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World Wide Web

The World Wide Web, abbreviated as WWW or W3 and commonly known as the Web, is a system of interlinked hypertext documents accessed via the Internet. With a web browser, one can view web pages that may contain text, images, videos, and other multimedia and navigate between them via hyperlinks. Using concepts from earlier hypertext systems, English engineer and computer scientist Sir Tim Berners-Lee, now the Director of the World Wide Web Consortium, wrote a proposal in March 1989 for what would eventually become the World Wide Web. At CERN in Geneva, Switzerland, Berners-Lee and Belgian computer scientist Robert Cailliau proposed in 1990 to use "HyperText ... to link and access information of various kinds as a web of nodes in which the user can browse at will", and publicly introduced the project in December.
"The World-Wide Web was developed to be a pool of human knowledge, and human culture, which would allow collaborators in remote sites to share their ideas and all aspects of a common project."



The terms Internet and World Wide Web are often used in every-day speech without much distinction. However, the Internet and the World Wide Web are not one and the same. The Internet is a global system of interconnected computer networks. In contrast, the Web is one of the services that runs on the Internet. It is a collection of interconnected documents and other resources, linked by hyperlinks and URLs. In short, the Web is an application running on the Internet.
Viewing a web page on the World Wide Web normally begins either by typing the URL of the page into a web browser, or by following a hyperlink to that page or resource. The web browser then initiates a series of communication messages, behind the scenes, in order to fetch and display it.

Pulse-code modulation

Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals, which was invented by Alec Reeves in 1937. It is the standard form for digital audio in computers and various Blu-ray, Compact Disc and DVD formats, as well as other uses such as digital telephone systems. A PCM stream is a digital representation of an analog signal, in which the magnitude of the analogue signal is sampled regularly at uniform intervals, with each sample being quantized to the nearest value within a range of digital steps.
PCM streams have two basic properties that determine their fidelity to the original analog signal: the sampling rate, which is the number of times per second that samples are taken; and the bit depth, which determines the number of possible digital values that each sample can take.

Service primitives of Network Software

Service primitives

A service is formally by a set of primitives or operations a user or other entities can invoke to access the service. That is what materializes an interface. We commonly classify service primitives into 4 classes:

primitive	meaning
request	an entity is requesting a service (we are requesting a connection to a remote computer)
indication	an entity is informed of an event (the receiver has just received a connection request)
response	an entity is responding to an event (the receiver is sending the permission to connect)
confirm	an entity acknowledges the response to its request (the sender acknoledge the permission to connect to the remote host)

Most primitives need parameters. For instance, parameters of a CONNECT.request (used to query a connection) are the machine you want to connect to, the service you want to use (FTP, telnet...) and the maximum size of exchanged packets.
A acknowledged service is a service that requires a request, an indication, a response and a confirm. A unacknowledged service is a service that requires only a request and an indication. Typically, the service that establishes a connection is an acknowledged service because the peer entity must agree to set the connection. On the other hand, data transmission may be an unacknowledged service, whether we want an acknowledgement or not.
On an implementation point of view, primitives correspond to functions we can use in a program to access a given service.

services/protocols relations

A service is a set of primitives a layer provides to the upper layer. The service defines the operations a layer may realize, but it does not tell how these operations are really realized. The most characteristic element of a service is the interface between two adjacent layers.
Conversely, a protocol is a set of rules that applies to the meaning and format of messages exchanged between two peer entities. Entities uses protocols to implement service specifications. A service may therefore remain the same with two different protocols.
Protocols and services are different, but they are close to each other. We must not confuse. A service is rather an abstract notion, although the protocol corresponds to what really happens. This distinction actually answers to modern programming and implementation requirements. It is equivalent to making the distinction between an algorithm and its implementation.

connection-oriented services and connectionless services

The connection-oriented service requires a connectio to be set between two points. The receiver then expects the sender to transmit data. At the end of the transmission, the connection is stopped. Such a service is for example the telephone: to use it, we must first take of the hook, and dial a number. The called person picks up the phone and the connection is then set. The two speakers converse until they hang up.
The connectionless service is characterized by the independance of transmitted messages. Someone can receive a message without being aware of it. Messages can then follow different routes. The consequence is that we can receive messages in an inverted order. The typical example for this kind of service is the mail system: someone writes a letter and sends it without warning the addressee. This letter may then arrive after a second letter the same guy may have sent to the same addressee. Routes followed by these two letters may be different.

