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Tuesday, March 30, 2010

IT-2nd YEAR syllabus

CSE-202 E Database Management Systems

L T P Class Work: 50
3 1 - Exam: 100
Total: 150
Duration of Exam: 3 Hrs.

Unit–1:Introduction Overview of database Management System; Various views of data, data Models, Introduction to Database Languages. Advantages of DBMS over file processing systems, Responsibility of Database Administrator,

Unit-2: Introduction to Client/Server architecture, Three levels architecture of Database Systems, E-R Diagram (Entity Relationship), mapping Constraints, Keys, Reduction of E-R diagram into tables.

Unit-3: File Organisation: Sequential Files, index sequential files, direct files, Hashing, B-trees Index files.

Unit-4: Relational Model, Relational Algebra & various operations, Relational and Tuple calculus.

Unit-5: Introduction to Query Languages :QLB , QBE, Structured query language – with special reference of (SQL of ORACLE), integrity constraints, functional dependencies & NORMALISATION – (up to 4th Normal forms), BCNF (Boyce – code normal forms)

Unit-6: Introduction to Distributed Data processing, parallel Databases, data mining & data warehousing, network model & hierarchical model, Introduction to Concurrency control and Recovery systems.

Text Books:
Database System Concepts by A. Silberschatz, H.F. Korth and S. Sudarshan, 3rd edition, 1997, McGraw-Hill, International Edition.
Introduction to Database Management system by Bipin Desai, 1991, Galgotia Pub.
Reference Books:
Fundamentals of Database Systems by R. Elmasri and S.B. Navathe, 3rd edition, 2000, Addision-Wesley, Low Priced Edition.

An Introduction to Database Systems by C.J. Date, 7th edition, Addison-Wesley, Low Priced Edition, 2000.
Database Management and Design by G.W. Hansen and J.V. Hansen, 2nd edition, 1999, Prentice-Hall of India, Eastern Economy Edition.
Database Management Systems by A.K. Majumdar and P. Bhattacharyya, 5th edition, 1999, Tata McGraw-Hill Publishing.
A Guide to the SQL Standard, Date, C. and Darwen,H. 3rd edition, Reading, MA: 1994, Addison-Wesley.
Data Management & file Structure by Looms, 1989, PHI

Note: Eight questions will be set in all by the examiners taking at least one question from each unit. Students will be required to attempt five questions in all.


CSE-204 E Programming Languages

L T P Class Work: 50
3 1 - Exam: 100
Total: 150
Duration of Exam: 3 Hrs.

Unit-1: Introduction: Syntactic and semantic rules of a Programming language, Characteristics of a good programming language, Programming language translators compiler & interpreters , Elementary data types – data objects, variable & constants, data types, Specification & implementation of elementary data types, Declarations ,type checking & type conversions , Assignment & initialization, Numeric data types, enumerations, Booleans & characters.

Unit-2: Structured data objects : Structured data objects & data types , specification & implementation of structured data types, Declaration & type checking of data structure ,vector & arrays, records Character strings, variable size data structures , Union, pointer & programmer defined data objects, sets, files.

Unit-3 : Subprograms and Programmer Defined Data Types: Evolution of data type concept ,abstraction, encapsulation & information hiding , Subprograms ,type definitions, abstract data types.

Unit–4: Sequence Control: Implicit & explicit sequence control ,sequence control within expressions, sequence control within statement, Subprogram sequence control: simple call return ,recursive subprograms, Exception & exception handlers, co routines, sequence control .

Unit-5: Data Control: Names & referencing environment, static & dynamic scope, block structure, Local data & local referencing environment, Shared data: dynamic & static scope. Parameter & parameter transmission schemes.

Unit-6: Storage Management: Major run time elements requiring storage ,programmer and system controlled storage management & phases , Static storage management , Stack based storage management, Heap storage management ,variable & fixed size elements.

Unit-7: Programming Languages: Introduction to procedural, non-procedural ,structured, functional and object oriented programming language, Comparison of C & C++ programming languages.

Text Book:
Programming languages Design & implementation by T.W. .Pratt, 1996, Prentice Hall Pub.
Programming Languages – Principles and Paradigms by Allen Tucker & Robert Noonan, 2002, TMH,
Reference Books:
Fundamentals of Programming languages by Ellis Horowitz, 1984, Galgotia publications (Springer Verlag),
Programming languages concepts by C. Ghezzi, 1989, Wiley Publications.,
Programming Languages – Principles and Pradigms Allen Tucker , Robert Noonan 2002, T.M.H.

Note: Eight questions will be set in all by the examiners taking at least one question from each unit. Students will be required to attempt five questions in all.


CSE-208 E Internet Fundamentals

L T P Class Work: 50
3 1 - Exam: 100
Total: 150
Duration of Exam: 3 Hrs.


Unit-1: Electronic Mail: Introduction, advantages and disadvantages, Userids, Pass words, e-mail addresses, message components, message composition, mailer features, E-mail inner workings, E-mail management, Mime types, Newsgroups, mailing lists, chat rooms.

Unit-2 : The Internet: Introduction to networks and internet, history, Working of Internet, Internet Congestion, internet culture, business culture on internet. Collaborative computing & the internet. Modes of Connecting to Internet, Internet Service Providers(ISPs), Internet address, standard address, domain name, DNS, IP.v6.Modems and time continuum, communications software; internet tools.

Unit-3 : World Wide Web : Introduction, Miscellaneous Web Browser details, searching the www: Directories search engines and meta search engines, search fundamentals, search strategies, working of the search engines, Telnet and FTP.
Introduction to Browser, Coast-to-coast surfing, hypertext markup language, Web page installation, Web page setup, Basics of HTML & formatting and hyperlink creation.
Using FrontPage Express, Plug-ins.

Unit-4: Languages: Basic and advanced HTML, java script language, Client and Server Side Programming in java script. Forms and data in java script, XML basics.

Unit-5 : Servers : Introduction to Web Servers: PWS, IIS, Apache; Microsoft Personal Web Server. Accessing & using these servers.

Unit-6: Privacy and security topics: Introduction, Software Complexity, Encryption schemes, Secure Web document, Digital Signatures, Firewalls.

Text Book:
Fundamentals of the Internet and the World Wide Web, Raymond Greenlaw and Ellen Hepp – 2001, TMH
Internet & World Wide Programming, Deitel,Deitel & Nieto, 2000, Pearson Education


Reference Books:
Complete idiots guide to java script,. Aron Weiss, QUE, 1997
Network firewalls, Kironjeet syan -New Rider Pub.
www.secinf.com
www.hackers.com
Alfred Glkossbrenner-Internet 101 Computing MGH, 1996
Note: Eight questions will be set in all by the examiners taking at least one question from each unit. Students will be required to attempt five questions in all.

IT-202 E Object Oriented Programming Using C++

L T P Class Work: 50
3 1 - Exam: 100
Total: 150
Duration of Exam: 3 Hrs.

Unit–1: Introduction to C++, C++ Standard Library, Basics of a Typical C++ Environment, Pre-processors Directives, Illustrative Simple C++ Programs. Header Files and Namespaces, library files.
Unit-2: Object Oriented Concepts : Introduction to Objects and Object Oriented Programming, Encapsulation (Information Hiding), Access Modifiers: Controlling access to a class, method, or variable (public, protected, private, package), Other Modifiers, Polymorphism: Overloading,, Inheritance, Overriding Methods, Abstract Classes, Reusability, Class’s Behaviors.
Unit–3: Classes and Data Abstraction: Introduction, Structure Definitions, Accessing Members of Structures, Class Scope and Accessing Class Members, Separating Interface from Implementation, Controlling Access Function And Utility Functions, Initializing Class Objects: Constructors, Using Default Arguments With Constructors, Using Destructors, Classes : Const(Constant) Object And Const Member Functions, Object as Member of Classes, Friend Function and Friend Classes, Using This Pointer, Dynamic Memory Allocation with New and Delete, Static Class Members, Container Classes And Integrators, Proxy Classes, Function overloading.
Unit-4: Operator Overloading: Introduction, Fundamentals of Operator Overloading, Restrictions On Operators Overloading, Operator Functions as Class Members vs. as Friend Functions, Overloading, <<, >> Overloading Unary Operators, Overloading Binary Operators.
Unit-5: Inheritance: Introduction, Inheritance: Base Classes And Derived Classes, Protected Members, Casting Base- Class Pointers to Derived- Class Pointers, Using Member Functions, Overriding Base –Class Members in a Derived Class, Public, Protected and Private Inheritance, Using Constructors and Destructors in derived Classes, Implicit Derived –Class Object To Base- Class Object Conversion, Composition Vs. Inheritance.
Unit–6: Virtual Functions and Polymorphism: Introduction to Virtual Functions, Abstract Base Classes And Concrete Classes, Polymorphism, New Classes And Dynamic Binding, Virtual Destructors, Polymorphism, Dynamic Binding.
Unit-7: Files and I/O Streams: Files and Streams, Creating a Sequential Access File, Reading Data From A Sequential Access File, Updating Sequential Access Files, Random Access Files, Creating A Random Access File, Writing Data Randomly To a Random Access File, Reading Data Sequentially from a Random Access File. Stream Input/Output Classes and Objects, Stream Output, Stream Input, Unformatted I/O (with read and write), Stream Manipulators, Stream Format States, Stream Error States.
Unit-8: Templates & Exception Handling: Function Templates, Overloading Template Functions, Class Template, Class Templates and Non-Type Parameters, Templates and Inheritance, Templates and Friends, Templates and Static Members.
Introduction, Basics of C++ Exception Handling: Try Throw, Catch, Throwing an Exception, Catching an Exception, Rethrowing an Exception, Exception specifications, Processing Unexpected Exceptions, Stack Unwinding, Constructors, Destructors and Exception Handling, Exceptions and Inheritance.

Text Books:
C++ How to Program by H M Deitel and P J Deitel, 1998, Prentice Hall
Object Oriented Programming in Turbo C++ by Robert Lafore ,1994, The WAITE Group Press.
Programming with C++ By D Ravichandran, 2003, T.M.H
Reference books:
Object oriented Programming with C++ by E Balagurusamy, 2001, Tata McGraw-Hill
Computing Concepts with C++ Essentials by Horstmann, 2003, John Wiley,
The Complete Reference in C++ By Herbert Schildt, 2002, TMH.
Note: Eight questions will be set in all by the examiners taking at least one question from each unit. Students will be required to attempt five questions in all.

CSE- 210 E Computer Architecture & Organization

L T P Class Work: 50
3 1 - Exam: 100
Total: 150
Duration of Exam: 3 Hrs.
Unit-1: Basic Principles: Boolean algebra and Logic gates, Combinational logic blocks(Adders, Multiplexers, Encoders, de-coder), Sequential logic blocks(Latches, Flip-Flops, Registers, Counters)
Unit-2: General System Architecture: Store program control concept, Flynn’s classification of computers (SISD, MISD, MIMD); Multilevel viewpoint of a machine: digital logic, micro architecture, ISA, operating systems, high level language; structured organization; CPU, caches, main memory, secondary memory units & I/O; Performance metrics; MIPS, MFLOPS.
Unit-3: Instruction Set Architecture: Instruction set based classification of processors (RISC, CISC, and their comparison); addressing modes: register, immediate, direct, indirect, indexed; Operations in the instruction set; Arithmetic and Logical, Data Transfer, Control Flow; Instruction set formats (fixed, variable, hybrid); Language of the machine: 8086 ; simulation using MSAM.
Unit-4: Basic non pipelined CPU Architecture: CPU Architecture types (accumulator, register, stack, memory/ register) detailed data path of a typical register based CPU, Fetch-Decode-Execute cycle (typically 3 to 5 stage); microinstruction sequencing, implementation of control unit, Enhancing performance with pipelining.
Unit-5: Memory Hierarchy & I/O Techniques: The need for a memory hierarchy (Locality of reference principle, Memory hierarchy in practice: Cache, main memory and secondary memory, Memory parameters: access/ cycle time, cost per bit); Main memory (Semiconductor RAM & ROM organization, memory expansion, Static & dynamic memory types); Cache memory (Associative & direct mapped cache organizations.
Unit-6: Introduction to Parallelism: Goals of parallelism (Exploitation of concurrency, throughput enhancement); Amdahl’s law; Instruction level parallelism (pipelining, super scaling –basic features); Processor level parallelism (Multiprocessor systems overview).

Unit-7: Computer Organization [80x86]: Instruction codes, computer register, computer instructions, timing and control, instruction cycle, type of instructions, memory reference, register reference. I/O reference, Basics of Logic Design, accumulator logic, Control memory, address sequencing, micro-instruction formats, micro-program sequencer, Stack Organization, Instruction Formats, Types of interrupts; Memory Hierarchy.
Text Books:
Computer Organization and Design, 2nd Ed., by David A. Patterson and John L. Hennessy, Morgan 1997, Kauffmann.
Computer Architecture and Organization, 3rd Edi, by John P. Hayes, 1998, TMH.
Reference Books:
Operating Systems Internals and Design Principles by William Stallings,4th edition, 2001, Prentice-Hall Upper Saddle River, New Jersey
Computer Organization, 5th Edi, by Carl Hamacher, Zvonko Vranesic,2002, Safwat Zaky.
Structured Computer Organisation by A.S. Tanenbaum, 4th edition, Prentice-Hall of India, 1999, Eastern Economic Edition.
Computer Organisation & Architecture: Designing for performance by W. Stallings, 4th edition, 1996, Prentice-Hall International edition.
Computer System Architecture by M. Mano, 2001, Prentice-Hall.
Computer Architecture- Nicholas Carter, 2002, T.M.H.
Note: Eight questions will be set in all by the examiners taking at least one question from each unit. Students will be required to attempt five questions in all.
IT-204 E Multimedia Technologies

L T P Class Work: 50
3 1 - Exam: 100
Total: 150
Duration of Exam: 3 Hrs.

