Guided media and Unguided media with example (Explained-In-Details)

 Guided media and Unguided media with example (Explained-In-Details)

Wired or bounded media (Guided Media)

Bounded media is the type of transmission media in which data and signals are transferred in a closed conductor through the use of cables or wires. Two or more devices that are near to each other can be connected directly using cables. This is an easy, fast and secure way to transfer data and information from one computer to another. The three types of cables that are used in a computer network are:

1. Twisted pair Wire
2.  Co-axial Cable
3. Fiber Optic Cable

Twisted pair cable

Twisted pair cables are used only for lower bandwidth. It consists of two isolated strands of copper wire twisted around each other. It is also widely used in landline telephone. The RJ-45 connector is the most popular connector used in twisted pair cables. There are two types of twisted-pair cables. They are UTP (Unshielded Twisted Pair) and STP (Shielded Twisted Pair).

UTP (Unshielded Twisted Pair)

UTP cables do not have metal shields except plastic coating. It contains several twisted pairs of wires with a simple plastic casing. It is commonly used to transfer data and information in telephone and LAN connections. It is cheaper and easier to work with, but does not offer high bandwidth and good protection from interference. Its grade starts from cat1 to cat7. It can support data transmission rates from 10 to 100 Mbps.

STP (Shielded Twisted Pair)

STP cable is shielded with a metal sheath along with a plastic coating. It offers high bandwidth and good protection from interferences. Cabling is more difficult to install and more expensive than UTP. Its bandwidth is 10 to 500 Mbps (Megabits per second). RJ 45 connector is used in STP. It is cheaper than fiber optic cable. It provides better protection against EMI(Electromagnetic Interference) than UTP.

Co-axial cable

Co-axial cable is made up of copper or aluminum wire with an inner conductor surrounded by an insulating layer and again surrounded by conducting shield. So it consists of two conductors inner and outer conductors. It carries higher bandwidth and noise immunity. It does not bend readily. This cable consists of one or more small cables in a protective covering. It offers a very high data transfer rate and can be placed underground and laid on the floors of lakes and oceans. BNC and T connectors are the most popular connector used in co-axial cable. 

Fiber optic cable

Fiber optic cable is a thin filament of plastic or glass fiber wrapped in a protective jacket to transmit data. It consists of strands of glass-like thread, each about the diameter of a human hair. It offers a high-speed data transmission rate because data travel as high-speed pulses of light. So it is a widely used cable especially in ISP (Internet Service Provider). ST (Straight Tip) connector, SMA (Screw Mounted Adaptors), SC (Subscriber Connector), etc. are the common connectors used in fiber optic cable.

Wireless or unbounded media (Unguided Media)

Unbounded media is the type of transmission media in which data and signals are transferred through the help of air. It is used to transfer data within large geographical areas or globally without the use of interconnecting wires or cables. It uses other components such as radio signals, microwaves, or infrared to connect networks for receiving and transmitting electronic data. The types of wireless communication are:

1. Radio wave
2. Microwave System
3. Infrared
4. Satellite Communication

1. Radio Wave

The radio wave is an electronic magnetic wave. It is used in rural and hilly areas. The data and information can be changed into audio signals using high-frequency waves based on frequency, amplitude, and phase modulation. It is a wave or RADIO WAVES pattern received after the modulation of signals. The types of modulation signal are FM (Frequency Modulation): The waves are modulated due to their frequency change. AM (Amplitude Modulation): The waves are modulated due to their amplitude change. PM (Phase Modulation): The waves are modulated due to their phase change.

2. Microwave Systems

Microwave signals are similar to radio and television signals and are used to transmit data signals through the atmosphere. It provides high-speed data transmission. It is also known as the line of sight communication as signals cannot be bent and cannot pass through obstacles like hills and tall buildings. So, very high towers are used to mount the signals that should be in a clear line of sight. Chain of towers I required to transmit the microwave signals in a long distance. Repeaters are used to amplify the signal. The other important devices are the digital modem and antenna.

