Very Important and Rare Computer Terms asked in Exams to Know.

 

• A

 



. AHCI:An interface specification that allows software to communicate with SATA devices such as host bus adapters, and enables advanced SATA features such as Native Command Queuing, native hot plugging, and power management. Advanced Host Controller Interface (AHCI).
 

. Array:An abstraction layer or collection of two or more disks used to manage RAID volumes existing on a same collection of disks. RAID arrays are not visible to the operating system.
 

. ATAPI device:A mass storage device with a parallel interface such as CD-ROM, CD-RW, DVD-ROM, Blu-ray Disc, and tape drives. Advanced Technology Attachment Packet Interface (ATAPI).
 

• D

 

. Disk:A hard or floppy disk. Also known as hard drive or hard disk drive.

• F

 

. Firmware:Permanent instructions and data programmed directly into the read-only memory (ROM) for controlling the operation of the computer. Firmware usually requires updates to fix defects or add features to the hardware.
 

• H

 

. Hot plug:Action to remove or insert a SATA disk when the system is powered on.
 

• I

 

. Increase volume size:Action to expand the data storage capacity of a volume by utilizing the available array space on a RAID 0, RAID 1, RAID 5, or RAID 10 volume.
 

. Initialize:Process of synchronizing all redundant data on a volume prior to creating a volume, verifying and repairing data, or changing volume type. Initialization is still required for non-redundant volumes such as RAID 0 to ensure that data is readable before starting the verification process.
 

. Intel® Rapid Recover Technology:Official name for Intel’s technology that allows the user to copy data from a master disk (source) to a recovery disk (destination) either continuously or on request.
 

. Intel® Rapid Storage Technology:Official name for Intel's Windows-based software to provide support for high-performance, fault-tolerant, and capacity SATA RAID arrays on select supported chipsets. Intel Rapid Storage Technology also provides support for Intel® Rapid Recover Technology, AHCI Native Command Queuing, and matrix RAID for two RAID volumes on a single array.
 

• M

 

. Master disk:The disk that is the designated source drive in a recovery volume.
 

. Migrating:Volume status indicative that data is being moved/transferred across selected storage devices due to a change request in the storage system configuration, such as changing volume type, creating a volume preserving existing data, increasing the volume capacity, or changing data strip size.

• N

 

. Native Command Queuing:Command protocol in SATA that allows multiple commands to be outstanding within a disk at the same time. The commands are dynamically reordered to increase disk performance.
 

. Normal:Volume, disk, and device status indicative that they are in a healthy state, functioning as expected, disks are properly connected, and data is fully accessible.

 

•O

 

. Offline:Disk status indicative that an array disk is locked (the volume status displays as locked), that the recovery volume is in on request update mode, or that your computer is running on battery and data updates to the recovery volume are not available.
 

. On request update mode:Update mode assigned to a recovery volume, where data on the master disk is copied to the recovery disk when the user requests it. Only changes since the last update process are saved to the recovery disk.
 

. Option ROM:
Firmware that is called by the system BIOS in order to communicate and provide support for a hardware device. For this product, the option ROM provides boot support for RAID volumes as well as a user interface for configuring and managing RAID volumes. Also known as OROM.
 

• P
 

. Port multiplier:
A device that allows multiple devices to communicate along a single SATA line in a similar manner to that of a USB hub.
 

. Port:An internal or external data connection of a computer (e.g., SATA controller) to which a peripheral device (e.g., SATA disk) can be attached.
 

• R
 

. RAID:Redundant Array of Independent/Inexpensive Disks is a technology used for computer data storage schemes that divide and/or replicate data among multiple disks. RAID can be designed to provide increased data reliability or increased I/O (input/output) performance, or both. A number of standard schemes have evolved which are referred to as levels or types. Intel® Rapid Storage Technology software supports RAID 0, RAID 1, RAID 5, and RAID 10 configurations (refer to each RAID type definition for more information).

 

. RAID 0:A RAID type or configuration where data is striped across multiple physical disks. Data is split into manageable blocks called strips across array members. Striping does not create data redundancy but improves read/write performance.