Unit-1: Basics of Multimedia Technology: Computers, communication and entertainment; multimedia an introduction; framework for multimedia systems; multimedia devices; CD- Audio, CD-ROM, CD-I, presentation devices and the user interface; multimedia presentation and authoring; professional development tools; LANs and multimedia; internet, World Wide Web & multimedia distribution network-ATM & ADSL; multimedia servers & databases; vector graphics; 3D graphics programs; animation techniques; shading; anti aliasing; morphing; video on demand.

Unit-2: Image Compression & Standards: Making still images; editing and capturing images; scanning images; computer color models; color palettes; vector drawing; 3D drawing and rendering; JPEG-objectives and architecture; JPEG-DCT encoding and quantization, JPEG statistical coding, JPEG predictive lossless coding; JPEG performance; overview of other image file formats as GIF, TIFF, BMP, PNG etc.

Unit-3: Audio & Video: Digital representation of sound; time domain sampled representation; method of encoding the analog signals; subband coding; fourier method; transmission of digital sound; digital audio signal processing; stereophonic & quadraphonic signal processing; editing sampled sound; MPEG Audio; audio compression & decompression; brief survey of speech recognition and generation; audio synthesis; musical instrument digital interface; digital video and image compression; MPEG motion video compression standard; DVI technology; time base media representation and delivery.

Unit-4: Virtual Reality: Applications of multimedia, intelligent multimedia system, desktop virtual reality, VR operating system, virtual environment displays and orientation making; visually coupled system requirements; intelligent VR software systems.
Applications of environment in various fields.

Text Books:
An introduction, Villamil & Molina, Multimedia Mc Milan, 1997
multimedia: Sound & Video, Lozano, 1997, PHI, (Que)

Reference Books:
Multimedia: Production, planning and delivery, Villamil & Molina,Que, 1997
Multimedia on the PC, Sinclair,BPB
Multimedia: Making it work, Tay Vaughan, fifth edition, 1994, TMH.
Multimedia in Action by James E Shuman, 1997, Wadsworth Publ.,
Multimedia in Practice by Jeff coate Judith, 1995,PHI.
Multimedia Systems by Koegel, AWL
Multimedia Making it Work by Vaughar, etl.
Multimedia Systems by John .F. Koegel, 2001, Buford.
Multimedia Communications by Halsall & Fred, 2001,AW.

Note: Eight questions will be set in all by the examiners taking at least one question from each unit. Students will be required to attempt five questions in all.

CSE- 216 E Database Management Systems Lab


L T P Class Work: 25
- - 2 Exam: 25
Total: 50
Duration of Exam: 3 Hrs.


I. Create a database and write the programs to carry out the following operation :

1. Add a record in the database
2. Delete a record in the database
3. Modify the record in the database
4. Generate queries
5. Generate the report
6. List all the records of database in ascending order.

II Develop a menu driven project for management of database system:

1. Library information system
(a) Engineering
(b) MCA

2. Inventory control system
(c) Computer Lab
(d) College Store

3. Student information system
(e) Academic
(f) Finance

4. Time table development system
(g) CSE, IT & MCA Departments
(h) Electrical & Mechanical Departments

Usage of S/w:

1. VB, ORACLE and/or DB2
2. VB, MSACCESS
3. ORACLE, D2K
4. VB, MS SQL SERVER 2000


Note: At least 5 to 10 more exercises to be given by the teacher concerned.

IT-206 E C ++ Programming Lab.

L T P Class Work: 25
- - 2 Exam: 25
Total: 50
Duration of Exam: 3 Hrs.

Q1. Raising a number n to a power p is the same as multiplying n by itself p times. Write a function called power ( ) that takes a double value for n and an int value for p, and returns the result as double value. Use a default argument of 2 for p, so that if this argument is omitted, the number will be squared. Write a main ( ) function that gets values from the user to test this function.
Q2. A point on the two dimensional plane can be represented by two numbers: an X coordinate and a Y coordinate. For example, (4,5) represents a point 4 units to the right of the origin along the X axis and 5 units up the Y axis. The sum of two points can be defined as a new point whose X coordinate is the sum of the X coordinates of the points and whose Y coordinate is the sum of their Y coordinates.
Write a program that uses a structure called point to model a point. Define three points, and have
the user input values to two of them. Than set the third point equal to the sum of the other two,
and display the value of the new point. Interaction with the program might look like this:
Enter coordinates for P1: 3 4
Enter coordinates for P2: 5 7
Coordinates of P1 + P2 are : 8, 11
Q 3. Create the equivalent of a four function calculator. The program should request the user to enter a number, an operator, and another number. It should then carry out the specified arithmetical operation: adding, subtracting, multiplying, or dividing the two numbers. (It should use a switch statement to select the operation). Finally it should display the result.
When it finishes the calculation, the program should ask if the user wants to do another
calculation. The response can be ‘Y’ or ‘N’. Some sample interaction with the program might
look like this.
Enter first number, operator, second number: 10/ 3
Answer = 3.333333
Do another (Y/ N)? Y
Enter first number, operator, second number 12 + 100
Answer = 112
Do another (Y/ N) ? N
Q4. A phone number, such as (212) 767-8900, can be thought of as having three parts: the area code (212), the exchange (767) and the number (8900). Write a program that uses a structure to store these three parts of a phone number separately. Call the structure phone. Create two structure variables of type phone. Initialize one, and have the user input a number for the other one. Then display both numbers. The interchange might look like this:
Enter your area code, exchange, and number: 415 555 1212
My number is (212) 767-8900
Your number is (415) 555-1212
Q 5. Create two classes DM and DB which store the value of distances. DM stores distances in metres and centimeters and DB in feet and inches. Write a program that can read values for the class objects and add one object of DM with another object of DB.
Use a friend function to carry out the addition operation. The object that stores the results maybe
a DM object or DB object, depending on the units in which the results are required.
The display should be in the format of feet and inches or metres and cenitmetres depending on
the object on display.
Q 6. Create a class rational which represents a numerical value by two double values- NUMERATOR & DENOMINATOR. Include the following public member Functions:
constructor with no arguments (default).
constructor with two arguments.
void reduce( ) that reduces the rational number by eliminating the highest common factor between the numerator and denominator.
Overload + operator to add two rational number.
Overload >> operator to enable input through cin.
Overload << operator to enable output through cout.
Write a main ( ) to test all the functions in the class.

Q 7. Consider the following class definition
class father {
protected : int age;
public;
father (int x) {age = x;}
virtual void iam ( )
{ cout < < “I AM THE FATHER, my age is : ”<< age<< end1:}
};
Derive the two classes son and daughter from the above class and for each, define iam ( ) to write
our similar but appropriate messages. You should also define suitable constructors for these
classes.
Now, write a main ( ) that creates objects of the three classes and then calls iam ( ) for them.
Declare pointer to father. Successively, assign addresses of objects of the two derived classes to
this pointer and in each case, call iam ( ) through the pointer to demonstrate polymorphism in
action.
Q 8. Write a program that creates a binary file by reading the data for the students from the terminal.
The data of each student consist of roll no., name ( a string of 30 or lesser no. of characters) and marks.

Q9. A hospital wants to create a database regarding its indoor patients. The information to store include
a) Name of the patient
b) Date of admission
c) Disease
d) Date of discharge
Create a structure to store the date (year, month and date as its members). Create a base class to
store the above information. The member function should include functions to enter information
and display a list of all the patients in the database. Create a derived class to store the age of the
patients. List the information about all the to store the age of the patients. List the information
about all the pediatric patients (less than twelve years in age).

Q 10. Make a class Employee with a name and salary. Make a class Manager inherit from Employee. Add an instance variable, named department, of type string. Supply a method to toString that prints the manager’s name, department and salary. Make a class Executive inherit from Manager. Supply a method to String that prints the string “Executive” followed by the information stored in the Manager superclass object. Supply a test program that tests these classes and methods.

Q11. Imagine a tollbooth with a class called toll Booth. The two data items are a type unsigned int to hold the total number of cars, and a type double to hold the total amount of money collected. A constructor initializes both these to 0. A member function called payingCar ( ) increments the car total and adds 0.50 to the cash total. Another function, called nopayCar ( ), increments the car total but adds nothing to the cash total. Finally, a member function called displays the two totals.


Include a program to test this class. This program should allow the user to push one key to count
a paying car, and another to count a nonpaying car. Pushing the ESC kay should cause the
program to print out the total cars and total cash and then exit.

Q12. Write a function called reversit ( ) that reverses a string (an array of char). Use a for loop that swaps the first and last characters, then the second and next to last characters and so on. The string should be passed to reversit ( ) as an argument.

Write a program to exercise reversit ( ). The program should get a string from the user, call
reversit ( ), and print out the result. Use an input method that allows embedded blanks. Test the
program with Napoleon’s famous phrase, “Able was I ere I saw Elba)”.

Q13. Create some objects of the string class, and put them in a Deque-some at the head of the Deque and some at the tail. Display the contents of the Deque using the forEach ( ) function and a user written display function. Then search the Deque for a particular string, using the first That ( ) function and display any strings that match. Finally remove all the items from the Deque using the getLeft ( ) function and display each item. Notice the order in which the items are displayed: Using getLeft ( ), those inserted on the left (head) of the Deque are removed in “last in first out” order while those put on the right side are removed in “first in first out” order. The opposite would be true if getRight ( ) were used.


Q 14. Create a base class called shape. Use this class to store two double type values that could be used to compute the area of figures. Derive two specific classes called triangle and rectangle from the base shape. Add to the base class, a member function get_data ( ) to initialize base class data members and another member function display_area ( ) to compute and display the area of figures. Make display_area ( ) as a virtual function and redefine this function in the derived classes to suit their requirements.
Using these three classes, design a program that will accept dimensions of a triangle or a
rectangle interactively and display the area.

Remember the two values given as input will be treated as lengths of two sides in the case of
rectangles and as base and height in the case of triangles and used as follows:
Area of rectangle = x * y
Area of triangle = ½ * x * y


IT-208 E Multimedia Technologies Lab.

L T P Class Work: 25
- - 2 Exam: 25
Total: 50
Duration of Exam: 3 Hrs.


1. Write a program to justify a text entered by the user on both the left and right hand side. For example, the test “ An architect may have a graphics program to draw an entire building but be interested in only ground floor”, can be justified in 30 columns as shown below. An architect may have a Graphics programs draw an Entric building but be interested in only ground floor.
2. Study the notes of a piano and stimulate them using the key board and store them in a file.
3. Write a program to read a paragraph and store it to a file name suggested by the author.
4. Devise a routine to produce the animation effect of a square transforming to a triangle and then to a circle.
5. Write a program to show a bitmap image on your computer screen.
6. Create a web page for a clothing company which contains all the details of that company and at-least five links to other web pages.
7. Write a program by which we can split mpeg video into smaller pieces for the purpose of sending it over the web or by small capacity floppy diskettes and then joining them at the destination.
8. Write a program to simulate the game of pool table.
9. Write a program to simulate the game Mine Sweeper.
10. Write a program to play “wave” or “midi” format sound files.


Note: At least 5 to 10 more exercises to be given by the teacher concerned.


CSE 214 E Internet Lab.

L T P Class Work: 25
- - 2 Exam: 25
Total: 50
Duration of Exam: 3 Hrs.


Exercises involving:



Sending and receiving mails.

Chatting on the net.

Using FTP and Tel net server.

Using HTML Tags (table, form, image, anchor etc.).

Making a Web page of your college using HTML tags.







Note: At least 10 exercises to be given by the teacher concerned.
vijaysharma9.blogspot.com

vijay.kaushis@mail.com












Web Server(unit-5)

Web Server
The term web server can mean one of two things:
A computer program that is responsible for accepting HTTP requests from clients (user agents such as web browsers), and serving them HTTP responses along with optional data contents, which usually are web pages such as HTML documents and linked objects (images, etc.).
A computer that runs a computer program as described above.
Common features

The rack of web servers hosting the My Opera Community site on the Internet. From the top, user file storage (content of files.myopera.com), "bigma" (the master MySQL database server), and two IBM blade centers containing multi-purpose machines (Apache front ends, Apache back ends, slave MySQL database servers, load balancers, file servers, cache servers and sync masters.
Although web server programs differ in detail, they all share some basic common features.
HTTP: every web server program operates by accepting HTTP requests from the client, and providing an HTTP response to the client. The HTTP response usually consists of an HTML document, but can also be a raw file, an image, or some other type of document (defined by MIME-types). If some error is found in client request or while trying to serve it, a web server has to send an error response which may include some custom HTML or text messages to better explain the problem to end users.
Logging: usually web servers have also the capability of logging some detailed information, about client requests and server responses, to log files; this allows the
webmaster to collect statistics by running log analyzers on these files.
In practice many web servers implement the following features also:
Authentication, optional authorization request (request of user name and password) before allowing access to some or all kind of resources.
Handling of static content (file content recorded in server's filesystem(s)) and dynamic content by supporting one or more related interfaces (SSI, CGI, SCGI, FastCGI, JSP, PHP, ASP, ASP.NET, Server API such as NSAPI, ISAPI, etc.).
HTTPS support (by SSL or TLS) to allow secure (encrypted) connections to the server on the standard
port 443 instead of usual port 80.
Content compression to reduce the size of the responses (to lower bandwidth usage, etc.).
Virtual hosting to serve many web sites using one IP address.
Large file support to be able to serve files whose size is greater than 2 GB on 32 bit
OS.
Bandwidth throttling to limit the speed of responses in order to not saturate the network and to be able to serve more clients.
Load limits
A web server (program) has defined load limits, because it can handle only a limited number of concurrent client connections (usually between 2 and 60,000, by default between 500 and 1,000) per IP address (and TCP port) and it can serve only a certain maximum number of requests per second depending on:
its own settings;
the HTTP request type;
content origin (static or dynamic);
the fact that the served content is or is not cached;
the hardware and software limits of the OS where it is working.
When a web server is near to or over its limits, it becomes overloaded and thus unresponsive.


