Download Operating System Question Bank Q1 : What is Operating System

Operating System Question Bank
Q1 : What is Operating System?
Operating systems control the functions performed by a computer. For example, the
operating system on your computer controls the input from the keyboard and mouse to
your computer, the opening and closing of programs, the transfer of information to a
printer, the organization of the files on your computer, and the screen display.
Q2: What is a desktop?
When you start your computer, the first thing you see is the desktop. The desktop is your
work area.
Q3: How do I shut down my computer?
To shut down your computer:
1. Click the Start button. The Start menu will appear.
2. Click Turn Off Computer. The Turn Off Computer dialog box will appear.
3. Click the Turn Off icon. Your computer will shut down.
Q4: What is Standby mode?
When your computer is in the Standby mode, your computer consumes less electricity, but
is ready for immediate use. However, if the computer loses electrical power while in the
standby mode, any information you have not saved will be lost.
Q5: What is Windows Explorer?
Windows Explorer is a place where you can view the drives on your computer and
manipulate the folders and files. Using Windows Explorer, you can cut, copy, paste, rename,
and delete folders and files.
Q6: What is the Most Recently Used Document list?
As you work, Windows XP tracks the last 15 files you used. It lists these files on the Most
Recently Used Document list. To view the Most Recently Used Document list:
1. Click the Start button.
2. Highlight Documents. The most recently used documents will display.
To open a file listed on the Most Recently Used Document list, click the file name.
Q7: How do I rename an item on the Start menu or on a Program menu?
To rename an item on the Start menu or on a Program menu:
1. Highlight the item.
2. Right-click the item.
3. Click Rename. The Rename dialog box will appear.
4. Type the new name in the New Name field.
5. Click OK.
Q8: How can you check the IP address of your computer ?
IPCONFIG /ALL
Q9: What is a Heat Sink ?
A component designed to lower the temperature of an electronic device by dissipating heat
into the surrounding air. All modern CPUs require a heat sink. Some also require a fan. A
heat sink without a fan is called a passive heat sink; a heat sink with a fan is called an active
heat sink. Heat sinks are generally made of an aluminium alloy and often have fins.
Q10: What is the difference between SATA and PATA Hard-Disk Drives?
Serial ATA and Parallel ATA are both specialized interface and data transfer devices, that are
used in computers to connect peripheral storage devices. Both serve the same purpose of
data transfer but differ in their basic technology, speed of performance and therefore their
niche applications these days.
Q11: What are Plug & Play devices ?
They are pieces of computer hardware that already have the software for them in you
system. simply put, you just have to plug it in and you computer does the rest.
Q12: What is the difference between a Serial and a Parallel Port ?
Basically a serial port sends and receives data 1 'bit' at a time over a single wire, while a
parallel port sends the data a 'byte' at a time over several wires simultaneously.
Q13:
What
do
you
know
about
the
PING
Command
?
Pinging is a command which tells you if the connection between your computer and a
particular domain is working correctly.
Eg : C:\Administrator\>Ping 192.168.1.100 or Ping server.domain.com
Q14: What is the difference between language and technology?
Language means it can follows some instructions, based on those instructions we need to
develop a technology. Technology is for develop some particular software, where language
provides communication between these software's.
Q15: What is the difference between win XP and win 7/8?
First of all graphic difference and then XP support IP Ver. 4 only and window 7 support IP
Ver. 4 and 6 both.
Q16: What is process migration?
It is the transfer of sufficient amount of the state of process from one machine to the target
machine.
Information Technology Question Bank
1. What are turnaround time and response time?
Turnaround time is the interval between the submission of a job and its completion.
Response time is the interval between submission of a request, and the first
response to that request.
2. What are rings in Windows NT?
Windows NT uses protection mechanism called rings provides by the process to
implement separation between the user mode and kernel mode.
3. When is a system in safe state?
The set of dispatchable processes is in a safe state if there exists at least one
temporal order in which all processes can be run to completion without resulting in a
deadlock.
4. What is Multiple Access?
If the physical links are shared by more than two nodes, it is said to be Multiple
Access.
5. What is a node?
A network can consist of two or more computers directly connected by some
physical medium such as coaxial cable or optical fiber. Such a physical medium is
called as Links and the computer it connects is called as Nodes.
6. What is Multimedia?
A Multimedia Application is an Application which uses a collection of multiple media
sources e.g. text, graphics, images, sound/audio, animation and/or video.
7. What are input devices and output devices of a computer?
An input device, such as a computer keyboard or mouse, can send information
(input) to the computer, but it cannot receive information (output) from the
computer.
An output device, such as a computer monitor or printer, can receive information
(output) from the computer, but it cannot send information (input) to the computer.
8. Define Information technology (IT)?
Information Technology refers to anything related to computing technology, such as
networking, hardware, software, the Internet, or the people that work with these
technologies.
9. Define Pointing Devices
A pointer represents a small symbol on the screen.It usually represents on the
screen in Graphical User Interface(GUI).Various Pointing Devices are MOUSE,
JOYSTICK etc.
10. Differentiate Impact and Non impact Printer?
An impact printer prints characters and graphics on the paper with strikes of
hammer on a ribbon and the paper e.g.DOT MATRIX PRINTER. NON IMPACT PRINTER
prints the output on paper without striking against the ribbon and the paper.
11. What is the difference between a copy and a scan?
Scan results in an image of your document being sent to your computer whereas
copy puts an image of your original on paper.
12. Differentiate Spyware vs. Malware.
Spyware and Malware both are software programs which are harmful. Both infect
the computer and steal the data by gaining access to the computer system.
Spyware is software that aids in gathering information about a person or
organization without their knowledge and that may send such information to
another entity without the consumer’s consent, or that asserts control over a
computer without the consumer’s knowledge.
Malware is software used or created by attackers to disrupt computer operation,
gather sensitive information, or gain access to private computer systems. It can
appear in the form of code, scripts, active content, and other software.
13. What do you mean by Gopher?
A system that pre-dates the World Wide Web for organizing and displaying files on
Internet servers. A Gopher server presents its contents as a hierarchically structured
list of files. With the ascendance of the Web, many gopher databases were
converted to Web sites which can be more easily accessed via Web search engines.
14. What is Extranet?
An extranet is a private network that uses Internet technology and the public
telecommunication system to securely share part of a business's information or
operations with suppliers, vendors, partners, customers, or other businesses.
15. What are System Utilities?
System utilities are the core software functions that allow you to manage your
computer in ways that you would find it inconceivable to be without. System utilities
may be already included in your computer or downloaded from the Internet.
16. What do you mean by Proxy server?
In computer networks, a proxy server is a server (a computer system or an
application) that acts as an intermediary for requests from clients seeking resources
from other servers.
17. What do you mean by WAIS?
WAIS (Wide Area Information Servers) is an Internet system in which specialized
subject databases are created at multiple server locations, kept track of by a
directory of servers at one location, and made accessible for searching by users with
WAIS client programs.
18. What is Virtual Reports?
Virtual Reports is a free, secure, web-hosted online reporting system that let’s you
take control of your transaction reporting. Merchants can access their account
information 24 hours a day, 7 days a week.
19. What is an Assembler?
An assembler is a program that takes basic computer instructions and converts them
into a pattern of bits that the computer's processor can use to perform its basic
operations. Some people call these instructions assembler language and others use
the term assembly language.
20. What is Cache Memory?
Cache (pronounced cash) memory is extremely fast memory that is built into a
computer’s central processing unit (CPU), or located next to it on a separate chip.
The CPU uses cache memory to store instructions that are repeatedly required to
run programs, improving overall system speed.
21. What do you mean by Multitasking?
A multitasking operating system is any type of system that is capable of running
more than one program at a time. Most modern operating systems are configured to
handle multiple programs simultaneously, with the exception of some privately
developed systems that are designed for use in specific business settings.
22. What are Positional and Non Positional number System?
A positional notation numeral system in which each position is related to the next by
a constant multiplier of that numeral system. For each position that the number is in,
in that system has a relative symbol or meaning, and in a way relates to the number
directly next to it. The total value of a positional number is the total of the resultant
values
of
all
positions.
In a non-positional number system, each number in each position does not have to
be positional itself. Every system varies by country and it depends on symbols and
values set by the people of that country. For example, the Egyptians use
Hieroglyphics, and the Greeks use a numeral system.
23. Define Machine code or machine language.
Machine code or machine language is a set of instructions executed directly by a
computer's central processing unit (CPU). Each instruction performs a very specific
task, such as a load, a jump, or an ALU operation on a unit of data in a CPU register
or memory.
24. Explain Assembly language.
Assembly language is converted into executable machine code by a utility program
referred to as an assembler; the conversion process is referred to as assembly, or
assembling the code. Assembly language uses a mnemonic to represent each lowlevel machine instruction or operation.
25. Difference Between RAM and ROM.
There is one major difference between a ROM and a RAM chip. A ROM chip is nonvolatile storage and does not require a constant source of power to retain
information stored on it. When power is lost or turned off, a ROM chip will keep the
information stored on it. In contrast, a RAM chip is volatile and requires a constant
source of power to retain information. When power is lost or turned off, a RAM chip
will lose the information stored on it.
C Programming Language Question Bank
1. Where is C programming language used or uses of C language?
C language is used to develop system applications that forms major portion of
operating systems such as Windows, UNIX and Linux. Operating systems, C compiler
and all UNIX application programs are written in C language. Below are some
examples of uses of C language.








