12th CBSE Computer Science Question Bank 09

7/30/2019 12th CBSE Computer Science Question Bank 09

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MAHARISHI VIDYA MANDIR SR. SEC. SCHOOLCLASS : XII COMPUTER SCIENCE

THEORY QUESTIONSCHAPTER NAME : STRUCTURES

1. Define a structure.

Ans. A structure is a collection of variables of different data types which arereferred under one common name.

2. What is the need for structure ?

Ans. To store any information in the form of record which contains information ofdifferent data types, the structure is used.

3. Differentiate between structure and class.

Ans.

Structure Class

All members are public by default All members are private by default

4. Differentiate between array and structure.Ans.

Structure Array

Collection of variables of different data

type.

Collection of variables of same data

type.

5. What is nested structure ? Give an example.Ans. A structure within another structure is called nested structure.

Eg. struct date{ int d,m,y;};

struct emp{ int eno;char ename[25];date doj;};

6. How to refer the structure elements outside the structure ?Ans. The structure elements are referred using the structure variable name followedby the dot operator.

7. When the memory is allocated for structure ?

Ans. The memory is allocated for structure only when the variable is declared of that

type.

8. When does the structure assignment takes place ?

Ans. The structure assignment is possible only when both the sides of theassignment operator has the variables of the same structure type.

9. What is typedef statement ? ExplainAns. Typedef statement is used for defining an alternative name for the datatype.typedef int a;

In this statement a is given an alternative name for int data type.


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10. What is #define ? Explain

Ans. It is used for defining constants and functions. It is a pre-processor directive.Eg. #define p 3.14#define str Maharishi Vidya Mandir

#define cube(a) a*a*a

11. What is the advantage and disadvantage of using #define ?Ans. Advantage :When we want to make any change in the constant value we can change it only in

the statement and it will be reflected in the program which uses the value. Functionoverhead is avoided in #define macro.

Disadvantage is that the function can include only one statement. Data types willnot specified any where in the statement.

12. What is self referential structure ?

Ans. A structure which refers to itself is called self referential structure.Eg. struct student

{int sno;char name[25];float avg;

student *next;};

CHAPTER NAME : CLASSES AND OBJECTS

1. How encapsulation is implemented in C++ ? Give an example.

Ans. Encapsulation is implemented in C++ through classes.Eg. class item{int itno;

char itemname[25];int qty;float price;public :void accept();void display();

float totcost();};

2. Define a class and an object.

Ans. A class is a collection of objects with common characteristics and behavior. Anobject is an individual entity with its own characteristics and behavior.

3. What are the ways of defining the member functions of a class ?Ans. There are 2 ways of defining the member functions of a class.

1. The function definition can be given within the class.

2. The function definition can be given outside the class using scope resolutionoperator.

4. What are access specifiers ?


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Ans. Access specifiers specifies the accessibility of the members of the class.They are private, public, protected.

Private - members can be accessed only within the classProtected - members can be accessed within the class and by the derived class.Public members can be accessed within the class, by the derived class and by

other functions.

5. Explain inline function .Ans. Member functions which are defined inside the class are automatically inline.The users can define their functions as inline by including the keyword inline before

the return type in their function header.

6. Discuss the advantages and disadvantages of inline function.Ans. Advantage : Function overhead is avoided.Disadvantage : Goto statements are to be avoided.

7. What is nested member function ? Give example.Ans. A member function call given in other member function definition is called

nested member function.Eg. class sample{int a,b;

public :void Calc(){couta>>b;Calc();}

};8. What is a friend function ?Ans. A non-member function given the privilege to access the private members of a

class is called a friend function.

9. Differentiate between member function and non-member function.

Member function Non-member function

It is a member of a class It is not a member of a class

It can access the private members of

the class.

Cannot access the private members of

the class.

10. What is the purpose of the scope resolution operator ?Ans. (i) It is used to access the global variable which has the same name as that of

the local variable.

(ii) It is used to define the member function outside the class.

11. How the memory is allocated for objects ?


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Ans. Data members occupy different memory allocation and member functionsoccupy common memory allocation.

12. Explain nested classes with an example.Ans. A class within another class is called a nested class.

Eg. class student{int sno;char name[25];float avg;

public :void accept();

void display();};class admission{

student s;public :

void in();void out();};

13. Why it is a bad idea to declare the data members of a class under thepublic category ?Ans. It is because the data members contain the information which has to beprotected from outside and data abstraction to be retained in the program.

14. What are the types of member functions ? explain.

Ans. (i) Accessor functions - It allows the user to access the data member. It donot change the value of the data members.(ii) Mutator functions :These member functions allows us to change the datamember.

(iii) Manager functions : These are the member functions with specific functionslike constructing and destroying the members of a class.

CHAPTER NAME : FUNCTION OVERLOADING

1. What is polymorphism ? How it is implemented in C++ ?Ans. Polymorphism is an ability of one object to exist in different forms indifferent situation.It is implemented in C++ through function overloading.

2. What is function overloading ? Explain

Ans. Functions with the same name with different function signature.void func(int);void func(float);void func(double);

3. What is function signature ?


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Ans. It is the function argument list.

4. What is an abstract class and concrete class ?Ans. The class which is meant only derivation that is the base class is called anabstract class.

The derived class is called the concrete class.

5. Give the steps involved in identifying the best match.Ans. (i) Exact match searches for an exact match with respect to the data type.(ii) Match through promotion - if exact match is not found the integral promotion

takes place.(iii) Match through standard C++ conversion if the step (ii) fails then match

through C++ conversion takes place ie. Int float and float double etc.(iv) Match through user defined conversion - if step(iii) fails the typecastingoccurs in which the user can do the conversion.

6. What is an ambiguous match ?Ans. The calling statement matches for more than one function definition is

called the ambiguous match.

7. Explain default arguments versus function overloading.Ans. Avoid using both default arguments and function overloading which will

result in ambiguous match.Eg.Int calculate( float p, int t=4,float r=0.05);

CHAPTER NAME : CONSTRUCTOR AND DESTRUCTOR

1. Define constructor.Ans. A constructor is a member function which has the same name as that of theclass and is used for initializing the data members with initial values.

2. What are the different types of constructor ? ExplainAns. (i) default constructor a constructor with no arguments(ii)argument constructor a constructor with the arguments(iii) copy constructor a constructor used to copy one objects value into anotherobject.