UNIT – 3 World Wide Web

UNIT – 3 World Wide Web

3.1 Introduction

The World Wide Web (commonly shortened to 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 using hyperlinks.
The World Wide Web enabled the spread of information over the Internet through an easy-to-use and flexible format. It thus played an important role in popularising use of the Internet, to the extent that the World Wide Web has become a synonym for Internet, with the two being conflated in popular use.
How it works
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.
First, the server-name portion of the URL is resolved into an IP address using the global, distributed Internet database known as the domain name system, or DNS. This IP address is necessary to contact and send data packets to the Web server.
The browser then requests the resource by sending an HTTP request to the Web server at that particular address. In the case of a typical Web page, the HTML text of the page is requested first and parsed immediately by the Web browser, which will then make additional requests for images and any other files that form a part of the page. Statistics measuring a website's popularity are usually based on the number of 'page views' or associated server 'hits', or file requests, which take place.
Client Server Architecture of WWW
WWW is based on Client-server architecture, where web browser is the client which sends HTTP request and web server filfills that request.
3.2 Web Browser

A Web browser is a software application which enables a user to display and interact with text, images, videos, music, games and other information typically located on a Web page at a Web site on the World Wide Web or a local area network. Text and images on a Web page can contain hyperlinks to other Web pages at the same or different Web site. Web browsers allow a user to quickly and easily access information provided on many Web pages at many Web sites by traversing these links. Web browsers format HTML information for display, so the appearance of a Web page may differ between browsers.
Web browsers are the most-commonly-used type of HTTP user agent. Although browsers are typically used to access the World Wide Web, they can also be used to access information provided by Web servers in private networks or content in file systems
Current Web browsers
Some of the Web browsers currently available for personal computers include Internet Explorer, Mozilla Firefox, Safari, Opera, Avant Browser, Konqueror, Lynx, Google Chrome, Flock, Arachne, Epiphany, K-Meleon and AOL Explorer.
Protocols and standards
Web browsers communicate with Web servers primarily using Hypertext Transfer Protocol (HTTP) to fetch Web pages. HTTP allows Web browsers to submit information to Web servers as well as fetch Web pages from them. The most-commonly-used version of HTTP is HTTP/1.1, which is fully defined in RFC 2616. HTTP/1.1 has its own required standards that Internet Explorer does not fully support, but most other current-generation Web browsers do.
Pages are located by means of a URL(Uniform Resource Locator, RFC 1738), which is treated as an address, beginning with http: for HTTP transmission. Many browsers also support a variety of other URL types and their corresponding protocols, such as gopher: for Gopher (a hierarchical hyperlinking protocol), ftp: for File Transfer Protocol (FTP), rtsp: for Real-time Streaming Protocol (RTSP), and https: for HTTPS (HTTP Secure, which is HTTP augmented by Secure Sockets Layer or Transport Layer Security).
The file format for a Web page is usually HTML (HyperText Markup Language) and is identified in the HTTP protocol using a MIME content type. Most browsers natively support a variety of formats in addition to HTML, such as the JPEG, PNG and GIF image formats, and can be extended to support more through the use of plugins. The combination of HTTP content type and URL protocol specification allows Web-page designers to embed images, animations, video, sound, and streaming media into a Web page, or to make them accessible through the Web page.
3.2.1 Web Browser Interface

3.2.2 Web Browser Details


3.2.2.1 Personal preferences

Most browsers have a number of options that you can set.
· Cookies:
HTTP cookies, more commonly referred to as Web cookies, tracking cookies or just cookies, are parcels of text sent by a server to a Web client (usually a browser) and then sent back unchanged by the client each time it accesses that server. HTTP cookies are used for authenticating, session tracking (state maintenance), and maintaining specific information about users, such as site preferences or the contents of their electronic shopping carts. The term "cookie" is derived from "magic cookie," a well-known concept in UNIX computing which inspired both the idea and the name of HTTP cookies.
Relevant count of maximum stored cookies per domain for the major browsers are:
Firefox 1.5: 50
Firefox 2.0: 50
Opera 9: 30
Internet Explorer 6: 20 (raised to 50 in update on August 14, 2007)
Internet Explorer 7: 20 (raised to 50 in update on August 14, 2007)
Enabling Cookies in Your Web Browser
In order for this service to work correctly, cookies must be enabled in your Web browser. A cookie is a message given to a Web browser by a Web server. The browser stores the message in a text file and sends it back to the server when it's needed. Cookies are used in this service to save your username and password and establish and maintain a path to a particular server during the research session.
To enable cookies in Internet Explorer,
1. From the Tools menu, choose Internet Options.
2. Click the Security tab and then click Custom Level.
3. Scroll to Cookies and select Enable. This allows cookies to be stored on your computer.
4. Click OK in the Security Settings dialog box.
5. Click OK in the Internet Options dialog box.
To enable cookies in Netscape,
1. From the Edit menu, choose Preferences.
2. Click Advanced in the left frame.
3. In the Cookies section, select Accept all cookies.
4. Click OK.

· Disk cache:
A disk cache is a mechanism for improving the time it takes to read from or write to a hard disk. Today, the disk cache is usually included as part of the hard disk. A disk cache can also be a specified portion of random access memory (RAM).
When a web page is displayed within your web browser, the text and any pictures are stored locally on your system or commonly known as temporary files. The next time the same web page is visited, you web browser communicates with the web browser to confirm that the page and pictures stored on your system are the latest version. If so, the page is loaded from your local hard disk versus loading the page from the web server.
Disk cache set up instructions for your Internet Explorer Web Browser:
Step 1.
Move your mouse to the top line of your web browser to the word "View" and press and hold your left mouse button.
Step 2.
Move your mouse pointer down to "Internet Options" and release the left mouse button.

Step 3.
Move your mouse pointer and press the button "Settings..."
Step 4.
Select one of the two options to:
Every visit to the page
or
Every time you start Internet Explorer






Step 5.
Press the button "OK".
Step 6.
Press the button "OK".







· Fonts
Set the fonts large enough to be seen easily, generally at least point size 12. There are often two settings, one for normal text, and one for old-fashioned typewriter type text that needs each character to take the same amount of space. Set the normal text -- perhaps called "Web page font", "Proportional", or "Variable width font" -- to a modern font like "Arial" or "Times New Roman". Set the typewriter style text -- perhaps called "Plain text font", "Fixed width font", or "Monospace" -- to "Courier New" or if not available then plain "Courier".
Explorer: Tools / Internet Options / General / FontsFirefox: Tools / Options / General / Fonts & Colors.

· URL display
Set the browser to display the site's URL in the top border, so that you can always see the full address of any page you visit.
Explorer: View / Toolbars / Address BarFirefox: Right-click on File / Edit bar at the top of window, select "Navigation Toolbar".

· Set home page
Set your home page to the Internet site you wish displayed when your browser starts. You can set your home page to your own home page, a search engine site, or a favorite subject page like a sports or gardening site. If you want your first page to start quickly, you should specify a simple page with fewer graphics, or no page at all.
Explorer: Tools / Internet Options / General / Home pageFirefox: Tools / Options / General / Home page

· Page reloading
Set your browser to use a copy of a web page in your computer's cache if it is not older than the maximum age specified by the server. Typically a browser will use a cached page throughout one browser session, unless the page is marked with HTML that specifies it be reloaded with some other frequency, such as every time, after one hour, after 24 hours, etc. This can speed up your surfing since it saves the time of reloading the page when it hasn't changed.
Explorer: Tools / Internet Options / General / Temporary Internet Files / Settings / Every time you start Internet ExplorerFirefox: Automatic setting.
· Images

Managing images in browsers:
Mozilla Firefox 2.0
On Windows, select the "Tools" menu, on Mac OSX, select the "Firefox" menu, or on Linux select the "Edit" menu.
Select "Options" on Windows, or "Preferences" on Mac OSX and Linux
Click the "Content" tab.
Uncheck the checkbox "Load images automatically."
Internet Explorer 7
Click the "Tools" button.
Select "Internet Options".
Click the "Advanced" tab.
Scroll down to "Multimedia" and uncheck "Show pictures".


· Javascript and JAVA

To enable JavaScript in Microsoft Internet Explorer 5.x or 6.x, perform the following steps:
From the Tools menu, click Internet Options.
From the Security tab, click Custom Level.
The Internet icon is highlighted by default.
Scroll to Java permissions and click to select High safety.
Click OK.

Click OK.

From the File menu, click Close.
Re-launch your browser.

To enable or disable Java
1. Open Internet Explorer by clicking the Start button , and then clicking Internet Explorer
2. Click the Tools button, and then click Internet Options.
3. Click the Advanced tab.
4. If Java is installed, there will be a Java section in the Settings list. To enable Java, select the option under Java. To disable Java, clear the option under Java. When you are finished, click OK.





3.2.2.2 Bookmarks/ Favourites
Internet bookmarks are stored Web page locations (URLs) that can be retrieved. As a feature of all modern Internet web browsers, their primary purpose is to easily catalog and access web pages that a user has visited and chosen to save. Saved links are called "favorites" in Internet Explorer, and by virtue of the browser's large market share, the term favorite has been synonymous with bookmark since the early days of widely-distributed browsers. Bookmarks are normally visible in a browser menu and stored on the user's computer, and commonly a folder metaphor is be used for organization. In addition to bookmarking methods within most browsers, many external applications exist for bookmark management.
Storage
Each browser has a built-in tool for managing the list of bookmarks. The list storage method varies, depending on the browser, its version, and the operating system on which it runs.
In Netscape-derived browsers, bookmarks are stored in the single HTML-coded file bookmarks.html. This approach permits publication and printing of a categorized and indented catalog, and works across platforms. Bookmark names need not be unique. Editing this file outside of its native browser requires editing HTML.
Firefox 3 stores bookmarks, history, cookies, and preferences in a transactionally secure database format (SQLite).
In Internet Explorer, "Favorites" (also "Internet Shortcuts") are stored as individual files named with the original link name, and the filename extension ".URL", for example "Home Page.URL". They are collected in a directory named "Favorites", which may have subdirectories. Bookmark names must be unique within a folder. Each file contains the original URL and Microsoft-specific metadata. Browsers have varying abilities to import and export bookmarks to favorites and vice versa.
Managing Bookmarks in Internet Explorer:
1. Launch Firefox from the icon on your desktop or through your "Start"(Explorer) menu by finding Mozilla Firefox in your "Programs" or "All Programs" section.
2. Click on "Bookmarks" in the top toolbar (in between "History" and "Tools"). Under this menu, click "Organize Bookmarks". Another browser window will pop up listing all your bookmarks. In this new window, there is a list of icons at the top.
3. Select "Bookmarks" from the far left pane, then click on "New Folder", which is the second icon button at the top. A new folder will appear at the bottom of your bookmark list in the far left pane, and a dialog window will appear.
4. Rename the folder to something appropriate, then click "Ok".

5. Scroll through your bookmarks in the right pane to find the ones you want to move to this folder.
Click on the first one you'd like to move.
Hold down the "Ctrl" key and continue to click on others to move. This will highlight only the bookmarks you select.

6. Click and drag your selections to the new folder you have created in the far left pane.
7. Repeat these steps to create additional folders and organize related bookmarks.

Managing favourites in Internet Explorer:
1. In Microsoft Internet Explorer, go to a Web site that you would like to go back to frequently.
2. Select Add to Favorites from the Favorites menu.
3. In the Name box, type in a name for the favorite page.
4. Create a new folder in which to organize your bookmark by clicking the New Folder button. (If the New Folder button is not visible, first click the Create In button.)
5. Type a name for the new folder, and then click OK.
6. In the Add Favorite dialog box, make sure the new folder is selected, and then click OK.
7. Whenever you want to view your new favorite page, click the Favorites menu. Point to the new folder that you created to view a list of the favorite pages contained within it, and then click the book marked Web site.
8. Keep adding sites to your Favorites list and organizing them into curriculum-related folders.


3.2.2.3 Plug-ins and Helper applications
Plug-ins:
A plug-in consists of a computer program that interacts with a host application (a web browser or an email client, for example) to provide a certain, usually very specific, function "on demand". Applications support plugins for many reasons.
Some of the main reasons include:
to enable third-party developers to create capabilities to extend an application
to support features yet unforeseen
to reduce the size of an application
to separate source code from an application because of incompatible software licenses.

