Computer Hardware and Networking

Internet and History of internet

noreply@blogger.com (Unknown) — Thu, 30 Apr 2020 06:19:00 -0700

Internet

Internet is an inter connection between several computers of different types belonging to various network all over the world.

It is a network of networks.

Millions of people throughout the world use internet to share information and ideas, to search information on any topic, etc.

Internet is an immensely complex combination of thousands of technology and dozens of service used by billions of people around

the world.

Growth and ownership of internet

The internet started as a united states government project in the year 1969, called the advanced research projects administration network (ARPANET).

In the late 1980s the national science Foundation of United States founded the development of a network using IP named as NSFNET to connect super computers network in America. In 1990s, ARPANET was dismantled and turned over to NSFNET. In 1993, NSF created inter NIC to provide internet services.

The backbone of the internet brink india at very high speed in year of 1994-95 , by AT and T and VSNL.

Characteristics of internet

---- Internet is a complex network.
---- A decentralized system.
---- Composed of billions of file.
---- It is widely used.
---- Dynamic(Internet is the changing every minute of everyday. Thousands of websites and other resources are daily upload on internet).

Anatomy of internet

Anatomy refers to study of structure of study of internet outlines the major components which are as follows:-

(I) Internet services.
(II) Elements of internet
(III) Uniform resource locator (URL)
(IV) Internet protocol

(I) Internet services :- Internet is a combination of variety of service and most popular of them are as follows:-

(a) Electronic mail :- In 1970 the first internet service for communicating cold email is used.

(b) File transfer protocol :- In 1973 an internet service design to share files among computers.

(c) Mailing list(1981)

(d) World wide web( WWW)(W3) :- In 1992 this service features user-friendly publicing. Web pages are creating using HTML.

(II) Elements of internet :- A simplified hierarical model of internet include client PC and server computers which entirely create a network.

(a) Client PC (personal computer) :- These are the computer that request information on internet. If your computer is connected to the internet then it is considered a client PC.

(b) Server computer :- A server is a computer that hold one or more websites a server can provide information to multiple clients simultaneously.

(III) Uniform Resource Locator (URL) :- URL are the unique address of the available resource . A URL is divided into four parts

(a) Transfer protocol :- https://

(b) Server name :- www.facebook.com

(c) Directory path :- /

(d) File name :- abhay maurya

https://www.facebook.com/abhaymaurya

(IV) Internet protocol :- IP is a method by which data is sent from one computer to another over the network.Each computer which is a connected to the internet has atleast one IP address which uniquely identifies one computer from another computer.

Domain name system (DNS)

noreply@blogger.com (Unknown) — Thu, 30 Apr 2020 03:50:00 -0700

DOMAIN

A domain is a set of network resources (applications, printers, and so forth) for a group of users. The user needs only to log in to the domain to gain access to the resources, which
may be located on a number of different servers in the network. The ‘domain’ is simply
your computer address not to confuse with an URL. A domain address might look
something like 211.170.469.

DNS( Domain Name System)

The Domain Naming System (DNS) is a service that resolves host names to IP addresses. These can be names of computers within an internal network or names of computers on the Internet. Clients send name resolution requests to a DNS server, and the DNS server responds with the IP address. The client computer then uses the returned IP address as the destination IP address for data traffic.

DNS is essential on a Microsoft domain. Active Directory requires DNS to locate servers running specific services, such as domain controllers.

BIOS

noreply@blogger.com (Unknown) — Wed, 29 Apr 2020 06:45:00 -0700

What is BIOS

Basic Input Output System

It is an essential set of programs(routines) stored on a chip on the motherboard of a computer.

It acts as an intermediary between computer hardware and its operating system without BIOS, the PC's operating system cannot be communicate with, Or take control, of the hardware.

How BIOS works

---- Power On Self Test (POST)

---- Bootstrap Loader

----- Setup utility program

---- BIOS drivers

Function of BIOS

(I) power on self test(POST)

BIOS conducts power-on-self-test(POST) built-in Diagnostic program that checks whether the computer has all of the necessary parts and functioning properly, such as memory and keyboard.

(II) Bootstrap Loader

Helps in loading the operating system.

The program searches for any available operating system and if found, it loads the operating system into RAM of the computer.

(III) Setup Utility Program

A non-volatile memory (NVRAM) is used to store information about the computer system.

During installation of a system the user runs BIOS setup program and enters the correct parameters.

The settings of memory, disk types and other setting are stored in NVRAM.

(IV) BIOS Drivers

BIOS drivers are collection of programs stored in one or more EEPROM and EPROM (memory) chips,depending on the computer design on the motherboard.