3. Differentiate between constructor and member function.Ans.

Constructor Member function

It is a member function with the samename as that of the class.

It can be of any name.

It cannot have return type. It must have return type.

4. What is a compiler constructor ?


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Ans. When the user defined constructor is not given by the user then thecompiler invokes the constructor of its class. It will be overridden by the user

defined constructor.

5. Give two situations when the copy constructor is called automatically .

Ans. (i) When any function takes an object as an argument by value.(ii) When the function returns an object.

6. What are the two ways of calling a constructor ?Ans. (i) implicity call - sample s;

(ii) explicit call - sample s=sample();In explicit call to a constructor temporary instances are created. It lives in the

memory as long as the statement is executed.

7. Give the special characteristics of a constructor.Ans. (i) Constructor does not have return type.

(ii) It cannot be static.(iii) We cannot take the address of the constructor.

(iv) It cannot be the member of the union.

8. What is destructor ?Ans. It is used for destroying objects created by the constructor.

9. Differentiate between constructor and destructor.Ans.

Constructor Destructor

It is used for creating objects It is used for destroying objects

It can take arguments It cannot take argumentsIt is labelled with the class name It is labeled with the tilde symbol andthe class name

10.What are temporary instances or anonymous objects ?

Ans. It is a temporary object that lives in the memory as long as the statementgets executed. It is created when an explicit call is made to a constructor.

11. Give any two characteristics of a destructor.Ans. (i) it doesnt take any arguments.(ii) it is used for destroying objects.

12. Give the order of constructor and destructor invocation in a nested class.Ans. First the constructors of the classes used inside a class will be called and theclasss constructor. Destructor invocation is just the opposite of the constructor

invocation.

CHAPTER NAME : INHERITANCE


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1. Define Inheritance.Ans. The capability of one class to inherit the properties and behavior of another

class is called inheritance.

2. Give the advantages of inheritance.

Ans. (i) Closest to the real world.(ii) reusability(iii) transitive nature of inheritance.

3. What are the types of inheritance ?

Ans. (i) Single (ii) Multiple (iii) Multi-level (iv) Hierarchial (v) Hybrid.

4. Explain the types of inheritance.Ans. (i) Single - one base class and one derived class.(ii) Multiple - many base classes and one derived class.(iii) Multi-level - inheritance in different levels ie. Class B is deriving from class A

and class C is deriving from class B.(iv) Hierarchial one base class and many derived classes.

(v) Hybrid - combination of any of the forms of inheritance.

5. What is visibility mode ?Ans. Visibility modes specifies the accessibility of the base class members in the

derived class.

6.Explain different visibility modes.Ans. (i) private private members are inherited but they cannot be accessed by

the derived class directly.Protected and public members of the base class goes as the private members of

the derived class.This visibility mode stops the inheritance.

(ii) protected - private members are inherited but they cannot be accessed by

the derived class directly.Protected and public members of the base class goes as the protected membersof the derived class.

(iii) public - private members are inherited but they cannot be accessed by thederived class directly.

Protected and public members of the base class goes as the protected and publicmembers of the derived class.

7.How constructors be used in Inheritance ?

Ans. Constructors and destructors cannot be inherited. In the case of theargument constructor, when we write the definition of the derived class

constructor, we have to pass the arguments inclusive of the base class members,because the derived class object is only be created in inheritance concept. Eg.

class A

{int a;


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public :A(int x)

{a=x;}

};class B :public A{int b;public :

B(int x,int y):A(x){

b=y;}};

8. What are virtual base classes ?Ans. Base classes which helps us to avoid two copies of the base classes in the

derived classes are called as virtual base classes.

9. Discuss some facts about inheritance.Ans. (i) When the global variable, the base class member and the derived class

member is with the same name, the global variable is hidden. To access theglobal variable the ::SRO is used. To access the base class member base classname::variable name is used.(ii) We cannot deny the access to certain data members.

Eg.class A

{public :int x; };class B : public A

{A::x; };By default as per the public derivation public goes public. But we have made thex to be in private of derived class which is not possible.

10. Explain constructors in nesting of classes.

Ans. In nested classes the constructors of the inner classes will be called firstand then the outer class.class A{

int x;public :

A(int);};

class B{int y;


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public :B(int);

};class C{

A a1;B b1;public :C(int m,int n):a1(m),b1(n){

}};

CHAPTER NAME : DATA FILE HANDLING

1. Define a file.

Ans. It is a collection of related information.2. What is a stream ?

Ans. It is a collection of bytes.3. Name the streams associated with file related operations.Ans. Input stream and output stream.4. Name the stream classes associated with file related operations.

Ans. ifstream, ofstream and fstream.5. Which header file is used for file related operations ?Ans. fstream.h

6. Differentiate between text and binary file.

Text file Binary fileIt stores information in ASCIIcharacters.

It stores information as block of data orrecords.

Character translation takes place. Character translation does not takeplace.

7. What are the ways of opening files ?Ans. There are 2 ways of opening files. They are (i) using constructor and (ii)using open function.

8. Differentiate between opening files using constructor and open().

Using constructor Using open()To open multiple files in succession

using the same object, constructor willnot work because the object has to becreated.

To open multiple files in succession

using the same object, the open() canbe used.

9.Differentiate between ios::app and ios::ate

Ans.Ios::app Ios::ate


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The file pointer will be positioned at theend of the file and insertion can take

place from the end.

The file pointer will be positioned at theend of the file whereas the insertion can

take place anywhere in the file.

Associated with ofstream Associated with ofstream and ifstream

10.Differentiate between ios::out and ios::appAns.

Ios::app Ios::out

Helps us to add the contents to the filewithout erasing the existing content

Helps us to overwrite the contents ofthe file.

11.Differentiate between ifstream and fstream

Ans.

Ifstream Fstream

It is meant only for reading theinformation from the file

It is meant for both reading and writing.

Eof(), read() Eof(), write(),getline()

12. Differentiate between ofstream and fstreamAns.

ofstream Fstream

It is meant only for writing theinformation from the file

It is meant for both reading and writing.

Write(),get() Eof(), read(),getline()

13.What is the purpose of ios::nocreate ?

Ans. ios::nocreate mode will not create the file if it is not there.

14.Differentiate between get() and getline() in files.Ans.