Following are the examples of Plug-ins:
Beatnik
QuickTime
RealPlayer
Shockwave
VivoActive Player
· Beatnik:
Beatnik delivers high-quality interactive sound from websites. It is provided by Headspace, Inc. and is available for Netscape Navigator and Communicator on both Macintosh PowerPC and Windows 95/NT. The Headspace website offers detailed information on Beatnik, as well as an array of sites that showcase the plug-in's capabilities.
· QuickTime:
QuickTime, a product of Apple, Inc., is capable of delivering multimedia such as movies, audio, MIDI soundtracks, 3D animation, and virtual reality. It is available to Macintosh and Windows 3.x/95/NT. The QuickTime package contains plug-in and helper applications. The QuickTime Plug-in allows QuickTime and QuickTime VR content to be viewed directly within a browser. The Movie Player and Picture Viewer, helper applications, allow all QuickTime multimedia to be played (file creation and editing can be completed with QuickTime Pro).
· RealPlayer:
RealPlayer is a live and on-demand RealAudio and Real Video player, which functions without, download delays. It is provided by Real Networks, Inc. and is available for Macintosh, Unix, and Windows 3.1/95/NT as both a plug-in and helper application. To test your RealPlayer plug-in, visit any of the sites listed in their showcase. The plug-in is compatible with many popular browsers.
· Shockwave:
The Shockwave plug-in, provided by Macromedia, Inc., allows multimedia files created using Macromedia's Director, Authorware, and Flash to be viewed directly in your web browser. The plug-in is compatible with Netscape Navigator 2.0 or later and Internet Explorer 3.0 or later on Macintosh and Windows 3.1/95/NT platforms.
· VivoActive Player:
VivoActive Player delivers on-demand video and audio from any website offering VivoActive content. This product, provided by Vivo Software, Inc., is available for Netscape Navigator and Microsoft Internet Explorer browsers on Power Macintosh and Windows 3.x/95/NT platforms.

Helper Applications:
A helper application is an external viewer program launched to display content retrieved using a web browser.
Unlike a plugin(whose full code is included into browser code), a small line is added to the browser code to tell it to open a certain helper application in case it encounters a certain file format.
Following are the examples of helper Applications:
· Adobe Acrobat Reader
· QuickTime
· RealPlayer
· Adobe Acrobat Reader
Acrobat Reader allows you to access PDF files on the web. It is provided by Adobe Systems, Inc. and is available for Macintosh, Unix, and Windows 3.x/95/NT.
· QuickTime
QuickTime, a product of Apple, Inc., is capable of delivering multimedia such as movies, audio, MIDI soundtracks, 3D animation, and virtual reality. It is available to Macintosh and Windows 3.x/95/NT. The QuickTime package contains plug-in and helper applications. The QuickTime Plug-in allows QuickTime and QuickTime VR content to be viewed directly within a browser. The Movie Player and Picture Viewer, helper applications, allow all QuickTime multimedia to be played (file creation and editing can be completed with QuickTime Pro).
· RealPlayer
RealPlayer is a live and on-demand RealAudio and RealVideo player which functions without download delays. It is provided by RealNetworks, Inc. and is available for Macintosh, Unix, and Windows 3.1/95/NT as both a plug-in and helper application. To test your RealPlayer plug-in, visit any of the sites listed in their showcase. The plug-in is compatible with many popular browsers. For a complete listing visit the RealPlayer system requirements page.




3.3 Search engine
A Web search engine is a tool designed to search for information on the World Wide Web. Information may consist of web pages, images, information and other types of files. Some search engines also mine data available in newsbooks, databases, or open directories. Unlike Web directories, which are maintained by human editors, search engines operate algorithmically or are a mixture of algorithmic and human input.
How Web search engines work
A search engine operates, in the following order
Web crawling
Indexing
Searching
1. Web crawling
A Web crawler (also known as a Web spider, Web robot, is a program or automated script that browses the World Wide Web in a methodical, automated manner. Other less frequently used names for Web crawlers are ants, automatic indexers, bots, and worms.
This process is called Web crawling or spidering. Many sites, in particular search engines, use spidering as a means of providing up-to-date data. Web crawlers are mainly used to create a copy of all the visited pages for later processing by a search engine that will index the downloaded pages to provide fast searches. Crawlers can also be used for automating maintenance tasks on a Web site, such as checking links or validating HTML code. Also, crawlers can be used to gather specific types of information from Web pages, such as harvesting e-mail addresses (usually for spam).
A Web crawler is one type of bot, or software agent. In general, it starts with a list of URLs to visit, called the seeds. As the crawler visits these URLs, it identifies all the hyperlinks in the page and adds them to the list of URLs to visit, called the crawl frontier. URLs from the frontier are recursively visited according to a set of policies.
Crawling policies
There are three important characteristics of the Web that make crawling it very difficult:
its large volume,
its fast rate of change, and
dynamic page generation.
The behavior of a Web crawler is the outcome of a combination of policies:
a selection policy that states which pages to download,
a re-visit policy that states when to check for changes to the pages,
a politeness policy that states how to avoid overloading Web sites, and
a parallelization policy that states how to coordinate distributed Web crawlers.
Web crawler architectures

Examples of Web crawlers
The following is a list of published crawler architectures for general-purpose:
RBSE
WebCrawler
World Wide Web
Google Crawler
PolyBot
FAST Crawler
Open-source crawlers
DataparkSearch
GNU Wget
Heritrix
HTTrack
ICDL Crawler.
Pavuk
YaCy

2. Indexing
Search engine indexing collects, parses, and stores data to facilitate fast and accurate information retrieval. Index design incorporates interdisciplinary concepts from linguistics, cognitive psychology, mathematics, informatics, physics and computer science. An alternate name for the process in the context of search engines designed to find web pages on the Internet is Web indexing.
The purpose of storing an index is to optimize speed and performance in finding relevant documents for a search query. Without an index, the search engine would scan every document in the corpus, which would require considerable time and computing power. For example, while an index of 10,000 documents can be queried within milliseconds, a sequential scan of every word in 10,000 large documents could take hours. The additional computer storage required to store the index, as well as the considerable increase in the time required for an update to take place, are traded off for the time saved during information retrieval.
Index Design Factors
Major factors in designing a search engine's architecture include:
a. Merge factors
How data enters the index, or how words or subject features are added to the index during text corpus traversal, and whether multiple indexers can work asynchronously.
b. Storage techniques
How to store the index data, that is, whether information should be data compressed or filtered.
c. Index size
How much computer storage is required to support the index.
d. Lookup speed
How quickly a word can be found in the inverted index.
e. Maintenance
How the index is maintained over time.
f. Fault tolerance
How important it is for the service to be reliable.

Document Parsing
Document parsing breaks apart the components (words) of a document or other form of media for insertion into the forward and inverted indices. The words found are called tokens, and so, in the context of search engine indexing and natural language processing, parsing is more commonly referred to as tokenization. It is also sometimes called word boundary disambiguation, tagging, text segmentation, content analysis, text analysis, text mining, concordance generation, speech segmentation, lexing, or lexical analysis. The terms 'indexing', 'parsing', and 'tokenization' are used interchangeably in corporate slang.


3. Searching
A web search query is a query that a user enters into web search engine to satisfy his or her information needs. Web search queries are distinctive in that they are unstructured and often ambiguous; they vary greatly from standard query languages which are governed by strict syntax rules.
Types
There are three broad categories that cover most web search queries[1]:
Informational queries – Queries that cover a broad topic (e.g., colorado or trucks) for which there may be thousands of relevant results.
Navigational queries – Queries that seek a single website or web page of a single entity (e.g., youtube or delta airlines).
Transactional queries – Queries that reflect the intent of the user to perform a particular action, like purchasing a car or downloading a screen saver.
Search engines often support a fourth type of query that is used far less frequently:
Connectivity queries – Queries that report on the connectivity of the indexed web graph.
Characteristics
Most commercial web search engines do not disclose their search logs, so information about what users are searching for on the Web is difficult to come by. Nevertheless, a study in 2001 [3] analyzed the queries from the Excite search engine showed some interesting characteristics of web search:
The average length of a search query was 2.4 terms.
About half of the users entered a single query while a little less than a third of users entered three or more unique queries.
Close to half of the users examined only the first one or two pages of results (10 results per page).
Less than 5% of users used advanced search features (e.g., Boolean operators like AND, OR, and NOT).





3.3.1 Metasearch engine
Meta-search engine is a search tool that sends user requests to several other search engines and/or databases and aggregates the results into a single list or displays them according to their source. Metasearch engines enable users to enter search criteria once and access several search engines simultaneously. Metasearch engines operate on the premise that the Web is too large for any one search engine to index it all and that more comprehensive search results can be obtained by combining the results from several search engines. This also may save the user from having to use multiple search engines separately.
The term Metasearch is frequently used to classify a set of commercial search engines, see the list of search engines, but is also used to describe the paradigm of searching multiple data sources in real time. The National Information Standards Organization (NISO) uses the terms Federated Search and Metasearch interchangeably to describe this web search paradigm.

Architecture of a metasearch engine




Operation
Metasearch engines create what is known as a virtual database. They do not compile a physical database or catalogue of the web. Instead, they take a user's request, pass it to several other heterogeneous databases and then compile the results in a homogeneous manner based on a specific algorithm.
No two metasearch engines are alike. Some search only the most popular search engines while others also search lesser-known engines, newsgroups, and other databases. They also differ in how the results are presented and the quantity of engines that are used. Some will list results according to search engine or database. Others return results according to relevance, often concealing which search engine returned which results. This benefits the user by eliminating duplicate hits and grouping the most relevant ones at the top of the list.

3.4 Telnet

Telnet (Telecommunication Network) is a client – server protocol, based on a reliable connection – oriented transport. Telnet is a program that allows a user to login to another computer from an account into which the user is already logged.
It was developed in 1969 beginning with RFC 15 and standardized as IETF STD 8, one of the first Internet standards. Typically, telnet provides access to a command-line interface on a remote machine

Most implementations of TELNET have no authentication to ensure that communication is carried out between the two desired hosts and not intercepted in the middle.
The term telnet also refers to software which implements the client part of the protocol. Telnet clients are available for virtually all platforms. Most network equipment with a TCP/IP stack support some kind of Telnet service server for their remote configuration (including ones based on Windows NT). Because of security issues with Telnet, its use has waned in favour of SSH(Secure Shell) for remote access.
"To telnet" is also used as a verb meaning to establish or use a Telnet or other interactive TCP connection, as in, "To change your password, telnet to the server and run the passwd command".
Most often, a user will be telnetting to a Unix-like server system or a simple network device such as a router. For example, a user might "telnet in from home to check his mail at school". In doing so, he would be using a telnet client to connect from his computer to one of his servers. Once the connection is established, he would then log in with his account information and execute operating system commands remotely on that computer, such as ls or cd.
On many systems, the client may also be used to make interactive raw-TCP sessions. It is commonly believed that a telnet session which does not include an IAC (character 255) is functionally identical. This is not the case however due to special NVT (Network Virtual Terminal) rules such as the requirement for a bare CR (ASCII 13) to be followed by a NULL (ASCII 0).
Protocol details
Telnet is a client-server protocol, based on a reliable connection-oriented transport. Typically this protocol is used to establish a connection to TCP port 23, where a getty-equivalent program (telnetd) is listening, although Telnet predates TCP/IP and was originally run on NCP(Network Control Program).
Various Commands Used By TELNET


telnet to open a TELNET prompt.

telnet > open hostname to connect to a host. Hostname is the machine domain
name (for example, hopper.unh.edu) or the numerical
Internet Address of the machine. In some cases, one may
have to specify a port number.

telnet > help or telnet > ? Result in the Telnet documentation being displayed
that provides on – line help.

telnet > close used to end the Telnet session after logging out of the
or telnet > quit remote machine.

telnet > mode try to enter line or characters.

telnet > send transmit special characters.

telnet > set set operating parameters.

telnet > unset unset operating parameters.

telnet > status print status information.

telnet > slc change state of special characters.

telnet > z suspend telnet.

telnet > ! Invoke a sub shell.

telnet > ? Print help information.

telnet > return leave a command mode.

3.5 FTP


FTP fundamentals
FTP sites are typically used for uploading and downloading files to a central server computer, for the sake of file distribution.
In order to download and upload files to an FTP site, you need to connect using special FTP software. There are both commercial and free FTP software programs, and some browser-based free FTP programs as well.
The typical information needed to connect to an FTP site is:
The "server address" or "hostname". This is the network address of the computer you wish to connect to, such as ftp.microsoft.com.
The username and password. These are the credentials you use to access the specific files on the computer you wish to connect to.

FTP (File Transfer Protocol)

File transfer is an application that allows the user to transfer files between two computers on the Internet or on the same network.

The two most important file transfer functions are:

Ø Copying a file from another computer to the sender’s own computer. (downloading).
Ø Sending a file from user’s own computer to another computer. (uploading).

FTP connection types:

FTP Session typically consists of two type of connection:
Data connection
Control connection


· Control connection goes from the FTP client to port 21 on the FTP server. This connection is used for logon and to send commands and responses between the endpoints.
· Data transfers (including the output of “ls” and “dir” commands) requires a second data connection.
The data connection is dependent on the mode that the client is operating in:
Passive Mode
(often the default for web browsers) -- The client issues a PASV command. Upon receipt of this command, the server listens on a dynamically-allocated port then sends a PASV reply to the client. The PASV reply gives the IP address and port number that the server is listening on. The client then opens a second connection to that IP address and port number.
Active Mode
(often the default for line-mode clients) -- The client listens on a dynamically-allocated port then sends a PORT command to the server. The PORT command gives the IP address and port number that the client is listening on. The server then opens a connection to that IP address and port number; the source port for this connection is 20.


FTP Clients


Graphical File Transfer Clients

These applications display the sending computer’s file system in one window and the receiving computer’s file system in a second window.