Database systems
Graphics packages
Word processors
Spread sheets
Operating system development
Compilers and Assemblers
Network drivers
Interpreters
2. What is the difference between top down approach and bottom up approach in
programming languages?
Top down approach and bottom up approach are involved in software development.
These approaches are not involved in program execution.




Structure/procedure oriented programming languages like C programming
language follows top down approach. Whereas object oriented programming
languages like C++ and Java programming language follows bottom up
approach.
Top down approach begins with high level design and ends with low level
design or development. Whereas, bottom up approach begins with low level
design or development and ends with high level design.
In top down approach, main() function is written first and all sub functions
are called from main function. Then, sub functions are written based on the
requirement. Whereas, in bottom up approach, code is developed for
modules and then these modules are integrated with main() function.
Now-a-days, both approaches are combined together and followed in
modern software design.
3. What do you mean by by programming language and give some examples?



Programming language is nothing but a language designed to communicate
to machines through instructions and commands.
Normally machines are computers. Programs are written using some
programming languages to control the behavior of machines/computers and
to make them to perform required tasks.
Programming language example: Assembly language, C language, C++
language, Java, C#, .NET, Python etc.
4. List the characteristics of C language?






Reliability
Portability
Flexibility
Interactivity
Modularity
Efficiency and Effectiveness
5. What is embedded C?




Embedded C is the extension of C programming language.
Embedded C is used to develop micro controller based applications.
Embedded C includes features not available in normal C like fixed-point
arithmetic, named address spaces, and basic I/O hardware addressing.
Cell phones, MP3 players are some example for embedded systems in which
embedded C is used to program and control these devices.
6. Which level is C language belonging to?


C language is belonging to middle level language. C language behaves as a
bridge between machine level (low level) languages and high level languages.
C language is more user friendly than machine level languages. And, C
language does not support all the concepts that high level languages offer.
So, C programming language is called as middle level language.
7. Differentiate structured oriented, object oriented and non-structure oriented
programming language?
Structured oriented programming language –





In this type of language, large programs are divided into small programs
called functions.
Prime focus is on functions and procedures that operate on data
Data moves freely around the systems from one function to another
Program structure follows “Top Down Approach”
Example: C, Pascal, ALGOL and Modula-2
Object oriented programming language –





In this type of language, programs are divided into objects
Prime focus is on the data that is being operated and not on the functions or
procedures
Data is hidden and cannot be accessed by external functions
Program structure follows “Bottom UP Approach”
Example: C++, JAVA and C# (C sharp)
Non-structure oriented programming language –
 There is no specific structure for programming this language.
 Example: BASIC, COBOL, FORTRAN
8. Differentiate between assembler, compiler and interpreter?


Assembler is a program that converts assembly level language (low level
language) into machine level language.
Compiler compiles entire C source code into machine code. Whereas,
interpreters converts source code into intermediate code and then this
intermediate code is executed line by line.
9. Define printf() and scanf() ?




printf() is an inbuilt library function in C which is available in C library by
default. This function is declared and related macros are defined in “stdio.h”
header file.
printf() function is used to print the “character, string, float, integer, octal and
hexadecimal values” onto the output screen.
scanf() function is an inbuilt library function in C which is available in C library
by default. This function is declared and related macros are defined in
“stdio.h” header file.
scanf() function is used to read character, string, numeric data from
keyboard.
10. What is the use of main() function in C?
main() function is the function from where execution of any C program begins. So,
main() function is mandatory for any C program.
11. List all the sections that a C program may/must have?
There are many sections in a C program structure. They are,







Documentation section
Link Section
Definition Section
Global declaration section
Function prototype declaration section
Main function
User defined function section
main() function section is the important section in a C program as program execution
starts from main() function only in C language. A C program may not have all other
sections
except main() function.
12. What is IDE stands for?


IDE is nothing but Integrated Development Environment. IDE is a tool that
provides user interface with compilers to create, compile and execute C
programs.
Example: Turbo C++, Borland C++ and DevC++. These provide Integrated
Development Environment with compiler for both C and C++ programming
language.
13. Is C language case sensitive?
Yes. C language instructions/commands/functions and everything used in C program are
case sensitive.
14. Define data type in C?



Data types in C language are defined as the data storage format that a
variable can store a data to perform a specific operation.
Data types are used to define a variable before to use in a program.
Size of variable, constant and array are determined by data types.
15. What is the difference between int , char, float & double data types?




Integer data type allows a variable to store numeric values. The storage size
of int data type is 2 or 4 or 8 byte. It varies depend upon the processor in the
CPU.
Character data type allows a variable to store only one character. Storage size
of character data type is 1.
Float data type allows a variable to store decimal values. Storage size of float
data type is 4. This also varies depend upon the processor in the CP.
Double data type is also same as float data type which allows up-to 10 digits
after decimal.
16. What is the use of sizeof() function in C?
sizeof() function is used to find the memory space allocated for each data type in C.
17. What is enum in C?