Get() Getline()

Get() can read a character and a stringfrom the file and the delimiter will beavailable in the input stream.

Getline() can read a character and astring from the file and the delimiterwill be removed from the input stream

by the complier.

15.Differentiate between seekp() and tellp()Ans.

Seekp() Tellp()It is used to move the put pointer tothe respective position for writing.

To show the position of where the putpointer is in the file.

16. Differentiate between seekp() and seekg()Ans.

Seekp() Seekg()

Moves the put pointer to the respective

location for writing.

Moves the get pointer to the respective

location for reading.

17. What is the prototype of eof() ?

Ans. int eof(); eof() returns a non-zero value when the end of file is reachedotherwise zero value.


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18. Give the use of remove() and rename().

Ans. remove() is used to delete the file from the system and rename() is used torename a file with a proper name.

CHAPTER NAME : POINTERS1. Define a pointer.Ans. A pointer is a variable which holds the memory address of another variable.

2. Differentiate between pointer and reference variable.

Ans.

Pointer variable Reference variable

It is a variable which has the memoryaddress of another variable.

It is an alias name given for a variable.

3. What is a heap memory ?Ans. The unallocated memory is called as free/heap memory.

4. Explain C++ memory map.Ans. The memory map is allocated as follows :(i) Compiled code.

(ii) Global variables(iii) Stack(iv) Heap memory(v)

5. What are the types of memory allocation ?Ans. Static and dynamic memory allocation.

6. What is dynamic memory allocation ?Ans. Memory which is allocated during run time is called dynamic memoryallocation.

7. Name the operators used for dynamic memory allocation.Ans. new and delete.

8. Which operator is called as the dereferencing or indirection operator ?Ans. * operator.

9. What is a wild pointer ?Ans. Uninitialized pointer is called wild pointer.

10. What is a null pointer ?Ans. A pointer variable which is initialized to NULL is called null pointer.

11. Name the operations performed using pointers.

Ans. Increment and decrement operations and assignment.

12. What is the base address ?Ans. A pointer variable holds the starting memory address of a variable.

13. Differentiate between the following statements :


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int *p=new int(5); //statement 1int *p=new int[5]; //statement 2

Ans. Statement 1 declares a pointer variable p and it holds the address of thememory location of where the value 5 is stored.Statement 2 declares a pointer variable p which holds the starting address of the array

of size 5.

14. What is memory leak ?Ans. When the memory is allocated dynamically using new and it is not deallocatedusing delete, it will result in memory leak.

15. Consider the following statements : int a[20],*p;p=a;

What is the difference between a and p variable ?Ans. a and p are the pointer variables. a is a pointer variable which always holds

the starting memory address of the array, but p is a pointer variable which can bemade to point to any memory location.

16. What operator is used for referencing structure elements using structure

pointer ?Ans. structure elements are accessed using structure pointer followed by the ->operator.

17. What is this pointer ?Ans. It is the pointer used by the compiler which points to the object that invokesthe member function of a class.

CHAPTER NAME :ARRAYS1. What is an array ?

Ans. An array is a collection of data of same data type referenced under onecommon name.

2. What is the need for an array ?

Ans. (i) The datas are stored in continuous memory location.(ii) The elements are referred under one name with the subscript number.

3. What is a subscript or index number ?Ans. The number which is used to access the array elements. The subscript numberin C++ starts with 0.

4. What is a Stack ?Ans. Stack is a collection of elements in which it follows the mechanism of Last InFirst Out (LIFO). Insertion or deletion of an element takes place at only one point

which is the top position.

5. What is a Queue ?Ans. Queue is a collection of elements in which it follows the mechanism of First InFirst Out (FIFO). Insertion takes place at the rear end and deletion takes place atthe front end.

6. What are the different types of arrays ?

Ans. (i) one-d array and (ii) multi-dimensional array.


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7. How an array is represented in memory ?Ans. It occupies continuous memory location.

8. Give the difference between linear and binary search technique ?Ans.

Linear search Binary searchSearches for an element in the entirearray from the beginning.

Minimises the comparison by dividingthe array into two halves.

The elements can be in any order. The elements must be in eitherascending or descending order.

9. What is overflow and underflow ?Ans. The number of elements inserted has reached the size of the array is called as

overflow condition. Deletion in an empty array results in underflow condition.

10. Give the formula for calculating the address of an element in row-majorand column-major form.

Ans. Row major form :Address of the A[i][j]element = BA + ES [n[i-l1] +[j-l2]]Column-major form :Address of the A[i][j] element = BA + ES [[i-l1] +m[j-l2]]BA Base Address, ES Element Size , n-no. of columns in the array , l1-lowerbound of row, m - no. of rows in the array, l2 lower bound of column.

11. Write the steps for conversion of infix to postfix expression .Ans. 1. Insert the parenthesis based on the priority of the operators.

2.When the left parenthesis is encountered push it on to the stack.

3. When the operand is encountered place it on the postfix expression.

4. When the operator is encountered place it on to the stack.5. When the right parenthesis is encountered pop the top most operator fromthe stack and place it on the postfix expression and remove one leftparenthesis from the stack.

12. Write the steps for evaluating the postfix expression.Ans. (i) Push the operand on to the stack.(ii) When the operator is encountered, pop the top 2 elements from the stack , performthe operation and push the result back on to the stack.

CHAPTER NAME : DATABASE CONCEPTS

1. What is a database ?Ans. A database is a collection of related data.

2. List out the advantages of database.Ans. 1. Data redundancy duplication of data is avoided.

2.Data consistency ensuring correct values are entered by the user.3. Sharing of data because of the usage by many users.4. Enforcing standards - to have a proper way of communication5. Data Security to prevent unauthorized access.

6. Data Integrity to check in the related records in the database.

3. What are the various levels of data abstraction ?Ans. External level, Conceptual level, Physical level.


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4. Name the types of users using the database .

Ans. (i) End user (ii) Application Programmer (iii) System Analyst.

5. What is data independence and explain its types ?

Ans. Data independence is that when any changes made in one level should not beaffected in the other level.Types are :Logical data independence Any change made in the conceptual level should not beaffected in the External level.

Physical data independence Any change made in the Physical level should not beaffected in the Conceptual level.

6. Give the types of data models .Ans. (i) Hierarchial data model records are organized as trees ie. Parent-childrelationship.