Connecting to a remote computer for transferring files involves log in process that asks for:

The hostname or the IP address of the remote computer being connected to,
user ID of the user, and
the password

To transfer a file from one system to another, one can “drag” it using the mouse and “drop” it on the other system.

Double clicking on a file will usually cause it to be automatically transferred to the other side.

Graphical FTP client provides the option for transfer setting mode. Most clients can have a text transfer mode (ASCII) and a binary transfer mode. The mode should be set to text when transferring text files, while it should be set to binary when transferring images, files containing special characters or executable files.

After completing the FTP session, it is closed by clicking on “CLOSE” button and then exit the FTP client by clicking on the “EXIT” button.

Text – based File Transfer Clients

The text – based file transfer clients can use the various commands for transferring files from one system to another.

A file transfer client called File Transfer Protocol (FTP) can be launched by entering the command:

Start-> Run-> FTP

Once an FTP client starts running, a prompt appears as

ftp >



Now the first command to be used is

ftp > open hostname

This will allow you to open a connection to another machine.
After connecting to the server you will be asked for User-name and Password.

ftp> username: anonymous
password: --------

For a public login anonymous as User-name and a valid E-maid ID or Anonymous as Password can be provided.


Various other commands provided are:

ftp > bye Terminate the session and exit the file transfer
program.

ftp > cd change directory.

ftp > get Download a file.

ftp > help view a list of commands or help on a specific
command.

ftp > ls list the files in the current directory.

ftp > put Upload a file.

ftp > pwd print the name of the current directory.

ftp > mget “multiple get” allows to retrieve multiple files.

ftp > mput “multiple put” allows to send multiple files at once.


If the user does not want to be asked whether to transfer each file, he can turn prompt off by using command:
ftp > prompt

To transfer binary files, it should be mentioned by using the command:

ftp > binary

After the completion of FTP session, use the bye command to terminate the session or use the following command for the purpose:

ftp > quit
Web Server
The term web server can mean one of two things:
A computer program that is responsible for accepting HTTP requests from clients (user agents such as web browsers), and serving them HTTP responses along with optional data contents, which usually are web pages such as HTML documents and linked objects (images, etc.).
A computer that runs a computer program as described above.
Common features
The rack of web servers hosting the My Opera Community site on the Internet. From the top, user file storage (content of files.myopera.com), "bigma" (the master MySQL database server), and two IBM blade centers containing multi-purpose machines (Apache front ends, Apache back ends, slave MySQL database servers, load balancers, file servers, cache servers and sync masters.
Although web server programs differ in detail, they all share some basic common features.
HTTP: every web server program operates by accepting HTTP requests from the client, and providing an HTTP response to the client. The HTTP response usually consists of an HTML document, but can also be a raw file, an image, or some other type of document (defined by MIME-types). If some error is found in client request or while trying to serve it, a web server has to send an error response which may include some custom HTML or text messages to better explain the problem to end users.
Logging: usually web servers have also the capability of logging some detailed information, about client requests and server responses, to log files; this allows the webmaster to collect statistics by running log analyzers on these files.
In practice many web servers implement the following features also:
Authentication, optional authorization request (request of user name and password) before allowing access to some or all kind of resources.
Handling of static content (file content recorded in server's filesystem(s)) and dynamic content by supporting one or more related interfaces (SSI, CGI, SCGI, FastCGI, JSP, PHP, ASP, ASP.NET, Server API such as NSAPI, ISAPI, etc.).
HTTPS support (by SSL or TLS) to allow secure (encrypted) connections to the server on the standard port 443 instead of usual port 80.
Content compression to reduce the size of the responses (to lower bandwidth usage, etc.).
Virtual hosting to serve many web sites using one IP address.
Large file support to be able to serve files whose size is greater than 2 GB on 32 bit OS.
Bandwidth throttling to limit the speed of responses in order to not saturate the network and to be able to serve more clients.
Load limits
A web server (program) has defined load limits, because it can handle only a limited number of concurrent client connections (usually between 2 and 60,000, by default between 500 and 1,000) per IP address (and TCP port) and it can serve only a certain maximum number of requests per second depending on:
its own settings;
the HTTP request type;
content origin (static or dynamic);
the fact that the served content is or is not cached;
the hardware and software limits of the OS where it is working.
When a web server is near to or over its limits, it becomes overloaded and thus unresponsive.

Introduction to networks and Internet

UNIT – 2 The Internet

Introduction to networks and Internet


Network:
A network is a series of points or nodes interconnected by communication paths. Networks can interconnect with other networks and contain sub networks.
A group of two or more computer systems linked together. There are many types of computer networks, including:
· Local-area networks (LANs) : The computers are geographically close together (that is, in the same building).
· Wide-area networks (WANs) : The computers are farther apart and are connected by telephone lines or radio waves.
· Metropolitan-area networks MANs): A data network designed for a town or city.

In addition to these types, the following characteristics are also used to categorize different types of networks:
· Topology : The geometric arrangement of a computer system. Common topologies include a bus, star, and ring. See the Network topology diagrams.
· Protocol : The protocol defines a common set of rules and signals that computers on the network use to communicate. One of the most popular protocols for LANs is called Ethernet. Another popular LAN protocol for PCs is the IBM token-ring network.
· Architecture : Networks can be broadly classified as using either a peer-to-peer or client/server architecture.
Computers on a network are sometimes called nodes. Computers and devices that allocate resources for a network are called servers.

Internet:
The Internet is a global system of interconnected computer networks that interchange data by packet switching using the standardized Internet Protocol Suite (TCP/IP). It is a "network of networks" that consists of millions of private and public, academic, business, and government networks of local to global scope that are linked by copper wires, fiber-optic cables, wireless connections, and other technologies.
The Internet carries various information resources and services, such as electronic mail, online chat, file transfer and file sharing, online gaming, and the inter-linked hypertext documents and other resources of the World Wide Web (WWW).


History of Internet
The history of the Internet began with the ARPANET and connected mainframe computers on dedicated connections. The second stage involved adding desktop PCs which connected through telephone wires. The third stage was adding wireless connections to laptop computers. And currently the Internet is evolving to allow mobile phone Internet connectivity ubiquitously using cellular networks.
The ARPANET (Advanced Research Projects Agency Network) developed by ARPA of the United States Department of Defense, was the world's first operational packet switching network, and the predecessor of the global Internet.
Packet switching, now the dominant basis for both data and voice communication worldwide, was a new and important concept in data communications. Previously, data communication was based on the idea of circuit switching, as in the old typical telephone circuit, where a dedicated circuit is tied up for the duration of the call and communication is only possible with the single party on the other end of the circuit.
Before the Internet:
In the 1950s and early 1960s, prior to the widespread inter-networking that led to the Internet, most communication networks were limited in that they only allowed communications between the stations on the network. Some networks had gateways or bridges between them, but these bridges were often limited or built specifically for a single use. One prevalent computer networking method was based on the central mainframe method, simply allowing its terminals to be connected via long leased lines.
Three terminals and an ARPA
A fundamental pioneer in the call for a global network, J.C.R. Licklider, articulated the ideas in his January 1960 paper, Man-Computer Symbiosis.
"A network of such [computers], connected to one another by wide-band communication lines [which provided] the functions of present-day libraries together with anticipated advances in information storage and retrieval and [other] symbiotic functions."
—J.C.R. Licklider, [2]
In October 1962, Licklider was appointed head of the United States Department of Defense's Advanced Research Projects Agency, now known as DARPA, within the information processing office. There he formed an informal group within DARPA to further computer research. As part of the information processing office's role, three network terminals had been installed: one for System Development Corporation in Santa Monica, one for Project Genie at the University of California, Berkeley and one for the Compatible Time-Sharing System project at the Massachusetts Institute of Technology (MIT). Licklider's identified need for inter-networking would be made obvious by the apparent waste of resources this caused.
"For each of these three terminals, I had three different sets of user commands. So if I was talking online with someone at S.D.C. and I wanted to talk to someone I knew at Berkeley or M.I.T. about this, I had to get up from the S.D.C. terminal, go over and log into the other terminal and get in touch with them. [...] I said, it's obvious what to do (But I don't want to do it): If you have these three terminals, there ought to be one terminal that goes anywhere you want to go where you have interactive computing. That idea is the ARPAnet."
Networks that led to the Internet
ARPANET
Promoted to the head of the information processing office at DARPA, Robert Taylor intended to realize Licklider's ideas of an interconnected networking system. Bringing in Larry Roberts from MIT, he initiated a project to build such a network. The first ARPANET link was established between the University of California, Los Angeles and the Stanford Research Institute on 22:30 hours on October 29, 1969. By 5 December 1969, a 4-node network was connected by adding the University of Utah and the University of California, Santa Barbara. Building on ideas developed in ALOHAnet, the ARPANET grew rapidly. By 1981, the number of hosts had grown to 213, with a new host being added approximately every twenty days.
ARPANET became the technical core of what would become the Internet, and a primary tool in developing the technologies used. ARPANET development was centered around the Request for Comments (RFC) process, still used today for proposing and distributing Internet Protocols and Systems. RFC 1, entitled "Host Software", was written by Steve Crocker from the University of California, Los Angeles, and published on April 7, 1969. These early years were documented in the 1972 film Computer Networks: The Heralds of Resource Sharing.
International collaborations on ARPANET were sparse. For various political reasons, European developers were concerned with developing the X.25 networks. Notable exceptions were the Norwegian Seismic Array (NORSAR) in 1972, followed in 1973 by Sweden with satellite links to the Tanum Earth Station and University College London.
X.25 and public access
Following on from ARPA's research, packet switching network standards were developed by the International Telecommunication Union (ITU) in the form of X.25 and related standards. In 1974, X.25 formed the basis for the SERCnet network between British academic and research sites, which later became JANET. The initial ITU Standard on X.25 was approved in March 1976. This standard was based on the concept of virtual circuits.
The British Post Office, Western Union International and Tymnet collaborated to create the first international packet switched network, referred to as the International Packet Switched Service (IPSS), in 1978. This network grew from Europe and the US to cover Canada, Hong Kong and Australia by 1981. By the 1990s it provided a worldwide networking infrastructure.
Unlike ARPAnet, X.25 was also commonly available for business use. Telenet offered its Telemail electronic mail service, but this was oriented to enterprise use rather than the general email of ARPANET.

Working of Internet

Internet is a Wide Area Network (WAN) spread allover the world which is used to connect different types of networks. This process of interconnecting the different kinds of networks is known as Internetworking.




The device used for Internetworking is router(R).



Because the Internet is a global network of computers each computer connected to the Internet must have a unique address. Internet addresses are in the form nnn.nnn.nnn.nnn where nnn must be a number from 0 - 255. This address is known as an IP address. (IP stands for Internet Protocol)
The picture below illustrates two computers connected to the Internet; your computer with IP address 1.2.3.4 and another computer with IP address 5.6.7.8. The Internet is represented as an abstract object in-between.


If you connect to the Internet through an Internet Service Provider (ISP), you are usually assigned a temporary IP address for the duration of your dial-in session. If you connect to the Internet from a local area network (LAN) your computer might have a permanent IP address or it might obtain a temporary one from a DHCP (Dynamic Host Configuration Protocol) server. In any case, if you are connected to the Internet, your computer has a unique IP address.
Protocol Stack:
Every computer needs one to communicate on the Internet and it is usually built into the computer's operating system (i.e. Windows, Unix, etc.). The protocol stack used on the Internet is referred to as the TCP/IP protocol stack because of the two major communication protocols used. The TCP/IP stack looks like this:
Protocol Layer
Comments
Application Protocols Layer
Protocols specific to applications such as WWW, e-mail, FTP, etc.
Transmission Control Protocol Layer
TCP directs packets to a specific application on a computer using a port number.
Internet Protocol Layer
IP directs packets to a specific computer using an IP address.
Hardware Layer
Converts binary packet data to network signals and back.(E.g. ethernet network card, modem for phone lines, etc.)
If we were to follow the path that the message "Hello computer 5.6.7.8!" took from our computer to the computer with IP address 5.6.7.8, it would happen something like this:
Diagram 2

The message would start at the top of the protocol stack on your computer and work its way downward.
If the message to be sent is long, each stack layer that the message passes through may break the message up into smaller chunks of data. This is because data sent over the Internet (and most computer networks) are sent in manageable chunks. On the Internet, these chunks of data are known as packets.
The packets would go through the Application Layer and continue to the TCP layer. Each packet is assigned a port number. Many programs may be using the TCP/IP stack and sending messages. We need to know which program on the destination computer needs to receive the message because it will be listening on a specific port.
After going through the TCP layer, the packets proceed to the IP layer. This is where each packet receives it's destination address, 5.6.7.8.
Now that our message packets have a port number and an IP address, they are ready to be sent over the Internet. The hardware layer takes care of turning our packets containing the alphabetic text of our message into electronic signals and transmitting them over the phone line.
On the other end of the phone line your ISP has a direct connection to the Internet. The ISPs router examines the destination address in each packet and determines where to send it. Often, the packet's next stop is another router. More on routers and Internet infrastructure later.
Eventually, the packets reach computer 5.6.7.8. Here, the packets start at the bottom of the destination computer's TCP/IP stack and work upwards.
As the packets go upwards through the stack, all routing data that the sending computer's stack added (such as IP address and port number) is stripped from the packets.
When the data reaches the top of the stack, the packets have been re-assembled into their original form, "Hello computer 5.6.7.8!"


