Java

Java Programming Language:

 Java is a computer programming language that is concurrent, class-based, object-oriented, and specifically designed to have as few implementation dependencies as possible. 

It is intended to let application developers "write once, run anywhere" (WORA), meaning that code that runs on one platform does not need to be recompiled to run on another. 

Java applications are typically compiled to byte-code (class file) that can run on any Java virtual machine (JVM) regardless of computer architecture. Java is, as of 2014, one of the most popular programming languages in use, particularly for client-server web applications, with a reported 9 million developers.

Figure :-Java Logo 

Java is:

Architectural-neutral: 

Java compiler generates an architecture-neutral object file format which makes the compiled code to be executable on many processors, with the presence of Java run-time system.

Distributed: 

Java is designed for the distributed environment of the internet.

Dynamic: 

Java is considered to be more dynamic than C or C++ since it is designed to adapt to an evolving environment. Java programs can carry extensive amount of run-time information that can be used to verify and resolve accesses to objects on run-time.

High Performance: 

With the use of Just-In-Time compilers, Java enables high performance.

Interpreted: 

Java byte code is translated on the fly to native machine instructions and is not stored anywhere. The development process is more rapid and analytical since the linking is an incremental and light weight process.

Multi-threaded: 

With Java's multi-threaded feature it is possible to write programs that can do many tasks simultaneously. This design feature allows developers to construct smoothly running interactive applications.

Object Oriented:

In Java, everything is an Object. Java can be easily extended since it is based on the Object model.

Platform independent: 

Unlike many other programming languages including C and C++, when Java is compiled, it is not compiled into platform specific machine, rather into platform independent byte code. This byte code is distributed over the web and interpreted by virtual Machine (JVM) on whichever platform it is being run.
 
Portable:

Being architectural-neutral and having no implementation dependent aspects of the specification makes Java portable. Compiler in Java is written in ANSI C with a clean portability boundary which is a PO SIX subset.

Robust:

Java makes an effort to eliminate error prone situations by emphasizing mainly on compile time error checking and run-time checking.

Secure:

 With Java's secure feature it enables to develop virus-free, tamper-free systems. Authentication techniques are based on public-key encryption.

Simple: 

Java is designed to be easy to learn. If you understand the basic concept of OOP Java would be easy to master.

PHP

1. PHP is a recursive acronym for "Hypertext Preprocessor".
2. PHP is a widely-used, open source scripting language.
3. PHP scripts are executed on the server.
4. PHP costs nothing, it is free to download and use.
5. PHP files can contain text, HTML, CSS, JavaScript, and PHP code.
6. PHP code are executed on the server, and the result is returned to the browser as plain HTML.
7. PHP files have extension ".php".
8. PHP can generate dynamic page content.
9. PHP can create, open, read, write, delete, and close files on the server.
10. PHP can collect form data.
11. PHP can send and receive cookies.
12. PHP can add, delete, modify data in your database.
13. PHP can restrict users to access some pages on your website.
14. PHP can encrypt data.
15. PHP runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.).
16. PHP is compatible with almost all servers used today (Apache, IIS, etc.).
17. PHP supports a wide range of databases.
18. PHP is easy to learn and runs efficiently on the server side.
19. With PHP you are not limited to output HTML. You can output images, PDF files, and even Flash movies.
20. You can also output any text, such as XHTML and XML.
21. In PHP, all user-defined functions, classes, and keywords (e.g. if, else, while, echo, etc.) are NOT case-sensitive.However; in PHP, all variables are case-sensitive.
22. PHP is a Loosely Typed Language.PHP automatically converts the variable to the correct data type, depending on its value.In other languages such as C, C++, and Java, the programmer must declare the name and type of the variable before using it.

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PHP Variables:-

As with algebra, PHP variables can be used to hold values (x=5) or expressions (z=x+y).

A variable can have a short name (like x and y) or a more descriptive name (age, carname, total_volume).

Rules for PHP variables:

1. A variable starts with the $ sign, followed by the name of the variable
2. A variable name must start with a letter or the underscore character
3. A variable name cannot start with a number
4. A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
5. Variable names are case sensitive ($y and $Y are two different variables)

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PHP Variables Scope:-

In PHP, variables can be declared anywhere in the script.