(ii) Network data model datas are represented as collection of records andrelationships among the datas are represented as links.

(iii) Relational data model - datas are represented in the form of table whichconsists of rows and columns.

7. Discuss the advantage of relational model over the other models .

Ans. In network and hierarchial data model insertion and deletion of records is adifficult process whereas in the relational model it is easier because the informationis available in the form of rows and columns.

8. Define the following terms : (i) relation (ii) attribute (iii) tuple (iv) cardinality(v) degree

Ans. (i) relation it is a table in which the data are organize in rows and columns.(ii) attribute a column or field in a relation.(iii) tuple a row or record in a relation.(iv) cardinality no. of tuples in a relation.

(v)degree no. of attributes in a relation.

9. Define the terms : (i) primary key (ii) candidate key (iii) alternate key (iv)foreign key.

Ans. (i) primary key it is a set of one or more attributes that identifies a tuple in arelation. It contains unique and not null values.

(ii) candidate key all attributes which qualifies to become a primary key.(iii) alternate key A candidate key that is not the primary key.(iv) foreign key A primary key of one relation if used in other relation it becomesthe foreign key of that relation.

10. What is select and project operation ?

Ans. Select operation selects the tuples that satisfies the given condition.Project operation is a subset of select operation which specifies particular attributesfor selection.

11. What are the conditions for applying union operation ?Ans. 1. The relations must be of the same degree.

2. One tuple should be in common in the relations.


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CHAPTER NAME : SQL1. What is SQL ?Ans. SQL is structured Query Language it is a language which is used to createand operate on relational databases. It was developed at IBMs San Jose ResearchLaboratory.

2. What is DDL, DML ?Ans. DDL is Data Definition Language has commands for designing the relationstructure.DML - Data Manipulation Language has commands for operating on the

records/tuples in the relation.

3. What is a constraint ?Ans. It is a condition to check on a field/attribute.

4. What are the different types of constraints ?Ans. Primary key - which contains unique and not null values .Unique which allows null values and different values.Not Null allows the user to enter values except null.

Check checks the value for a conditionDefault assigns the default value for an attribute.

5. What is the purpose of distinct keyword in the select statement ?Ans. It selects the different values from an attribute for display.

6. Differentiate between order by and group by clause.Ans. Order by Arranges all the tuples based on a particular attribute.Group by Groups the tuples based on an attribute.

7. Differentiate between where and having clause.Ans. Where it is applicable for all the tuples in the relation.

Having it is applicable for grouped records in the relation.

8. Differentiate between drop table and delete command.Ans. Drop table will remove the entire table from the database if the table is empty.

Delete command will remove the records from the table.

9. What is a view ?Ans. View is the virtual table created from the existing base table for displaypurposes.

10. Differentiate between alter table and update command.Ans. Alter table will alter only the design of the table.

Update command is used to update the values in the records.


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CHAPTER NAME : COMMUNICATION AND NETWORK CONCEPTS

1. Define a network.Ans. A network is an interconnected collection of autonomous computers.

2. What is the need for networking ? or Discuss the advantages of network.

Ans. Networking helps us to do the following :(i) Resource sharing : helps us to share the datas, peripherals and the

programs across the network.(ii) Reliability : The files can be stored in different systems on the network. If

one copy is lost due to system crash still the file can be used which isstored in the other systems.

(iii) Cost factor : PCs have better price and performance. So its better to have oneuser per PC whereas the datas are shared on the network.

(iv) Communication medium : It is easier to share the messages to different peopleall over the world which speeds up the cooperation among the users.

3. Write the disadvantages of network.

Ans. (i) The systems are to be managed by the special person to run the network.(ii) If it is not managed properly it becomes unusuable .(iii) If the software and the files are located on the central system called server, ifthe server fails, the entire network fails and it is very difficult to share the files.

(iv)File Security is more important because if connected to WANs full protection isrequired against viruses.

4. Explain evolution of networking.


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Ans. 1. In 1969 the first network was developed called ARPANET ie. AdvancedResearch Projects Agency Network. This network was designed to connectcomputers at different universities and U.S. defense.2. In mid 80s another agency, the National Science Foundation, created a highcapacity network called NSF net which allowed only academic research on the

network.3. So, many private companies developed their own network and linked it with theARPANET and NSFNet and that was named as Internet.

5. What is a node ?

Ans. A node is the computer attached to the network. It is also called asworkstation, terminal. It seeks to share the resources of the network.

6. What is a server ?Ans. The main computer which facilitates the sharing of data, software andhardware on the network is called a server.

7. Give the different types of server ?

Ans. (i) dedicated server - The system which is purely meant for serving purposeson the network, to help workstations access data, software and hardware. Eg.modem server, file server, print server. The network using such servers are calledMaster-Slave network.

(ii) non-dedicated server The system on the network which plays the dual role ofthe server and the workstation is called as non-dedicated server. The network using

such servers are called Peer-to-Peer Network.

8. What is NIU ?

NIU is Network Interface Unit is a device attached to each of the

workstations and the server. It helps the workstation establish all connectionwith the network.

Each NIU attached to the workstation has a unique address .The NIU

manufacturer assigns a unique physical address to each NIU. This physicaladdress is called as MAC Address. MAC Address is Media Access ControlAddress.

NIU is also called as TAP (Terminal Access Point) or NIC (Network

Interface Card).

9. What do you mean by switching techniques ?

Ans. The switching techniques are used for transmitting data across the network.

10. What are the three types of switching techniques ?Ans. (i) Circuit switching (ii) message switching and (iii) packet switching.

11. Explain the switching techniques Or Differentiate between any of theswitching techniques.

Ans. (i) Circuit switching The physical connection is established between the

source and the destination computer and then the datas are transmitted. It is usedwhen end-to-end path between the computers is needed.


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(ii) Message switching It uses the technique of store and forward. The data aresent from the source computer to the switching office and then to the destination

computers. In this technique the data are stored in the disk. There is no limit on theblock size of the data.

(iii) Packet switching The data is divided into different packets in this technique.Packet means the datas are divided into byte format. All the packets of fixed size arestored in the main memory. It places a tight upper limit on the block size.

12. Define transmission media or communication channel.

Ans. It means connecting cables or connecting media in a network.