Internet-culture
Internet-culture is the culture that has emerged, or is emerging, from the use of computer networks for communication, entertainment and business.
Internet-culture is a wide social and cultural movement closely linked to advanced information science and information technology, their emergence, development and rise to social and cultural prominence between the 1960s and the 1990s. Internet-culture was influenced at its genesis by those early users of the internet, frequently including the architects of the original project. These individuals were often guided in their actions by the hacker ethic. While early internet-culture was based on a small cultural sample, and its ideals, the modern internet-culture is a much more diverse group of users and the ideals that they adopt.
Demonstration of Internet-culture
Demonstration of Internet-culture includes various human interactions mediated by computer networks.
They can be activities, pursuits, games, places and metaphors, and include a diverse base of applications. Some are supported by specialized software and others work on commonly accepted web protocols. Examples include but are not limited to:
Blogs
Social Networks
Games
Chat
USENET
Bulletin Board Systems
E-Commerce
Peer to Peer Networks
Virtual worlds
Features of Internet-culture
There are several features that internet-cultures share that make them warrant the prefix “cyber-“. Some of those qualities are that internet-culture:
Is a community mediated by ICTs(Information and Communications Technology).
Is culture “mediated by computer screens.”
Relies heavily on the notion of information and knowledge exchange.
Depends on the ability to manipulate tools to a degree not present in other forms of culture (even artisan culture, e.g., a glass-blowing culture).
Allows vastly expanded weak ties and has been criticized for overly emphasizing the same (see Bowling Alone and other works).
Multiplies the number of eyeballs on a given problem, beyond that which would be possible using traditional means, given physical, geographic, and temporal constraints.
Is a “cognitive and social culture, not a geographic one.”
Is “the product of like-minded people finding a common ‘place’ to interact."[10]
Is inherently more "fragile" than traditional forms of community and culture.
Identity in Internet-culture
Internet-culture, like culture in general, relies on establishing identity and credibility. However, in the absence of direct physical interaction, it could be argued that the process for such establishment is more difficult.
How does internet-culture rely on and establish identity and credibility? This relationship is two way, with identity and credibility being both used to define community in cyberspace and to be created within and by online communities.
In some senses, online credibility is established in much the same way that it is established in the off line world, however, since there are two separate worlds, it is not surprising that there are both differences in the mechanisms found in each and interactions of the markers found in each.
Architectures of Credibility
Following the model put forth by Lawrence Lessig in Code 2.0[11], the architecture of a given online community may be the single most important factor regulating the establishment of credibility within online communities. Some factors may be:
· Anonymous versus Known
· Linked to Physical Identity versus Internet-based Identity Only
· Unrated Commentary System versus Rated Commentary System
· Positive Feedback-oriented versus Mixed Feedback (positive and negative) oriented
· Moderated versus Unmoderated
Anonymous versus KnownMany sites allow anonymous commentary, where the user-id attached to the comment is something like "guest" or "anonymous user". In an architecture that allows anonymous posting about other works, the credibility being impacted is only that of the product for sale, the original opinion expressed, the code written, the YouTube video, or other entity about which comments are made (e.g., a Slashdot post). Sites that require "known" postings can vary widely from simply requiring some kind of name to be associated with the comment to requiring registration, wherein the identity of the registrant is visible to other readers of the comment. These "known" identities allow and even require commentators to be aware of their own credibility, based on the fact that other users will associate particular content and styles with their identity. By definition, then, all blog postings are "known" in that the blog exists in a consistently defined virtual location, which helps to establish an identity, around which credibility can gather. Note that a "known" identity need have nothing to do with a given identity in the physical world.
Linked to Physical Identity versus Internet-based Identity OnlyArchitectures can require that physical identity be associated with commentary, as in Lessig's example of Counsel Connect.However, to require linkage to physical identity, many more steps must be taken (collecting and storing sensitive information about a user) and safeguards for that collected information must be established-the users must have more trust of the sites collecting the information (yet another form of credibility). Irrespective of safeguards, as with Counsel Connect[12], using physical identities links credibility across the frames of the internet and real space, influencing the behaviors of those who contribute in those spaces. However, even purely internet-based identities have credibility. Just as Lessig describes linkage to a character or a particular online gaming environment, nothing inherently links a person or group to their internet-based persona, but credibility (similar to "characters") is "earned rather than bought, and because this takes time and (credibility is) not fungible, it becomes increasingly hard" to create a new persona.
Unrated Commentary System versus Rated Commentary SystemIn some architectures those who review or offer comments can, in turn, be rated by other users. This technique offers the ability to regulate the credibility of given authors by subjecting their comments to direct "quantifiable" approval ratings.
Positive Feedback-oriented versus Mixed Feedback (positive and negative) orientedArchitectures can be oriented around positive feedback or a mix of both positive and negative feedback. While a particular user may be able to equate fewer stars with a "negative" rating, the semantic difference is potentially important. The ability to actively rate an entity negatively may violate laws or norms that are important in the jurisdiction in which the internet property is important. The more public a site, the more important this concern may be, as noted by Goldsmith & Wu regarding eBay.
Moderated versus UnmoderatedArchitectures can also be oriented to give editorial control to a group or individual. Many email lists are worked in this fashion (e.g., Freecycle). In these situations, the architecture usually allows, but does not require that contributions be moderated. Further, moderation may take two different forms: reactive or proactive. In the reactive mode, an editor removes posts, reviews, or content that is deemed offensive after it has been placed on the site or list. In the proactive mode, an editor must review all contributions before they are made public.
In a moderated setting, credibility is often given to the moderator. However, that credibility can be damaged by appearing to edit in a heavy-handed way, whether reactive or proactive (as experienced by digg.com). In an unmoderated setting, credibility lies with the contributors alone. It should be noted that the very existence of an architecture allowing moderation may lend credibility to the forum being used (as in Howard Rheingold's examples from the WELL), or it may take away credibility (as in corporate web sites that post feedback, but edit it highly).
Business Culture

E-Business:
Subsets
Applications can be divided into three categories:
Internal business systems:
customer relationship management
enterprise resource planning
document management systems
human resources management
Enterprise communication and collaboration:
VoIP
content management system
e-mail
voice mail
Web conferencing
Digital work flows (or business process management)
electronic commerce - business-to-business electronic commerce (B2B) or business-to-consumer electronic commerce (B2C):
internet shop
supply chain management
online marketing
offline marketing
Models
When organizations go online, they have to decide which e-business models best suit their goals. A business model is defined as the organization of product, service and information flows, and the source of revenues and benefits for suppliers and customers. The concept of e-business model is the same but used in the online presence. The following is a list of the currently most adopted e-business models:
E-shops
E-commerce
E-procurement
E-malls
E-auctions
Virtual Communities
Collaboration Platforms
Third-party Marketplaces
Value-chain Integrators
Value-chain Service Providers
Information Brokerage
Telecommunication
Classification by provider and consumer
Roughly dividing the world into providers/producers and consumers/clients one can classify e-businesses into the following categories:
business-to-business (B2B)
business-to-consumer (B2C)
business-to-employee (B2E)
business-to-government (B2G)
government-to-business (G2B)
government-to-government (G2G)
government-to-citizen (G2C)
consumer-to-consumer (C2C)
consumer-to-business (C2B)
Types of Internet Connections (Modes of connecting to the internet)

Technology is developing rapidly and methods for connecting to the Internet change almost daily. In the Ithaca area, the following types of connections are most commonly available:
1. Cable: a cable data connection transfers information from the Internet to your computer and from your computer to the network, through your cable television connection. Cable connections provide high speeds of data transfer downstream, from the Internet to your computer, but are slower when sending data from your computer to the network. Additionally, the number of subscribers online affects transfer rates simultaneously. All connections originate on one line per street, so signals degrade as more subscribers come online. Cable connections can be used by individual subscribers to connect one computer to one line, or can be used to connect multiple computers in a building to the Internet.
2. Dial-up: data is transmitted through an analog phone connection. You connect to the Internet by using your phone line to dial into an ISP’s line. An analog connection is the slowest type of connection available, and will not permit you to use your telephone for a voice connection at the same time that you are connected to the Internet. Dial-up connections allow only one computer at a time, per line, to be connected. Cornell offers the EZ-Remote dial-up service.
3. Direct connection: Cornell Information Technologies (CIT) can provide a direct connection depending on your location. In locations where CIT can provide service, the connection is made via fiber optic cabling from the site to the Cornell University network backbone and then to CIT installed, owned and maintained network electronics. Connections are typically 10 Mbps or 100 Mbps; however, Gigabit connections are available at an additional cost.
4. DSL (Digital Subscriber Line): DSL and its variations (such as ADSL - Asymmetric Digital Subscriber Line), use normal phone lines to transmit and receive data digitally. Unlike a cable connection, DSL allows you exclusive use of the line – there is no signal degradation caused by other users. Like cable connections, DSL offers high-speed connectivity, and allows you to use your phone and be online at the same time. DSL can be used for individuals who want to connect one computer to one line, or for an extra investment DSL can be used to connect a building to the Internet.
5. ISDN (Integrated Services Digital Network): ISDN is a slightly older technology that also provides a high-speed connection. ISDN offers connections over ordinary telephone wire, facilitating both voice and data transmission so you can maintain your connection to the Internet while placing telephone calls. ISDN can be used for individuals who need to connect one computer to one line, or can be used to connect multiple computers in a building to the Internet.
6. T1: is a digital transmission technology that uses copper wire. T1 could be used to provide data service to an entire building, and data wiring would distribute the service throughout the building. T1 is the technology used on the Cornell campus. A T1 connection requires a substantial investment and because of this, may not be the most desirable means of connecting your house.
7. Wireless: is a high-speed technology that transmits data over radio waves. Wireless transmission can be used to provide connectivity from an ISP to an entire building, however, service will be dependent on the existence of a clear line of sight between the ISP and the building. Within a building, a wireless local area network (LAN) can connect multiple computers to each other and to the Internet. Wireless is a technology that is continually developing.
Internet service provider

Internet service provider (ISP, also called Internet access provider or IAP) is a company that offers their customers access to the Internet. The ISP connects to its customers using a data transmission technology appropriate for delivering Internet Protocol datagrams, such as dial-up, DSL, cable modem or dedicated high-speed interconnects.
ISPs may provide Internet e-mail accounts to users which allow them to communicate with one another by sending and receiving electronic messages through their ISPs' servers. ISPs may provide other services such as remotely storing data files on behalf of their customers, as well as other services unique to each particular ISP.
End-User-to-ISP Connection
ISPs employ a range of technologies to enable consumers to connect to their network.
For home users and small businesses, the most popular options include dial-up, DSL (typically Asymmetric Digital Subscriber Line, ADSL), broadband wireless, cable modem, fiber to the premises (FTTH), and Integrated Services Digital Network (ISDN) (typically basic rate interface).
For customers with more demanding requirements, such as medium-to-large businesses, or other ISPs, DSL (often SHDSL or ADSL), Ethernet, Metro Ethernet, Gigabit Ethernet, Frame Relay, ISDN (BRI or PRI), ATM, satellite Internet access and synchronous optical networking (SONET) are more likely to be used.
With the increasing popularity of downloading music and online video and the general demand for faster page loads, higher bandwidth connections are becoming more popular.[citation needed]
Typical home user connection
DSL
Broadband wireless access
Cable Internet
ISDN
WiFi
1. DSL, is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop, although in recent years, the term digital subscriber line has been widely adopted as a more marketing-friendly term for ADSL, which is the most popular version of consumer-ready DSL. DSL can be used at the same time and on the same telephone line with regular telephone, as it uses high frequency, while regular telephone uses low frequency.
Typically, the download speed of consumer DSL services ranges from 256 kilobits per second (kbit/s) to 24,000 kbit/s, depending on DSL technology, line conditions and service level implemented. Typically, upload speed is lower than download speed for Asymmetric Digital Subscriber Line (ADSL) and equal to download speed for the rarer Symmetric Digital Subscriber Line (SDSL).
2. Wireless Broadband is a fairly new technology that provides high-speed wireless internet and data network access over a wide area.
According to the 802.16-2004 standard, broadband means 'having instantaneous bandwidth greater than around 1 MHz and supporting data rates greater than about 1.5 Mbit/s. This means that Wireless Broadband features speeds roughly equivalent to wired broadband access, such as that of ADSL or a cable modem.
3. In telecommunications, cable Internet is a form of broadband Internet access that uses the cable television infrastructure.
Like digital subscriber lines and fiber optic networks, cable Internet bridges the last kilometre or mile from the Internet provider to the subscriber. It is layered on top of the existing cable television network infrastructure; just as DSL uses the existing telephone network. Cable networks and telephone networks are the two predominant forms of residential Internet access. Recently, both have seen increased competition from fiber deployments, wireless, and mobile networks.
4. Integrated Services Digital Network(ISDN) is a telephone system network. Prior to the ISDN, the phone system was viewed as a way to transport voice, with some special services available for data. The key feature of the ISDN is that it integrates speech and data on the same lines, adding features that were not available in the classic telephone system. There are several kinds of access interfaces to the ISDN defined: Basic Rate Interface (BRI), Primary Rate Interface (PRI) and Broadband-ISDN (B-ISDN).
ISDN is a circuit-switched telephone network system, that also provides access to packet switched networks, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in better voice quality than an analog phone. ISDN B-channels can be bonded to achieve a greater data rate, typically 3 or 4 BRIs (6 to 8 64 kbit/s channels) are bonded.
5. Wi-Fi is a trademark of the Wi-Fi Alliance, founded in 1999 as WECA (Wireless Ethernet Compatibility Alliance). The organisation comprises more than 300 companies, whose products are certified by the Wi-Fi Alliance, based on the IEEE 802.11 standards (also called WLAN (Wireless LAN) and Wi-Fi). This certification warrants interoperability between different wireless devices.
A Wi-Fi enabled device such as a PC, game console, mobile phone, MP3 player or PDA can connect to the Internet when within range of a wireless network connected to the Internet. Wi-Fi technology has served to set up mesh networks.

