Personal Growth Informatics Practices Class 12 Ebook


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eBook features: Highlight, take notes, and search in the book; Page numbers are just like the physical edition; Format: Print Replica; Due to its large file size, this. A Text Book on INFORMATICS PRACTICES. (Class XII). To Download Click Following link: Part Courtesy: CBSE. << Go Back To Main Page · Downloads. A Text Book on Informatics Practices. (Class XI). Contents: INFORMATICS PRACTICES. myavr.infoRE CONCEPTS; myavr.infoRE CONCEPTS.

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Download latest NCERT Book for Class 12 Informatics Practices. The books can be download in pdf format for Class 12 Informatics Practices. Download entire. CBSE Books -Class XIIDownload ePub Reader · Home · Classes I-V · Classes VI -VIII · Classes Informatics Practices. Class: XII. Lang: English. Sub: IT. book. Ip Book for Class Xii - Cbse - Free ebook download as PDF File .pdf), Text File . txt) or read book The text book of Informatics Practices for Class XII is ready.

Which property you will set to ensure that only one item gets selected in a list. Which method you would use to insert Hello at 10th position in the Text Area control. Which method you would like to use to insert an Icon picture on a Push Button. Which method would you like to hide a push button jButton1.

Which Event Handler method would you like to run with a list to handle its items selections? Which property would you like to set to make a Combo editable? What is Layout Manager? Discuss briefly about layout managers offered by NetBeans?

Name three commonly used properties and methods of the following controls. What is dispose used for? What is the significance of following properties of a text area? What is the significance of a button group? How do you create a button group?

Discuss about some commonly used properties of lists and a combo boxes. What methods obtains the current selection of a combo box? Give a code example. Identify the error in following code that is written in action event handler of a button namely OKBtn.

What is the role of a return statement in a method? How many values can be returned? What is composite data type? What is user defined data type? Can every class be referred to as a user-defined data type? What is this keyword? What is its significance? Define a method. What is method prototype and signature? Discuss some advantages of using methods in a program. How are parameterized constructors different from non-parameterized constructors? List some of the special properties of the constructor methods.

Differentiate between Instance member and static members of a class. What do you mean by actual and formal parameters of a method? Given the method below write an ActionPerformed event method that includes everything necessary to call this method.

Write a method in Java to do the following assume method name and parameter yourself a. A method takes two integer numbers and returns sum of them. A method that takes an integer number and returns 1 if it is even otherwise returns 0. A method takes an integer parameter and returns its factorial e. A method takes an integer parameter and returns true if number is prime otherwise returns false.

A method that takes two integer arguments and returns 0 if both the arguments are equal, return -1 if the first argument is smaller than the second and 1 if the second argument is smaller than the first? We would like to make a member of a class visible in all subclasses regardless of what package they are in. Which key words would achieve this? What will be the scope of: a A public class c A protected class? What does round return if a negative float value is passed to it?

What are use of pow and round method of math library , with an example? Name the package you need to import for performing input and output.

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Which package is by default imported in every Java program? What is the difference between equals and equalIgnorecase string functions? What is the difference between length and capacity string functions? Which command creates a package in java?

What is friendly access of class member? How are private members different from public members of a class? How are protected members different from public and private members of a class? How does a class enforce information hiding?

Write a program to extract a portion of character string and print the extracted string. Assume that m characters are extracted, starting with nth character?

Write a program, which will read a text and count all occurrences of a particular character. How do we design a package? Define a class for date with required data members like day, month, year and functions like constructors, printing a date, validating a date etc. Using the above defined class date create two objects such as birthDate and joinDate.

Define a class named Book with the following details- assume data type your self Data members- Title, Author, Subject, Edition and Price. Method MembersDisplay to display the details of the book. Parameterized constructor method to initialize data members with given value. Non-parameterized constructor to initialize String data members with and numeric members with 0.

Discuss its various forms. How are these related? Define Inheritance? Why it is an important concept of in object Oriented Languages. How does the visibility mode control the access of members in the derived class?

Explain with examples. What is the difference between protected and private members? How are arguments sent to the base constructors in multiple inheritances? Explain with suitable code example? If a base class as well as its derived class contain a member function with the same name, say func , can an object of the derived class access both these functions i.

Define an abstract class and abstract methods. What is an interface? What is the use of Interface. What do you mean by Overriding Methods and Hiding Member variables? What do you mean by Method Overloading? What conditions to fulfilled to overload a method?

We know that a private member of a base class is not directly accessible by a subclass. Is it anyway possible for the objects of a derived class to access the private members of the base class?