The scope of a variable is the part of the script where the variable can be referenced/used.

PHP has three different variable scopes:

1. local
2. global
3. static

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PHP Data Types:-
PHP Integers:

An integer is a number without decimals.

Rules for integers:

1. An integer must have at least one digit (0-9)
2. An integer cannot contain comma or blanks
3. An integer must not have a decimal point
4. An integer can be either positive or negative
5. Integers can be specified in three formats: decimal (10-based), hexadecimal (16-based - prefixed with 0x) or octal (8-based - prefixed with 0)

Example
<?php
$x = 5985;
var_dump($x);
echo "<br>";
$x = -345; // negative number
var_dump($x);
echo "<br>";
$x = 0x8C; // hexadecimal number
var_dump($x);
echo "<br>";
$x = 047; // octal number
var_dump($x);
?>

Basic PHP Syntax:-
A PHP script can be placed anywhere in the document.
A PHP script starts with <?php and ends with ?>

Example:

<!DOCTYPE html>
<html>
<body>

<h1>My first PHP page</h1>

<?php
echo "Hello World!";
?>

</body>
</html>

PHP statements are terminated by semicolon (;).
The closing tag of a block of PHP code also automatically implies a semicolon.
So you do not have to have a semicolon terminating the last line of a PHP block.

Mac OS

The Mac OS is designed to run on Machintosh computers .
It is a very powerful and easy-to-use operating system .It is the world most advanced operating system and the newest version of OS X is free with strongest security.
The latest version of the Machintosh operating system is OS X. This operating system provides a number of unique features:

• Aqua  is an intuitive user interface.
• Dock provides a flexible tool for organizing files.
• Sherlock locates information on the Web as well as on the user's computer system.

                                                      Figure :- OS X

OS X:-
OS X is the line of graphical operating systems developed, marketed, and sold by Apple Inc.
which succeeded the original Mac OS, which had been Apple's primary operating system since 1984.

Unlike the earlier Macintosh operating system, OS X is a Unix-based operating system built on
technology developed at NeXT from the second half of the 1980s until early 1997,
when Apple purchased the company.

Latest version of OS X is OS X Yosemite  (version 10.10) is the upcoming eleventh major release of OS X, Apple Inc.'s desktop and server operating system for Macintosh computers. OS X Yosemite was announced and released to developers and beta testers on June 2, 2014, at WWDC 2014. Yosemite will be released to consumers in late 2014.Following the new naming scheme introduced with OS X Mavericks, Yosemite is named after the national park in California.
System requirements:-No changes in system requirements have been made for Yosemite, meaning that all Macintosh products capable of running OS X Mavericks will be supported by Yosemite; as with Mavericks, 2 GB of RAM, 8 GB of available storage, and OS X 10.6.8 (Snow Leopard) or later are required.

Device Drivers

What are Device drivers? How are device drivers updated?
 Answer:-

Device drivers  are specialized programs that allow device such as mouse, printer, scanner or keyboard to communicate with the rest of the computer system.

Every device, such as a mouse or printer , that is connected to a computer system, has a special program associated with it. This program , called a device driver or simply a driver, works with the operating system to allow communication between the device and the rest of the computer system.
Each time the computer system is started, the operating system loads all the device drivers into memory.

Whenever a new device is added to a computer system, a new device driver must be installed before the device can be used .
Windows supplies hundreds of different device drivers with its system software. If a particular device driver is not included , the product's manufacturer will supply one.
Many time these drivers are available directly form manufacturer's website.

You probably never think abut the drivers in your computer.
However when your computer behaves unpredictably , you find updating your drivers solves your problems.
Windows makes it easy to update the drivers on your computer using Windows Update.

Process States and Transitions

List containing complete set of process states:
1. The process is executing in user mode.
2. The process is executing in kernel mode.
3. The process is not executing but is ready to run as soon as the kernel schedules it.
4. The process is sleeping and resides in main memory .
5. The process is ready to run , but swapper (process 0) must swap the process into main memory before the kernel can schedule it to execute.
6. The process is sleeping, and the swapper has swapped the process to secondary storage to make room for other processes in main memory.
7. The process is returning from the kernel to user mode ,but the kernel preemprts it and does a context switch to schedule another process.The distinction between this state and state 3 (ready to run) will be brought out shortly.
8. The process is newly created and is in a transition state ; the process exists, but it is not ready to run , nor is it sleeping . This state  is the start for all processes except process 0.
9. The process executed the exit system call and is in the zombie state. The process no longer exists , but it leaves a record containing an exit code and some timing statistics for its parent process to collect .The zombie state is the final state of a process.

