the bits in the IP address which are used

to represent the host ID, the corresponding bit in the subnet mask will be zero. For example, if the first

two bytes of the IP address are used to represent the network (class B address) and the third byte is

used to represent the sub-network, and the last byte is used to represent the host, then the subnet

mask will be 255.255.255.0

Why a host needs to know about its subnet mask?

When a host "A" needs to communicate with another host "B", it must know whether host "B" is in the

same network or in a different network. If the host "B" is in the same network then host "A" can send

the datagram directly to host "B". But if the host B is in a different network, then host "A" must send

the datagram to a proper router. By determining the network class of the IP address of host "B", host"A" can determine whether host "B" is in the same network or in a different network. By using the

subnet mask host "A" can find out whether host "B" is in the same subnet or in a different subnet.

How to determine to the network ID, sub-network ID and the host ID, given the IP address and the

subnet mask?

The network class (A or B or C) of a given IP address can be easily determined by looking at the value of

the first 4 bits of the first byte. From the network class, the number of bytes used to represent the

network can be determined and hence the network ID can be determined. By performing a "AND"

logical operation of the IP address and the subnet mask, the sub-network ID can be determined. In the

value resulting from the "AND" operation, by removing the bytes used for the network ID, the


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remaining bits for which the corresponding bit in the subnet mask is one, represents the sub-network

ID.

What are the two types of subnetting?

The two types of subnetting are:

1. Static length2. Variable length

What is 'Static Length' subnetting?

If all the subnetworks in a single network use the same subnet mask, it is called as 'Static Length'

subnetting.

What is 'Variable Length' subnetting?

If the different subnetworks in a single network use different subnet masks, it is called as 'Variable

Length' subnetting.

What is the disadvantage in using 'Static Length' subnetting?

In the case of a 'Static Length' subnetwork, irrespective of the number of hosts in the subnetwork, asingle subnet mask is used for all the subnetworks. Because of this, a large number of IP addresses will

be wasted. For example, let us say, we have a class C IP network address 192.9.205.0 subnetted using a

subnet mask 255.255.255.192. The total number of possible subnetworks is 4 and the total number of

possible hosts per subnetwork is 32. Even if a subnetwork has just 4 hosts, it will be allocated the above

subnetwork IP address, in this case 28 host IP addresses will be wasted.

What is the advantage in using 'Static Length' subnetting?

It is easy to configure a network using 'Static Length' subnetting. In addition, native IP routing

understands only static subnetting.

What is the advantage is using 'Variable Length' subnetting?

In the case of 'Variable Length' subnetwork, IP addresses are allocated depending on the number ofhosts present in the subnetwork. So available host IP addresses are efficiently used and are not wasted.

What is the disadvantage in using 'Variable Length' subnetting?

All the routers in a 'Variable Length' subnetted network must understand this type of subnetting.

What are the special subnetwork IP addresses?

The subnet addresses in which all the bits are zero or one are special subnet IP addresses. The subnet

address in which all the bits are zero, represents the local subnetwork in which the datagram

originated. The subnet address in which all the bits are one represents a subnet broadcast address. In

the broadcast address, all the other bits including the network and host ID must be one.

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