. RAID 1:A RAID type or configuration where data is mirrored across a second physical disk in the array. Mirroring is a key feature that ensures real-time data redundancy and increased fault tolerance. There is no striping.
 

. RAID 10:A RAID type or configuration that uses four disks to create a combination of RAID type 0 and 1. The data is striped across a two-disk array forming a RAID 0 component. Each of the disks in the RAID 0 array is mirrored by a disk in the RAID 1 array.
 

. RAID 5:A RAID type or configuration where data and parity are striped into manageable blocks called strips across three or more physical disks. This type is a preferred configuration as it combines efficiency, fault-tolerance, and data performance.
 

. Read-only:Recovery volume status indicative that the recovery or master disk files are accessed, allowing files on the disk to be read or copied, but not changed or saved.
 

. Rebuild:The process of restoring a recovery, RAID 1, RAID 5, and RAID 10 volume in the event that a volume disk has failed or is missing. If a spare disk is present and compatible, the application will automatically use it as a replacement for the failed disk. An automatic rebuild process will also occur if a RAID 1 member is removed and then reconnected, in order to re-establish the mirroring. This process does not apply to RAID 0 volumes.
 

. Recover data:The action of retrieving data in the event that a recovery volume has failed due to a missing or failed master disk. Data from the recovery disk is copied to a new or healthy master disk, restoring data redundancy. Selecting this option will overwrite all master disk data with data on the recovery disk.
 

. Recovery disk:The disk that is the designated destination drive in a recovery volume.
 

. Recovery volume:A two-disk redundant volume that includes a master disk (source) and a recovery disk (destination) and uses Intel® Rapid Recover Technology. This configuration provides flexibility of volume data updates and maximum data redundancy.
 

. Repair:The process of fixing verification errors and blocks with media errors found during the verification process. This feature is only available for volumes with a normal or at risk status. A RAID 0 cannot be repaired due to its non-redundant configuration.
 

. Reset disk to normal:Action to return a failed or at risk disk to a normal state. We recommend that you contact the manufacturer for more information to prevent potential data loss.
 

. Reset to available:Action to return a disk previously marked as a spare to an available state.
 

. Reset volume to normal:Action to return a failed volume where both array disks are present and normal to a normal state. This feature allows you to access and attempt a recovery of healthy volume data.
 

• S
 

 SATA:A successor to ATA and PATA, SATA is a computer bus technology primarily designed for transfer of data between storage devices such as hard drives or optical devices, and a computer. Benefits of this technology are: usage of high-speed serial cables, air cooling to work more efficiently, faster transfers, the ability to remove devices while operating (hot plugging), enables more reliable operation with tighter data integrity checks. Also known as Serial Advanced Technology Attachment or Serial ATA.

 

. SATA disk:A disk with an interface that transmits data using a serial protocol in order to communicate with the SATA controller.
 

. SATA transfer rate:Rate at which the SATA controller and SATA disk communicate with each other. Transfer rates are important when large contiguous blocks of data are being used, such as video and image files. Reported in gigabits/seconds (Gb/s).
 

. Size:Reports the total capacity of a physical device such as a SATA disk, a volume, or an array.
 

. Storage system:One or more physical disks or devices that act as a unit for data storage.
 

. System disk:A disk that contains system files required to start and run the operating system. By default, the Windows operating system files are in the WINDOWS folder, and the supporting files are in the WINDOWS\System32 folder.

. System volume:A volume that refers to the disk(s) volume that contains the hardware-specific files that are needed to start Windows, such as Ntldr, Boot.ini, and Ntdetect.com, as well as the Windows operating system files and supporting files. The system volume can be the same volume as the boot volume.
 

• U
 

. Unknown:Disk status indicative that its usage could not be determined, due to a possible incompatibility between this software version and the disk configuration, or a virus. Also a volume status indicative that the volume is in an unexpected state due to a configuration error. Data on the volume can no longer be accessed.
 

. Update mode:Type of update assigned to a recovery volume. The update mode can be set to continuous, where master disk changes are automatically saved to the recovery disk, or set to on request, where updates of the recovery disk can be requested immediately.
 