Enumeration is a data type that consists of named integer constants as a list.
It start with 0 (zero) by default and value is incremented by 1 for the
sequential identifiers in the list.
18. What is void?
void is an empty data type that has no value.

We use void data type in functions when we don’t want to return any value
to the calling function.
Example:void sum (int a, int b); – This function won’t return any value to the calling
function.
19. What are the types of C tokens?


C tokens are the basic buildings blocks in C language which are constructed
together to write a C program.
Each and every smallest individual unit in a C program are known as C tokens.
C tokens are of six types. They are,
1.
2.
3.
4.
5.
6.
Keywords
Identifiers
Constants
Strings
Special symbols
Operators
(eg: int, while),
(eg: main, total),
(eg: 10, 20),
(eg: “total”, “hello”),
(eg: (), {}),
(eg: +, /,-,*)
20. What is identifier in C?



Each program elements in a C program are given a name called identifiers.
Names given to identify Variables, functions and arrays are examples for
identifiers.
Example: x is a name given to integer variable in above program
21. What is keyword in C?



Keywords are pre-defined words in a C compiler. Each keyword is
meant to perform a specific function in a C program.
Since keywords are referred names for compiler, they can’t be
used as variable name.
auto, double, int, struct, break, else, long, switch, case, enum,
register, typedef, char, extern, return, union, const, float, short,
unsigned, continue, for, signed, void, default, goto, sizeof, volatile,
do, , if, static, while
22. What do you mean by constants in C?


Constants refer to fixed values. They are also called as literals.
C Constants are also like normal variables. But, only difference is, constant
values can’t be modified by the program once they are defined. Constants
may be belonging to any of the data type.
23. Classify the types of constants in C?


Integer constants
Real or Floating point constants




Octal & Hexadecimal constants
Character constants
String constants
Backslash character constants
24. What is variable in C?



C variable is a named location in a memory where a program can manipulate
the data. This location is used to hold the value of the variable.
The value of the C variable may get change in the program.
C variable might be belonging to any of the data type like int, float, char etc.
25. What is the difference between constant and variable in C?
Constant values can’t be modified by the program once it is declared. But, variable
values can be modified by the program.
26. Can variable name start with numbers?
No. Variable names can’t start with numbers as per the variable naming rule.
27. What is the difference between variable declaration and variable definition in C?



Variable declaration tells the compiler about data type and size of the
variable. Whereas, variable definition allocates memory to the variable
Variable can be declared many times in a program. But, definition can
happen only one time for a variable in a program.
Variable declaration is for assignment of properties and identification to a
variable. Whereas, variable definition is for assignments of storage space to a
variable
28. What is operator in C?


The symbols which are used to perform logical and mathematical operations
in a C program are called C operators.
These C operators join individual constants and variables to form expressions.
Operators, functions, constants and variables are combined together to form
expressions.
29. What are the different types of operators in C?
C language offers many types of operators. They are,




Arithmetic operators
Assignment operators
Relational operators
Logical operators




Bit wise operators
Conditional operators (ternary operators)
Increment/decrement operators
Special operators
30. What is the syntax for ternary operator in C?



Ternary operator is same as if else control statement in C.
Syntax :
(Condition? true_value: false_value);
Example:
(A > 100? 0: 1);
31. What are all decision control statements in C?
There are 3 types of decision making control statements in C language. They are,



if statements
if else statements
nested if statements
32.What are all loop control statements in C?


Loop control statements in C are used to perform looping operations until the
given condition is true. Control comes out of the loop statements once
condition becomes false.
There are 3 types of loop control statements in C language. They are,



for
while
do-while
33.What is the difference between while and do-while loops in C?


While loop is executed only when given condition is true.
Whereas, do-while loop is executed for first time irrespective of the
condition. After executing while loop for first time, then condition is checked.
34.What is the difference between single equal “=” and double equal “==” operators in C?


Single equal is an assignment operator used to assign the values to the
variables.
But, double equal is relational operator used to compare two variable values
whether they are equal are not.
35.What is the difference between pre increment operator and post increment operator
in C?


Pre increment operator is used to increment variable value by 1 before
assigning the value to the variable.
Post increment operator is used to increment variable value by 1 after
assigning the value to the variable.
36.What is the difference between pre decrement operator and post decrement
operator?


Pre decrement operator is used to decrement variable value by 1 before
assigning the value to the variable.
Post decrement operator is used to decrement variable value by 1 after
assigning the value to the variable.
37.What is “&” and “*” operators in C?


“*” Operator is used as pointer to a variable. Example: * a where * is pointer
to the variable a.
& operator is used to get the address of the variable. Example: &a will give
address of a.
38. What will happen if break statement is not used in switch case in C?


Switch case statements are used to execute only specific case statements
based on the switch expression.
If we do not use break statement at the end of each case, program will
execute all consecutive case statements until it finds next break statement or
till the end of switch case block.
39. Why is default statement used in switch case in C?
Switch case statements are used to execute only specific case statements based on the
switch expression. If switch expression does not match with any case, default statements
are executed by the program.
40.What is the use of “goto” statement?
goto statement is used to transfer the normal flow of a program to the specified label in the
program.
41. What value will be assigned to the variable X if a = 10, b = 20, c = 30, d = 40 in below
expression?
X = a/b+c*d-c;




The above arithmetic operation is performed based on the precedence of the
operators.
In above mentioned expression, c*d will be performed first. Then, a/b, then
(c*d)-c, then (a/b) + ((c*d)-c).
Please check the operator precedence table to know the priority and
associativity of the C operators.
Output of the above expression is 1170.
42. What value is assigned to the below variables?
int X1 = 13/3;
int X2 = 13%3;


The value of X1 is 4
The value of X2 is 1
43. What is the difference between auto variable and register variable in C?
Storage class of all variables are auto by default unless we specify a variable is register or
static or extern in C program.

Both auto variable and register variable are local variables. Register
variables are stored in register memory. Whereas, auto variables are
stored in main CPU memory.
 Register variables will be accessed very faster than the normal/auto
variables since they are stored in register memory rather than main
memory.
 But, only limited variables can be used as register since register size is
very low. (16 bits, 32 bits or 64 bits)
44. What is the difference between auto variable and static variable in C?



Both auto and static variables are local variables.
Static variables can retain the value of the variable between different
function calls.
But, scope of auto variable is within the function only. It can’t retain the value
of the variable between different function calls.
45. How many arguments can be passed to a function in C?


Any number of arguments can be passed to a function. There is no limit on
this. Function arguments are stored in stack memory rather than heap
memory. Stack memory allocation is depending on the operating system.
So, any number of arguments can be passed to a function as much as stack
has enough memory. Program may crash when stack overflows.
46. What is the difference between exit() and return() in C?


exit() is a system call which terminates current process. exit() is not an
instruction of C language.
Whereas, return() is a C language instruction/statement and it returns from
the current function (i.e. provides exit status to calling function and provides
control back to the calling function).
47. What is the use of “#define” in C?
#define is a pre-processor directive which is used to define constant value. This
constant can be any of the basic data types.
48. What is the syntax for comments in C?
The characters or words or anything which are given between “/*” and “*/”, won’t
be considered by C compiler for compilation process. These will be ignored by C
compiler during compilation.
Syntax: /* comments */
49. Can array subscripts have negative value in C?
No. Array subscripts should not have negative value. Always, it should be positive.
50. What are library functions and their use in C language? Can we write our own
functions and include them in C library?