If yes, how? Remember, the base class cannot be modified. What is a dialog? What all classes can you use to create dialogs in Java? Name them. Which component of Swing Windows lets you create a general purpose dialog? Which component of Swing Windows lets you create built in dialog styles? How many dialog types does Java support? Which import command do you need to write before creating an Option Pane dialog window?

Which method would you invoke to display i message dialog ii confirm dialog iii input dialog? Which methods are used to insert and remove rows from an existing table?

How do you provide data to a table? What type of value is returned by Confirm Dialog? What is the difference between a general purpose dialog JDialog type dialog and a pre-defined dialog JOptionPane type dialog?

Write command to display a message dialog to display prompt as Hello World, title as My dialog and icon as question icon. By default, what all buttons are shown by : i Confirm dialog ; ii Message dialog ; iii Input dialog 4. Write code fragment to obtain a number from user and display whether it is odd or even. Make use of dialogs only. Write code fragment to obtain a temperature-value in degree Fahrenheit and display it in Celsius. Write code to add a row to a table atbl containing details number, square.

Write code to remove first and last row of a table namely atbl. What is a Table Model? What is its role in a Table control? What is a connection? What does Class.

Informatics Practice Handbook-Class XII-CBSE

What is result set? What does DriverManager do? Which methods are used to execute SQL queries? Write a statement to register driver com. Driver with DriverManager? Name the methods for the following? Which package must be import to implement databse connection?

What all task are performed using JDBC? What is following code doing? What are steps to connect to a database from with java application?

What is difference between executeQuery and executeUpdate method.? Write code to a mysql database namely school and then fetch all those records from table student where grade is A. Find errors in the following code : Import java. What do you mean by Web Browser, and Web Server? What is WWW? How does it function?

Comment on these statements? What is URL? What are its components? What is CGI? How it works in Dynamic web Page service?

Differentiate between Static and Dynamic Web Service? Assignment No. What is HTML? Why it is used? What is Tag? Differentiate between Container and Empty tag? What is an Attribute? Write the HTML code for the followings. What types of list are supported by HTML? Which three tags let you create the definition list? Which three tags let you create the i un numbered lists?

What is a table? Which tag is used to create tables in HTML? Which attributes are used to give border to a table? Which attribute lets you control the display of select border sides of a table? Which attributes is used to control the inside table border?

How is spacing in cells of table controlled? How can you specify following in table? What tag is used to specify i Table data ii Table header iii Table row? Name the attributes used for following? What are forms? Which methods and actions are commonly used with Forms? Name different control types supported by HTML forms. How will you nest an un order list inside an ordered list? How would you indent a single word and put a square bullet in front of it? Write code to produce following HTML tables?

What is XML? What do you mean by Extensible in XML?. Name some markup language based on XML. What is prolog? What is data instance? Write some features of XML. What is valid document? Name a meta-language? What is the role of Style sheet in XML file system? Define the following terms: I DBMS ii View iii data security iv data integrity v Relation vi domain vii tuple viii attribute ix Degree x cardinality 1.

What is data redundancy? What are the problems associated with it? What is data model? Name various data model? How do database management systems ensure data security and privacy? What do you mean by referential Integrity?

How it is enforced in DBMS? What is Key? What types of commands are used in the following categories? DDL 2.

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DML 3. TCL 4. System control commands 7. What do you mean by Data dictionary? What it consist of? What is data type? Name some data types available in MySQL. Compare Char and Varchar data types? Which keyword eliminates the redundant data from a query result? How would you display system date as the result of a query?

Which function is used to substitute Null values in a query result? Which operator concatenates two strings in a query result? What command is used for1. To view the table structure. Which comparison operator is used for comparing?

Define a function. Why they are useful? Write commands to display the system date. Write a command to display the name of current month.

Write command to print the day of the week of your birthday in the year Write commands to find out and display the approximate age of an employee as on joining date. Which is a constraint? Name some constraint that you can apply to enhance database integrity.

What is Primary key? How would you view the structure of table Dept? What is Database Management System? Discuss its advantages. What is Data Abstraction? Draw a diagram explaining various levels of data abstraction.

What is meant by Data independence? Explain difference between Logical and Physical data independence. What is MySQL? Describe its features? How constraints ensure the validity of data? Explain various types of constraints with example. How do you define foreign key in your table? What is default value? That's why they are widely used for communication, both indoors and outdoors. These waves are omni-directional, so the transmitting and receiving antennas need not be aligned.

Recall when you throw a stone in a pond, circular waves are generated and spread outwards. Similarly, radio waves are generated by the transmitter and spread in all the directions.

Relatively inexpensive than wired media. It offers ease of communication over difficult terrain The transmission can be interfered by motors or other electrical equipment Permission from concerned authorities is required for use of radio wave transmission Less secure mode of transmission Micro waves have a frequency range of MHz 0.