• V
 

. Verify:Action of scanning data to detect any types of data damage, disk read errors, and volume data inconsistencies. As an option, errors found can be corrected on redundant RAID volumes. This feature is only available for volumes with a normal or at risk status.
 

. Volume size:Amount of data that can be stored on a volume; reported in bytes (B) or %.
 

. Volume type:Configuration of a volume which determines how data is stored and managed to improve read/write performance, increase fault tolerance and/or storage capacity.
 

. Volume write-back cache:A cache memory used to enhance the read/write performance of a RAID volume by grouping multiple I/O requests into fewer requests and by writing from the cache to the volume at defined intervals.
 

. Volume:A fixed amount of space across a RAID array that is structured to emulate a single physical hard drive and appears as such to the operating system. Volumes have drive letters assigned to them and some volumes can span multiple hard disks.
 

• W
 

. Windows Disk Management*:Microsoft Windows* system utility for managing the disks and partitions or volumes that they contain. Disk Management allows the initialization of new disks, volume creation, and formatting. Most disk-related tasks can be performed using this system utility without shutting down or restarting the computer; most configuration changes take effect immediately.
 

. Write-back cache allocation:Size of the dynamic random access memory (DRAM) that is allocated for write-back caching on all volumes present on the system. The cache size is set to 16 megabytes (MB) by default.

MB GB TB in Process

STORAGE CAPACITY



As used for storage capacity:
One Megabyte (MB) = one Million bytes,
One Gigabyte  (GB)  = one Billion bytes, and
One Terabyte  (TB)  = one Trillion bytes.

 

Total accessible capacity varies depending on operating environment.

 

As used for buffer or cache:

One Megabyte (MB) = 1,048,576 bytes.

 

As used for transfer rate or interface:

Megabyte per second (MB/s) = one million bytes per second, Megabit per second      (Mb/s)  = one million bits per second, and Gigabit per second         (Gb/s)   = one billion bits per second. 

All Windows command line elaborated

An A to Z Index of the Windows command line

windows command line

A

ADDUSERS                   Add or list users to/from a CSV file
ARP                                Address Resolution Protocol
ASSOC                           Change file extension associations
ASSOCIAT                    One step file association
ATTRIB                         Change file attributes

B BOOTCFG                    Edit Windows boot settings
BROWSTAT                Get domain, browser and PDC info

C CACLS                         Change file permissions
CALL                           Call one batch program from another
CD                                Change Directory - move to a specific Folder
CHANGE                    Change Terminal Server Session properties
CHKDSK                    Check Disk - check and repair disk problems
CHKNTFS                  Check the NTFS file system
CHOICE                     Accept keyboard input to a batch file
CIPHER                      Encrypt or Decrypt files/folders
CleanMgr                    Automated cleanup of Temp files, recycle bin
CLEARMEM            Clear memory leaks
CLIP                           Copy STDIN to the Windows clipboard.
CLS                             Clear the screen
CLUSTER                  Windows Clustering
CMD                          Start a new CMD shell
COLOR                     Change colors of the CMD window
COMP                       Compare the contents of two files or sets of files
COMPACT               Compress files or folders on an NTFS partition
COMPRESS             Compress individual files on an NTFS partition
CON2PRT                Connect or disconnect a Printer
CONVERT               Convert a FAT drive to NTFS.
COPY                        Copy one or more files to another location
CSC                           cmd Client-side caching (Offline Files)
CSVDE                      Import or Export Active Directory data

D DATE                        Display or set the date
DEFRAG                  Defragment hard drive
DEL                          Delete one or more files
DELPROF               Delete NT user profiles
DELTREE              Delete a folder and all subfolders
DevCon                   Device Manager Command Line Utility
DIR                         Display a list of files and folders
DIRUSE                 Display disk usage
DISKCOMP          Compare the contents of two floppy disks
DISKCOPY          Copy the contents of one floppy disk to another
DISKPART           Disk Administration
DNSSTAT             DNS Statistics
DOSKEY              Edit command line, recall commands, and create macros
DSACLs               Active Directory ACLs
DSAdd                 Add items to active directory (user group computer)
DSGet                  View items in active directory (user group computer)
DS                        Query Search for items in active directory (user group computer)
DSMod                 Modify items in active directory (user group computer)
DSMove               Move an Active directory Object
DSRM                  Remove items from Active Directory