Buffer

Definition :-
The kernel could read and write directly to and from the disk for all file system accesses,but system response time and throughput would be poor because of the slow disk transfer rate . The kernel therefore attempts to minimize frequency of disk access by keeping a pool  of internal data buffers,called the buffer cache which contains the data in recently used disk blocks.

A buffer contains two parts:
a memory array that contains data from the disk and
a buffer header that identifies the buffer.

The status of buffer is a combination of the following conditions:
1. The buffer is  currently locked.
2. The buffer contains valid data 
3. The kernel must write the buffer contents to disk before reassigning the buffer this condition is known as "delayed-write"
4. The kernel is currently reading or writing the contents of the buffer to disk.
5. A process is currently waiting for the buffer to become free

Structure of the buffer pool:
The kernel caches data in the buffer pool according to a least recently used algorithm .
The kernel maintains a free list of buffers that preserves the last recently used order.
The free list is a doubly linked circular list of buffers with a dummy buffer header that marks its beginning and end .
Kernel organizes the buffer into separate queues, hashed as a function of the device and block number.

Five typical scenarios the kernel may follow in getblk to allocate a buffer for a disk block
1. The kernel finds the block on its hash queue, and its buffer is free.
2. The kernel cannot find the block on the hash queue,so it allocates a buffer from the free list .
3. The kernel cannot find the block on the hash queue and in attempting to allocate a buffer from the free list ,finds a buffer on the free list that has been marked "delayed write." The kernel must write the "delayed write" buffer to disk and allocate another buffer.
4. The kernel cannot find the block on the hash queue , and the free list of buffers is empty.
5. The kernel finds the block on the hash queue , but its buffer is currently busy.


 

Solve and Test Arithmetic questions

Solve and Test Arithmetic questions

Q 1. The  base of a  triangular field is three times its altitude.If the cost of cultivating the field at Rs.24 per hectare be Rs.324, find its base and height.

Ans. Height = 300m , base= 900m

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Q 2. The average monthly expenditure of a family was Rs.4,050 during first 3 months, Rs. 4,260 during next 4 month and Rs.4,346 during last 5 month of the year. If the total saving during the year be Rs.8,720, find the average monthly income.

Ans. Rs. 4,970

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Q 3. The student in three classes are in the ratios 2:3:5. If 20 students are increased in each class ,the ratios changes to 4:5:7. What is the total number of student before the increase?

Ans. 100

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Q 4. A papaya tree was planted 2 year ago. It increase at the rate of 20% every year . If  at present , the height of the tree is 540 cm, What was it when the tree was planted?

Ans. 375 cm

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Q 5. The sum of the ages of a father and son is 45 year. Five year ago , the product of their ages was 4 times the  father's age at that time.Find the present ages of the father and son.

Ans. Father's age i.s 36 year and son 's age is 9 years

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Q 6. A man sold an article for Rs.161, gaining 1/6th of his outlay. Find the cost price of the article.

Ans. Rs. 138

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Q 7. Divide Rs.560 among A,Band C so that A may get half as much as C and B may get half as much as C.

Ans. A's shave =Rs. 140, B's shave =Rs. 140, C 's shave= Rs.280

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Q 8. If in a long division sum ,the dividend is 380606 and the successive remainders from the first to the last are 434,125 and 413,find the divisor.

Ans. 843

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Q 9. In a hostel there were some students.Average expenditure on their meal was Rs.60.10 more students joined and the expenses increased by Rs.350 ,but average reduced by Rs. 5 .How many students were in the hostel originally?

Ans. 40

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Q 10. A grocer purchased 80 kg of rice at RS .13.50 per kg and mixed it with 120 kg available at Rs. 16 per kg.At what rate per kg should he sell the mixture to have a gain of 20 per cent?

