Window XP Registry Structure & Backup of Registy

Structure
The Windows registry is divided in 2 Panes. If you open the registry editor you will see on the left side there are five main keys which are further divided in Sub-Key, and these Sub-Keys are further divided in many Sub-Keys again. The structure of the registry is show below.
Hkey_Classes_Root
Hkey_Current_User
Hkey_Local_Machine
Hkey_Users
Hkey_Current_Config
This is a good idea that before playing with registry you must learn that how you can back up and restore the registry.

HOW TO BACKUP REGISTR
Go to start and then in Run type regedit and press enter. When the registry editor opens go to file and open Export there are many option allow you to save the back file in different formats, these are as under.
REGISTRY HIVE FILES   *.*
REGISTRATION FILES     *.REG
TEXT FILES    *.TXT
ALL FILES
Backup file with the extension of Reg

There are two ways to save the file you can either saved it as a text file and later on change it in note pad without starting registry editor, when you finish the changes right click on file and use the command (merge) to save the changes in registry.

Hive File
When you save the file as Hive, the windows saved it as a binary format and there is no way to change the file using any word processor nor note pad, however this is the best way to backup a registry to restore it later on in original form. It takes perfect image of registry.

Text Format
If you want to backup a particular key, or sub-key, and want to later on re-set your registry in original form then save the file in that format

Computer Types

GENERAL PURPOSE
These computers are used at homes, offices, and in businesses etc, these computers are designed to work at every location and every benefit from it. These computers are different from those who are design for a particular task. Digital computers are general computers.

SPECIAL PURPOSE
These computers are designed for a particular task, and their hardware and software do nothing else without performing that task. Analog computers are special purpose computers. These computers are mostly used in big industries.

SUPER COMPUTERS
These computers are used only in organizations where a huge data is required to be stored process, manipulate with high speed, these computers are used in big governmental and industrial organizations. These computers are no affordable, due to its tremendous speed, and storage capacity, which may measured in billions of processes per second.

Different Type of Errors

Different types Errors
Normally when a computer shows you an error, its mean that the programmer made mistake in program, Normally its occur when a programmer made a program and do not test it properly, there are 3 main errors occur generally such as Syntax Error, Logical Error, and Run Time Errors.

SYNTAX ERRORS
The computer programmers used different languages to made programs, these computer languages have pre define rules to follow, same as when we talk with each other and use different  languages but follow grammar of that language, when a program make a program and ignore or violate the rules of that language, then syntax errors occur.

LOGICAL ERRORS
Logical errors are hard to find, because these errors are not occur due to mistakes in programs, even when the programmer complied the program its show that there is no error in program, its mean that programmer follow all the rules which are pre-defined in that programming language, but this error occurs when a programmer do something else wrong, such as if there is need to add two values and the programmer put the sign of minus, it means that there is no mistake in program while he compile but the out put result will be wrong. So its called logical error.

RUN TIME ERRORS
Run time errors occur when the user put invalid data, such as if a program required numeric data and the user enter alphabets, this type of errors close the program automatically.

Printers

PRINTER
When we process, calculate our data in computers and we require the out put result in hard form, we use printers to print our data on papers or other medium either in text form or in image, there are several types of printers, such as Dot Matrix, Line, Laser, Daisy wheel, etc.


DOT MATRIX
In this printer a wire pin strokes the ink tap as it was used in type writers, the quality of printing depends on how much dots made up by pin on paper and how much pins it have. This printer is categorized by the number of pins, such as 9 – 24 are typical printers.

LINE Printer
This printer is normally use with mainframes, in networks, or with minicomputers, this printer prints data line by line and gives out put page by page on 11 by 17 inches of paper, this printer is use in organizations where high speed is required.

LASER
Photocopier technology is used in laser printers, a mirror and a laser beam puts the data on photosensitive drum in an image form, this image stored in electro statically form on the drum, from where with the help of heat this data transferred from drum to paper.

DAISY WHEEL
In this printer the characters are embossed on the wheel and this wheel spins with a very high speed, at that time a hammer hit the specific character, which push the ribbon and that specific character pasted on paper.

Wireless Networking

Wireless Networking
In a wireless network computers send and receive data through radio signals, laser, or infrared, in this network every computer have antenna (transceiver) these transceivers are used to send and receive data, if you have computers in long distance then, cellular, microwave transmission or in more distance like country to country or continent to continent we connect through satellite technology. The wireless technology is best option where cabling is hard to install, or where laptops are used in office and the location of computers may change time to time.



Wireless Security:-
There are 3 ways through which you can save your data which are floating in the air, this is the main problem when you decide to install a wireless network at your home or in office, and have fear that may be it will use by the neighbours. Because the data is traveled in the air and not through secure cables, with the help of SSID you can give the network name. thus only the computers will access the network with the same given network name, with the help of MAC filtering you can also secure your wireless network, through this you can create a list of MAC addresses and thus only the computers will access the network having the MAC address which are in the MAC list, you can also secure your data while it is floating in the air with the help of WEP /  Wi-Fi (WPA).