Library functions in C language are inbuilt functions which are grouped together and
placed in a common place called library. The use of library function is to get the predefined output instead of writing our own code to get those outputs.

Yes. We can write our own functions and include them in C library.
51. What are the different storage classes in C?
The scope and lifetime of a variable or / and function within a C program is defined by
storage class. There are four storage classes in C
auto - It is the default storage class for all variables and / or functions.
register - Allows for defining variables to store in CPU register instead of RAM. Unary
operator is not applied for register variable.
static – The static storage class allows the updated variable values available for the next
time when the function, in which the variable is defined , is invoked for the next time.
extern - It allows a global variable to be visible to all the program files / external files
52. Can include files be nested?
Yes. Include files can be nested any number of times. As long as you use precautionary
measures, you can avoid including the same file twice. In the past, nesting header files
was seen as bad programming practice, because it complicates the dependency tracking
function of the MAKE program and thus slows down compilation. Many of today’s
popular compilers make up for this difficulty by implementing a concept called
precompiled headers, in which all headers and associated dependencies are stored in a
precompiled state.
53. What is a null pointer?
There are times when it’s necessary to have a pointer that doesn’t point to anything.
The macro NULL, defined in, has a value that’s guaranteed to be different from any valid
pointer. NULL is a literal zero, possibly cast to void* or char*.
The null pointer is used in three ways:
1) To stop indirection in a recursive data structure.
2) As an error value.
3) As a sentinel value.
54. What are header files and what are its uses in C programming?
Header files are also known as library files. They contain two essential things: the
definitions and prototypes of functions being used in a program. Simply put, commands
that we use in C programming are actually functions that are defined from within each
header files. Each header file contains a set of functions. For example: stdio.h is a header
file that contains definition and prototypes of commands like printf and scanf.
55. Write down the equivalent pointer expression for referring the same
element a[i][j][k][l] ?
a[i] == *(a+i)
a[i][j] == *(*(a+i)+j)
a[i][j][k] == *(*(*(a+i)+j)+k)
a[i][j][k][l] == *(*(*(*(a+i)+j)+k)+l)
56. Difference between const char* p and char const* p
In const char* p, the character pointed by ‘p’ is constant, so we can’t change the
value of character pointed by p but we can make ‘p’ refer to some other location.
In char const* p, the ptr ‘p’ is constant not the character referenced by it, so we
can’t make ‘p’ to reference to any other location but we can change the value of the
char pointed by ‘p’.
57. When should the register modifier be used?
The register modifier hints to the compiler that the variable will be heavily used and
should be kept in the CPU’s registers, if possible, so that it can be accessed faster.
58. Why n++ executes faster than n+1?
The expression n++ requires a single machine instruction such as INR to carry out the
increment operation whereas; n+1 requires more instructions to carry out this
operation.
59. Why doesn't the following statement work?
char str[ ] = "Hello" ;
strcat ( str, '!' ) ;
Answer: The string function strcat( ) concatenates strings and not a character. The
basic difference between a string and a character is that a string is a collection of
characters, represented by an array of characters whereas a character is a single
character. To make the above statement work writes the statement as shown below:
strcat ( str, "!" ) ;
60. What is the purpose of main( ) function ?
The function main( ) invokes other functions within it. It is the first function to be
called when the program starts execution.
· It is the starting function
· It returns an int value to the environment that called the program
· Recursive call is allowed for main( ) also.
· It is a user-defined function
· Program execution ends when the closing brace of the function main( ) is reached.
· It has two arguments 1) argument count and 2) argument vector (represents strings
passed).
· Any user-defined name can also be used as parameters for main( ) instead of argc
and argv
61. What will be the output of the following:
main()
{
static int var = 5;
printf("%d ",var--);
if(var)
main();
}
Answer: 5 4 3 2 1
Explanation: When static storage class is given, it is initialized once. The change in the value
of a static variable is retained even between the function calls. Main is also treated like any
other ordinary function, which can be called recursively.
62. main()
{
char *p;
printf("%d %d ",sizeof(*p),sizeof(p));
}
Answer: 1 2
Explanation: The sizeof() operator gives the number of bytes taken by its operand. P
is a character pointer, which needs one byte for storing its value (a character). Hence
sizeof(*p) gives a value of 1. Since it needs two bytes to store the address of the
character pointer sizeof(p) gives 2.
63. main()
{
int i=3;
switch(i)
{
default:printf("zero");
case 1: printf("one");
break;
case 2:printf("two");
break;
case 3: printf("three");
break;
}
}
Answer: three
Explanation: The default case can be placed anywhere inside the loop. It is executed only
when all other cases doesn't match.
64.
main()
{
int
printf("%d%d%d%d%d%d",i++,i--,++i,--i,i);
}
Answer: 45545
i=5;
Explanation: The arguments in a function call are pushed into the stack from left to right.
The evaluation is by popping out from the stack. And the evaluation is from right to left,
hence the result.
65. #define square(x) x*x
main()
{
int i;
i = 64/square(4);
printf("%d",i);
}
Answer: 64
Explanation: the macro call square(4) will substituted by 4*4 so the expression becomes i =
64/4*4 . Since / and * has equal priority the expression will be evaluated as (64/4)*4 i.e.
16*4 = 64
66. #include <stdio.h>
#define a 10
main()
{
#define a 50
printf("%d",a);
}
Answer: 50
Explanation: The preprocessor directives can be redefined anywhere in the program. So the
most recently assigned value will be taken.
67. What are the auto variables? Where are they stored?
The auto variables are stored in the memory of the system. The keyword ‘auto’ is optional.
Many of the variables used by the program / application are ‘auto’ variables, being the main
memory is faster. These variables are stored in the memory runtime stack.
68. What is a structure?
Structure is a collection of heterogeneous (i.e. related data items which can be of different
types) held together to a single unit. The data items enclosed within a structure are called
its members which may be of data type int, float, char, array etc.
69. What is a pointer?
Pointer is a variable that contains address of another variable in the memory. Pointers are
quite useful in creation of linked data structures (such as linked lst, trees graphs), managing
object allocated memory dynamically, optimize the program to execute faster and use less
memory.
70. What are macros? What are its advantages and disadvantages?
Macro is a Pre-processor. Major advantage of using the macro is to increase the speed of
the execution of the program.
Major disadvantage of the macros are:
(i) No type checking is performed in macro. This may cause error.
(ii) A macro call may cause unexpected results.
71. What is difference between Structure and Unions?
(i) In structure every member has its own memory whereas in union its members share
the same member space.
(ii) In structure, it is possible to initialize all the members at the same time which is not
possible in case of union.
(iii) A structure requires more space than union(for the same type of members).
(iv) In union different interpretations of the same memory space are possible which is not so
in case of structures.
72. What are the advantages of using Unions?
(i) Efficient use of memory as it does not demand memory space for its all members rather it
require memory space for its largest member only.
(ii) Same memory space can be interpreted differently for different members of the union.
73. What is the difference between ordinary variable and pointer in C?
An ordinary variable is like a container it can hold any value and we can change the value of
ordinary variable at a time throughout the program .A pointer is a variable that stores the
address of another Variable.
74. How are pointer variables initialized?
Pointer variable are initialized by one of the following two ways
- Static memory allocation
- Dynamic memory allocation
75. What is modular programming?
If a program is large, it is subdivided into a number of smaller programs that are called
modules or subprograms. If a complex problem is solved using more modules, this approach