This range has some overlapping portion 0. Microwaves travel in straight lines and cannot penetrate any solid object. Therefore for long distance microwave communication, high towers are built and microwave antennas are put on their tops.

Distance between two microwave towers depends on many factors including frequency of the waves being used and heights of the towers. These waves travel in straight lines and therefore the sending and receiving antennas have to be aligned with each other. An example of usage of microwaves for communication is as follows: In the big cities where land is very costly and a lot of formalities have to be completed to get permission to dig land for cabling, microwave antennas can be put on top of high rise buildings and communication can be started in a short time.

Free from land acquisition rights Relatively inexpensive than wired media Offers ease of communication over difficult terrain The transmission is in straight lines so the transmitting and receiving antennas need to be properly aligned line of sight transmission Infrared waves have a frequency range of GHz to THz. Infrared waves are so called because they have a frequency range of just less than that of red light. These waves are used for short range communication approx.

Home-entertainment remote-control devices, Cordless mouse, and Intrusion detectors are some of the devices that utilize infrared communication. These waves are easy to build but have a major drawback- they do not pass through solid objects try standing between your remote control and your television and see if it still works.

On the other hand, these waves do not pass through solid walls is a plus point also. Because of this, infrared system in one room of a building will not interfere with a similar system in adjacent rooms you cannot control TV in another room with the remote in your hand in a room. It is a line of sight transmission; therefore information passed to one device is not leaked to another device. No government license is required for their use It is a line of sight transmission, therefore at a time only two devices can communicate.

The waves do not cross any solid object in between Performance drops with longer distances Bluetooth technology uses radio waves in the frequency range of 2. This technology is used for short range communication approx. Baby monitors, door openers, and cell phones are some of the devices that utilize Bluetooth communication.

Characteristics of Bluetooth Transmission: Line of sight between communicating devices is not required. Think Why? Bluetooth can connect upto eight devices simultaneously. Slow data transfer rate upto 1Mbps. Satellite links are used for very long distance wireless communication which may range from intercity to intercontinental. Transmission from the earth to a satellite is known as uplink.

Transmission from a satellite to the earth is known as downlink. There are multiple micro wave frequency bands which are used for satellites links. Frequency used for uplink varies from 1. Downlink frequency is always lower than the uplink frequency. For example, the uplink frequency is 6. A communications satellite is a relay station in orbit above the earth that receives, regenerates, and redirects signals carried on a specific frequency.

The satellite system is very expensive but its area coverage and fringe benefits compensate for the expenses. Communication satellites are normally owned by governments or by government approved organizations of various countries.

Satellites cover large area of earth Since communication over very long distances is possible, this becomes a commercially attractive option.

This system is expensive Requires legal permissions. Some of these devices are: A computer communicates with other computers on a network with the help of an NIC only. A hub has ports into which the cables from individual computers' NICs are inserted. This way each computer's NIC is connected to hub and hence all the computers are connected together. Whenever a computer has to send some information to some other computer s , the information is sent by the NIC to the hub.

Then the hub re- transmits this information to the other computers attached to it. The computer s for which the information is intended receive s this information and accept s it. Other computers on the network simply reject this information. A switch is an intelligent hub. It looks exactly like a hub. It has the same function as that of a hub: But the difference between the two is in the way they re-transmit the received information.

Unlike a hub, instead of broadcasting sending to each device attached to it the received information, a switch sends the information selectively only to those computers for which it is intended. This makes a switch more efficient than a hub. A Switch is an intelligent device that connects several nodes to form a network and redirects the received information only to the intended node s. When the data is transmitted over a network for long distances, the data signal gets weak after certain distance.

This distance depends on the data transfer range of transmission channel being used and can be from a few meters to a few kilometers. If the signal becomes weak, it cannot reach its destination. Therefore, some device is required which can re-strengthen the data signal before it gets too weak. Repeater is such a device. A repeater regenerates the received signal and re-transmits it to its destination A Repeater is a device that is used to regenerate a signal which is on its way through a communication channel.

A repeater regenerates the received signal and re-transmits it to its destination. There are a large number of computer networks in this world. As common examples you can consider your school's computer network, ATM network of a bank, a big company's computer network spread over a city, etc. There are thousands of computer networks that exist.

These networks use different hardware and software. Many times these networks need to communicate with each other. For example, companies X, Y, and Z do business with each other and therefore they want to interconnect their computer networks. Another example is the internet which contains a large number of different types of networks spread over the globe.

Different networks are sometimes incompatible Switch: It is like a group of persons using different languages for conversation. When two or more networks using different hardware and software have to be connected, some device is needed which can translate one network's language into the other's.