Typical business type connection
DSL
SHDSL
Ethernet technologies
· Single-pair High-speed Digital Subscriber Line (SHDSL) is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. Compared to ADSL, SHDSL employs frequencies that include those used by traditional POTS (Plain old telephone service) telephone services to provide equal transmit and receive (i.e. symmetric) data rates. As such, a frequency splitter, or microfilter, can not be used to allow a telephone line to be shared by both an SHDSL service and a POTS service at the same time. Support of symmetric data rates has made SHDSL a popular choice by businesses for PBX, VPN, web hosting and other data services.
· Ethernet is a family of frame-based computer networking technologies for local area networks (LANs). The name comes from the physical concept of the ether(medium that carries light). It defines a number of wiring and signaling standards for the Physical Layer of the OSI networking model, through means of network access at the Media Access Control (MAC) /Data Link Layer, and a common addressing format.
Ethernet is standardized as IEEE 802.3. The combination of the twisted pair versions of Ethernet for connecting end systems to the network, along with the fiber optic versions for site backbones, is the most widespread wired LAN technology. It has been in use from around 1980[1] to the present, largely replacing competing LAN standards such as token ring, FDDI, and ARCNET.



ISP Interconnection
Just as their customers pay them for Internet access, ISPs themselves pay upstream ISPs for Internet access. An upstream ISP usually has a larger network than the contracting ISP and/or is able to provide the contracting ISP with access to parts of the Internet the contracting ISP by itself has no access to.
In the simplest case, a single connection is established to an upstream ISP and is used to transmit data to or from areas of the Internet beyond the home network; this mode of interconnection is often cascaded multiple times until reaching a Tier 1 carrier. In reality, the situation is often more complex. ISPs with more than one point of presence (PoP) may have separate connections to an upstream ISP at multiple PoPs, or they may be customers of multiple upstream ISPs and may have connections to each one of them at one or more point of presence.

Services provided by ISP’s:
1. Broadband Internet access
· Fixed wireless access
· Cable
· Triple play
2. Internet hosting service
· Web hosting service
· E-mail hosting service
· DNS hosting service
3. Dynamic DNS
1. Broadband Internet access, often shortened to just broadband, is high data rate Internet access—typically contrasted with dial-up access over a modem.
Dial-up modems are generally only capable of a maximum bitrate of 56 kbit/s (kilobits per second) and require the full use of a telephone line—whereas broadband technologies supply at least double this bandwidth and generally without disrupting telephone use.
Technology used:
The standard broadband technologies in most areas are DSL and cable modems. Newer technologies in use include VDSL(Very High Bitrate DSL) and pushing optical fiber connections closer to the subscriber in both telephone and cable plants. Fiber-optic communication, while only recently being used in fiber to the premises and fiber to the curb schemes, has played a crucial role in enabling Broadband Internet access by making transmission of information over larger distances much more cost-effective than copper wire technology. In a few areas not served by cable or ADSL, community organizations have begun to install Wi-Fi networks, and in some cities and towns local governments are installing municipal Wi-Fi networks.
Broadband implementations and standards
Digital Subscriber Line (DSL), digital data transmission over the wires used in the local loop of a telephone network
Local Multipoint Distribution Service, broadband wireless access technology that uses microwave signals operating between the 26 GHz and 29 GHz bands
WiMAX, a standards-based wireless technology that provides high-throughput broadband connections over long distances
Satellite Internet access
Cable modem, designed to modulate a data signal over cable television infrastructure
Fiber to the premises, based on fiber-optic cables and associated optical electronics
High-Speed Packet Access (HSPA), a new mobile telephony protocol, sometimes referred to as a 3.5G (or "3½G") technology
Evolution-Data Optimized (EVDO), is a wireless radio broadband data standard adopted by many CDMA mobile phone service providers
2. An Internet hosting service is a service that runs Internet servers, allowing organizations and individuals to serve content to the Internet. There are various levels of service and various kinds of services offered.
A common kind of hosting is web hosting. Most hosting providers offer a combined variety of services. Web hosting services also offer e-mail hosting service, for example. DNS hosting service is usually bundled with domain name registration.
Following are some Internet hosting services:
· Web hosting service is a type of Internet hosting service that allows individuals and organizations to provide their own website accessible via the World Wide Web. Web hosts are companies that provide space on a server they own for use by their clients as well as providing Internet connectivity, typically in a data center. Web hosts can also provide data center space and connectivity to the Internet for servers they do not own to be located in their data center, called colocation.
· An email hosting service is an Internet hosting service that runs email servers.
Email hosting services usually offer premium email at a cost as opposed to advertising supported free email or free webmail.
Email hosting services thus differ from typical end-user email providers such as webmail sites. They cater mostly to demanding email users and Small and Mid Size (SME) businesses, while larger enterprises usually run their own email hosting service. Email hosting providers allow for premium email services along with custom configurations and large number of accounts. In addition, hosting providers manage user's own domain name, including any email authentication scheme that the domain owner wishes to enforce in order to convey the meaning that using a specific domain name identifies and qualifies email senders.
· A DNS hosting service is a service that runs Domain Name System servers. Most, but not all, domain name registrars include DNS hosting service with registration. Free DNS hosting services also exist. Almost all DNS hosting services are "shared"; except for the most popular Internet sites, there is no need to dedicate a server to hosting DNS for a single website. Many third-party DNS hosting services provide Dynamic DNS.
DNS hosting service is better when the provider has multiple servers in various geographic locations that minimize latency for clients around the world.
DNS can also be self-hosted by running DNS software on generic Internet hosting services.
3. Dynamic DNS is a method, protocol, or network service that provides the capability for a networked device using the Internet Protocol Suite, such as an IP router or computer system, to notify a domain name server to change, in real time (ad-hoc) the active DNS configuration of its configured hostnames, addresses or other information stored in DNS.
numerous providers, called Dynamic DNS service providers, offer such technology and services on the Internet. They provide a software client program that automates this function. The client program is executed on a computer or device in the private network. It connects to the service provider's systems and causes those systems to link the discovered public IP address of the home network with a hostname in the domain name system. Depending on the provider, the hostname is registered within a domain owned by the provider or the customer's own domain name. These services can function by a number of mechanisms. Often they use an HTTP service request since even restrictive environments usually allow HTTP service. This group of services is commonly also referred to by the term Dynamic DNS, although it is not the standards-based DNS Update method. However, the latter might be involved in the providers systems.




ISPs having all-India license include:
BSNL
CMC
RPG Infotech
Essel Shyam Communications
Sify
Siti Cable Network
Gateway Systems (India)
World Phone Internet Services
VSNL
Guj Info Petro
Hughes Escorts Communications
Astro India Networks
Reliance
Primus Telecommunications India
ERNET India
RailTel Corporation
Data Infosys
GTL
Jumpp India
L&T Finance
HCL Infinet
Primenet Global
Tata Internet Services
Tata Power Broadband
Bharti Infotel
Pacific Internet India
In2Cable (India)
Reliance Engineering Associates
BG Broad India
Swiftmail Communications
Estel Communication
Bharti Aquanet
Trak Online Net India
Spectra Net
Reach Network India
i2i Enterprise
Tata Teleservices (Maharashtra)
Comsat Max
Gujarat Narmada Valley Fertilizers Corporation
HCL Comnet Systems and Services
Harthway Cable


Internet Addressing

Each computer on the Internet has a numerical address, called an IP address. Because the numbers are hard to remember, popular servers on the Internet have names associated with their numbers. These names are known as domain names.
There are several parts to an internet name:
Top Level Domain (TLD)
This is the last part of the name. It can be .com for companies, .org for non profit organizations, .net for network infrastructure providers, .edu for educational institutions, .mil for military, .gov for government, or a code for a country, for example, .us for United States or .jp for Japan.
Domain Name
This is the middle part of the name and often the most important. It is specific to the company / organization. Example: google, yahoo, onion.
Host Name
This is the name of the server within the company, usually named after the service provided. Example: www, ftp, news, mail.
Method/Scheme
This is the method used for the communication. It is usually a few letters followed by a colon and two forward slashes. Example: http:// for web connections, ftp:// for ftp connections.
So a complete example is:
http://people.yahoo.com
In the above example,
· http:// is the scheme indicating that this is a web connection.
· people is the server name, indicating something to do with people (in this case, finding them).
· yahoo is the domain name, indicating that this people searching functionality is provided by the company Yahoo!.
· com is the top level domain, indicating that Yahoo! is a company.

IP Addresses


An Internet Protocol (IP) address is a numerical identification (logical address) that is assigned to devices participating in a computer network utilizing the Internet Protocol for communication between its nodes.

Format:

An IP address is made up of four bytes of information (totaling 32 bits) expressed as four numbers between 0 and 255 shown separated by periods. For example, your computer's IP address might be 238.17.159.4, which is shown below in human-readable decimal form and in the binary form used on the Internet.

Example IP Address
Decimal:
238 . 17 . 159 . 4
Binary:
11101110 00010001 10011111 00000100
Each of the four numbers uses eight bits of storage, and so can represent any of the 256 numbers in the range between zero (binary 00000000) and 255 (binary 11111111). Therefore, there are more than 4 billion possible different IP addresses in all:
4,294,967,296 = 256 * 256 * 256 * 256

Private And Public IP Addresses

A computer on the Internet is identified by its IP address. In order to avoid address conflicts, IP addresses are publicly registered with the Network Information Centre (NIC). Computers on private TCP/IP LANs however do not need public addresses, since they do not need to be accessed by the public. For this reason, the NIC has reserved certain addresses that will never be registered publicly. These are known as private IP addresses, and are found in the following ranges:
From 10.0.0.0 to 10.255.255.255From 172.16.0.0 to 172.31.255.255From 192.168.0.0 to 192.168.255.255


Classes of IP addresses
The four octets that make up an IP address are conventionally represented by a, b, c, and d respectively. The following table shows how the octets are distributed in classes A, B, and C.
Class
IP Address
Network ID
Host ID
A
a.b.c.d
a
b.c.d
B
a.b.c.d
a.b
c.d
C
a.b.c.d
a.b.c
D
D
a.b.c.d
Multicast Addresses
E
a.b.c.d
Reserved for future use

Class A - 0nnnnnnn hhhhhhhh hhhhhhhh hhhhhhhh
· First bit 0; 7 network bits; 24 host bits
· Initial byte: 0 - 127
· 126 Class As exist (0 and 127 are reserved)
· 16,777,214 hosts on each Class A
Class B - 10nnnnnn nnnnnnnn hhhhhhhh hhhhhhhh
· First two bits 10; 14 network bits; 16 host bits
· Initial byte: 128 - 191
· 16,384 Class Bs exist
· 65,532 hosts on each Class B
Class C - 110nnnnn nnnnnnnn nnnnnnnn hhhhhhhh
· First three bits 110; 21 network bits; 8 host bits
· Initial byte: 192 - 223
· 2,097,152 Class Cs exist
· 254 hosts on each Class C
Class D - 1110mmmm mmmmmmmm mmmmmmmm mmmmmmmm
· First four bits 1110; 28 multicast address bits
· Initial byte: 224 - 247
· Class Ds are multicast addresses
Class E - 1111rrrr rrrrrrrr rrrrrrrr rrrrrrrr
· First four bits 1111; 28 reserved address bits
· Initial byte: 248 - 255
· Reserved for experimental use
IP versions
The Internet Protocol (IP) has two versions currently in. Each version has its own definition of an IP address. Because of its prevalence, "IP address" typically refers to those defined by IPv4.
1. IP version 4 addresses( IPv4)
IPv4 uses 32-bit (4-byte) addresses, which limits the address space to 4,294,967,296 (232) possible unique addresses. However, IPv4 reserves some addresses for special purposes such as private networks (~18 million addresses) or multicast addresses (~270 million addresses). This reduces the number of addresses that can be allocated as public Internet addresses, and as the number of addresses available is consumed, an IPv4 address shortage appears to be inevitable in the long run. This limitation has helped stimulate the push towards IPv6, which is currently in the early stages of deployment and is currently the only offering to replace IPv4.
IPv4 addresses are usually represented in dotted-decimal notation (four numbers, each ranging from 0 to 255, separated by dots, e.g. 208.77.188.166). Each part represents 8 bits of the address, and is therefore called an octet. It is possible, although less common, to write IPv4 addresses in binary or hexadecimal. When converting, each octet is treated as a separate number. (So 255.255.0.0 in dot-decimal would be FF.FF.00.00 in hexadecimal.)
IPv4 networks
IP address as a structure of network number and host number.
The highest order octet (most significant eight bits) were designating the network number, and the rest of the bits were called the rest field or host identifier and used for host numbering within a network.
This method soon proved inadequate as local area networks developed that were not part of the larger networks already designated by a network number. In 1981, the Internet addressing specification was revised with the introduction of classful network architecture. [2]
Classful network design allowed for a larger number of individual assignments. The first three bits of the most significant octet of an IP address was defined as the "class" of the address, instead of just the network number and, depending on the class derived, the network designation was based on octet boundary segments of the entire address. The following table gives an overview of this system.
Class
First octet in binary
Range of first octet
Network ID
Host ID
Possible number of networks
Possible number of hosts
A
0XXXXXXX
0 - 127
a
b.c.d
128 = (27)
16,777,214 = (224 - 2)
B
10XXXXXX
128 - 191
a.b
c.d
16,384 = (214)
65,534 = (216 - 2)
C
110XXXXX
192 - 223
a.b.c
d
2,097,152 = (221)
254 = (28 - 2)
IPv4 private addresses
Computers not connected to the Internet, such as factory machines that communicate only with each other via TCP/IP, need not have globally-unique IP addresses. Three ranges of IPv4 addresses for private networks, one range for each class (A, B, C). These addresses are not routed on the Internet, and thus need not be coordinated with an IP address registry.
IANA Reserved Private Network Ranges
Start of range
End of range
Total addresses
24-bit Block (/8 prefix, 1 x A)
10.0.0.0
10.255.255.255
16,777,216
20-bit Block (/12 prefix, 16 x B)
172.16.0.0
172.31.255.255
1,048,576
16-bit Block (/16 prefix, 256 x C)
192.168.0.0
192.168.255.255
65,536
Any user may use any block. Typically, a network administrator will divide a block into subnets; for example, many home routers automatically use a default address range of 192.168.0.0 - 192.168.0.255 (192.168.0.0/24).
IPv4 address depletion
The IP version 4 address space is rapidly nearing exhaustion of available, officially assignable address blocks.
2. IP version 6 addresses( IPv6)
The rapid exhaustion of IPv4 address space, despite conservation techniques, prompted the Internet Engineering Task Force (IETF) to explore new technologies to expand the Internet's addressing capability. The permanent solution was deemed to be a redesign of the Internet Protocol itself. This next generation of the Internet Protocol, aimed to replace IPv4 on the Internet, was eventually named Internet Protocol Version 6 (IPv6). The address size was increased from 32 to 128 bits (16 bytes), which, even with a generous assignment of network blocks, is deemed sufficient for the foreseeable future. Mathematically, the new address space provides the potential for a maximum of 2128, or about 3.403 × 1038 unique addresses.
Example of an IPv6 address:2001:0db8:85a3:08d3:1319:8a2e:0370:7334