13. What are the types of communication media ?Ans. The communication media is categorized as guided media and unguided media.(i) Guided media includes cables and (ii) unguided media include waves

through air, water or vacuum.

14. What are the types of guided media.

Ans. The types of guided media are(i) Twisted pair cable(ii) Co-axial cable(iii) Fibre optic cable

15. What is twisted pair cable ?

Ans. The twisted pair cable consists of two identical wires wrapped together in adouble helix. The twisting of wires reduces crosstalk, which is the bleeding of signal

from one wire to another which in turn can cause network errors.

16. List out the advantages and disadvantages of twisted pair cable .Ans. Advantages :

1. It is easy to install and maintain.2. It is very inexpensive.

Disadvantages :1. It is incapable of carrying a signal over long distances without using the

repeaters.

2. It supports maximum data rates of 1 Mbps without conditioning to 10 Mbps withconditioning.

17. List out the types of twisted pair cable.

Ans. 1. Unshielded twisted pair cable2.Shielded twisted pair cable.

18. Differentiate between Unshielded and shielded twisted pair cable.Ans.

Unshielded twisted pair Shielded twisted pair

It can support only 100 Mbps

bandwidth

It can support 500 Mbps bandwidth


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It has interference whilecommunication.

It offers greater protection frominterference and crosstalk due to

shielding.

19. What is coaxial cable ?

Ans. Coaxial cable consists of a solid wire core surrounded by one or more foil orwire shields, each separated by an insulator. The inner core carries the signal andthe shield provide the ground. It is widely used for television signals which supports

high speed communication.

20. List out the advantages and disadvantages of coaxial cable .Ans. Advantages :1. Offer high bandwidth upto 400 Mbps.2. It can be used for broadband transmission.

Disadvantages :

1. Expensive when compared to twisted pair.2. It is not compatible with twisted pair.

21. List out the types of coaxial cable.

Ans. 1. Thicknet : This type of cable can be upto 500 mts long.2.Thinnet : This type of cable can be upto 185 mts. Long.

22. What is optical fibre ?

Ans. Optical fibres consists of thin strands of glass that carry light from a source atone end of the fiber to a detector at the other end. The fiber optic cable consists of 3pieces : (i) the core the glass or plastic through which the light travels. (ii) the

cladding which is the covering of the core which reflects light back to the core and(iii) protective coating - which protects the fiber cable from hostile environment.

23. List out the advantages and disadvantages of fibre optic cable .

Ans. Advantages :1. It is immune to interference either magnetic or electrical.2. It supports secured transmission and a very high transmission capacity.Disadvantages :1. Installation is very hard.2. They are most expensive.

24. What is microwave transmission ?Ans. The microwave transmission are used to transmit without the use of cables. Itconsists of a transmitter, receiver and the atmosphere. Parabolic antennas are

mounted on towers to send a beam to other antennas ten kms away. The higher thetower, the greater the range. When the radio wave frequency is higher than 3 GHz it

is named as microwave.

25. List out the advantages and disadvantages of microwave transmission.Ans. Advantages :

1. It offers freedom from land acquisition rights that are required for laying,repairing the cables.


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2. It has the ability to communicate over oceans.

Disadvantages :1. It is an insecure communication.2. The cost of design, implementation and maintenance is high.

26. What is radio wave transmission ?Ans. The transmission making use of radio frequencies is termed as radio wavetransmission. It has two parts : the transmitter and the receiver. The transmittertakes the message and encodes it onto a sine wave and transmits it with radio

waves. The receiver receives the radio waves and decodes the message from thesine wave it receives. Both of them uses antennas to radiate and capture the radio

signal.

27. List out the advantages and disadvantages of radiowave transmission.Ans. Advantages :

1. It offers mobility.2. It offers ease of communication over difficult terrain.

Disadvantages :1. It is an insecure communication.2. It is susceptible to weather conditions.

28. What is satellite means of communication ?

Ans. Satellite communication is a special way of microwave relay system. In thiscommunication, the earth station consists of a satellite dish that functions as anantenna and the communication equipment to transmit and receive the data fromsatellites passing overhead.

29. List out the advantages and disadvantages of satellite transmission.Ans. Advantages :

1. The area coverage through satellite transmission is large.2. The heavy usage of intercontinental traffic makes the satellite commercial

attractive.

Disadvantages :1. The high investment cost.2. Over crowding of available bandwidths due to low antenna gains.

30. Explain other unguided media .Ans. (i) Infrared : This type of transmission uses infrared light to send data. Eg. TV

remotes. It offers secured transmission.(ii) Laser : The laser transmission requires direct line-of-sight. It is

unidirectional and it transmits data at a higher speed than microwave.

31. Define the following :(i) Data Channel : It is the medium to carry data from one end to another.

(ii) Baud : It is the unit of measurement for the information carrying capacityof the communication channel.


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(iii)Bandwidth : It refers to the difference between the highest and the lowestfrequencies of a transmission channel.

(iii) Broadband : High bandwidth channels are called broadband.(iv) Narrowband : Low bandwidth channels are called narrowband.(v) Hertz : Frequency is measured in hertz.

(vi) Data transfer rates : The amount of data transferred per second by acommunication channel is called data transfer rates.

32. Expand the following :Ans. bps bits per second kHz kilohertz

Bps Bytes per second MHz - Megahertzkbps kilo bits per second GHz - gigahertz

Kbps Kilo Bytes per second THz - Terahertzmbps mega bits per secondMbps Mega bytes per second

33. What are the types of network ?Ans. (i) LAN Local Area Network(ii) MAN Metropolitan Area Network

(iii)WAN Wide Area Network

34. Explain the types of network .Ans. (i) LAN Small computer networks that are limited to a localized area is known

as LAN.(ii)MAN The network which is spread over a city is called MAN.(iii)WAN The network which is spread across countries and continents is called WAN.

35. Differentiate between LAN and WAN

LAN WAN

Diameter is not more than a fewkilometers

Span across countries and continents.

Very low error rates Higher error rates.

36. What is topology ?

Ans. The layout of the computers on the network is called topology.

37. List out the different types of topology.Ans. (i) Star (ii) bus (iii) ring (iv) Tree (v) graph (vi) Mesh

38. What is star topology ? List out the advantage and disadvantage of it.

Ans. Star topology consists of a central node to which all other nodes are connected.Advantage :

1. Centralized control 2. One device per connection failure of one node willnot affect the network.

Disadvantage :1. Long cable length 2. Central node dependency.