Ans. Rs 18 per kg

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Solved General knowledge questions and answers

General Knowledge Questions :-

1) What should be the minimum interval between two successive blood donations?
A) 6 weeks
B) 3 months
C) 6 months
D) 8 months

Ans::- B) 3 months

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2) Food is mainly digested in-
A) Liver
B) Large intestine
C) Small intestine
D) Mouth
 

Ans::- C) Small intestine

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3) The large cell in the human body is -
A) Nerve Cell
B) Muscle Cell
C) Liver Cell
D) Kidney Cell

Ans::- A) Nerve Cell

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4) Which of the following is a flightless bird?
A) Emu
B) Hen
C) Swan
D) None of these

Ans::- A) Emu

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5) Meningitis is a disease which affects the -
A) Kidneys
B) Liver 
C) Heart
D) Brain

Ans::- D) Brain

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6) Which of the following is a vector quantity?
A) Force
B) Momentum
C) Energy
D) Temperature

Ans ::- A) Force

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7) The three famous Buddhist sites Ratnagiri ,Lalitgiri and Udaigiri  are located in which of the following States?
A) Bihar
B) Maharashtra
C) U.P.
D) Orissa

Ans:: - Orissa

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8) Who among the following earned the title of a 'Liberator'?
A) Chandragupta Vikramaditya 
B) Ashoka
C) Chandragupta Maurya
D) Alexander

Ans::- C) Chandragupta Maurya

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9) The strategy of  'Divide and Rule' was adopted by whom?
A) Lord Curzon
B) lord  Wellesley 
C) Lord  Minto 
D) Lord  Canning

Ans:: - C) Lord Minto

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10) Delhi became the Capital of India in -
A) 1910
B) 1911
C) 1916
D) 1923

Ans ::- B) 1911

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11) The first President of independent India was -
A) Dr. Rajendra Prasad
B) M.K.Gandhi
C) Dr. S.Radhakrishnan
D) J.L.Nehru

Ans::- A) Dr. Rajendra Prasad

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12) Who was the first European to translate the Bhagwad Gita into English?

A) William Jones
B) Charles Wilkins
C) James Prinsep
D) Sir Alexander Cunningham

Ans:: -B) Charles Wilkins

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13. The  population of which of the following is maximum on  the earth

A) Reptiles
B) Fishes
C) Birds
D) Beetles

Ans. B) Fishes

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14. Which of the following is the largest living mammal?
A) Giraffe
B) White elephant
C) Rhinoceros
D) Blue Whale

Ans. D) Blue Whale

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15. Which first is given by a herb?

A) Mango
B) Banana
C) Apple
D) Jack-  fruit

Ans. D) Jack- fruit

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16. Which of  the following is hereditary?
A) Dysentery
B) Tuberculosis
C) Haemophilia
D) Cancer

Ans. C) Haemophilia

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17. Which of the following is knows as the jain Temple City?
A) Gimar
B) Rajagriha
C) Varanasi
D) Ilahabad

Ans. A) Gimar

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18. Who was the first King  to conquer Malwa,Gujarat and Maharashtra?

A) Skandagupta
B) Samudragupta
C) Chandragupta Maurya
D) Harshavardhan 

Ans. C) Chandragupta Maurya

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19. The slogan 'Inquilab Zindabhad' was raised by whom?

A) Lokmanya Tilak
B) Veer Savarkar
C) Chandrashekar Azad
D) Bhagat Singh

Ans. D) Bhagat Singh

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20. The Muslim League started demanding a separate nation for the Muslims from which year?
A) 1919
B) 1925
C) 1929
D) 1940

Ans. D) 1940

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21. When did the British Parliament pass the Indian Independence Bill  ?
A) 20th February, 1947
B) 24th March, 1947
C) 1st July, 1947
D) 14th August,1947

Ans. C) 1st July,1947

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22. Who among the following has the final power to maintain order within the House of People?