Wireless speed
In 1997 IEEE 802.11 standards was adopted, Wireless Fidelity (Wi-Fi) is non-profit organization which provide standards for wireless networking.
In standards 802.11g supports 300 feet with 54 Mbps
In standards 802.11b support 300 feet with 11 Mbps
In standards 802.11a support 150 feet with 54 Mbps

Cabling

There are several types of network cables which are used in LANs, through cables we transfer our data from one computer to another in LAN. The selection of cable for your network depends on what type of topology you choose for your network, what type of protocols you will use, your network size, future expansion in your network if any. Few famous cables are as under:-
Unshielded Twisted Pair (UTP) Cable,  Shielded Twisted Pair (STP) Cable, Coaxial Cable, Fiber Optic Cable.

UTP (unshielded twisted pair cable)
There are two types of twisted pair cable, UTP (unshielded twisted pair) STP (Shielded Twisted Pair) This cable has 8 cables (4 pairs).  Below is the list of 6 categories of Twisted Pair Cable categorized by Electronic Industry Association / Telecommunication Industry Association.
Category 1 support 1 Mbps Speed and Voice Only (telephonic wire)
Category 2 support 4 Mbps Speed and Local Talk, phone
Category 3 support 16 Mbps Speed and 10 Base T Ethernet
Category 4 support 20 Mbps Speed and Token Ring
Category 5 support 100 Mbps (2pari) 100 Base T Ethernet, 1000 Mbps (4pair) Gigabit Ethernet
Category 5a support 1000 Mbps Speed and Gigabit Ethernet
Category 6 support 10000 Mbps Speed and Gigabit Ethernet
UTP Connector
The plastic connector called RJ-45 is used to connect UTP cable with LAN card.

STP Cable
There are 3 different types of configuration of STP cable, in first category each pair in STP cable is shielded, in the second category inside the jacket a braid or foil cover all the pairs, and in third category all pairs covered with braid or in foil individually and then all pairs are again covered with on braid or foil again as a whole, STP cable is best option where radio and electrical signals interrupt your cable’s traffic, STP cable is the solution where other electrical equipments are installed. With the help of Shielded Twisted Pair cable your can save your data from interruption.

Coaxial Cable
This cable contains a central copper conductor, which is covered with a plastic, which isolate the central copper conductor from outer braided metal, this outer braided metal stop any interference from outside. Coaxial cable work in long distance, and connect network devices in long distance, it also have better resistance due to braided metal. There are two types of Coaxial cables, 10Base2 which carry Ethernet signals about 200 meters. The other coaxial cable 10Base5 carry signals about 500 meters.

Coaxial Connector
Bayone-Neill-Concelman (BNC) connector is use with Coaxial cable, this connector included with barrel , terminator, and T-connector.

Network's Hardware

To establish a network the following hardware is required.
NIC (Network Interface Card), Switch, Repeater, Bridge, Router


NIC Card
Network interface card is use to connect the computer with the network, if you want that your network work fast then always purchase NIC Card that support high speed.
Ethernet Card
If you design a network you need Ethernet Cards, so that your computers may connect with the network cables, many companies offer built-in LAN cards in computer but many did not, so you will purchase it, there are different type of cables used in network so you must first determined which particular card you required for your network connection, such as if you have Coaxial in your network then you require BNC (British Novel Connector), but if you have STP TP Cables, then you require RJ-45 connector, and for that RJ-45 connector you need that particular Ethernet Card, There are Ethernet Cards built for both types of cables.

Bridge
If you have a large network and want to segment it into two, then bridge is the best option to you. A bridge is helpful if you want to join your old networks with old cables and want to join it with your new one, bridge also monitors the both side of network traffic, and can manage it and send data to the right destination, a bridge can automatically store the addresses of computers (each) on both segments, even a bridge can monitor messages and send them to other segments if necessary.
A bridge can manage network traffic of both segments in a way that it avoid un-necessary and provide your best network performance, it also support different topologies at the same time, support different types of cabling at the same time, but its necessary that you have same protocols in each network.


Switch
Switch is used in start topology or in a tree topology, they are also called hub, they are configured with 8, 12, or 24, Rj-45 Ports, where twisted-pair cables is installed,  there are two types of switches active and passive, active switches boost up the singles, while the passive switches did not. Switches remember the addresses of each computer in the network and send data directly to the targeted computer.

Repeater
When the length of cable increases the signal became weak which may cause lost of data, or interruption in communication, a device called Repeater is used to boost up these weak signals, for example if you are using UTP cable, the maximum length of this cable is 100 meters and after 100 meters the signals will be weak, so in that case you must install Repeater after 100 meters so that the repeater can regenerate your weak signals.

Router
Router is use to route the network traffic on its shortest way, from the sender computer to the destination, router is also use for translating information of one network to others networks. Router also figures out your networks that which part of your network is busy, router know about the addresses of each computer, bridge, and routers on your network. Routers send your data on that section of your network in which you have less traffic. Routers send data on different topologies such as star wire ring, bus and star etc, it also send data on networks using different types of cables such as twisted pairs, coaxial, fiber optics, it also send data on networks using different protocols.