39. What is bus topology ? List out the advantage and disadvantage of it.


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Ans. It is linear topology which consists of a single length of the transmissionmedium onto which the various nodes are connected. The bus has terminators at

both the ends which absorb the signal, removing it from the bus.Advantage :1. Short cable length 2. Resilient architecture means which has a single

cable through which all the datas are transmitted.Disadvantage :1. Fault diagnosis is difficult 2. Fault isolation is difficult if a node is not

working in the bus it has to be rectified at the point where the node is connected.

40. What is ring topology ? List out the advantage and disadvantage of it.Ans. Nodes are connected in a circular fashion. The data can be transmitted in only

one direction.Advantage :1. Short cable length. 2. No wiring closet space is required Since there is

only one cable connecting each node to its neighbouring node, no separate space

is allocated for wiring.Disadvantage :

1. Node failure causes network failure. 2. Difficult to diagnose faults.

41. What is tree topology ?Ans. The shape of the network is that of an inverted tree with the central node

branching to various nodes and the sub-branching to the extremities of the network.

42. What is graph topology ?Ans. Nodes that are connected in an arbitrary fashion is called graph topology. A link

may or may not connect nodes.

43. What is mesh topology ?Ans. In this topology, each node is connected to more than one node to provide analternative route.

44. Define modem.Ans. A modem is a device which allows us to connect and communicate with othercomputers via telephone lines.MODEM MOdulator DEModulator

45. What is RJ-45 ?

Ans. RJ-45 is Registered Jack -45. It is an eight-wire connector, which is commonlyused to connect computers on the local area networks.

46. What is Ethernet Card ?

Ans. Ethernet is a LAN architecture which used bus or star topologies . Thecomputers that are part of Ethernet, must have an Ethernet card. It contains

connections for either coaxial cable or twisted pair cable. Some Ethernet cards alsocontain an AUI connector (ie. Attachment Unit Interface 15 pin connector that canbe used for attaching coaxial, fibre optic or twisted pair cable).

47. What is a hub ? Explain its types.Ans. A hub is a device used to connect several computers together. Hub is also

referred as multi-slot concentrator.Hub can be classified as active and passive hub.


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(i) Active hubs : These electrically amplifies the signal as it moves from oneconnected device to another.

(ii) Passive hubs : It allows the signal to pass from one computer to anotherwithout any change.

48. What is a switch ?Ans. A switch is a device that is used to segment networks into differentsubnetworks called subnets or LAN segments. It prevents the traffic overloading in anetwork. It can filter traffic in the network.

49. What is a repeater ?Ans. A repeater is a device which is used to amplify the signals being transmitted in

a network.

50. What is a bridge ?Ans. A bridge is a network device that connects two similar networks which supports

the same protocol.

51. What is a router ?Ans. A router is a network device that connects networks which supports differentprotocols.

52. What is a gateway ?Ans. It is a device that connects dissimilar networks.53. What is a protocol ?Ans. It is a formal description of message formats and the rules to be followed for

communication in a network.

54. Expand and explain the following protocols.Ans. 1. HTTP Hyper Text Transfer Protocol is an application level protocol usedfor distributed, collaborative, hypermedia information systems.2. FTP File Transfer Protocol is a protocol used for transferring files from one

system to another.3. TCP/IP Transmission Control Protocol/Internet Protocol It is a protocol used

for sending and receiving messages which are divided into packets.4. SLIP Serial Line Internet Protocol It was the first protocol for relaying IP

packets over dial-up lines. This doesnt support dynamic address assignment.5. PPP Point to Point Protocol - It is the Internet Standard for transmission of IP

packets over serial lines. It is a layered protocol which contains Link ControlProtocol (LCP) for link establishment, Network Control Protocol (NCP) fortransport traffic, IP Control Protocol (IPCP) permits the transport of IP packetsover a PPP link.

55. What is Datagram ?

Ans. A Datagram is a collection of the data that is sent as a single message.

56. What is Wireless communication ?Ans. Wireless refers to the method of transferring information between a computing

device and a data source without a physical connection. It is a data communicationwithout the use of landlines. Eg. two-way radio, fixed wireless, laser or satellite

communications. The computing device is continuously connected to the basenetwork.


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57. What is Mobile computing ?

Ans. Mobile computing device means that the computing device is not continuouslyconnected to the base or central network. Eg. PDA, laptop computers, cell phones.These products may communicate with the base location with or without wireless

connection.

58. What is GSM ?Ans. GSM stands for Global System for Mobile Communications. In covered areas,cell-phone users can buy one phone that will work anywhere where the standard is

supported. GSM users simply switch SIM cards. (Subscriber Identification Module).GSM uses narrowband TDMA, which allows eight simultaneous calls on the same

radio frequency.

59. What is TDMA ?Ans. TDMA means Time Division Multiple Access is a technology which works on

dividing a radio frequency into time slots and then allocating slots to multiple calls.

60. What is SIM ?Ans. SIM stands for Subscriber Identification Module which is a chip that gives acellular device a unique phone number. It has the memory, the processor and theability to interact with the user. Current SIMs have 16 to 64 kb of memory.

61. What is CDMA ?Ans. CDMA stands for Code Division Multiple Access is a technology which uses aspread spectrum technique where the data is sent in small pieces over a number ofdiscrete frequencies available for use. Each users signal is spread over the entire

bandwidth by unique spreading code and at the receiver end the same unique codeis used to recover the signal.

62. What is WLL ?Ans. WLL is Wireless in Local Loop is a system that connects subscribers to thePublic Switched Telephone Network (PSTN) using radio signals as a substitute for

other connecting media.

63. Discuss the advantages of WLL ?Ans. (i) It does not suffer from weather conditions.

(ii)It offers better bandwidth than the traditional telephone systems.(iii) It supports high quality transmission, signaling services.

64. What is 3G and EDGE ?Ans. 3G stands for Third Generation also called as UMTS ( Universal MobileTelecommunication Systems) is a broadband, packet- based transmission of text,

digitized voice, video and multimedia at data rates upto and possibly higher that 2mbps (mega bits per second), offering consistent services to mobile computer and

phone users where ever they are in the world.