Frame Relay

Frame Relay is a standardized wide area network technology that specifies the physical and logical link layers of digital telecommunications channels using a packet switching methodology. Originally designed for transport across Integrated Services Digital Network (ISDN) infrastructure, it may be used today in the context of many other network interfaces.
Network providers commonly implement Frame Relay for voice (VoFR) and data as an encapsulation technique, used between local area networks (LANs) over a wide area network (WAN). Each end-user gets a private line (or leased line) to a frame-relay node. The frame-relay network handles the transmission over a frequently-changing path transparent to all end-users.
Frame Relay has become one of the most extensively-used WAN protocols. Its cheapness (compared to leased lines) provided one reason for its popularity. The extreme simplicity of configuring user equipment in a Frame Relay network offers another reason for Frame Relay's popularity.
With the advent of Ethernet over fiber optics, MPLS, VPN and dedicated broadband services such as cable modem and DSL, the end may loom for the Frame Relay protocol and encapsulation

Frame relay is a synchronous HDLC protocol based network. Data is sent in HDLC packets, referred to as "frames". The diagram below of an HDLC frame may be familiar, since without adding specific definitions of how the Address, Control and CRC is used, the diagram is applicable to IBM's SDLC, to X.25, to HDLC, to Frame Relay, as well as other protocols.

Binary Data Representation

A binary number may also have a binary point, in addition to the sign. The binary point is used for representing fractions, integers and integer-fraction numbers. Registers are high-speed storage areas within the Central Processing Unit (CPU) of the computer. All data is brought into a register before it can be processed. For example, if two numbers are to be added, both the numbers are brought in registers, added, and the result is also placed in a register. There are two ways of representing the position of the binary point in the register - fixed point number representation and floating point number representation.

The fixed point number representation assumes that the binary point is fixed at one position. The binary point is not actually present in the register, but its presence is assumed based on whether the number which is stored is a fraction or an integer.

The floating point number representation uses two registers. The first register stores the number without the binary point. The second register stores a number that indicates the position of the binary point in the first register.

We shall now discuss representation of data in the fixed point number representation and floating point number representation.

4.1. Fixed Point Number Representation

The integer binary signed number is represented as follows –

• For a positive integer binary number, the sign bit is 0 and the magnitude is a positive binary number.
• For a negative integer binary number, the sign bit is 1. The magnitude is represented in any one of the three ways-
• Signed Magnitude representation - The magnitude is the positive binary number itself.
• Signed 1’s complement representation - The magnitude is the 1’s complement of the positive binary number.
• Signed 2’s complement representation - The magnitude is the 2’s complement of the positive binary number.

 the representation of the signed number 18.

Signed magnitude and signed 1’s complement representation are seldom used in computer arithmetic. Let’s now perform arithmetic operations on the signed binary numbers. We use the signed 2’s complement representation to represent the negative numbers.

Addition of signed binary numbers – The addition of any two signed binary numbers is performed as follows -

• Represent the positive number in binary form.(For e.g., +5 is 0000 0101 and +10 is 0000 1010)
• Represent the negative number in 2’s complement form. (For e.g., -5 is 1111 1011 and -10 is 1111 0110)
• Add the bits of the two signed binary numbers.
• Ignore any carry out from the sign bit position.
Please note that the negative output is automatically in the 2’s complement form. We get the decimal equivalent of the negative output number, by finding its 2’s complement, and attaching a negative sign to the obtained result. Let’s understand the addition of two signed binary numbers with the help of some examples. Example 1. Add +5 and +10. We represent +5 in binary form, i.e., 0000 0101. We represent +10 in binary form, i.e., 0000 1010. Add the two numbers. The result is 0000 1111 i.e. +15.
Example 2. Add -5 and +10. We represent -5 in 2’s complement form, i.e., 1111 1011. We represent +10 in binary form, i.e., 0000 1010. Add the two numbers. The result is 0000 0101 i.e. +5. Example 3. Add +5 and -10. We represent +5 in binary form, i.e., 0000 0101. We represent -10 in 2’s complement form, i.e., 1111 0110. Add the two numbers. The result is 1111 1011. The result is in 2’s complement form. To find the decimal equivalent of the result 1111 1011 – Find the 2’s complement of 1111 1011, i.e., 0000 0100 + 1 = 0000 0101. This is binary equivalent of +5. Attaching a negative sign to the obtained result gives us -5.
Example 4. Add -5 and -10.
We represent -5 in 2’s complement form, i.e., 1111 1011. We represent -10 in 2’s complement form, i.e., 1111 0110. Add the two numbers. The result is 1111 0001. The result is in 2’s complement form.
To find the decimal equivalent of the result 1111 0001- Find the 2’s complement of 1111 0001, i.e., 0000 1110 + 1 = 0000 1111. This is binary equivalent of +15. Attaching a negative sign to the obtained result gives us -15.