Protocols

As a human when we communicate with each other we use different languages to communicate, in the same way when computers in a network communicate with each other they use different protocols, in protocols there are pre-defined rules which guide two computers how to communicate with each other, no matter if you have different operating systems, different LAN cards on the other end, HTTP, FTP, SMPT, DNS, TCP, SPX, IP, IPX are the common protocols we use generally.

OSI Layer	Layers List	Common Protocols
7	Application
6	Presentation	HTTP, FTP, SMTP, DNS
5	Session
4	Transport	TCP, SPX
3	Network	IP, IPX
2	Data Link	Ethernet
1	Physical

Advantages & Disadvantages of Networking

Advantages of Networking
Speed With the help of networking you can save your time, such as you can share and transfer your files and data easily, without a network the data is transfer through discs, memory cards, from one computer to another. This is time consuming.
Resource sharing Sharing of network resources in the main feature of networking, Its mean that you can share your printer, CD player fax machine and other peripherals with other computer on network. You can also restrict any user from a particular network devise.
Security The main advantage of networking is its security features, with the help of user, group policies you can save your files, from illegal copying and editing, you can save your network resources from miss use, you can restrict your office mates to access a particular data, you can save your registered software from illegal copying.
Costs In market there are softwares available for network computers on very considerable prices, as compared, if you purchase software for every computer separately in your office.

Disadvantages of Network
Administration You need experts to maintain and administer your network properly which require more budget for their services.
File Server Goes Down If your data is stored in one computer on a network and it goes down, it will stop all your work,
First time installation charges You must have initial budget for designing a network at the time of first time installation, because you require LAN Cards, Cables, Routers, software that work on network, a network technician who design network for you.
Security You must check your network security issues, such as if your are using wireless must check its security issues time to time, you must have antivirus installed on your network computer to save your data.
Cable Break The break in cable of your network may stop your entire network to work.

WAN

This network connect the computers in long distance such as city to city, usually this network is used by university different campuses, big corporations having offices in different cities. Through satellite communications WAN also extended country to country and to other continents. The medium through which network computers are connected with each others are almost the same and there is no much difference in both of networks except in WAN we use telephone lines, Satellite technology, wireless equipments etc.

LAN (Local Area Network)

LAN stands for local area network, normally this network is limited in a office building, or in a school building. In a LAN usually one computer is dedicated as main server through which network administrator control the entire network through user and group policies, and all other users on LAN are bound to their assigned tasks, and they use network resources only on which they have rights. There are also other servers on LAN such as mail server, print server, file server etc. All other computers in LAN are known as workstations.

Network Definition

The basic purpose to design a network is to share network resources, such as network printer, files, and other peripherals, the computers and other resources may be linked through wireless, phone lines, network cables, infrared technology, or with the help of satellite advanced technology. There are 2 types of networks, LAN and WAN (LAN stands for Local Area Network, usually designed for schools, libraries, universities, and office buildings, while on the other hand WAN stand for Wide Area Network and as the name shows it is usually designed between two cities, or long distance offices of one big corporation or company. The media of designing these networks are different from each other, but the aim of both type of networks are the same to share resources. There are other types of networks to such as WWAN (Wireless WAN) WLAN (Wireless LAN) MAN (Metropolitan Area Network)

Topologies

Bus (Topology)
In Bus Topology a single wire is used for network, and only one cable is used as a communication medium, which is cheap from other topologies. Installation of cabling is easy and all network computers, printers and other peripherals are connected with this main cable. 10Base-2 & 10Base T types of cables are used in this topology. This Topology is very effective in small networks where  network resources are limited,  usually 10 to 20 computers is suffient in this network to maintain properly. The break in cable or if the computer is physically disconnected from main cable without proper method, or any other devise which is disconnected from main cable may disable all the network to function, and communication between all computer can break.


Ring (Topology)
The use of this Topology is very rare now a days. In this topology all the computers and network devices are connected with one single cable and the token (FDDI, SONET or Token) in this topology move clock wise or either anti-clock wise. Like bus topology if the cable is break, or any computer may disconnect from main cable without proper way this will disable the network to function. This topology is usefully in office, schools, or buildings.


Star (Topology)
This Topology is very useful, and all the computers, printers, and other devices are connected with the central device called (hub, switch or router) this topology is very useful in schools, buildings, and in offices,  the advantage of this topology is that, if one computer is disconnected from network or if a cable is break, this will not effected the remaining network, but if a central devise like hub, switch, or router my damage will break down the entire network, In this network the UTP or STP cable are used. In this network more cabling is required, so it is costly as compare with bus Topology.


Tree (Topology)
If multiple Star Topology is connected on a linear or bus topology, this is called Tree Topology. In this Topology all the computers connected with each hub and these hubs are then connected with main cable as in bus topology.

Mesh (Topology)
In start, bus, and tree topologies when a user send a data to another device on network, this data was broadcasted on network which make network busy and slow down the performance of overall network, but in mesh topology the data is send directly to the destination through router, a router find the shortest route to send the data directly to the targeted computer.