is known as modular programming
76. Where do global, static, local, register variables and C Program instructions get
stored?
Global, static, local: In main memory
Register variable: In registers
C program: In main memory.
77. Why are all header files not declared in every C program?
Declaring all header files in every program would lead to increase in the overall file size and
load
of
the
program.
It
is
not
a
good
programming.
The choice header files that you want to declare in the program depends on the
commands/functions you want to use in the program. Each header file contains different
commands and functions. So we use only the files relevant to our program.
78. Define Operator, Operand, and Expression in 'C'?
Operators are symbols which take one or more operands or expressions and perform
arithmetic or logical computations.
Operands are variables or expressions which are used in operators to evaluate the
expression.
Combination of operands and operators form an expression.
79. Predict the output or error
enum colors {BLACK,BLUE,GREEN}
main()
{
printf("%d..%d..%d",BLACK,BLUE,GREEN);
return(1);
}
Answer: 0..1..2
Explanation: enum assigns numbers starting from 0, if not explicitly defined.
80. What are the four types of scope in c?
Block scope.
Function scope.
File scope.
Program scope.
81. What is nested structure?
A structure is a collection of one or more variables, possibly of different data types, grouped
together under a single name for convenient handling. Structures can contain other
structures as members; in other words, structures can nest.
82. What
is
difference
between
declaration
and
definition?
During declaration we just specify the type and no memory is allocated to the
variable. But during the definition an initial value is assigned and memory is
allocated to the variable.
83. Differentiate between #include<...> and #include "..."
#include<...> means that the directories other than the current one will be searched for the
header file.
#include "..." means that the current directory will be searched for the header file before
any other directories.
84. What is self referential structure?
A self-referential structure is one of the data structures which refer to the pointer to
(points) to another structure of the same type.
85. What are the uses of a pointer?
(i) It is used to access array elements
(ii) It is used for dynamic memory allocation.
(iii) It is used in Call by reference
(iv) It is used in data structures like trees, graph, linked list etc.
86. What does *p++ do? What does it point to?
*p++ increments p.
It returns the value pointed to by p before incrementation.
87. What are enumerations?
They are a list of named integer-valued constants. Example: enum color { black ,
orange=4,yellow, green, blue, violet };This declaration defines the symbols “black”,
“orange”, “yellow”, etc. to have the values “1,” “4,” “5,” … etc. The difference between an
enumeration and a macro is that the enum actually declares a type, and therefore can be
type checked.
88. Are pointers integer?
No, pointers are not integers. A pointer is an address. It is a positive number.
89. What is static memory allocation?
Compiler allocates memory space for a declared variable. By using the address of operator,
the reserved address is obtained and this address is assigned to a pointer variable. This way
of assigning pointer value to a pointer variable at compilation time is known as static
memory allocation.
90. What is dynamic memory allocation?
A dynamic memory allocation uses functions such as malloc() or calloc() to get memory
dynamically. If these functions are used to get memory dynamically and the values returned
by these function are assigned to pointer variables, such a way of allocating memory at run
time is known as dynamic memory allocation.
91. List out differences between structures and arrays
The following are the differences between structures and arrays:
- Array elements are homogeneous. Structure elements are of different data type.
- Array allocates static memory and uses index / subscript for accessing elements of the
array. Structures allocate dynamic memory and uses (.) operator for accessing the member
of a structure.
- Array is a pointer to the first element of it. Structure is not a pointer
- Array element access takes less time in comparison with structures.
92. What is FILE?
FILE is a predefined data type. It is defined in stdio.h file.
93. What is a file?
A file is a region of storage in hard disks or in auxiliary storage devices. It contains
bytes of information .It is not a data type.
94. What is wrong with this statement? myName = “Vansh”;
We cannot use the = sign to assign values to a string variable. Instead, use the strcpy
function. The correct statement would be: strcpy(myName, “Vansh”);
95. How do you determine the length of a string value that was stored in a variable?
To get the length of a string value, use the function strlen(). For example, if we have a
variable named Name, we can get the length of the stored string value by using this
statement: I = strlen(Name); the variable I will now have the character length of the string
value.
96. What is the difference between text files and binary files?
Text files contain data that can easily be understood by humans. It includes letters, numbers
and other characters. On the other hand, binary files contain 1s and 0s that only computers
can interpret.
97. What are merits and demerits of array in c?
Merits:
(a) We can easily access each element of array.
(b) Not necessity to declare too many variables.
(c) Array elements are stored in continuous memory location.
Demerits:
(a) Wastage of memory space. We cannot change size of array at the run time.
(b) It can store only similar type of data.
98. What are pre-processor directives?
Pre-processor directives are placed at the beginning of a C program. They begin with #
symbol.
This is the place, where library files are specified depending on the functions to be used in
the program.
Pre-processor directives are also used for declaration of constants.
99. Is it possible to pass an entire structure to functions?
Yes, it is possible to pass an entire structure to a function in a call by method style. Some
programmers prefer to declare the structure globally, and then pass a variable of that
structure type to a function. It helps in maintaining the consistency and uniformity in terms
of argument type.
100.
How do you access the values within an array?
Arrays contain a number of elements, depending on the size you assigned it during variable
declaration. Each element is assigned a number from 0 to number of elements-1.
To assign or retrieve the value of a particular element, refer to the element number. For
example: if we have a declaration that says “int marks[6];”, then we have 6 accessible
elements, namely: marks[0], marks[1], marks[2], marks[3], marks[4] and marks[5].
Software Engineering Question Bank
1. What is computer software?
Computer software is a complete package, which includes software program, its
documentation and user guide on how to use the software.
2. Can you differentiate computer software and computer program?
A computer program is piece of programming code which performs a well defined task
where as software includes programming code, its documentation and user guide.
3. What is software engineering?
Software engineering is an engineering branch associated with software system
development.
4. When you know programming, what is the need to learn software engineering
concepts?
A person who knows how to build a wall may not be good at building an entire house.
Likewise, a person who can write programs may not have knowledge of other concepts of
Software Engineering. The software engineering concepts guide programmers on how to
assess requirements of end user, design the algorithms before actual coding starts, create
programs by coding, testing the code and its documentation.
5. What is software process or Software Development Life Cycle (SDLC)?
Software Development Life Cycle, or software process is the systematic development of
software by following every stage in the development process namely, Requirement
Gathering, System Analysis, Design, Coding, Testing, Maintenance and Documentation in
that order.
6. What are SDLC models available?
There are several SDLC models available such as Waterfall Model, Iterative Model, Spiral
model, V-model and Big-bang Model etc.
7. What are various phases of SDLC?
The generic phases of SDLC are: Requirement Gathering, System Analysis and Design,
Coding, Testing and implementation. The phases depend upon the model we choose to
develop software.
8. Which SDLC model is the best?
SDLC Models are adopted as per requirements of development process. It may very
software-to-software to ensuring which model is suitable.
We can select the best SDLC model if following answers are satisfied 
Is SDLC suitable for selected technology to implement the software ?