3. Infrared

Infrared light is an electromagnetic form of radiation. It comes from heat and thermal radiation, and it is not visible to the naked eyes. In infrared transmission, senders can be simple Light Emitting Diode (LED) or laser diodes. Photodiode act as receivers. Infrared is used in wireless technology devices or systems that convey data through infrared radiation. It is used for short-range communications and control. Infrared technology is used in instruction detectors; robot control systems, medium-range line of sight laser communication, cordless microphone, headsets, modems, etc.

4. Satellite communication

Both microwaves signals and telephone signals can be relayed to an earth station for transmission to a communication satellite. Satellite communication is used to transfer data wirelessly worldwide. The earth station consists of a satellite disk that functions as an antenna communication equipment to transmit and receive data from satellites passing overhead. It is not disturbed by hills and tall buildings and is visible from any point. So sender and receiver can easily communicate with each other using antenna by aiming the satellite. It is very expensive for placing satellites along the earth's orbit. It is an artificial satellite placed in outer space and most of the countries are using their own satellite to communicate.

Click here for more...

Computer Network Components

Computer Network Components

Different network component

The basic elements of a computer network include hardware, software, and protocols. The hardware used in the network is a modem, routers, switches, bridges, hubs, etc.

MODEM

MODEM stands for Modulation and Demodulation. The modem is a device that directly converts the digital signal from a computer into analog form for transmission over an analog link such as a telephone line which is called the modulation phase. It receives analog signals from the phone line and converts them into digital signals for the computer which is called the demodulation phase. So, it is a device that connects computers to ISP (Internet Service Provider) with the help of a telephone line or router device. The modem which is placed inside the CPU Casing is called an internal modem. The modem which is placed outside the Casing is called an external modem. Wireless modems convert digital data into radio signals and vice versa. Modems came into existence in 1960. The main features of modem are:

1. Automatic cable sensor and calling card dialing
2.  Call progress detection and caller ID
3. Analog Cellular and GSM communications
4. Dialing stored phone numbers and digital line guard
5. Exclusive line probing and redialing the last dialed number

NIC

It is a Network Interface Card, which connects each computer to the wiring to the network. NIC is placed in motherboard expansion slots. It provides a port on the back of the computer to connect to the network. It controls the flow of data to and from computers in a network environment. It is used in LAN. Token ring and Ethernet are examples of NIC cards.

Hub

Hub is a connectivity device. It contains multiple ports for connecting to network components. It connects the computers in a star topology. It is simple, easier to install, low in cost, as compared to other devices. It can receive or send information data, so data packets are sent to all connected devices.

Switch

The switch is a connective device that is capable of forwarding packets directly to the ports associated with particular network addresses. It coordinates file servers and computers. The selected computer can get information through the switch. The switch is new technology and intelligent as compared to the hub. It works faster than a hub.

Connector

Connectors attach components together that are used to connect communication media with network devices. Several types of connectors are available, serving various purposes. It connects NIC cards such as an Ethernet card. It connects cable segments. RJ-45 connector for UTP cable, ST connector for fiber optics cable, BNC connector for co-axial cable, etc. is the different types of connectors. Bridge and gateway are the two connectors that link between two network systems.

Bridge

Bridge connects networks using the same communication protocols or similar networks so that information can be passed from one to the other. The signals are inspected by the bridge and decide whether to forward.

Gateway

The gateway connects networks using different communication protocols or dissimilar networks. It is also called a protocol converter and sends data in any network layer. It is more complex than a switch or router.

Repeater

The repeater is a network device that accepts weak signals and regenerates the signal over the same network to extend the length to which the signal can transmit. It makes it possible for long-distance data transfer. It does not amplify the signal. When the signal becomes weak, they copy the signal bit by bit and regenerate it at the original strength. It is a two-port device.

Router

A router is a device that is used to connect different LANs and WANs in the network. It receives transmitted messages and forwards them to their correct destinations over the most efficient available route. It is a device that routes data packets based on their IP addresses. It has a dynamically updating routing table based on which they make decisions on routing the data packets.