A) Marshal of the People
B) Prime Minister
C) Speaker
D) Chief of Security Staff

Ans. C) Speaker

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23. Which is laughing gas?
a) Carbon dioxide
b) Sulphur dioxide
c) Carbon monoxide
d) Nitrous  oxide

Ans. d) Nitrous  oxide

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24. Detergents used for cleaning clothes and utensils contains-

a) Nitrates
b) Bicarbonates
c) Sulphonates
d) Bismutnates

Ans. c) Sulphonates

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25. Floppy disc in a computer system is-

a) Compiler
b) Core memory
c) Software
d) Device for storage and retrieving data

Ans. d) Device for storage and retrieving data

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26. The tooth with there roots is-

a) Molar
b) Pre- Molar
c) Incisor
d) Canine

Ans. a) Molar

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27. Bamboo is a-
a) Grass
b) Herb
c) Shrub
d) Tree

Ans. a) Grass

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28. Which of the following cannot be controlled by vaccination?
a) Small pox
b) Diabetes
c) Polio
d) Whooping cough

Ans. b) Diabetes

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29. Which of the following terms is used for several individuals of a species living together in a locality?

a) Biosphere
b) Ecosystem
c) Bio- community
d) Population

Ans. c) Bio- community

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30. Raman effect is associated with characteristics of-a) Heat
b) Light
c) Electricity
d) Magnetism

Ans. b) Light

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31. Which of the following is known as the queen of  spices?
a) Coriander
b) Cardamom
c) Fenugreek
d) Chillies

Ans. b) Cardamom

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32. The Peacock throne was made for -

a) Jahangir
b) Akbar
c) Shahjehan
d) Aurangzeb

Ans. c) Shahjehan

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33. Which of the following was built  by Akbar?
a) Agra fort
b) Fort of Daulatabad
c) Red fort
d) Fort of Ahmednagar

Ans. a) Agra fort

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34. Ramayan refers to-

a) Satyuga
b) Tretayuga
c) Dwaparyuga
d) Kalyuga

Ans. b) Tretayuga

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35. Who is regarded as the greatest law giver of  ancient India?

a) Kautilya
b) Manu
c) Panini
d) Patanjali

Ans. b) Manu

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36. When did the Indian National Congress ask for the 'Dominion Status'?

a) 1908
b) 1929
c) 1942
d) 1947

Ans. a) 1908

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37. The first woman's university in India was founded by-

a) Gandhiji
b) J.K.Kumarappa
c) Dhondo Keshave Karve
d) Rani Ahilya Devi

Ans. c) Dhondo Keshave Karve

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Full forms

Full Forms ::-

Write full form of  :

AGP ::- Accelerated Graphics Port

AI  ::- Artificial Intelligence

ALU  ::- Arithmetic Logic  Unit

AOL ::- American Online

ARPANET  ::- Advanced Research Project Agency Network

ASCII   ::-American Standard Code for Information Interchange

ATM  ::- Automated Teller Machine

B2B  ::- Business To Business

B2C  ::- Business To Consumer

C2C  ::- Consumer To Consumer

CCTV  (camera)::- Closed-Circuit Television (camera)