E ECHO                     Display message on screen
ENDLOCAL          End localisation of environment changes in a batch file
ERASE                   Delete one or more files
EVENTCREATE Add a message to the Windows event log
EXIT                      Quit the current script/routine and set an error level
EXPAND               Uncompress files
EXTRACT            Uncompress CAB files

F
FC                        Compare two files
FIND                    Search for a text string in a file
FINDSTR            Search for strings in files
FOR /F                 Loop command: against a set of files
FOR /F                 Loop command: against the results of another command•
FOR                     Loop command: all options Files, Directory, List
FORFILES         Batch process multiple files
FORMAT           Format a disk
FREEDISK        Check free disk space (in bytes)
FSUTIL              File and Volume utilities
FTP                     File Transfer Protocol
FTYPE               Display or modify file types used in file extension associations•

G GLOBAL              Display membership of global groups
GOTO                  Direct a batch program to jump to a labelled line
GPUPDATE        Update Group Policy settings

H HELP                   Online Help

I  
iCACLS                Change file and folder permissions
IF                           Conditionally perform a command
IFMEMBER        Is the current user in an NT Workgroup
IPCONFIG           Configure IP

K KILL                     Remove a program from memory

L
LABEL                 Edit a disk label
LOCAL                Display membership of local groups
LOGEVENT       Write text to the NT event viewer
LOGOFF             Log a user off
LOGTIME          Log the date and time in a file

M MAPISEND        Send email from the command line
MBSAcli              Baseline Security Analyzer.
MEM                    Display memory usage
MD                       Create new folders
MKLINK            Create a symbolic link (linkd)
MODE                 Configure a system device
MORE                Display output, one screen at a time
MOUNTVOL    Manage a volume mount point
MOVE               Move files from one folder to another
MOVEUSER    Move a user from one domain to another
MSG                  Send a message
MSIEXEC         Microsoft Windows Installer
MSINFO            Windows NT diagnostics
MSTSC              Terminal Server Connection (Remote Desktop Protocol)
MUNGE            Find and Replace text within file(s)
MV                    Copy in-use files

N NET                       Manage network resources
NETDOM              Domain Manager
NETSH                 Configure Network Interfaces, Windows Firewall & Remote access
NETSVC             Command-line Service Controller
NBTSTAT           Display networking statistics (NetBIOS over TCP/IP)
NETSTAT           Display networking statistics (TCP/IP)
NOW                   Display the current Date and Time
NSLOOKUP       Name server lookup
NTBACKUP       Backup folders to tape
NTRIGHTS         Edit user account rights

O OPENFILES        Query or display open files

P PATH                  Display or set a search path for executable files
PATHPING        Trace route plus network latency and packet loss
PAUSE                Suspend processing of a batch file and display a message
PERMS               Show permissions for a user
PERFMON         Performance Monitor
PING                   Test a network connection
POPD                 Restore the previous value of the current directory saved by PUSHD
PORTQRY         Display the status of ports and services
POWERCFG     Configure power settings
PRINT                Print a text file
PRNCNFG         Display, configure or rename a printer
PRNMNGR              Add, delete, list printers set the default printer
PROMPT                 Change the command prompt
PsExec                      Execute process remotely
PsFile                        Show files opened remotely
PsGetSid                  Display the SID of a computer or a user
PsInfo                       List information about a system
PsKill                       Kill processes by name or process ID
PsList                       List detailed information about processes
PsLoggedOn            Who's logged on (locally or via resource sharing)
PsLog                        List Event log records
PsPasswd                 Change account password
PsService                  View and control services
PsShutdown             Shutdown or reboot a computer
PsSuspend                Suspend processes
PUSHD                     Save and then change the current directory

Q
QGREP Search file(s) for lines that match a given pattern.

