What is User Agent?

This component of an electronic mail system provides service to the user to make the process of sending and receiving a message earlier.  A user agent is a software that composes,  read,  replies and forward messages. It also handles the mail boxes.

What is Recursive Function ?

A recursive function is a function that contain a call to the function itself. Recursive function allows us to divide complex problem into identical single cases which can be handled easily.

What is Constructor ?

A constructor is a special method that is created when the object is created. This particular method holds the same name as that of the object and it initialises the instance of the object whenever that object is created. The constructor also usually holds the initialisations of the different declared member variables of its object. Constructor does not return a value.

What does MIME stands for and where it is used ?

Multipurpose internet mail extensions. It is an Internet standard that extends the format of e-mail to support, text in character sets other than ASCII and non text attachments.

What information does a superblock of a file system contain ?

A superblock is a record of the characteristics of a file system including its size, block size, the empty and filled blocks and their respective counts, the size and location of the inode tables, the disk block map and usage information.

List two disadvantges of a database system as compared to a file-based system.

Database systems are complex, difficult and time consuming.
Damage to data base affects virtually all application programs.

List the basic difference between DOS and UNIX.

DOS is a single user operating system and UNIX is multiuser operating system.

What is ARP ? How it differ from IP?

ARP: Address Resolution Protocol is a computer networking protocol for determining a network host's hardware address when only its logical address is given. This hardware address is required to transfer data from one node to another.

IP: Internet Protocol is the primary protocol in the internet layer of internet protocol suite. It is used for delivering datagrams from the source host to the destination host solely based on their logical addresses.

In OSI protocol suite ARP comes in data link layer and IP is in network layer.

Is a two dimensional array passed as a value or reference argument to a function ?

Two dimensional arrays are passed as reference argument. If a two dimensional array is to be passed to a function, the parameter declaration in the function must include the number of columns. The number of rows is irrelevant since what is passed is a pointer to an array to rows.

What is a foreign key in an RDBMS?

A foreign key in a relation is an attribute which is primary key of some other relation.

Mention two advantages of a DBMS over a file storage of data.

Data redundary can be avoided by using DBMS.
DBMS provide backup and recovery and concurrency control.

Between the iterative routine sum-iter and recursive routine sum-rec, which is more efficient and why?

Sum-iter function is more efficient than the recursive function sum-rec. Ever time a recursive function calls itself all the local variables are saved in a stack. At the time of returning the values stored in stack are poped out. Thus recursive functions consume more memory space and time.

A Relational operator ?

Yields of a Boolean result

A static variable is one ?

Which retains its value throughout the life of the program.

How is XCOPY a better command than COPY ?

XCOPY command copy the whole directory, sub folders and all files within it. It also copies all hidden files.

COPY command only copies the files mentioned as arguments in the command XCOPY is much powerful than COPY command.

Distinguish berween break and continue statements in C.

A break statement terminates the execution of the loop and the control is transferred to the statement immediately following the loop.

Continue statement is used to bypass the remainder of the current pass through a loop.

What is the difference between process and processor ?

Process is a program under execution. It include the program executed, associated data and stack space.

Processor is the hardware that executes the program. It is the CPU of computer.

Distinguish between the block variable and the local variable?

A block variable is valid only within the block in which it is defined.  It is not visible outside the block.  It is created when program control enters the block and is destroyed when program control exits the block.

A local variable is visible throughout the function in which it is defined.

What is Bitwise Operator?

A bitwise operator operates on each bit of data. These operators are used for testing,  complementing and shifting bits to the right or left.

What is Program Counter? What information does it store?

Program Counter is a register inside a processor that contain address of the next instruction to be executed. After executing an instruction,  program counter contents are incremented by the length of the instruction that is read,  recently so that it again contain the address of next instruction to be executed.

List the desirable features of an algorithm?