A gateway is a device, which is used to connect different types of networks. A gateway is capable of understanding address architectures used in different networks and seamlessly translate between these address architectures.

A Gateway is a device, which is used to connect different types of networks and perform the necessary translation so that the connected networks can communicate properly. Before we start discussion on network topologies, let us understand the term 'NODE'.

Any device Computer, Scanner, Printer, etc. Suppose you are working on a PC at your home and then you connect it to internet. As soon as it becomes a part of internet which is a computer network , it becomes a node.

Similarly, in your school, all the computers which are linked to school's computer network are nodes. A Node is a device, which is directly connected to a computer network.

It can be a computer or any other device like printer, scanner etc. Once we know about different communication media and devices to form a computer network, we can procure these media and devices and start constructing a computer network. Suppose we have 10 computers and we want to interconnect them to form a network.

How can we interconnect them? Recall the puzzle given in the beginning of this lesson.

Is that not similar to the problem of connecting nodes in a network? A Topology is an arrangement of physical connections among nodes in a network. There exist different network topologies. Let us discuss a few of them. In bus topology all the nodes are connected to a main cable called backbone. If any node has to send some information to any other node, it sends the signal to the backbone.

The signal travels through the entire length of the backbone and is received by the node for which it is intended.

A small device called terminator is attached at each end of the backbone. When the signal reaches the end of backbone, it is absorbed by the terminator and the backbone gets free to carry another signal. This prevents the reflection of signal back on the cable and hence eliminates the chances of signal interference. Characteristics of Bus topology: It is easy to install.

It requires less cable length and hence it is cost effective. Failure of a node does not affect the network. In case of cable backbone or terminator fault, the entire network breaks down.

Fault diagnosis is difficult. At a time only one node can transmit data. Bus Topology:. Tree Topology: This signal is then broadcast in case of a hub to all the nodes but is accepted by the intended node s.

In the case of a switch the signal is sent only to the intended node s. Bus Topology Star topology generally requires more cable than bus topology.

Characteristics of Star topology: It is more efficient topology as compared to bus topology. It is easy to install It is easy to diagnose the fault in Star topology.

Tree topology is a combination of bus and star topologies. It is used to combine multiple star topology networks. All the stars are connected together like a bus.

This bus-star hybrid approach supports future expandability of the network. It offers easy way of network expansion Even if one network star fails, the other networks remain connected and working.

A computer network can be set up after procuring all the required hardware. But the network devices will be able to communicate with each other only after they know the rules of communication. Think of a group discussion session where all the participants can speak. Each participant can speak a lot. But the group discussion can be started and can be conducted well if each participant knows the rules of discussion.

If all the participants start speaking suddenly and suddenly they stop, or a person stands up randomly and starts interrupting the discussion, or any such thing happens, the group discussion cannot be conducted at all. A more complex situation exists in the case of computer networks where the participating devices have no common sense and they follow each defined rule to the T.

So it is essential that the rules of communication are very well defined. A set of rules is also known as a protocol. Protocols generally includes rules of how and when a device can send or receive the data, how is the sent data packaged, and how it reaches its destination. There are a number of protocols defined for computer networks. HTTP is used to transfer all files and other data collectively called resources from one computer to another on the world wide web. This transfer of requests and responses is done following HTTP protocol.

It is the basic protocol of the Internet. When data is to be sent from one computer to another over internet, it is first broken into smaller packets which are actually sent. When these packets are received by the receiver computer, they are assembled into the original message.

This job of dividing the original message into packets and re-assembling the received packets into the original message is done following TCP protocol.

Internet protocol is followed to ensure that each of these packets gets to the right destination. Different packets from the same message may be routed differently, but they reach the same destination and are reassembled there. It is a protocol for direct communication between two computers, typically a personal computer connected by phone line to a server. PPP is used over many types of physical networks including cellular telephone, serial cable, phone line, trunk line, specialized radio links, and fiber optic links.

You can explore the net to find more about these protocols. Know More! A computer network may span any amount of geographical area. It can be on a table, in a room, in a building, in a city, in a country, across continents or around the world.

On the basis of area covered computer networks are classified as: It can cover an area of a few meters radius. When you have to transfer songs from one cell phone to another, you set up a PAN of two phones. There can also be multiple devices in PAN. It can cover an area of a few meters to a few kilometers radius. A networked office building, school, or home usually contains a single LAN, though sometimes one building can contain a few small LANs Like some schools have independent LANs in each computer lab.

Occasionally a LAN can span a group of nearby buildings. In addition to operating in a limited space, a LAN is owned, controlled, and managed by a single person or organization. It can cover an area of a few kilometers to a few hundred kilometers radius.