NOS

NOS stands for Network Operating System. It is the Operating System that can support controls and manage the computer network environment. Examples of Network Operating systems are Windows XP, Windows NT, server, UNIX, LINUX, Novel Netware, etc. The most popular Network Operating System is Novell Netware. The major functions of a Network Operating System are  

1. It is used to set up and install a computer network.
2. It enables users to have access, manages, and control all the resources. 
3. It allows adding or removing users from the network.

Click here for more...

Q-basic Problem (WAP-to-find-even-odd-eligible-for-vote-or-not-divisible-greater-isoceles)

Q-basic Problem (WAP-to-find-even-odd-eligible-for-vote-or-not-divisible-greater-isoceles)

1. Write a program to input the age of the person and check whether the person is eligible to vote.

CLS

INPUT "Enter your age"; A

IF A >= 18 THEN

PRINT "You are eligible to vote"

END IF

END

2. Write a program to input any number and check whether the number is even or odd.

CLS

INPUT "Enter any number"; NUM

IF NUM MOD 2= 0 THEN

PRINT "The given number is even"

ELSE

PRINT "The given number is odd"

END IF

END

3. Write a program to input the age of a person and check whether the person is eligible to vote or not.

CLS

INPUT "Enter age of person"; A

IF A >=18 THEN

PRINT "Person is eligible to vote"

ELSE

PRINT "Person is not eligible to vote"

END IF

END

4. Write a program to display whether the given number is exactly divisible or not.

CLS

INPUT "Enter any number"; N

IFN MOD 7= 0 THEN

PRINT "The given number is exactly divisible by 7"

ELSE

PRINT "The given number is not exactly divisible by 7"

END IF

END

5. Write a program to display the greatest number among any three different numbers.

CLS

INPUT "Enter the first number"; N1

INPUT "Enter the second number"; N2

INPUT "Enter the third number"; N3

IF N1>N2 AND N1>N3 THEN

PRINT "The greatest number is"; N1 ELSEIF N2>N1 AND N2>N3 THEN

PRINT "The greatest number is"; N2

ELSE

PRINT "The greatest number is"; N3

END IF

END

6. Write a program to input three sides of a triangle and display whether the triangle is equilateral, isosceles, or scalene.

CLS

INPUT "Enter the first side"; A

INPUT "Enter the second side"; B

INPUT "Enter the third side";C

IF A=B AND B=C AND C=A THEN

PRINT "The triangle is equilateral"

ELSEIF A<>B AND B<>CAND C<>A THEN

PRINT "The triangle is scalene"

ELSE

PRINT "The triangle is isosceles"

END IF

END

What is the best online payment system? Online-payment-gateway-in-Nepal

What is the best online payment system? Online-payment-gateway-in-Nepal

Online payment gateway in Nepal

An international online payment gateway from Nepal just started at the end of 2017 provides a safe, secure and easy payment solution. Both Visa and MasterCard have accepted credit cards for online payment gateways in Nepal.

The most used online payment gateways in Nepal are:

1. Esewa: It is a trusted and recognized Internet payment service provider offering all types of online payment solutions operating since 2009.
2.  Khalti: It is known as an online payment provider for services as mobile balance recharging, bill payments, and online ticket booking.
3. I pay: It is used as an online payment service provider that allows for easy payments of utility bills and mobile balance top-ups.
4.  Qpay: It has revolutionized the mobile payment option into a user-friendly and simple payment gateway or payment application. 
5. nPay: It is an online payment service provider that works together with the banks for an easy setup of the payment gateway. Focusing on m-banking, e-banking and accepts credit and debit cards.
6. IME Pay: It is known as the mobile payment service in Nepal, IME Pay allows its consumers to pay easily and safely by mobile. Payments such as utility bills, money transfers, mobile top-up, and even the withdrawal of cash at local IME agents are possible.
7. ePay: It is an e-payment or electronic payment system from where no bank account is needed, it allows for a fast and safe payment from cash to digital.
8. PayWay: It is a basic online payment service provider that allows merchants to integrate a payment gateway into their website.