R RASDIAL             Manage RAS connections
RASPHONE         Manage RAS connections
RECOVER           Recover a damaged file from a defective disk.
REG Registry:     Read, Set, Export, Delete keys and values
REGEDIT            Import or export registry settings
REGSVR32          Register or unregister a DLL
REGINI                Change Registry Permissions
REM                      Record comments (remarks) in a batch file
REN                       Rename a file or files
REPLACE            Replace or update one file with another
RD                          Delete folder(s)
RMTSHARE         Share a folder or a printer
ROBOCOPY         Robust File and Folder Copy
ROUTE                  Manipulate network routing tables
RUNAS                  Execute a program under a different user account
RUNDLL32           Run a DLL command (add/remove print connections)

S
SC                           Service Control
SCHTASKS           Schedule a command to run at a specific time
SCLIST                  Display NT Services
SET                         Display, set, or remove environment variables
SETLOCAL           Control the visibility of environment variables
SETX                      Set environment variables permanently
SFC                         System File Checker
SHARE                   List or edit a file share or print share
SHIFT                     Shift the position of replaceable parameters in a batch file
SHORTCUT          Create a windows shortcut (.LNK file)
SHOWGRPS          List the NT Workgroups a user has joined
SHOWMBRS         List the Users who are members of a Workgroup
SHUTDOWN         Shutdown the computer
SLEEP                    Wait for x seconds
SLMGR                  Software Licensing Management (Vista/2008)
SOON                       Schedule a command to run in the near future
SORT                        Sort input
START                     Start a program or command in a separate window
SU                              Switch User
SUBINACL              Edit file and folder Permissions, Ownership and Domain
SUBST                      Associate a path with a drive letter
SYSTEMINFO         List system configuration

T
TASKLIST        List running applications and services
TASKKILL      Remove a running process from memory
TIME                 Display or set the system time
TIMEOUT        Delay processing of a batch file
TITLE               Set the window title for a CMD.EXE session
TLIST               Task list with full path
TOUCH            Change file timestamps
TRACERT       Trace route to a remote host
TREE                Graphical display of folder structure
TYPE                Display the contents of a text file

U USRSTAT        List domain usernames and last login

V VER                 Display version information
VERIFY          Verify that files have been saved
VOL                 Display a disk label

W WHERE           Locate and display files in a directory tree
WHOAMI        Output the current UserName and domain
WINDIFF         Compare the contents of two files or sets of files
WINMSD         Windows system diagnostics
WINMSDP      Windows system diagnostics II
WMIC              WMI Commands

X XCACLS          Change file and folder permissions
XCOPY            Copy files and folders

IP Addresses Explained

Introduction

Every machine on the the Internet has a unique number assigned to it, called an IP address. Without a unique IP address on your machine, you will not be able to communicate with other devices, users, and computers on the Internet. You can look at your IP address as if it were a telephone number, each one being unique and used to identify a way to reach you and only you.

IPv4 and IPv6 Addresses

There are two flavors of IP Addresses that can be used on a network.

The first, and the version that the Internet and most routers are currently configured for, is IPv4 or Internet Protocol version 4. This version uses 32-bit addresses, which limits the amount of addresses to 4,294,967,296 possible unique addresses. Some of these addresses, about 290 million, are also reserved for special purposes. Due to the popular growth of the Internet there has been concern that the pool of possible addresses would be exhausted in the near future.

With this in mind, a new version of IP addresses was developed called IPv6, or Internet Protocol version 6, that would change the address size from 32-bit address to 128-bit addresses. This change would allow for generous IP address allocations to networks without any foreseeable problem with the amount of addresses available. In order to use IPv6 addresses, though, existing routers and hardware would need to be upgraded or configured to use this new version of IP addresses.

As IPv4 is still the most commonly used.

The Address Itself

An IP address always consists of 4 numbers separated by periods, with the numbers having a possible range of 0 through 255.

An example of how an IP address appears is: 192.168.1.10

This representation of an IP address is called decimal notation and is what is generally used by humans to refer to an IP address for readability purposes.

With the ranges for each number being between 0 and 255 there are a total 4,294,967,296 possible IP addresses.

Out of these addresses there are 3 special ranged that are reserved for special purposes.

The first is the 0.0.0.0 address and refers to the default network and the 255.255.255.255 address which is called the broadcast address.

These addresses are used for routing.