Subtraction of signed binary numbers – The subtraction of signed binary numbers is changed to the addition of two signed numbers. For this, the sign of the second number is changed before performing the addition operation.

(-A) – (+B) = (-A) + (-B) (+B in subtraction is changed to –B in addition)

(+A) – (+B) = (+A) + (-B) (+B in subtraction is changed to –B in addition)

(-A) – (-B) = (-A) + (+B) (-B in subtraction is changed to +B in addition)

(+A) – (-B) = (+A) + (+B) (-B in subtraction is changed to +B in addition)

We see that the subtraction of signed binary numbers is performed using the addition operation.

Signed and Unsigned Numbers

A binary number may be positive or negative. Generally, we use the symbol “+” and “-” to represent positive and negative numbers, respectively. The sign of a binary number has to be represented using 0 and 1, in the computer. An n-bit signed binary number consists of two parts – sign bit and magnitude. The left most bit, also called the Most Significant Bit (MSB) is the sign bit. The remaining n-1 bits denote the magnitude of the number.

In signed binary numbers, the sign bit is 0 for a positive number and 1 for a negative number. For example, 01100011 is a positive number since its sign bit is 0, and, 11001011 is a negative number since its sign bit is 1. An 8-bit signed number can represent data in the range -128 to +127 (-2⁷ to +2⁷-1). The leftmost bit is the sign bit.

In an n-bit unsigned binary number, the magnitude of the number n is stored in n bits. An 8-bit unsigned number can represent data in the range 0 to 255 (2⁸= 256).

Complement of Binary Numbers

Complements are used in computer for the simplification of the subtraction operation. We now see, how to find the complement of a binary number. There are two types of complements for the binary number system – 1’s complement and 2’s complement.

• 1’s complement of Binary number is computed by changing the bits 1 to 0 and the bits 0 to 1. For example,
• 2’s complement of Binary number is computed by adding 1 to the 1’s complement of the binary number. For example,
• 1’s complement of 110 is 001
• 1’s complement of 1011 is 0100
• 1’s complement of 1101111 is 0010000
• 2’s complement of 110 is 001 + 1 = 010
• 2’s complement of 1011 is 0100 + 1 = 0101
• 2’s complement of 1101111 is 0010000 + 1 = 0010001

BINARY SYSTEM & ARITHMATIC

The binary number system  is used in the computer systems. The digits 0 and 1 are combined to get different binary numbers like 1001, 11000110 etc. In a binary number, a digit 0 or 1 is called a bit. For example, 1001 is a 4-bit binary number, and, 11000110 is an 8-bit binary number. All kinds of data, be it alphabets, numbers, symbols, sound data or video data, are represented as combination of bits i.e. 0’s and 1’s. Each character is a unique combination of bits. We shall now discuss how to perform basic arithmetic operations in the binary number system. 

 

2.1. Binary Addition

Binary addition involves adding of two or more binary numbers. The binary addition rules are used while performing the binary addition. Table 1 shows the binary addition rules.

Table 1. Binary Addition Rules for two inputs

Binary addition of three inputs, when all the inputs are 1, follows the rule shown in Table 2.

Table 2. Binary Addition Rules for three inputs

Addition of the binary numbers involves the following steps-

1. Start addition by adding the bits in unit column (the rightmost column). Use the rules of binary addition.
2. The result of adding bits of a column is a sum with or without a carry.
3. Write the sum in the result of that column.
4. If carry is present, the carry is carried-over to the addition of the next left column.
5. Repeat steps 2-4 for each column, i.e., the tens column, hundreds column and so on.

Let us now understand binary addition with the help of some examples.

Example 1. Add 10 and 01. Verify the answer with the help of decimal addition.

When we add 0 and 1 in the unit column, sum is 1 and there is no carry. The sum 1 is written in the unit column of the result. In the tens column, we add 1 and 0 to get the sum 1. There is no carry. The sum 1 is written in the tens column of the result.

Example 2. Add 01 and 11. Verify the answer with the help of decimal addition.