CD ::- Compact Disc

CERN  ::-  Center for European Nuclear Research

CISC  ::- Complex Instruction Set Computer

CMOS   ::- Complementary Metal Oxide Semiconductor

CPU   ::- Central Processing Unit

CRT  ::- Cathode Ray Tube

DBMS  ::- Database Management System

DNS  ::- Domain Name System

DSL  ::- Digital Subscriber Line

DVD  ::- Digital Versatile (or Video ) Disc

EBCDIC   ::- Extended Binary Coded Decimal Interchange Code

E-Mail ::-  Electronic mail

FTP  ::- File Transfer Protocol

HDTV  ::-  High Definition Tele Vision

HPSB  ::- High Performance Serial Bus

HTML  ::- Hyper Text Markup Language

HTTP ::- Hyper Text Transfer Protocol

IP  ::-   Internet Protocol

IRC  ::- Internet Relay Chat

ISA  ::- Industry Standard Architecture

ISP  ::- Internet Service Provider

IT ::- Information Technology

LAN  ::- Local Area Network

LCD  ::-  Liquid Crystal Display

MAN  ::- Metropolitan Area Network 

MICR  ::- Magnetic  Ink  Character Recognition

NIC  ::- Network Interface Card

NOS   ::- Network operating System

OCR  ::- Optical Character Recognition

OLE  ::- Object Linking and Embedding

OMR  ::- Optical Mark Recognition 

PC  ::-  Personal Computer

PCI  ::-  Peripheral Component Interconnect

PCMCIA  ::- Personal Computer Memory Card International Association

PDA  ::- Personal Digital Assistant

RAID  ::- Redundant Arrays of Inexpensive Disks

RAM  ::- Random Access Memory

RISC  ::- Reduced Instruction Set Computer

ROM  ::- Read Only Memory

SQL  ::- Structured Query Language

SVGA  ::- Super Video Graphics Array

SXGA  ::- Super Extended Graphics Array

 TCP ::- Transmission Control Protocol

TFT  ::- Thin Film Transistor

TV  ::-   Tele Vision

UPC ::-  Universal Product Code

URL  ::- Uniform Resource Locators

USB ::-  Universal Serial Bus

UXGA  ::- Ultra Extended Graphics Array 

VR  ::- Virtual Reality

VRML  ::- Virtual Reality Modeling Language

WAN  ::- Wide Area Network

WWW ::- World Wide Web 

XGA   ::-  Extended Graphics Array 

Technical Exam preparation Qs

1. What is the decimal equivalent to the hexadecimal number E6D3?
A. 59019
B. 59091
C. 59136
D. 59093
Answer::-B.

2. Convert the decimal number 2989 to hex.
A. FDD1
B. BAD
C. TED
D. CAD
Answer::- B.

3. MAC address are _________ bits in length.
A. 12
B. 24
C. 48
D. 64
Answer::- C.

4. Where does the MAC address reside?
A. Transceiver
B. Computer BIOS
C. NIC
D. CMOS
Answer::- C.

5. Which of the following statements best describes communication between two devices on a LAN?
A. The source device encapsulates data in a frame with the MAC address of the destination device, and then transmits it. Everyone on the LAN sees it, but the devices with non-matching addresses otherwise ignore the frame.
B. The source encapsulates the data and places a destination MAC address in the frame. It puts the frame on the LAN, where only the device with the matching address can check the address field.
C. The destination device encapsulates data in a frame with the MAC address of the source device, puts it on the LAN, and the device with the matching address removes the frame.
D. Each device on the LAN receives the frame and passes it up to the computer, where software decides whether to keep or to discard the frame.
Answer::-A.

6. Which are the functions associated with framing?
A. Identifies which computers are communicating with one another
B. Signals when communication between individual computers begins and when it ends
C. Flags corrupted frames
D. All of the above
Answer::-D.

7. How does a computer on a LAN detect an error in a frame?
A. It sends a copy of the frame back to the sender for verification.
B. It checks the destination address to verify that the frame was really intended for them.
C. It compares an FCS in the frame to one that the computer calculates from the contents of the frame.
D. It calculates a checksum from the data in the frame, and then sends it back to the source for verification.
Answer::- C.

8. Which best describes a CSMA/CD network?
A. One node's transmission traverses the entire network and is received and examined by every node.
B. Signals are sent directly to the destination if the source knows both the MAC and IP addresses.
C. One node's transmission goes to the nearest router, which sends it directly to the destination.
D. Signals are always sent in broadcast mode.
Answer::- A.

9. Which best describes broadcasting?
A. Sending a single frame to many stations at the same time
B. Sending a single frame to all routers to simultaneously update their routing tables
C. Sending a single frame to all routers at the same time
D. Sending a single frame to all hubs and bridges at the same time
Answer::- A.

10. A half-duplex circuit means
A. Only one side can talk at a time
B. The signal strength is cut in half
C. The signal strength is doubled
D. Two hosts can talk simultaneously
Answer::-A.

11. Attenuation means
A. Travel
B. Delay
C. A signal losing strength over distance
D. Loss of signal due to EMI
Answer::-C.

12. Which of the following is an external source of electrical impulses that can attack the quality of electrical signals on a cable?
A. EMI caused by electrical motors
B. RFI caused by electrical motors
C. Impedance caused by radio systems
D. EMI caused by lightning
Answer::- A.

13. What is the primary cause of crosstalk?
A. Cable wires that are too large in diameter
B. Too much noise in a cable's data signal
C. Electrical motors and lighting
D. Electrical signals from other wires in a cable
Answer::-D.