A network of schools, or banks, or Government offices etc. All types of communication media guided and unguided are used to set up a MAN.

A MAN is typically owned and operated by a single entity such as a government body or a large corporation.

A good example of a MAN is the interconnected offices of a state government. It can cover an area of over hundreds of kilometer radius. All types of communication media guided and unguided are used to set up a WAN.

The best known example of a WAN is the internet. But for proper communication, the nodes should be uniquely identifiable. If a node X sends some information for node Y on a network, then it is mandatory that nodes X and Y are uniquely identifiable on the network. Let us see how this is achieved. Each NIC has a universally unique address assigned to it by its manufacturer. MAC addresses are digit hexadecimal or 48 bit numbers.

By convention, MAC addresses are usually written in one of the following two formats: The second half SS: For example, in the following MAC address, C9 indicates that the manufacturer is Intel Corporation. And the last three numbers Every machine in a network has another unique identifying number, called its IP Address.

An IP address is a group of four bytes or 32 bits each of which can be a number from 0 to A typical IP address looks like this: Do you recall IP protocol? IP protocol identifies a machine with its IP address to route the packets. MAC address is used only when a specific machine is to be targeted. For example, suppose we want to block a specific PC to access some network resource.

An IP Internet Protocol address is a unique 4 digit hexadecimal number assigned to each node on a network. IP address settings of a node can be changed by the user IP Address: There are two versions of IP addresses: Using IPv4 only 2 approximately 4 billion distinct devices can be addressed. In the current scenario and in the near future, this is a small fraction of the number of objects which need to be allocated IP addresses.

As the human population and also the number of devices which need to be online mobile phones, home appliances, personal communication devices, etc. To address this problem IPv6 was developed and it is now being deployed. IPv6 also includes an important feature: There are many other features of IPv6. You can explore the internet and find more information about IPv6. In fact, the IP address is assigned by the network administrator or the internet service provider while the MAC address is assigned by the manufacturer.

Thus if a computer is transferred from one network to another, its IP address gets changed where as the MAC address remains the same. From the IP address it is usually possible to track the tentative location of the computer but this is not the case with a MAC address. So, whenever we have to communicate with a computer on internet, we can do so by using its IP address. But it is practically impossible for a person to remember the IP addresses of all the computers one may have to communicate with.

Therefore, a system has been developed which assigns names to some computers web servers and maintains a database of these names and corresponding IP addresses. These names are called Domain Names.

Examples of some domain names are cbse. Domain names are used in URLs to identify particular Web servers. For example, in the URL http: Domain Name: For example, in the domain name , in is the primary domain name; nic is the sub-domain of in; cbse is the sub-domain of nic.

There are only a limited number of top level domains, and these are divided into two categories: For example: Generic Domain Names: A domain name usually has more than one parts: Domain Name Resolution is the process of getting the corresponding IP address from a domain name. It happens as follows: Suppose you mention a URL in the web-browser to visit a website.

The browser first checks your computer to find if the IP address of the server corresponding to the Domain Name embedded in the URL is present. If this address is present then with the help of this address, the corresponding server is contacted and then the website opens in your browser. Otherwise the browser sends this domain name to some specific servers called domain name servers to find the corresponding IP address.

Once the IP address is known, the server is contacted and then the website opens in your browser. Domain Name Resolution is the process of getting corresponding IP address from a domain name. These services were originally performed under U. Computer networks are communication highways on which the data travels.

Data travels on a network when an e-mail is sent or received, any transaction is made using a credit or a debit card, a web site is accessed, chatting is done, or any other work is done on a network. Data travelling over a network is vulnerable to attacks and thefts. There are some people who want to illegally access this data for any reason: These people Know More! As the data goes from one point to another point on the Internet, for example, it may pass through several points along the way, giving other users the opportunity to access, and even alter it.

Even other users on your system may maliciously transform your data. Unauthorized access to your system may be obtained by intruders, who then use advanced knowledge to impersonate you, steal information or even deny your access to your own resources.

Therefore, there is always a threat of some kind of attacks on computer networks' security. Some kinds of attacks on network security are as follows: A Denial of Service DoS attack is an attempt to make one or more network resources unavailable to their legitimate users.

Informatics Practices A text book for Class 12

Examples of such attacks are: Denial of Access to Information: Corrupting, Encrypting, or changing the status of information so that it is not accessible to its legitimate user. Denial of Access to Application: Forced shutting of an application as soon as the user opens it.

Denial of Access to Resources: Blocking a resource, may be a printer or scanner or USB port, of a computer from proper working. Denial of Access to a Website: Continuously sending bulk requests to a website so that it is not available to any other user.