IP subnetworks

The technique of subnetting can operate in both IPv4 and IPv6 networks. The IP address is divided into two parts: the network address and the host identifier. The subnet mask (in IPv4 only) or the CIDR prefix determine how the IP address is divided into network and host parts.
The term subnet mask is only used within IPv4. Both IP versions however use the Classless Inter-Domain Routing (CIDR) concept and notation. In this, the IP address is followed by a slash and the number (in decimal) of bits used for the network part, also called the routing prefix. For example, an IPv4 address and its subnet mask may be 192.0.2.1 and 255.255.255.0, respectively. The CIDR notation for the same IP address and subnet is 192.0.2.1/24, because the first 24 bits of the IP address indicate the network and subnet.
Static and dynamic IP addresses
When a computer is configured to use the same IP address each time it powers up, this is known as a Static IP address. In contrast, in situations when the computer's IP address is assigned automatically, it is known as a Dynamic IP address.
Method of assignment
Static IP addresses are manually assigned to a computer by an administrator. The exact procedure varies according to platform. This contrasts with dynamic IP addresses, which are assigned either randomly, or assigned by a server using Dynamic Host Configuration Protocol (DHCP). Even though IP addresses assigned using DHCP may stay the same for long periods of time, they can generally change. In some cases, a network administrator may implement dynamically assigned static IP addresses. In this case, a DHCP server is used, but it is specifically configured to always assign the same IP address to a particular computer, and never to assign that IP address to another computer. This allows static IP addresses to be configured in one place, without having to specifically configure each computer on the network in a different way.
In the absence of both an administrator (to assign a static IP address) and a DHCP server, the operating system may assign itself an IP address using state-less autoconfiguration methods. These IP addresses, known as link-local addresses, default to the 169.254.0.0/16 address range in IPv4.
In IPv6, every interface, whether using static or dynamic address assignments, also receives a local-link address automatically in the fe80::/64 subnet.
Advantage of using dynamic addressing
Dynamic IP addresses are most frequently assigned on LANs and broadband networks by Dynamic Host Configuration Protocol (DHCP) servers. They are used because it avoids the administrative burden of assigning specific static addresses to each device on a network. It also allows many devices to share limited address space on a network if only some of them will be online at a particular time. In most current desktop operating systems, dynamic IP configuration is enabled by default so that a user does not need to manually enter any settings to connect to a network with a DHCP server. DHCP is not the only technology used to assigning dynamic IP addresses. Dialup and some broadband networks use dynamic address features of the Point-to-Point Protocol.



Domain names


The most basic functionality of a domain name is to provide symbolic representations, i.e., recognizable names, to mostly numerically addressed Internet resources. This abstraction allows any resource (e.g., website) to be moved to a different physical location in the address topology of the network, globally or locally in an intranet, in effect changing the IP address. This translation from domain names to IP addresses (and vice versa) is accomplished with the global facilities of Domain Name System (DNS).
Examples
The following example illustrates the difference between a URL (Uniform Resource Locator) and a domain name:
URL: http://www.example.net/index.html
Domain name: www.example.net
Registered domain name: example.net
virtual hosting
As a general rule, the IP address and the server name are interchangeable. For most Internet services, the server will not have any way to know which was used. However, the explosion of interest in the Web means that there are far more Web sites than servers. To accommodate this, the hypertext transfer protocol (HTTP) specifies that the client tells the server which name is being used. This way, one server with one IP address can provide different sites for different domain names. This feature goes under the name virtual hosting and is commonly used by Web hosts.
For example, as referenced in RFC 2606 (Reserved Top Level DNS Names), the server at IP address 208.77.188.166 handles all of the following sites:
example.com
www.example.com
example.net
www.example.net
example.org
www.example.org
When a request is made, the data corresponding to the hostname requested is provided to the user.


Top-level domains
Every domain name ends in a top-level domain (TLD) name, which is always either one of a small list of generic names (three or more characters), or a two-character territory code. Top-level domains are sometimes also called first-level domains.
Following typre of TLDs are there:
1. Country code top-level domain (ccTLD)
2. Generic top-level domain (gTLD)
1. A country code top-level domain (ccTLD) is an Internet top-level domain generally used or reserved for a country or a dependent territory.
All ccTLD identifiers are two letters long, and all two-letter top-level domains are ccTLDs. Creation and delegation of ccTLDs is performed by the Internet Assigned Numbers Authority (IANA).
Examples:
.aeUnited Arab Emirates
.atAustria *
.auAustralia
.beBelgium *
.brBrazil *
.caCanada
.cyCyprus
.deGermany
.frFrance
.itItaly
.jpJapan
.lkSri Lanka
.muMauritius *
.mvMaldives
.mxMexico *
.myMalaysia
.ngNigeria
.nlNetherlands *
.nzNew Zealand *
.pkPakistan *
.saSaudi Arabia
.thThailand *
.usUnited States *
.zaSouth Africa *
.zwZimbabwe

2. A generic top-level domain (gTLD) is one of the categories of top-level domains (TLDs) maintained by the Internet Assigned Numbers Authority (IANA) for use on the Internet.

gTLD
Entity
.aero
air-transport industry
.asia
Asia-Pacific region
.biz
business
.cat
Catalan
.com
commercial
.coop
cooperatives
.edu
educational
.gov
governmental
.info
information
.int
international organizations
.jobs
companies
.mil
U.S. military
.mobi
mobile devices
.museum
museums
.name
individuals, by name
.net
network
.org
organization
.pro
professions
.tel
Internet communication services
.travel
travel and tourism industry related sites


Domain aftermarket prices and trends
Domain name sales occurring in the aftermarket are frequently submitted to the DN journal. The sales are listed weekly and include the top aftermarket resellers which include but are not limited to Sedo, Traffic (auctions), Afternic, NameJet, Moniker and private sales.
To date, and according to Guinness World Records and MSNBC, the most expensive domain name sales on record as of 2004 were[3]:
Business.com for $7.5 million in December 1999
AsSeenOnTv.com for $5.1 million in January 2000
Altavista.com for $3.3 million in August 1998
Wine.com for $2.9 million in September 1999
CreditCards.com for $2.75 million in July 2004
Autos.com for $2.2 million in December 1999
The week ending January 27, 2008, DNJournal reported that CNN, a cable news channel purchased iReport.com for $750,000. This signifies another turning point in domain name sales. This name has neither organic traffic, nor does it have a dictionary term alone. Instead it is a highly brandable domain name utilizing the second most popular prefix for a "dictionary" and commercial word.



Communication software

Communication software is used to provide remote access to systems and exchange files and real-time messages in text, audio and/or video formats between different computers or user IDs. This includes terminal emulators, file transfer programs, chat and instant messaging programs, as well as similar functionality integrated within MUDs.
In computer gaming, a MUD (Multi-User Dungeon), pronounced /mʌd/, is a multi-user real-time virtual world described entirely in text. It combines elements of role-playing games, hack and slash, interactive fiction, and online chat. Players can read descriptions of rooms, objects, other players, non-player characters, and actions performed in the virtual world. Players interact with each other and the world by typing commands that resemble a natural language.
Traditional MUDs implement a fantasy world populated by fictional races and monsters, with players being able to choose from a number of classes in order to gain specific skills or powers. The object of this sort of game is to slay monsters, explore a fantasy world, complete quests, go on adventures, create a story by roleplaying, and advance the created character. Many MUDs were fashioned around the dice rolling rules of the Dungeons & Dragons series of games.


INTERNET TOOLS

NETWORK INFORMATION RETRIEVAL (NIR) TOOLS
Utilities
Finger
Definition: Finger retrieves information about user registered on a host computer.
Netfind
Definition: Netfind is a research prototype that provides a simple Internet `white pages' user directory.
Nslookup
Definition: Nslookup is an interactive program to query Internet domain name servers (gives IP address).
Ping
Definition: Ping requests echo from network host; see if remote host is up.
WHOIS
Definition: WHOIS provides info on registered network names.
X.500
Definition: X.500 (OSI Directory Service) provides globally distributed directory service.
Tools
Archie
Definition: Archie locates files at anonymous FTP sites by filename search.
Astra
Definition: Astra retrieve documents from databases.
Bitftp
Definition: Bitftp allows the user to use electronic mail to obtain files at an ftp site via email.
Essence
Definition: Essence is a resource discovery system using indexes.
File Service Protocol (FSP)
Definition: FSP is a conectionaless protocol for transferring files.
File Transfer Protocol (FTP)
Definition: FTP retrieves or puts copies of files at remote FTP sites.
Knowbot
Definition: Knowbot provides a uniform interface to heterogeneous remote directory services.
Netserv
Definition: Netserv is a server for access to data files and programs of general interest.
Soft Pages
Definition: Soft Pages aids in retrieval of documents, software, and other resources from servers.
Telnet
Definition: Telnet allows a user to login to a remote computer to use applications.
Veronica
Definition: Veronica locates titles of Gopher items by keyword search.
Systems
Alex
Definition: Alex provides transparent read of remote files at anonymous FTP sites.
Gopher
Definition: Gopher locates and retrieves resources using a graph of menus.
Moo Gopher
Definition: Moo Gopher is a MUD-based gopher interface.
Wide Area Information Server (WAIS)
Definition: WAIS retrieves resources by searching indexes of databases.
World Wide Web (WWW)
Definition: WWW retrieves resources by hyptertext browser of databases.
Interfaces
Lists
For a longer list of World Wide Web broswers, see:
Cello
Definition: Cello is a DOS-based Internet browser incorporating WWW, Gopher, FTP, Telnet, News.
Emacs World Wide Web Browser
Definition: Emacs WWW browser is a means to access the World Wide Web.
Lynx
Definition: Lynx is an ASCII terminal browser for the World Wide Web.
Samba
Definition: Samba is a Macintosh browser for the World Wide Web.
Viola
Definition: Viola is a World Wide Web hypermedia browser for X Window System.
COMPUTER-MEDIATED COMMUNICATION (CMC) FORUMS
Interpersonal
Email
Definition: Email allows a user to send message(s) to another user (or many users via mailing lists).
Talk
Definition: Talk provides real-time interactive text with another user.
Group
Clover
Definition: Clover is a real-time text-based group conferencing system.
Collage
Definition: Collage is a client/server group collaboration system which includes shared dialogue, text, and graphics spaces, from NCSA.
CU-SeeMe
Definition: CU-SeeMe is a real-time, multiparty video-conferencing system for the Internet.
Listproc
Defintion: Listproc is a system that automates mailing lists and archives.
LISTSERV
Definition: LISTSERV is mailing-list server for group communication.
Majordomo
Definition: Majordomo is a mailing list manager.
Moo
Definition: A Moo is an object-oriented Multiple User Dialogue (MUD).
Multiple-User Dialogue (MUD)
Definition: MUDs are real-time interaction usually for social role-playing. Note: Variants include MUCK, MUSH, MUSE, MOO.
Procmail
Definition: Procmail is a mail manager--create mail-servers, mailing lists, sort your incoming mail.
Mass
Interactive Webbing (IW)
Definition: Interactive Webbing gives people a common space for network distributed multimedia writing.
Internet Relay Chat (IRC)
Definition: IRC provides real-time, many-many text discussion divided into channels.
Internet Talk Radio (ITR)
Definition: ITR is an audio multicast on the Internet.
Mbone
Definition: Mbone is a live audio and video multicast virtual network on top of Internet.
Usenet
Definition: USENET provides asynchronous text discussion on many topics separated into newsgroups.