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EDGE stands for Enhanced Data Rates for Global Evolution is a radio based high-speed mobile data standard. It allows data transmission speeds of 384 kbps to be

achieved when all eight time slots are used.

65. Define SMS.

Ans. SMS Short Message Service is the transmission of short text messages to andfrom a mobile phone, fax machine and/or IP address.

66. How the SMS is being sent ?Ans. Once the message is sent by the sender, it is received by the Short Message

Service Center (SMSC), which will get into the appropriate mobile phone. To dothis,the SMSC sends the SMS Request to the Home Location Register (HLM) to find

the roaming customer. Once the HLR receives the request, it will respond to theSMSC with the subscribers status : (i) inactive or active, (ii) where subscriber isroaming.

67. What is e-mail ?Ans. E-mail is Electronic mail is sending and receiving messages by the computer.

68. List the advantages of E-mail.Ans. (i) low cost (ii) speed (iii) waste reduction (i.e. paper) (iv) ease of use (v)record maintenance .

69. What is Voice mail ?

Ans. The voice mail refers to e-mail systems supporting audio. Users can leavespoken messages for one another and listen to the messages by executing theappropriate command in the e-mail system.

70. What is chat ?Ans. Online textual talk in real time is called chatting.

71. What is video-conferencing ?Ans. A two-way videophone conversation among multiple participants is calledvideo- conferencing. Eg. Microsoft NetMeeting is the software which supports video-

conferencing.

72. Define the following terms :Ans. (i) WWW - World Wide Web is a set of protocols that allows the user to access

any document on the internet through a naming system based on URL.

(ii) URL Uniform Resource Locator is the distinct address for each resource on theinternet, which acts a pointer to information on the WWW.

(iii)Domain Name The characters based naming system by which servers are

identified is known as Domain Naming system. Eg. .com, .gov, .edu

(iv) Telnet is an internet utility that let us log onto remote computersystems.


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(v) Web browser It is software which the WWW client that navigatesthrough the World Wide Web and displays Web pages.

(vi) Web Server It is a WWW server which responds to the requests madeby the Web browser.

(vii) Web site is a collection of web pages.

(viii) Web page The documents residing on web sites are called web pages.(ix) Web Hosting is a means of hosting web-server application on a computer

system through which electronic content on the internet is readily availableto any web-browser client.

73. Give the types of Web Hosting .Ans. (i) Free Hosting (ii) Virtual or Shared Hosting (iii) Dedicated Hosting (iv) Co-

location Hosting.

74. Define the following :Ans. (i) HTML - Hyper Text Markup Language It is a document layout and

hyperlink specification language which contains pre-defined tags that let us controlthe presentation of the information on the web-pages. It supports only static

webpages.

(ii) XML Extensible Markup Language It is a language for documents containingstructured information ie. Which contains both content and some indication of what

role that content plays. The tags are not predefined and it allows the user to definethe tag and their semantics. It supports dynamic web pages.

(iii)DHTML Dynamic Hyper Text Markup Language The language which uses the

combinations of HTML, style sheets and scripts that allows documents to beanimated.

(iii) Web Scripting : the process of creating and embedding scripts in a webpage is known as web scripting.

(iv) Script It is a list of commands embedded in a web-page. Scripts areinterpreted and executed by a certain program or scripting engine.

(v) Types of Script :(i) Client Side Script : This type of scripting enables interaction within a web

page. They are browser dependent. Popular Client side scripting are VBScript,

JavaScript, PHP (Hyper Text Preprocessor).(ii) Server-Side Script : This type of scripting enables the completion or carryingout a task at the server- end and then sending the result to the client-end.Popular server side scripting are PHP,ASP (Active Server Pages), JSP (Java

Server Pages).It is not browser dependent.

75. What is a free software ?Ans. Free software means the software is freely accessible and can be freely used,changes, improved, copied and distributed by all who wish to do so. No paymentsare needed to be made for free software.

76. What is Open Source Software ?


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Ans. Open Source Software can be freely used which means making modifications,constructing business models , but it does not have to be free of charge. In open

source software the source code is freely available to the customer and it can bemodified and redistributed without any limitation.

77. List out the criteria for distributing open source software.Ans. (i) Free redistribution (ii) Source code (iii) Derived works (iv) Integrity of theAuthors Source code (v) No discrimination against persons or groups (vi) Nodiscrimination against fields of endeavor (vii) Distribution of License (viii) Licensemust not be specific to a product (ix) The license must not restrict other software

(x) License must be technology neutral.

78. What is FLOSS ?Ans. FLOSS refers to Free Libre and Open Source Software or Free Livre and OpenSource Software. FLOSS is used to refer a software which is both free software aswell as open source software. Libre or Livre means freedom.

79. What is GNU ?

Ans. GNU refers to GNUs Not Unix. It emphasizes on freedom and thus its logotypeis an animal living in freedom. It was initiated by Richard M. Stallman with anobjective to create a system compatible to Unix but not identical with it. Now, itoffers a wide range of software, including applications apart from OS.

80. What is FSF ?Ans. FSF stands for Free Software Foundation is a non-profit organization created for

the purpose of supporting free software movement.

81. Explain OSI.Ans. OSI is Open Source Initiative is an organization dedicated to cause of

promoting open source software.

82. What is W3C ?Ans. W3C is an acronym for World Wide Web Consortium which is responsible forproducing the software standards for the world wide web.

83. What is a Proprietory software ?Ans. It is the software that is neither open nor freely available. Further distributionand modification of the software required special permission by the supplier or thevendor. Source code is not readily available.

84. What is Freeware ?

Ans. The software which is available free of cost which allows copying andredistribution but not modification whose source code is not available.

85. What is Shareware ?

Ans. Shareware is a software, which is made available with the right to redistributecopies, but it is limited ie. If one intends to use the software after a certain period of

time, a license fee should be paid. Source code is not available and the modificationscannot be made.


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86. What are the problems encountered under network security ?

Ans. It can be classified as (i) Physical Security holes(ii) Software security holes (iii) Inconsistent Usage holes

87. What are the protection methods followed to secure the network ?Ans. (i) Authorization login-id(ii) Authentication password-protection(iii)Encrypted Smart Cards It is a hand held card that can generate a token that a

computer can recognize. Everytime a new and different token is generated.

(iv) Biometric systems finger-prints(v) Firewall It is a system designed to prevent unauthorized access to or

from a private network. It can be implemented in both hardware andsoftware.