The third address, 127.0.0.1, is the loopback address, and refers to your machine. Whenever you see, 127.0.0.1, you are actually referring to your own machine. That means if you clicked on this link, http://127.0.0.1, you are actually trying to connect to your own computer, and unless you have a web server running, you will get a connection error.

There are some guidelines to how IP address can appear.

The four numbers must be between 0 and 255, and the IP address of 0.0.0.0 and 255.255.255.255 are reserved, and are not considered usable IP addresses.

IP addresses must be unique for each computer connected to a network.
That means that if you have two computers on your network, each must have a different IP address to be able to communicate with each other.
If by accident the same IP address is assigned to two computers, then those computers would have what is called an "IP Conflict" and not be able to communicate with each other.

IP address classes

These IP addresses can further be broken down into classes.

These classes are A, B, C, D, E and their possible ranges can be seen in Figure 2 below.

Class		Start address		Finish address
A		0.0.0.0		126.255.255.255
B		128.0.0.0		191.255.255.255
C		192.0.0.0		223.255.255.255
D		224.0.0.0		239.255.255.255
E		240.0.0.0		255.255.255.255

Figure 2. IP address Classes

If you look at the table you may notice something different.

The range of IP address from Class A to Class B skips the 127.0.0.0-127.255.255.255 range.

That is because this range is reserved for the special addresses called Loopback addresses that have already been discussed above.

The rest of classes are allocated to companies and organizations based upon the amount of IP addresses that they may need. Listed below are descriptions of the IP classes and the organizations that will typically receive that type of allocation.

Default Network: The special network 0.0.0.0 is generally used for routing.

Class A: From the table above you see that there are 126 class A networks. These networks consist of 16,777,214 possible IP addresses that can be assigned to devices and computers. This type of allocation is generally given to very large networks such as multi-national companies.

Loopback: This is the special 127.0.0.0 network that is reserved as a loopback to your own computer. These addresses are used for testing and debugging of your programs or hardware.

Class B: This class consists of 16,384 individual networks, each allocation consisting of 65,534 possible IP addresses. These blocks are generally allocated to Internet Service Providers and large networks, like a college or major hospital.

Class C: There is a total of 2,097,152 Class C networks available, with each network consisting of 255 individual IP addresses. This type of class is generally given to small to mid-sized companies.

Class D: The IP addresses in this class are reserved for a service called Multicast.

Class E: The IP addresses in this class are reserved for experimental use.

Broadcast: This is the special network of 255.255.255.255, and is used for broadcasting messages to the entire network that your computer resides on.


Private Addresses

There are also blocks of IP addresses that are separated for internal private use for computers not directly connected to the Internet.

These IP addresses are not supposed to be routed through the Internet, and most service providers will block the attempt to do so.

These IP addresses are used for internal use by company or home networks that need to use TCP/IP but do not want to be directly visible on the Internet. These IP ranges are:

Class		Private Start Address		Private End Address
A		10.0.0.0		10.255.255.255
B		172.16.0.0		172.31.255.255
C		192.168.0.0		192.168.255.255

If you are on a home/office private network and want to use TCP/IP, you should assign your computers/devices IP addresses from one of these three ranges. That way your router/firewall would be the only device with a true IP address which makes your network more secure.

Common Problems and Resolutions

The most common problem people have is by accident assigning an IP address to a device on your network that is already assigned to another device. When this happens, the other computers will not know which device should get the information, and you can experience erroneous behaviour.
On most operating systems and devices, if there are two devices on the local network that have the same IP address, it will generally give you a "IP Conflict" warning. If you see this warning, that means that the device giving the warning, detected another device on the network using the same address.

The best solution to avoid a problem like this is to use a service called DHCP that almost all home routers provide.

DHCP, or Dynamic Host Configuration Protocol, is a service that assigns addresses to devices and computers. You tell the DHCP server what range of IP addresses you would like it to assign, and then the DHCP server takes the responsibility of assigning those IP addresses to the various devices and keeping track so those IP addresses are assigned only once.

Conclusion

IP addresses and their function on the Internet is an important concept to understand. Hopefully this will give you a firmer grasp on this concept, which should help you troubleshoot problems and bring a better understanding of how the Internet works.