Types Of E-Commerce

Types of E-Commerce

It can be run in different models. The three basic types of E-Commerce are:

1. Business-to-Business (B2B) 
2. Business-to-Customer (B2C)
3. Customer -to-Customer (C2C)

Business to Business (B2B)

Business to Business E-Commerce activity between business companies. The transactions are usually carried out through Electronic Data Interchange (EDI) in B2B. EDI is an automated format of exchanging information between businesses over private networks. The individual customer cannot buy from this type of E-Commerce. Manufacturers and wholesalers typically operate with this type of Electronic Commerce.

Business to Customer (B2C)

Business to Customer (B2C) is an E-Commerce activity that is focused on customers. It establishes the electronic business relationships between the business organization and the final customer. It corresponds to the retail section of E-Commerce. The E-Commerce website is the main platform where all the business transactions take place between a business organization and customer directly in B2C. For instance, a book retailer would be a B2C company such as Amazon.com.

Customer to Customer (C2C)

Customer to Customer (C2C) is an E-Commerce activity, which uses an auction-style model or is conducted between customers. It enables customers to directly deal with each other. The transactions are conducted via an online platform where the transactions are actually carried out. E-Commerce websites help customer to sell their assets like residential property, cars, motorcycles, etc., or rent a room by publishing their information on the website. The website may or may not charge the customer for its services. Hamrobaza com is an example of a C2C website in Nepal. The other example of this is peer auction giant, E Bay.

M-Commerce (MobilE-Commerce)

M-commerce (MobilE-Commerce) is the extended version of E-Commerce. It is the buying and selling of goods and services through wireless technology i.e., handheld devices such as smartphones and personal digital assistants (PDA). It is also known as next-generation E-Commerce. The content delivery over wireless devices becomes faster, more secure, and scalable for digital commerce transactions. This includes purchases on websites or apps, paying for travel, hotel, events or bills, or any type of commerce The examples of m-commerce are purchasing airline tickets, top-up charges, fun transfer, purchasing movie tickets, balance inquiry, utility payment, and restaurant hotel booking and reservation. 

Online Payment

Online payment or E-Payment refers to money that is exchanged electronically. I payment collected over the Internet is accepting online payment. Online payment is the transaction that results in the transfer of monetary funds from the customer ban or credit card account to a bank account. It is one of the major components of an E-Commerce transaction. It is the payment for buying goods or services through the Internet using different online payment gateway.

The typical online payment process has the following stages:

1. The customer submits the payment information to the merchant. For example, the customer completes the payment form on the merchant website and submits the information
2. The merchant submits the payment information to the online payment gateway.
3. The online payment gateway submits the payment to the payment processor.
4. The payment processor authorizes the payment and responds to the payment gateway
5. The payment gateway responds back to the merchant
6. The merchant responds back to the customer showing if the online payment was successful or not and taking the appropriate action.

Click here for more

Business Opportunity Of Social Media And Its Threats

Business Opportunity Of Social Media And Its Threats

Opportunities of Social Media

Social media may take the form of a variety of tech-enabled activities. These activities include photo sharing, blogging, social networks, video sharing, business networks, virtual worlds, etc. Governments and politicians use social media to engage with constituents and voters. Social media is used to keep in touch with friends and family individuals. People will use various social media applications to network career opportunities and share their thoughts, feelings, insight, and emotions. Social media is an indispensable tool for business. Companies use the platform to find and engage with customers, drive sales through advertising and promotion, and offer customer service or support.

Some of the opportunities and benefits of social media are as follow:

1. Revenue

The most apparent opportunity is to generate revenue. This can be done through advertising products services within the social media platform. To advertise on social media, the ads can be linked to media pages or websites. This can be able to benefit from social media without needing to channel.