Is SDLC appropriate for client’s requirements and priorities ?

Is SDLC model suitable for size and complexity of the software ?

Is the SDLC model suitable for type of projects and engineering we do ?

Is the SDLC appropriate for the geographically co-located or dispersed developers ?
9. What is software project management?
Software project management is process of managing all activities like time, cost and
quality management involved in software development.
10. Who is software project manager?
A software project manager is a person who undertakes the responsibility of carrying out
the software project.
11. What does software project manager do?
Software project manager is engaged with software management activities. He is
responsible for project planning, monitoring the progress, communication among
stakeholders, managing risks and resources, smooth execution of development and
delivering the project within time, cost and quality contraints.
12. What is software scope?
Software scope is a well-defined boundary, which encompasses all the activities that are
done to develop and deliver the software product.
The software scope clearly defines all functionalities and artifacts to be delivered as a part
of the software. The scope identifies what the product will do and what it will not do, what
the end product will contain and what it will not contain.
13. What is project estimation?
It is a process to estimate various aspects of software product in order to calculate the
cost of development in terms of efforts, time and resources. This estimation can be derived
from past experience, by consulting experts or by using pre-defined formulas.
14. How can we derive the size of software product?
Size of software product can be calculated using either of two methods 
Counting the lines of delivered code

Counting delivered function points
15. What are function points?
Function points are the various features provided by the software product. It is
considered as a unit of measurement for software size.
16. What are software project estimation techniques available?
There are many estimation techniques available.The most widely used are 
Decomposition technique (Counting Lines of Code and Function Points)

Empirical technique (Putnam and COCOMO).
17. What is baseline?
Baseline is a measurement that defines completeness of a phase. After all activities
associated with a particular phase are accomplished, the phase is complete and acts as a
baseline for next phase.
18. What is Software configuration management?
Software Configuration management is a process of tracking and controlling the changes
in software in terms of the requirements, design, functions and development of the
product.
19. What is change control?
Change control is function of configuration management, which ensures that all changes
made to software system are consistent and made as per organizational rules and
regulations.
20. How can you measure project execution?
We can measure project execution by means of Activity Monitoring, Status Reports and
Milestone Checklists.
21. Mention some project management tools.
There are various project management tools used as per the requirements of software
project and organization policies. They include Gantt Chart, PERT Chart, Resource
Histogram, Critical Path Analysis, Status Reports, Milestone Checklists etc.
22. What are software requirements?
Software requirements are functional description of proposed software system.
Requirements are assumed to be the description of target system, its functionalities and
features. Requirements convey the expectations of users from the system.
23. What is feasibility study?
It is a measure to assess how practical and beneficial the software project development
will be for an organization. The software analyzer conducts a thorough study to understand
economic, technical and operational feasibility of the project.

Economic - Resource transportation, cost for training, cost of additional utilities and
tools and overall estimation of costs and benefits of the project.

Technical - Is it possible to develop this system ? Assessing suitability of machine(s)
and operating system(s) on which software will execute, existing developers’
knowledge and skills, training, utilities or tools for project.

Operational - Can the organization adjust smoothly to the changes done as per the
demand of project ? Is the problem worth solving ?
24. How can you gather requirements?
Requirements can be gathered from users via interviews, surveys, task analysis,
brainstorming, domain analysis, prototyping, studying existing usable version of software,
and by observation.
25. What is SRS?
SRS or Software Requirement Specification is a document produced at the time of
requirement gathering process. It can be also seen as a process of refining requirements
and documenting them.
26. What are functional requirements?
Functional requirements are functional features and specifications expected by users from
the proposed software product.
27. What are non-functional requirements?
Non-functional requirements are implicit and are related to security, performance, look
and feel of user interface, interoperability, cost etc.
28. What is software measure?
Software Measures can be understood as a process of quantifying and symbolizing various
attributes and aspects of software.
29. What is software metric?
Software Metrics provide measures for various aspects of software process and software
product. They are divided into –

Requirement metrics : Length requirements, completeness

Product metrics :Lines of Code, Object oriented metrics, design and test metrics

Process metrics: Evaluate and track budget, schedule, human resource.
30. What is modularization?
Modularization is a technique to divide a software system into multiple discreet modules,
which are expected to carry out task(s) independently.
31. What is concurrency and how it is achieved in software?
Concurrency is the tendency of events or actions to happen simultaneously. In software,
when two or more processes execute simultaneously, they are called concurrent processes.
Example
While you initiate print command and printing starts, you can open a new application.
Concurrency, is implemented by splitting the software into multiple independent units of
execution namely processes and threads, and executing them in parallel.
32. What is cohesion?
Cohesion is a measure that defines the degree of intra-dependability among the elements
of the module.
33. What is coupling?
Coupling is a measure that defines the level of inter-dependability among modules of a
program.
34. Mentions some software analysis & design tools?
These can be: DFDs (Data Flow Diagrams), Structured Charts, Structured English, Data
Dictionary, HIPO (Hierarchical Input Process Output) diagrams, ER (Entity Relationship)
Diagrams and Decision tables.
35.What is level-0 DFD?
Highest abstraction level DFD is known as Level 0 DFD also called a context level DFD,
which depicts the entire information system as one diagram concealing all the underlying
details.
36. What is the difference between structured English and Pseudo Code?
Structured English is native English language used to write the structure of a program
module by using programming language keywords, whereas, Pseudo Code is more close to
programming language and uses native English language words or sentences to write parts
of code.
37. What is data dictionary?
Data dictionary is referred to as meta-data. Meaning, it is a repository of data about data.
Data dictionary is used to organize the names and their references used in system such as
objects and files along with their naming conventions.
38. What is structured design?
Structured design is a conceptualization of problem into several well-organized elements
of solution. It is concern with the solution design and based on ‘divide and conquer’
strategy.
39. What is the difference between function oriented and object oriented design?
Function-oriented design is comprised of many smaller sub-systems known as functions.
Each function is capable of performing significant task in the system. Object oriented
design works around the real world objects (entities), their classes (categories) and
methods operating on objects (functions).
40.Briefly define top-down and bottom-up design model.
Top-down model starts with generalized view of system and decomposes it to more
specific ones, whereas bottom-up model starts with most specific and basic components
first and keeps composing the components to get higher level of abstraction.
41. What is the basis of Halstead’s complexity measure?
Halstead’s complexity measure depends up on the actual implementation of the program
and it considers tokens used in the program as basis of measure.
42. Mention the formula to calculate Cyclomatic complexity of a program?
Cyclomatic complexity uses graph theory’s formula: V(G) = e – n + 2
43. What is functional programming?
Functional programming is style of programming language, which uses the concepts of
mathematical function. It provides means of computation as mathematical functions,
which produces results irrespective of program state.
44. Differentiate validation and verification?
Validation checks if the product is made as per user requirements whereas verification
checks if proper steps are followed to develop the product.
Validation confirms the right product and verification confirms if the product is built in a
right way.
45. What is black-box and white-box testing?
Black-box testing checks if the desired outputs are produced when valid input values are
given. It does not verify the actual implementation of the program.
White-box testing not only checks for desired and valid output when valid input is provided
but also it checks if the code is implemented correctly.
Criteria
Knowledge of software program, design
and structure essential
Knowledge of Software Implementation
essential
Who conducts this test on software
baseline reference for tester
Black Box Testing
White Box Testing
No
Yes
No
Yes
Software
Employee
Testing
Software Developer
Requirements
Design
and
specifications
structure details
46. Quality assurance vs. Quality Control?
Quality Assurance monitors to check if proper process is followed while software
developing the software.
Quality Control deals with maintaining the quality of software product.
47. What are various types of software maintenance?
Maintenance types are: corrective, adaptive, perfective and preventive.