An Intrusion problem is an attempt to mischievously steal some information from someone's computer. Examples of Intrusion are: Have you ever tried to read someone else's slam book secretly? This is snooping. Do you think your parents try to secretly check your mobile phone to find its contents? If yes, then what your parents are doing is snooping.

In context of network security, snooping refers to gaining unauthorised access to another person's or organization's data. This may be done in a number of ways: Denial of service attacks: Intrusion Problems: Snooping -. Reading the files on someone's computer in an unauthorised manner Using some softwares which keeps track of the activities and data being sent or received on someone's computer.

Snooping refers to gaining unauthorised access to another person's or organization's data. Do you ever find that when you are talking to someone else, another person is secretly trying to listen to your talks? What that person is doing is 'eavesdropping'. Have you ever tried to secretly listen to the conversation between two teachers regarding your class?

If yes, then what you have done is 'eavesdropping'. In context of network security Eavesdropping refers to unauthorised access to another person's or organization's data while the data is on its way on the network.

By setting up parallel telephone lines. By installing some software spyware in the target computer. By installing some receiver which captures the data while on its way. The term Network Security refers to all activities undertaken to protect a computer network from attacks to its security. This covers protection of computers in the premises and data on the network from both internal and external attacks.

To protect a network from security attacks, a number of steps are taken. These steps include: By assigning login names and strong passwords to the users of a system, it can be ensured that only authorized people access a computer. This helps in increasing the computer as well as network security. A strong password is the one which is easy to. Eavesdropping - Login-Password: On the other hand a weak password is generally the name of a person or organization, the registration number of a vehicle, year of birth of a person and so on.

A weak password can be cracked in a few attempts. Examples of strong passwords may be raavanisdead raavan is dead - with spaces removed , 2aur2paanch name of an old Hindi movie or anything like that.

These days anti-virus softwares work against not only the virus but also against almost all kinds of malware. Therefore by installing a full version legal not the pirated one or freeware anti-virus software network security can be increased. A data file on a computer can be created, read, or modified.

An application file can be run or executed. Accordingly, different rights privileges can be given to different users of a computer to perform one or more of these tasks. For example, suppose there is a data file containing students' marks in a school. The system administrator has created that file. If there is a need to create another such file, then again only the system administrator can create it. So, system administrator is given the 'Create' right. A teacher can read this file to go through the marks of the students.

She can also enter or alter the marks in this file. Therefore a teacher has 'Read', 'Write', and 'Modify' rights to this file. The students can only view their marks; therefore, the students are given only the 'Read' right to this file.

If report cards have to be printed for a class, the class teacher makes a request to the computer operator, who can run a program to print the report cards. This computer operator has been given the 'Execute' right to the application program which prints the report cards.

This way by giving appropriate rights to respective users, computer security as well as network security can be increased. Let us now take an example to see how can a computer network be setup.

Anti Virus Software: File Permissions: Setting up a computer network 30 office in Chennai Tamil Nadu and schools in various parts of the globe. The 'SF School' will have 3 computer labs with 30 computers in each, 1 Accounts office with 3 computers, 1 Administrative block with 5 computers, and 1 Principal's office with 1 computer. Let us see how a computer network can be set up in the school. First of all we can draw a rough sketch of the school with computers at various locations as follows: Independent LANs can be set up in each of the following buildings: For this 1 switch with suitable number of ports will be required in each of these buildings.

More than one switches can be used in computer labs if a switch with more than 30 ports is not available. Two internet connections broadband for high speed can be procured in Administrative Office. Two connections should be procured from two different ISPs so that i Internet connection in Administrative office can be kept separate from the other Computer labs where students may do a lot of experimentation.

This interconnection will ensure that each building is directly connected to Admisnistrative block. This way internet connection will be available in each building irrespective of the status of the other building. Server if any of the school may be placed in Administrative block so that it remains safe physically and a firewall can be set up so that the whole network remains safe from any kinds of virus or intrusion attacks. There is no need to do any extra efforts or expenses to link the school to its head office.

This can be taken care of using the internet connections. Communication Media are the links over which the data is sent from one node to another over a network.

Hardware devices used to form a network are: Repeaters are used to regenerate the signal which gets weakened during its transmission. Repeater are generally used to connect two networks which are more than 80 m apart. Gateway is a device which connects two different types of networks.

Basic network topologies are bus, star and tree. Each machine on a network is identified by its IP address. Network security can be increased by applying some preventive methods.

The scenario of how computers are networked is changing very fast. Before full implementation of a technology, a new technology is visible at the horizon.