88. Give the types of firewall techniques.

Ans. (i) Packet filter (ii) Application gateway (iii) Circuit-level gateway (iv) Proxyserver.

89. What are cookies ?Ans. Cookies are messages that a web server transmits to a web browser so that theweb server can keep track of the users activity on a specific web site.

90. Differentiate between Hackers and Crackers.Ans. The Crackers are the malicious programmers who break into secure systems.The Hackers are more interested in gaining knowledge about the computers andpossibly using this knowledge form playful pranks.

91. What is Cyber Law ?Ans. It is a term which refers to all the legal and regulatory aspects of internet andthe world wide web. Information Technology Act, 2000 is based on the UnitedNations Commission for International Trade related laws(UNCITRAL) model law.

92. Explain Cyber Crime ?Ans. Cyber Crime are the crimes committed with the use of computers or relating tocomputers, especially through the internet.Classification of Cyber Crime :

(i) Tampering with the computer source documents(ii) Hacking

(iii) Publishing of information, which is obscene in electronic form(iv) Child Pornography(v) Accessing protected system(vi) Breach of confidentiality and privacy

93. What is IPR ?


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Ans. The Intellectual Property may be defined as a product of the intellect that hascommercial value, including copyrighted property such as literary or artistic works

and ideational property.

94. What is a Computer Virus ?

Ans. Computer virus is a malicious program that requires a host and is designed tomake a system sick.

95. List out the damages that the virus can cause.Ans. (i) to make the system unstable. (ii) destroy file allocation table.

(iii)can create bad sectors in the disk, destroying parts of programs and files.(iv)can destroy specific executable files. (v) Can cause the system to hang.

96. What is Trojan Horse ?Ans. A Trojan Horse is code hidden in a program such as a game or spreadsheetthat looks safe to run but has hidden side effects.

97. What is a worm ?

Ans. A worm is a program designed to replicate.

98. What is SPAM ?Ans. SPAM refers to electronic junk mail or junk newsgroup postings. It is the

unsolicited usually commercial e-mail sent to a large number of addresses.

99. Discuss the ways of avoiding Spam.Ans. (i) to create a filter that finds and does something to email that you suspect as

spam. (ii) Not to register with true id on the internet.

100. How to prevent viruses ?Ans. The following are the points that we must remember to follow to prevent

viruses : 1. Use Licensed software.2. Install and use antivirus software.3. Check for virus when using secondary storage devices in the system.4. Keep antivirus software up to date.5. Always scan files downloaded from the internet or other sources.

101. What is meant by GPRS?GeneralPacketRadio Service, a standard for wireless communications whichsupports a wide range ofbandwidths. it is a second generation (2G) and thirdgeneration (3G) wireless data service that extends GSM data capabilities for Internet

access, multimedia messaging services, and early mobile Internet applications viathe wireless application protocol (WAP), as well as other wireless data services.

102. Explain 1G.1G (or 1-G) refers to the first-generation of wireless telephone technology. These arethe analog telecommunications standards that use digital signaling to connect the

radio towers (which listen to the handsets) to the rest of the telephone system, thevoice during a call is is modulated to higher frequency, typically 150 MHz and up.

103. Explain 2G.
http://www.webopedia.com/TERM/S/standard.htmhttp://www.webopedia.com/TERM/B/bandwidth.htmhttp://www.webopedia.com/TERM/S/standard.htmhttp://www.webopedia.com/TERM/B/bandwidth.htm


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2G (or 2-G) is short for second-generation wireless telephone technology. 2G cellulartelecom networks were commercially launched on the GSM standard and were

significantly more efficient on the spectrum allowing for far greater mobile phonepenetration levels. 2G technologies can be divided into TDMA-based and CDMA-basedstandards depending on the type of multiplexing used.

104. Explain SMTP and POP3 Protocols.The SMTP (Simple Mail Transfer Protocol) protocol is used by the Mail TransferAgent (MTA) to deliver the EMail to the recipient's mail server. The SMTP protocol canonly be used to send emails, not to receive them.The POP (Post Office Protocol 3) protocol provides a simple, standardized way forusers to access mailboxes and download messages to their computers. When usingthe POP protocol all the EMail messages can be downloaded from the mail server to

the local computer.105. Define VoIP.

Voice-over-IP (VoIP) implementations enables users to carry voice traffic (forexample, telephone calls and faxes) over an IP network. VoIP uses Internet Protocol

for transmission of voice as packets over IP networks.

106. Define Wi-Fi and Wimax.Wi-Fi ( Wireless Fidility) is a mechanism for wirelessly connecting electronic devices.A device enabled with Wi-Fi, such as a personal computer, video gameconsole, smartphone, or digital audio player, can connect to the Internet via

a wireless network access point.WiMAX (Worldwide Interoperability for Microwave Access) is a communicationtechnology for wirelessly delivering high-speed Internet service to large geographicalareas. It is a part of a fourth generation, or 4G, of wireless-communication

technology, far surpasses the 30-metre (100-foot) wireless range of aconventional Wi-Fi (LAN), offering a metropolitan area network with a signal radius of

about 50 km (30 miles). WiMAX networks can deliver good VOIP quality

107. What is meant by Web2.0?Web 2.0 refers to added features and applications that make the web more

interactive, support easy online information exchange and interoperatibility.Some noticeable features of Web 2.0 are blogs, wikis, video-sharing websites,social networking websites etc.,Tools are available free and widely used by people some of them are facebook.Youtube, Blogger, Twitter etc.,

108. Explain PAN.Network organized around an individual person (typically involve a mobile computer,a cell phone and/or a handheld computing device such as a PDA) is called PAN(Personal Area Network)

109. What is meant by Remote Login?Remote access is the ability to get access to a computer or a network from a remotedistance. In simple words Remote Login means to access other computers on the

network or on the other network by the use of telnet or rlogin command
http://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Wireless_networkhttp://en.wikipedia.org/wiki/4Ghttp://en.wikipedia.org/wiki/Wi-Fihttp://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Wireless_networkhttp://en.wikipedia.org/wiki/Wireless_networkhttp://en.wikipedia.org/wiki/4Ghttp://en.wikipedia.org/wiki/Wi-Fi


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12th CBSE Computer Science Question Bank 09

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