Corrective
Removing errors spotted by users

Adaptive
tackling the changes in the hardware and software environment where the
software works

Perfective maintenance
implementing changes in existing or new requirements of user

Preventive maintenance
taking appropriate measures to avoid future problems
48. What is software re-engineering?
Software re-engineering is process to upgrade the technology on which the software is
built without changing the functionality of the software. This is done in order to keep the
software tuned with the latest technology.
49. What are CASE tools?
CASE stands for Computer Aided Software Engineering. CASE tools are set of automated
software application programs, which are used to support, accelerate and smoothen the
SDLC activities.
Computer Network Question Bank
1. Define Network?
A network is a set of devices connected by physical media links. A network is recursively is a
connection of two or more nodes by a physical link or two or more networks connected by
one or more nodes.
2. What is a node?
A network can consist of two or more computers directly connected by some physical
medium such as coaxial cable or optical fiber. Such a physical medium is called as Links and
the computer it connects is called as Nodes.
3. What is a gateway or Router?
A node that is connected to two or more networks is commonly called as router or Gateway.
It generally forwards message from one network to another.
4. What do you mean by Multiple Access?
If the physical links are shared by more than two nodes, it is said to be Multiple Access.
5. List the advantages of Distributed Processing?
a. Security/Encapsulation
b. Distributed database
c. Faster Problem solving
d. Security through redundancy
e. Collaborative Processing
6. Point the criteria necessary for an effective and efficient network?
a. Performance
It can be measured in many ways, including transmit time and response time.
b. Reliability
It is measured by frequency of failure, the time it takes a link to recover from a failure, and
the network's robustness.
c. Security
Security issues includes protecting data from unauthorized access and virues.
7. Name the factors that affect the performance of the network?
a. Number of Users
b. Type of transmission medium
c. Hardware
d. Software
8. List the factors that affect the reliability of the network?
a. Frequency of failure
b. Recovery time of a network after a failure
9. Define Protocol?
A protocol is a set of rules that govern all aspects of information communication.
10. What are the key elements of protocols?
The key elements of protocols are
a. Syntax
It refers to the structure or format of the data, that is the order in which they are
presented.
b. Semantics
It refers to the meaning of each section of bits.
c. Timing
Timing refers to two characteristics: When data should be sent and how fast they can be
sent.
11. What are the key design issues of a computer Network?
a. Connectivity
b. Cost-effective Resource Sharing
c. Support for common Services
d. Performance
12. Define Bandwidth and Latency?
Network performance is measured in Bandwidth (throughput) and Latency (Delay).
Bandwidth of a network is given by the number of bits that can be transmitted over the
network in a certain period of time. Latency corresponds to how long it t5akes a message to
travel from one end off a network to the other. It is strictly measured in terms of time.
13. Define Routing?
The process of determining systematically hoe to forward messages toward the destination
nodes based on its address is called routing.
14. What is a peer-peer process?
The processes on each machine that communicate at a given layer are called peer-peer
process.
15. Define semantic gap?
Defining a useful channel involves both understanding the applications requirements and
recognizing the limitations of the underlying technology. The gap between what
applications expects and what the underlying technology can provide is called semantic gap.
16. What is Round Trip Time?
The duration of time it takes to send a message from one end of a network to the other and
back, is called RTT.
17. Define the terms Uni casting , Multi casting and Broadcasting?
When the message is sent from a source to a single destination node, it is called Unicasting.
The message is sent to some subset of other nodes, it is called Multicasting.
If the message is sent to all the m nodes in the network it is called Broadcasting.
18. What is Multiplexing?
Multiplexing is the set of techniques that allows the simultaneous transmission of multiple
signals across a single data link.
19. Name the categories of Multiplexing?
a. Frequency Division Multiplexing (FDM)
b. Time Division Multiplexing (TDM)
i. Synchronous TDM
ii. ASynchronous TDM Or Statistical TDM.
c. Wave Division Multiplexing (WDM)
20. Define FDM, WDM, TDM.
FDM is an analog technique that can be applied when the bandwidth of a link is greater than
the combined bandwidths of the signals to be transmitted.
WDM is conceptually the same as FDM, except that the multiplexing and demultiplexing
involve light signals transmitted through fiber optics channel.
TDM is a digital process that can be applied when the data rate capacity of the transmission
medium is greater than the data rate required by the sending and receiving devices.
21. What is Synchronous TDM ?
In STDM, the multiplexer allocates exactly the same time slot to each device at all times,
whether or not a device has anything to transmit.
22. List the layers of OSI Reference Model.
a. Physical Layer
b. Data Link Layer
c. Network Layer
d. Transport Layer
e. Session Layer
f. Presentation Layer
g. Application Layer
23. Which layers are network support layers?
a. Physical Layer
b. Data link Layer and
c. Network Layers
24. Which layers are user support layers?
a. Session Layer
b. Presentation Layer and
c. Application Layer
25. Write the various concerns of the Physical Layer?
Physical layer coordinates the functions required to transmit a bit stream over a physical
medium.
a. Physical characteristics of interfaces and media
b. Representation of bits
c. Data rate
d. Synchronization of bits
e. Line configuration
f. Physical topology
g. Transmission mode
26. List the various responsibilities of Data Link Layer?
The Data Link Layer transforms the physical layer, a raw transmission facility, to a reliable
link and is responsible for node-node delivery.
a. Framing
b. Physical Addressing
c. Flow Control
d. Error Control
e. Access Control
27. What are the responsibilities of Network Layer?
The Network Layer is responsible for the source-to-destination delivery of packet possibly
across multiple networks (links).
a. Logical Addressing
b. Routing
28. Write the various responsibilities of Transport Layer?
The Transport Layer is responsible for source-to-destination delivery of the entire message.
a. Service-point Addressing
b. Segmentation and reassembly
c. Connection Control
d. Flow Control
e. Error Control
29. Discuss the responsibilities of Session Layer?
The Session layer is the network dialog Controller. It establishes, maintains and synchronizes
the interaction between the communicating systems.
a. Dialog control
b. Synchronization
30. What are the responsibilities of Presentation Layer?
The Presentation layer is concerned with the syntax and semantics of the information
exchanged between two systems.
a. Translation
b. Encryption
c. Compression
31. What are the categories of Transmission media?
a. Guided Media
i. Twisted - Pair cable
1. Shielded TP
2. Unshielded TP
ii. Coaxial Cable
iii. Fiber-optic cable
b. Unguided Media
i. Terrestrial microwave
ii. Satellite Communication
32. What are the types of errors?
a. Single-Bit error
In a single-bit error, only one bit in the data unit has changed
b. Burst Error
A Burst error means that two or more bits in the data have changed.
33. What is Error Detection? What are its methods?
Data can be corrupted during transmission. For reliable communication errors must be
deducted and Corrected. Error Detection uses the concept of redundancy, which means
adding extra bits for detecting errors at the destination. The common Error Detection
methods are
a. Vertical Redundancy Check (VRC)
b. Longitudinal Redundancy Check (VRC)
c. Cyclic Redundancy Check (VRC)
d. Checksum
34. Define Redundancy?
The concept of including extra information in the transmission solely for the purpose of
comparison. This technique is called redundancy.
35. What is VRC?