2. Brand development

Using social media allows customers to connect and interact with businesses on a more personal. If you already have an established brand, social media might be an opportunity to further develop the brand.

3. Target audience

Customers can find you through social media platforms. We can choose to maintain a presence on particular platforms that are in line with the target audience. For example, by targeting young people you could reach them through Snapchat. If seeking business customers, LinkedIn may be the best channel.

4. Customer interaction

You can deliver improved customer service and respond effectively to feedback. Positive feedback is public and can be persuasive to other potential customers. Negative feedback highlights areas for improvement.

5. Attracting customers

Social media can be a good way of attracting new customers. For example, when considering social media campaigns, you could try to attract followers with promotions or giveaways. Once you have a good following you can focus on more personalized social media campaigns to encourage them to stay.

Social Media Threats

Social media is a collection of Internet-based websites that promote the personal and business-focused interaction of individuals worldwide. There are many threats or risks with the popularity of social media. They are:

A. Social engineering

Social media platforms allow attackers to find personal information that can be used to target specific individuals. Using information from employee profiles, a plausible fake account can be created to establish trust over time. Once the trust is built, the attacker foursquare might start asking for specific information, like internal server names, project names, open an infected document, or visit a prepared website that will drop a backdoor onto their computer.

b. Targeted phishing attacks 

Such attacks are carried out to steal money or confidential information. This social media threat is an example of social engineering tactics, whereby attackers exploit fear and anxiety, instead of system vulnerability to get users to part with their money. Since these attacks are so specific and targeted, the chances of success are higher.

c. Fake accounts

The seriousness of social media threats gets underscored when one considers that the fake account, in this case, was successful in connecting with hundreds of people from various organizations, including military, government, and security firms.

d. Social media used for spreading spam and malware

Social networking sites like Twitter and Facebook are often used to spread malware. The growing popularity of shortened URLs is also giving rise to several social media threats. Cybercriminals often mask their links with a short URL, making it difficult for them to identify whether it is pointing to a legitimate or malicious site. This threat is a real possibility for social bookmarking and microblogging sites, which are used to spread links and news in a very short period.

e. Confidential information leak

The scariest of social media threats is where employees start revealing seemingly uncritical technical information to the public. This could be a Twitter comment stating that the user is fed up configuring a particular firewall product at work or a status message indicating that the user finally found a way around a Web proxy product being used, and is now able to post to his profile again. An attacker could use this information to identify the security software of the user or the company.

Click here for more...

Types Of Computer (Classification-Of-Computer-On-The-Basis-Of-Size)

Types Of Computer (Classification-Of-Computer-On-The-Basis-Of-Size)

There are various types of computers based on size. But, mainly there are four types of computers. They are:

1. Super Computer
2. Mainframe Computer 
3. Mini Computer
4. Micro Computer

Super Computer

Supercomputers are the fastest computer. It is a digital computer with very processing with many processors. The same computer can be shared using the terminals. It has very storage capacities. It is very expensive and very large in size too. Supercomputers are used for very complex types of processing like weather forecasting, nuclear science research, etc.

They are fast processing with multi-user and multi-processor large computers of the very difficult and complex problem within nanoseconds. The word length of this computer is 64 bits. 

Example: CRAY X-MP-14, PARAM, etc,

Application of Supre Computer

1. They are used for weather forecasting.
2. They are used in military research and defense systems.
3. They are used for digital film rendering.
4. They are used to study DNA structure and genetic engineering.
5. They are used in automobiles, aircraft, and spacecraft design.
6. They are used in seismography, plasma, and nuclear research.

Mainframe Computer

Mainframe computers are smaller than a supercomputer. This is also very expensive and with very high speed. It supports about 100 users. It also contains more than one processor and can process the jobs simultaneously. It is also a multi-user computer system. This computer is not so popular these days.