One such new technology is 4G. Change from one generation to another involves a major advancement in the technology used. Today we are living in the world of 3G. Soon, 4G will rule the mobile market. Unlike previous generations of mobile technology, 4G mobile technology will be used for internet access on computers also, and it will be totally wireless!

You can explore more about 4G technology on the internet. This is also referred to as 'Green IT'. You can explore more about Cloud Computing on the internet. Which of the following topologies is a combination of more than one topologies? Bus b. Tree c. Star d. None of these 2. Which of the following is used for wireless communication? Optical Fiber b. UTP cable c. Radio Waves d. Coaxial Cable 3. Which of the following is not a transmission medium? Telephone Network b.

Coaxial Cable c. Modem d. Microwaves 4. IP addresses of two computers on a network: Can be the same b. Cannot be the same c. Are not defined d. Must match with a third computer 5. Bluetooth can be used for a. Long distance communication b. Short distance communication c.

In mobile phones only d. None of the above 6. Micro waves are a. Uni directional b. Omni directional c. Guided media d. Not used for communication. Snooping is a. A threat to data security b. Not a threat to data security c. Good for laptops d. A topology 8. A repeater a. Regenerates the received signal b.

Destroys the received signal c. Can be used as a hub d. None of the above 9. Satellite links are generally used for a. PANs b. LANs c. MANs d. All of the above A domain name maps to a. A URL b. An IP address c. A website d. All of the above 1.

What is a computer network? What are its advantages? What is meant be communication channels? Give two examples of guided media and two examples of unguided media. Setting up a LAN b. Transfer of data from a laptop to a mobile phone. Transfer of data from one mobile phone to another. Creating a remote control that can control multiple devices in a home. Very fast communication between two offices in two different countries. Communication in a hilly area g. Communication within a city and its vicinity where cost of cabling is too high.

Why is a switch called an intelligent hub? When is a repeater used in a computer network? Diagramatically show how would you connect 6 PCs, 1 server, 1 printer, and 2 scanners in a. Star topology b. Bus topology 7. Two engineers in the same room have connected their Palm-tops using bluetooth for working on a Group presentation. Out of the following, what kind of Network have they formed? What is a MAC address?

Give some examples of domain names and URLs. How is a domain name different from a URL? What is domain name resolution? Define Network security? What kind of attacks can be made on data and computer networks? List some methods which are used for network security. Differentiate with examples wherever possible between: Hub and Switch d.

Guided and Unguided media Write one advantage of star topology over bus topology and one advantage of bus topology over star topology. Ishika Industries has set up its new production unit and sales office at Ranchi. The company compound has 4 buildings as shown in the diagram below: Suggest a cable layout of connections between the buildings so that each building is directly connected to Administrative Office. Suggest the most suitable place i. Suggest the placement of the following devices with justification: The Administrative office of this unit is to be linked with the head office situated in Patiala Punjab.

What will be the most economical way to do this? Justify your answer. Find the IP addresses of at least five computers in your school.

Find the MAC addresses of at least 2 computers in your lab. Then verify their manufacturer's name on the net. Find the layout of LAN in your school's labs. If you think some modifications can be done in the layout, note these down in your notebook.

Find the name of Internet Service Provider of your school. Find the IP address of your school's web site. Team size recommended: A school building is divided into 4 blocks A, B, C, and D.

Each block is at a distance of 25m from its adjacent blocks.

Each block has 1 computer lab with 15 computers each. Each block also has some other rooms maximum 10 with 1 computer each. The school has only one internet connection. The computer network in the school has to be restructured with the following goals in mind: Each lab has to have an independent LAN. All the computers in the school should have internet access.

The school does not want to have any other new internet connection. For internet access a computer should be dependent only on one point and not on multiple points. It means that if the internet connection is active, any computer should be able to access it directly irrespective of whether some other computer in the school is ON or OFF. Any two computers in the school should be able to communicate with each other irrespective of whether any other computer in the school is ON or OFF.

The job of each team is to design a layout for this new network structure. Each team has to specify The layout of the network structure diagrammatically. How the design will be able to fulfill all the mentioned requirements. Find the average price and specifications of each of the following network devices in the market: Each team has to specify: Different types of switches available in the market, their prices, and number of ports.

Names of brands of UTP Cable available in the market, along with their prices. Different types of LAN cards available in the market along with their prices.

Computers and internet have transformed our lives. It is next to impossible to modify the compiled version of the software. At times we feel the need to change certain features of the software but are unable to do so. In this chapter we will study about software which are developed collaboratively and they can be modified as well.

Well, have you noticed something common in all these terms. That's right! It is the word free. People often correlate this word with the cost.