It is the most common and least expensive mechanism for Error Detection. In VRC, a parity
bit is added to every data unit so that the total number of 1s becomes even for even parity.
It can detect all single-bit errors. It can detect burst errors only if the total number of errors
in each data unit is odd.
36. Define LRC?
In LRC, a block of bits is divided into rows and a redundant row of bits is added to the whole
block. It can detect burst errors. If two bits in one data unit are damaged and bits in exactly
the same positions in another data unit are also damaged, the LRC checker will not detect
an error. In LRC a redundant data unit follows n data units.
37. What is CRC?
CRC, is the most powerful of the redundancy checking techniques, is based on binary
division.
38. What do you mean by Checksum?
Checksum is used by the higher layer protocols (TCP/IP) for error detection
39. List the steps involved in creating the checksum.
a. Divide the data into sections
b. Add the sections together using 1's complement arithmetic
c. Take the complement of the final sum, this is the checksum.
40. Compare Error Detection and Error Correction:
The correction of errors is more difficult than the detection. In error detection, checks only
any error has occurred. In error correction, the exact number of bits that are corrupted and
location in the message are known. The number of the errors and the size of the message
are important factors.
41. What are Code Words?
"r" redundant bits are added to each block to make the length n = k + r. The resulting n-bit
blocks are called codeword's. 2n - 2k codeword's that are not used. These codeword's are
invalid or illegal.
42. What is a Linear Block Code?
A linear block code is a code in which the exclusive OR (addition modulo-2) of two valid
codeword's creates another valid codeword.
43. Explain Cyclic Codes?
Cyclic codes are special linear block codes with one extra property. In a cyclic code, if a
codeword is cyclically shifted (rotated), the result is another codeword.
44. Define Encoder?
A device or program that uses predefined algorithms to encode, or compress audio or video
data for storage or transmission use. A circuit that is used to convert between digital video
and analog video.
45. What is Framing?
Framing in the data link layer separates a message from one source to a destination, or from
other messages to other destinations, by adding a sender address and a destination address.
The destination address defines where the packet has to go and the sender address helps
the recipient acknowledge the receipt.
46. Define Character Stuffing?
In byte stuffing (or character stuffing), a special byte is added to the data section of the
frame when there is a character with the same pattern as the flag. The data section is
stuffed with an extra byte. This byte is usually called the escape character (ESC), which has a
predefined bit pattern. Whenever the receiver encounters the ESC character, it removes it
from the data section and treats the next character as data, not a delimiting flag.
47. What is Bit Stuffing?
Bit stuffing is the process of adding one extra 0 whenever five consecutive Is follow a 0 in
the data, so that the receiver does not mistake the pattern 0111110 for a flag.
48. What is Flow Control?
Flow control refers to a set of procedures used to restrict the amount of data that the
sender can send before waiting for acknowledgment.
49. What is Error Control ?
Error control is both error detection and error correction. It allows the receiver to inform
the sender of any frames lost or damaged in transmission and coordinates the
retransmission of those frames by the sender. In the data link layer, the term error control
refers primarily to methods of error detection and retransmission.
50. What Automatic Repeat Request (ARQ)?
Error control is both error detection and error correction. It allows the receiver to inform
the sender of any frames lost or damaged in transmission and coordinates the
retransmission of those frames by the sender. In the data link layer, the term error control
refers primarily to methods of error detection and retransmission. Error control in the data
link layer is often implemented simply: Any time an error is detected in an exchange,
specified frames are retransmitted. This process is called automatic repeat request (ARQ).
51. What is Stop-and-Wait Protocol?
In Stop and wait protocol, sender sends one frame, waits until it receives confirmation from
the receiver (okay to go ahead), and then sends the next frame.
52. Define Pipelining
In networking and in other areas, a task is often begun before the previous task has ended.
This is known as pipelining.
53. What is Piggy Backing?
A technique called piggybacking is used to improve the efficiency of the bidirectional
protocols. When a frame is carrying data from A to B, it can also carry control information
about arrived (or lost) frames from B; when a frame is carrying data from B to A, it can also
carry control information about the arrived (or lost) frames from A.
54. Difference between the communication and transmission.
Transmission is a physical movement of information and concern issues like bit polarity,
synchronization, clock etc.
Communication means the meaning full exchange of information between two
communication media.
55. Define SAP?
Series of interface points that allow other computers to communicate with the other layers
of network protocol stack.
56. What is terminal emulation, in which layer it comes?
Telnet is also called as terminal emulation. It belongs to application layer.
57. What is Beaconing?
The process that allows a network to self-repair networks problems. The stations on the
network notify the other stations on the ring when they are not receiving the transmissions.
Beaconing is used in Token ring and FDDI networks.
58. What is NETBIOS and NETBEUI?
NETBIOS is a programming interface that allows I/O requests to be sent to and received
from a remote computer and it hides the networking hardware from applications.
NETBEUI is NetBIOS extended user interface. A transport protocol designed by microsoft
and IBM for the use on small subnets.
59. What is RAID?
A method for providing fault tolerance by using multiple hard disk drives.
60. How Gateway is different from Routers?
A gateway operates at the upper levels of the OSI model and translates information
between two completely different network architectures or data formats.
61. What is attenuation?
The degeneration of a signal over distance on a network cable is called attenuation.
62. What do you mean by MAC address?
The address for a device as it is identified at the Media Access Control (MAC) layer in the
network architecture. MAC address is usually stored in ROM on the network adapter card
and is unique.
63. Difference between bit rate and baud rate.
Bit rate is the number of bits transmitted during one second whereas baud rate refers to the
number of signal units per second that are required to represent those bits.
baud rate = (bit rate / N)
where N is no-of-bits represented by each signal shift.
64. Define Bandwidth?
Every line has an upper limit and a lower limit on the frequency of signals it can carry. This
limited range is called the bandwidth.
65. What are the different type of networking / internetworking devices?
1. Repeater: Also called a regenerator, it is an electronic device that operates only at
physical layer. It receives the signal in the network before it becomes weak,
regenerates the original bit pattern and puts the refreshed copy back in to the link.
2. Bridges: These operate both in the physical and data link layers of LANs of same
type. They divide a larger network in to smaller segments. They contain logic that
allow them to keep the traffic for each segment separate and thus are repeaters that
relay a frame only the side of the segment containing the intended recipent and
control congestion.
3. Routers: They relay packets among multiple interconnected networks (i.e. LANs of
different type). They operate in the physical, data link and network layers. They
contain software that enable them to determine which of the several possible paths
is the best for a particular transmission.
4. Gateways: They relay packets among networks that have different protocols (e.g.
between a LAN and a WAN). They accept a packet formatted for one protocol and
convert it to a packet formatted for another protocol before forwarding it. They
operate in all seven layers of the OSI model.