When we add 1 and 1 in the unit column, sum is 0 and carry is 1. The sum 0 is written in the unit column of the result. The carry is carried-over to the next column, i.e. the tens column. In the tens column, we add 0, 1 and the carried-over 1, to get sum 0 and carry 1. The sum 0 is written in the tens column of the result. The carry 1 is carried-over to the hundreds column. In the hundreds column, the result is 1.

Example 3. Add 11 and 11. Verify the answer with the help of decimal addition.

When we add 1 and 1 in the unit column, sum is 0 and carry is 1. The sum 0 is written in the unit column of the result. The carry is carried-over to the tens column. In the tens column, we add 1, 1 and the carried-over 1. We use the rule for binary addition of three inputs shown in Table 2. We get sum 1 and carry 1. The sum 1 is written in the tens column of the result. The carry 1 is carried-over to the hundreds column. In the hundreds column, the result is 1.

Example 4. Add 1101 and 1111. Verify the answer with the help of decimal addition.

Example 5. Add 10111, 11100 and 11. Verify the answer with the help of decimal addition.

TOLLFREE Nos 4 PC Problems

TOLL FREE Nos for any  PC Problems

AMD   18004256664

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IBM  1800443333


Microsoft  1800111100

How to use Remote Desktop Connection (RDC)

If your home computer has Windows XP Pro (or Media Center Edition) installed, you can access it from any other computer running Windows from anywhere in the world using Remote Desktop Connection. Some versions of Windows

, like 98, Me, 2000 and require software available from Microsoft.com:
http://www.microsoft.com/windowsxp/downloads/tools/rdclientdl.mspx
There are a few steps required to configure your home network to accept connections from outside computers and additional security measures required to keep your PC safe from people who might be scanning for computers with RDC installed.

Set A Complex Password

Remote Desktop relies on Windows XP passwords for login. If you don't currently have a password configured for your account, or if your password is something simple, change it. At minimum, your password should be 10-12 characters long, with a combination of numbers, letters and special characters. This password is no longer just designed to keep out your roommate or family members, it's going to keep the entire Internet from accessing your computer.
Change the password for your Windows user account from the Users section of the Control Panel.

Enable Remote Desktop Connections

The first thing to do is enable Remote Desktop on the machine you want to connect to. Open System Properties either by right clicking the My Computer icon in the Start menu and choosing properties or Windows Key + Pause/Break on your keyboard. Click the Remote tab in System Properties and check the box next to Allow users to connect remotely to this computer.

You can verify RDC is working by connecting from any other computer on your local network.

Configure Your Router

If your router still has the factory default password, change it. While it's unlikely anyone will find your router on the Internet, not changing the password is asking to have it hacked. A strong password of 10-16 characters is advised.
The next step in the procedure is to configure your router to allow inbound connections to Remote Desktop on your local computer. This requires mapping a port on your router to a port on your local computer. The process for forwarding a port varies depending on who made your router, but in general there are a similar series of steps. Linksys refers to the port forwarding page as Applications & Gaming, most other routers refer to port forwarding options as Virtual Servers. To forward a router port your need to configure the following details:
Application or Description field: RDC
Port Range Start: 3389
Port Range End: 3389
Protocol Type: Both (or TCP if a both option isn't available)
IP Address of your PC: Type ipconfig at the command line if you don't know this
Enable: check a box to enable the port forward

For security reasons, if you don't travel often, disable this router port when you return from your trip.

Change the Remote Desktop Listening Port

For added security of your RDC setup, you can change the default port Remote Desktop Connection listens on from the host computer. This prevents detection by anyone doing a routine scan for RDC. This is also convenient if you want to connect to more than one RDC computer remotely. For instance, I have 3 computers that never leave home. By default, RDC watches the same port on all computers, which means I'll either get a conflict of some kind or I won't be able to connect at all. An alternative is to redirect RDC traffic to each computer.
You can read more about the process in Microsoft Knowledge Base article 306759
To change the listening port, you need to modify the Windows Registry. Locate the appropriate Registry key using Regedit.exe:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TerminalServer\WinStations\RDP-Tcp\PortNumber
From the Edit menu, click Modify and then click Decimal. Choose a new port number. In general, choosing a number between 49152 and 65535 will avoid conflict with any other apps on your system, but you could theoretically use any port on the system. Once you set the port number you also need to configure your router to pass the specified port to your computer.
To access your computer remotely, instead of typing just the IP address, you need to type the IP address followed by the port number like this: 192.168.1.1:50001

Test Your Connection

The real trick is you need to leave home to test your configuration, so you don't really know it works until you are in the field. You need to know the IP address provided by your ISP to make the connection (Find your IP address). Visit a local coffee shop with WiFi to test the connection. Launch the Remote Desktop Connection client from Start > All Programs > Accessories > Communications.