14. Which of the following describes cancellation?
A. Wires in the same circuit cancel each other's electrical current flow.
B. Cancellation is a commonly used technique to protect the wire from undesirable interference.
C. The magnetic fields from one cable run cancel magnetic fields of another cable run.
D. External magnetic fields cancel the fields inside network cabling.
Answer::- B.

15. What is it called when two bits from two different communicating computers are on a shared medium at the same time?
A. Latency
B. Dispersion
C. Collision
D. Obstruction
Answer::-C.

16. Reflection does not occur with what kind of signals?
A. Electrical
B. Radio waves
C. Microwaves
D. None of the above
Answer::- D.

17. __________ means to convert binary data into a form that can travel on a physical communications link.
A. Encoding
B. Decoding
C. Encrypting
D. Decrypting
Answer::- A.

18. Which of the following is the correct order for the network layers?
A. 1: Physical 2: Data Link 3: Transport 4. Network 5: Presentation 6: Session 7: Application
B. 1: Physical 2: Data Link 3: Network 4: Transport 5: Session 6: Presentation 7: Application
C. 1: Physical 2: Data Link 3: Network 4: Session 5: Transport 6: Application 7: Presentation
D. 1: Physical 2: Network 3: Session 4: Data Link 5: Transport 6: Application 7: Presentation
Ans::- B.

19. Which layer of the OSI model handles error detection, network topology, and medium access?
A. The physical layer
B. The data link layer
C. The transport layer
D. The network layer
Ans::- B.

20. Which layer of the OSI model establishes, maintains, and manages sessions between applications?
A. The transport layer
B. The session layer
C. The presentation layer
D. The application layer
Answer::-B.

21. Which best describes the function of the presentation layer?
A. It provides data representation and code formatting.
B. It handles error notification, network topology, and flow control.
C. It provides network services to user applications.
D. It provides electrical, mechanical, procedural, and functional means for activating and maintaining the link between systems.
Answer::-A.

22. Which layer of the OSI model provides network services to user applications?
A. The transport layer
B. The session layer
C. The presentation layer
D. The application layer
Answer::-D.

23. Which layer offers provisions for data expedition, class of service, and exception reporting?
A. Session
B. Presentation
C. Network
D. Data link
Answer::-A.

24. Which of the following statements regarding encapsulation is untrue?
A. Encapsulation allows computers to communicate data.
B. If one computer wants to send data to another computer, the data first must be packaged by a process called encapsulation.
C. Encapsulation occurs at one layer.
D. Encapsulation wraps data with the necessary protocol information before network transit.
Answer::- C.

25. Which of the following correctly describes the five conversion steps of data encapsulation when one computer sends an e-mail message to another computer?
A. Data, segments, packets, frames, bits
B. Bits, frames, packers, segments, data
C. Packets, segments, data, bits, frames
D. Segments, packets, frames, bits, data
Answer::- A.

26. An e-mail message is sent from Host A to Host B on a LAN. To send this message, the data must be encapsulated. Which of the following best describes the first step of data encapsulation?
A. Alphanumeric characters are converted into data.
B. The message is segmented into easily transportable chunks.
C. A network header is added to the message (source and destination addresses).
D. The message is converted into binary format.
Answer::- A.

27. An e-mail message is sent from Host A to Host B on a LAN. Before you can send this message, the data must be encapsulated. Which of the following best describes what happens after a packet is constructed?
A. The packet is transmitted along the medium.
B. The packet is put into a frame.
C. The packet is segmented into frames.
D. The packet is converted to binary format.
Answer::- B.

28. An e-mail message is sent from Host A to Host B on a LAN. Before you can send this message, the data must be encapsulated. Which of the following best describes what happens after the e-mail message's alphanumeric characters are converted into data?
A. The data is converted into binary format.
B. A network header is added to the data.
C. The data is segmented into smaller chunks.
D. The data is put into a frame.
Answer::- C.

29. Which best describes a datagram?
A. A message sent to the source to confirm the receipt of uncorrupted data
B. A binary representation of routing information
C. A data packet less than 100 bytes in size
D. A network layer packet
Answer::- D.

30. Which of the following layers of the OSI model is not present in the TCP/IP protocol stack?
A. Transport
B. Network
C. Internet
D. Data link
Answer::- D.