They think that these software are available for free. Practically, these software can be acquired at very little or no cost. But, here, "free" means freedom to use. These software can be studied, copied, redistributed freely and even modified according to one's need without seeking any kind of permission. In order to modify such software the developers also provide the source code to the users.

There do exist software which are actually "free" in the sense of price.

Buying Options

These are known as Freeware. Lots of freeware can be downloaded from the internet for various different purposes such as currency converters, drawing graphs and charts etc. But freeware may not come with the source code. Therefore freeware differ from free software.

The focus in this chapter is on free software rather than freeware. The first formal definition of "free software" was given in by Richard Stallman, a long time member of the hacker community at the MIT Artificial Intelligence Laboratory.

He insisted that a free software should give the following four freedoms to users: Freedom 0: The freedom to run the program for any purpose. Freedom 1: The freedom to study how the program works, and change it to make it do what you wish. Freedom 2: The freedom to redistribute copies so as to help your neighbour. Freedom 3: The freedom to improve the program, and release your improvements and modified versions in general to the public, so that the whole community benefits.

You can get more information on open source software from opensource. Operating systems and Desktop environments Linux - Operating system kernel Ubuntu - Linux distribution with full complement of software for everyday use. Songbird - similar to iTunes with built-in browser. Comparable to Microsoft Office.

Unix-like operating systems are built from a collection of libraries, applications and developer tools, plus a kernel to allocate resources and to talk to the hardware. GNU is often used with the Linux kernel. Firefox is a free and open source web browser produced by Mozilla Foundation.

Open Office is the leading open source office suite for word processing, spreadsheets, presentations, databases etc.

It is available in many languages. It stores files in open document format ODF for data interchange that is its default file format. The NetBeans community has since continued to grow, thanks to individuals and companies using and contributing to the project.

A commonly voiced concern about open source software: Open Source Software Security "If anyone can contribute to open source software, doesn't it become a free-for-all full of loopholes?

Getting a change incorporated into an open source project is thus rather like getting an article published in a scientific journal. Open source software is more heavily tested than their commercial counterparts as it can be downloaded by anybody around the world and any one of them can discover a bug or security flaw and submit those reports back to the project. Also the loop-hole or bug is available to every one and the customer can take the preventive measure accordingly and fix comes faster.

The Open Document format ODF is a format for office documents, such as spreadsheets, databases, presentations and word-processing documents. Open Document is a free and open format. For governments, businesses, archivists and others, it's critical to store documents in a way that can be read for years to come.

Proprietary digital file formats are typically changing with every new version of the software, so there should be some format which supports files created in any application. The data should be the center of importance not the application. Office suite applications, as always, need a file format that is designed to organize the data when it moves away from the application.

People with different machines in different places should be able to open and edit the data in a file. ODF offers an open alternative to the formats used by all of the existing Office application versions for text, spreadsheet, presentation, and other kinds of documents.

Open Document's main file extensions are. These will be more commonly recognized when more people and organizations adopt Open Document-ready software. Ogg Vorbis is a new audio compression format developed by Xiph.

It is an open, patent-free, professional audio encoding and streaming technology with all the benefits of Open source. Let us recall from Annexure I of Class XI that in order to communicate with the computers some kind of a binary code is required. In this regard, a detailed study was made on BCD code which is a 4 bit code. However, BCD code is not sufficient enough to accommodate even all the characters of English alphabet and digits.

To accommodate all these, a higher bit code is required. In the earlier days most computers were using an 8 bit system. This extra bit gave computer developers lot of empty spaces which was used for different purposes. In order to work with Indian languages, these unspecified spaces were used for Indic characters.

The efforts were very creative and gave good results despite the fact that there was no or very little support from the operating systems. Since no general rules and methodologies were adopted in developing Indic characters, different developers developed these characters in their own ways.

This created compatibility issues across different programs and across different operating systems. For example browsers like Internet Explorer did not support all Indic characters and displayed distorted texts. On one hand, more and more work had been undertaken to facilitate the use of Indian languages on computers but on the other hand it was becoming difficult to maintain consistency across different programs developed for the same set of Indic characters. In such a scenario, it was important to have a common standard for coding Indian scripts.

The Indic scripts are a family of abugida alphabetic-syllabary writing systems.Suppose you are working on a PC at your home and then you connect it to internet. The loop has four different elements that have different purposes.

Denial of Access to Information: On the basis of their configuration, fonts are categorized as static fonts and dynamic fonts. Compare Char and Varchar data types? Name different control types supported by HTML forms.

How has society benefitted for e-business? Future Trends You can get more information on Indian script keymaps from http: However, as different materials require different containers, and so we used different data types to hold different values.

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