Enter your home IP address and cross your fingers. If all went well, you'll see the Windows Login screen

Installing Remote Desktop connection on non-XP systemsInstalling Remote Desktop connection on non-XP systems

Non-Windows XP systems can also access Windows systems running Windows Remote Desktop. The local system used to access the remote computer must have the remote connectivity client software installed. To install the required Terminal Services components:

1. Insert a Windows XP Professional CD in the local system’s CD or DVD drive.
2. From the resulting Welcome To Microsoft Windows XP screen, click Perform Additional Tasks.
3. Click Setup Remote Desktop Connection from the What Do You Want To Do Screen.
4. The InstallShield Wizard will open; click Next on the Welcome To The InstallShield Wizard for Remote Desktop Connection.
5. Read and accept the license agreement and click Next.
6. Enter the customer name and organization, and specify whether the desktop connection is to be available to all users or only the logged in user and click Next.
7. Click Install.
8. Click Finish.

The older Windows system can now open the Remote Desktop Connection menu by clicking Start | Programs | Accessories | Communications | Remote Desktop Connection or by opening a command prompt and typing mstsc.

The Remote Desktop Connection

The Remote Desktop Connection software is pre-installed with Windows XP. To run it, click Start, click All Programs, click Accessories, click Communications, and then click Remote Desktop Connection. This software package can also be found on the Windows XP Professional and Windows XP Home Edition product CDs and can be installed on any supported Windows platform. To install from the CD, insert the disc into the target machine's CD-ROM drive, select Perform Additional Tasks, and then click Install Remote Desktop Connection.

Windows Remote Desktop

Connecting to a remote desktop is fairly straightforward, but a few elements must be in place first:

• The host desktop must have Internet access (preferably high-speed).
• The local system (the PC connecting to the remote desktop that will serve as the host) must be running Windows XP Professional (or a Windows 2003-flavor server) or have the appropriate Terminal Services tools installed.
• Firewalls between the local system and the remote host must be configured to pass the appropriate traffic.
• Remote Desktop must be installed and enabled on the target system.

Installing Remote Desktop

Remote Desktop is an optional Windows XP Professional service. To install it on a host system (to enable a computer to accept a remote connection request), Microsoft recommends you:

1. Click Start.
2. Click Control Panel.
3. Select Add Or Remove Programs.
4. Select Add/Remove Windows Components.
5. Select Internet Information Services.
6. Click the Details button.
7. Select World Wide Web Service.
8. Click the Details button.
9. Check the Remote Desktop Web Connection checkbox.
10. Click OK.
11. Click Next.
12. Click Finish to complete the wizard.
13. Click Start.
14. Select Run.
15. Enter Net Stop w3svc and click the OK button or press Enter.
16. Click Start.
17. Select All Programs.
18. Select Microsoft Update.
19. Select Scan For Updates.
20. Install all critical updates on the host system.
21. Click Start.
22. Select Run.
23. Enter Net Start w3svc and click the OK button.

Risk Management in IT

It is the method, by which the business managers control the overall operational and financial costs, on all their important business procedures which ultimately yield them profits.

Asset is an entity that demands security/safety. For e.g.

1. Information assets: e.g.

 Databases: about customers, personnel, production, sales, marketing, financial. These Information assets are critical for the business its confidentiality, integrity and availability is of utmost importance.
Data files: transaction data giving up to date information about each event.
Operation and support procedures: These have been developed over the years and provide detailed instructions on how to perform various activities.
Archived Information : Old Information that may be required to maintain by law.
 Continuity plans: These would be developed to overcome any disaster and maintain the continuity of business. Absence of these will lead to Ad-hoc decisions in crisis.


2. Software Assets:

 Application softwares.
 System Softwares.


3. Physical Assets:

 Computer Equipments
 Communication Equipments
 Storage Media
 Technical Equipments
 Furnitures and fixtures.

4. Services:

Computing services that the organization has outsourced.
Communication services like voice communication, data communication, value added services, wide area network. Environmental Conditioning services like heating, lighting, air conditioning and power.



Risk Assessment:

 A step in Risk Management Process
It is the determination of quantitative or qualitative value of risk related to a real situation and a well-known threat.
Quantitative risk assessment requires calculations of two components of risk:
R, the magnitude of the potential loss L, and the probability p that the loss will occur.