It is a powerful multi-user computer used in large organizations such as businesses, industries, defense, etc. It can respond to any number of requests at a time. It uses several CPUs for data processing. More than 100 users can use it at a time because it works in time-sharing mode. Its word length is 48 bits to 64 bits. IBM built the first Mainframe Computer System/ 360, in 1964.

Application of Mainframe Computer

1. Electronic card processing
2. Bank management system
3. Marketing and advertisement 
4. Air traffic control system 
5. Industries and automation
6. Population census

Mini Computer

Mini-Computers are mid-range computers. Most of these types of computers are replaced by a client-server model nowadays. These computers can support about 20/25 users. Mini-computes are more powerful than microcomputers. It is costly than microcomputers. It is also used in universities, large business organizations to process complex data. It is also used in scientific research, engineering analysis and industrial proceed monitoring and control. Examples of these computers are PSP-11, VAX, etc.

Micro Computer 

A microcomputer is a computer with a microprocessor as its central processing unit. They are physically small compared to mainframe and minicomputers. Many microcomputers  (when equipped with a keyboard and screen for input and output) are also personal computers. 

The abbreviation "micro'' was common during the 1970s and 1980s but has now fallen out of common usage. Most notably, the microcomputer replaced the many separate components that made up of the mini computer's CPU with one integrated microprocessor chip. Microprocessors and semiconductor memory became less expensive so that microcomputers in turn grew cheaper and easier to use. Monitors keyboards and other devices for input and output may be integrated or separate. Computer memory in the form of RAM and at least one other less volatile, memory storage service is usually combined with the CPU on a system bus in one unit. Other devices that make up a complete microcomputer system include batteries, a power supply unit, a keyboard, and various input/output devices used to convey information to and from human operators (printers, monitors, human interface devices). Microcomputers are designed to serve only one user at a time, although they can often be modified with software or hardware to concurrently serve more than one user.

Desktop Computer

A desktop computer is a personal computer is a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer. Before the widespread use of microprocessors, a computer that could fit on a desk was considered remarkably small. Desktop computers come in a variety of types ranging from large to small. ''Desktop'' can also indicate a  horizontally-oriented computer case usually intended to have the display screen placed on the top to save space on the desktop. Most modern desktop computers have separate screens and keyboards. 

The desktop has the advantage over laptops in that the spare parts and extensions tend to be standardized and upgraded to a greated\r extent too. This tends not to be the case for laptops, though adding or replacing some parts, like the optical drive, hard disk, and adding an extra memory module is often quite simple.

Laptop 

A laptop is a personal computer designed for mobile use. A laptop integrates most of the typical components of a desktop, a pointing device (a touchpad, also known as a trackpad, and/or a pointing stick), and speakers into a single unit. A laptop is powered by mains electricity via an AC adapter and can be used away from an outlet using a rechargeable battery. A laptop battery in new condition typically stores enough energy to run the laptop for three to five hours, depending on the computer usage configuration and power management settings. When the laptop is plugged into the mainline, the battery charges, whether or not the computer is running.

 Portable computers, originally monochrome CRT- based and developing into the modern laptop. ere originally considered to be a small market, mostly for specialized field applications such as the military, accountants, and sales representatives. As portable computers became smaller, lighter, and cheaper and as screens became larger and better quality, laptops became very widely used for all sorts of purposes.

PAD (Personal Digital Assistants)

A small-sized portable hand-held electronic device that has all the features of personal computers is called PDA. It has input, processing, storage, and output capability like the other microcomputers. This is used for diaries, calendars, address books, etc. We can transfer data from PDA. A personal digital assistant (PDA), also known as a palmtop computer, or personal data assistant, is a mobile device that functions as a personal information manager. Many PDAs can access the internet, intranets, or extranets via Wi-Fi or Wireless Wide Area Networks.

Tablet

Tablet is a portable computer that uses a touch screen as its primary input device. Tablets are less functional than laptops so it is cheaper. It is more portable and easy to carry on. It has touch and multi-figure gestures. IPad, Samsung, ZTE are the brand of tablets.

Click here for more...