(a) Top to down structured flow.
(b) Large algorithms must be broken into smaller ones with minimum coupling between them.
(c) The modules must be as independent as possible. That is high cohesion must be there.
(d) It must be easy to implement with minimum memory and must be fast.

What is a Router?

Router is a device used to determine the routes that a packet must take upon arrival at its input line. Routers decide the routes dynamically or statistically. They operate in network layer.

What is Bridge?

It is a device that is used to connect two LANs together. They LAN's can be of different type. Bridge receives packets from one LAN and convert the packet into a form acceptable for another LAN of different type. Bridges operate at data link layer.

What is a key word and what are the restrictions of using them?

Key word is a word with special meaning. For example in C programming language words int, float etc are key words. The users are not supposed to use key words as variable names.

Distinguish between the data and information?

Data is a collection of useful values. Processed data gives information. Collection of marks obtained by students is raw data. When sorted it gives the student marks rank wise. This is information.

What is Telnet?

It is a popular client server application program. TELNET is an abbreviation for terminal network. It is a standard application layer protocol that provides an interface through which a program on a host can access the resources of another host.

How does a 'while' control structure differ from 'do while ' structure?

The while loop first check the condition given in the while statement. If this condition is satisfied, then the statements in the while loop is executed.

In 'do while ' loop first the statements in the loop are executed then the condition is checked. If condition is true then again the statements are executed. In do while loop at least once the statements in the loop are guaranteed to be executed.

What is memory management? Why is it essential in a multi -user environment?

Memory management is schemes for using the available memory in a computer system in an effective manner. Memory management is one of the very important task performed by operating system.
In multiuser systems,  multiple processes reside in memory at the same time. Each process belong to different users. In order to avoid one process from interfacing with another process area, proper memory management is required. Usually available memory is partitioned and each process is allowed to reside in a separate partition. If a process try to violate the alloted memory space then it is detected automatically and the process is suspended. All these activities are done by operating systems memory management modules.

What is EPROM? How is it different from PROM?

EPROM: Erasable and programmable read only memory. It is a type of semiconductor read only memory in which contents can be erased and rewritten any number of times. To erase either electrical signals are used.

PROM: Programmable read only memory. It is read only memory which can be programmed only once. Any number of read operation can be done. To program the PROM internal fuses are burnt, connecting or disconnecting transistors, which acts as switches internally.

Why are NAND and NOR gates called universal gates?

NAND and NOR gates are called universal gates because any boolean function can be implemented using NAND or NOR gates only.

What is meant by Compiling a program?

Compiling is the process of translating a high level language program into its machine language form. For the purpose of compilation, software called Compilers are used.

What is ternary operator? Is any such operator available in C language? If yes, explain with an example?

In C ternary operator is available and is denoted by symbol? :

A traditional C statement and its equivalent C ternary construct is shown below :

If A==0
X=1
Else X=0;
X=A==0? 1:0;

The scope of a variable refers to the?

Portion of code in which the variable may be meaningful.

What are the important ways in which windows operating system is different from DOS?

Windows is a multi-threaded operating system. Multiple threads are executed on time sharing basis. Thus while one activity is going on in a window another activity may appear to be going on in another window simultaneously. Windows use graphical user interface. Windows run over the DOS layers.
DOS is a single threaded operating system. Only one activity is done at a time. It uses character user interface. Modern windows support advanced file systems.

What is BIOS in DOS?

BIOS is a collection of program stored in hardware ROM. BIOS contain device drivers for standard devices so that DOS could just call them to do I/O BIOS is located at the top of the address space. BIOS contain calls to read and write from absolute disk addresses and to read characters from keyboard and write to screen kernal access BIOS services by making procedure calls to io.sys instead of using interrupts to ROM. The file io.sys is loaded immediately after the computer is booted. BIOS also contain a rich collection of routines which can be accessed by user programs through software interrupts.

What is Copy Sales *.Data?

This command copy all files whose name start with SALES and extension DATA under root directory.