Benefits of BIOS for Desktop / Laptop

---- Enforcing Security

---- Hardware Monitoring

---- Operating system Booting

---- Hardware Testing

---- Hardware Troubleshooting

Compiler,Interpreter and Assembler

noreply@blogger.com (Unknown) — Mon, 6 Apr 2020 06:42:00 -0700

Compiler

It is a program which translates a high level language program into machine language program.Compiler is more intelligent than and assembler it checks all kinds of limits Rangers error etc,. but it's program run time is more and occupies a large part of the memory. It has low speed because a compiler goes through the entire program and then translate the entire program into machine code for . If compiler runs on a computer and produce the machine codes for the same computer then it it is known as a self compiler and resident compiler.On the other hand if a compiler runs a computer and produces the machine code for other computer than is known as a cross compiler.

Interpreter

An interpreter is a program which you translate statements of a program into machine code it translate only one statement of the program at a time it reads only one statement of program translate it and executes it then it reads the next statement of the computer program again translate it and execute it in this way it proceeds further till all the statements are translated and executed on the other hand a compiler goes through the entire program and the translate the entire program into machine code.It occupies less memory space so it can be used in a smaller system which has Limited memory space

Assembler

A Computer will not understand any program written in language, other than its machine language. The programs written in other languages must be translated into the machine language. Such translation is performed with the help of software. A program which translates an assembly language program into machine language program is called assembler. If an assembler which runs on a computer and produce the machine codes for the same computer than it is called self assembler or residence assembler. If an assembler that runs on a computer and produce the machine codes for other computer then it called cross assembler.

Difference between TCP and UDP

noreply@blogger.com (Unknown) — Mon, 6 Apr 2020 06:22:00 -0700

Transmission control protocol (TCP) and User Datagram Protocol(UDP) is a transportation protocol that is one of the core of protocols of the internet protocol Suite. Both TCP and UDP work at transport layer TCP/IP model and both have very different usage.

TCP and UDP

TCP

-- TCP protocol is a communication oriented protocol. It needs to open a connection to the device before sending the data and closes the connection once the data has been sent.

-- You are a assures about the reliability of the data transfer.

-- TCP provides with error detection to assure acknowledgement of the data.

-- Sequencing of data is done in TCP.

-- TCP also assures guarantee of data delivery.

-- Lost packets can be retransmitted in case of packet loss in TCP.

-- As TCP has extensive error checking mechanism, TCP is slow protocol.

-- Example:- Mailing system.

UDP

-- UDP is connection less protocol. So no need of overhead of for opening and closing the connections.

-- UDP does not assure reliability of data transfer.

-- No sequencing of data is possible in UDP.

-- UTP provides only basic error checking mechanism.

-- UDP never assure guarantee of that delivery.

-- There is no retransmission of Lost packets in UDP.

-- As UDP does not have extensive error checking mechanism it is faster, simpler and more efficient than TCP but is comparatively less robust.

-- Example:- Live concert

Email

noreply@blogger.com (Unknown) — Fri, 3 Apr 2020 09:27:00 -0700

Introduction to Email

- Email is abbreviated as ELECTRONIC MAIL.

- Email is used to exchange(i.e. Send and receive)mails across internet.

- Email is a message that may contain text, files ,image or other attachments sent through a network to are specified you individual or group of individuals.

- from year 2000 onwards, electronic mail was a preferred medium over postal mail.

- Email is one of the ways on internet to send message to another person across the network.

Advantages of email

- E-mail is faster than postal mail.

- E-mail cannot be lost like letters and can be stored for lifelong.

- It can be edited and forwarded to other users.

- Email are not affected by distance. It can be sent anywhere in the world seconds unlike postal emails.

- You can add video and audio with the e-mail.

- Privacy : Your email is delivered to your own personal and private account with a password required to access and view emails.

- A valid mail is required to access to Web Services some shopping sites like Amazon Flipkart. Email is also required for social networking sites like Facebook.

Disadvantages of email

- There must be computer or alternatively suitable mobiles devices and network connection should be available at the sender and recipient unlike postal mails.

- There is a need of knowledge of opening email account and how can be sent.

History of E-mail

Internet based e-mail was designed by a computer engineer - Ray Tomlinson in late 1971 while working with ARPANET. Tomlinson used a file transfer protocol to send electronic message to any computer on the ARPANET network. The first email was sent between two computers that were actually sitting besides each other but connected through ARPANET.

The first important email standard was called SMTP or simple message transfer protocol. SMTP was very simple and if still in use - however, SMTP has a problem it makes no attempt to find out whether the person claiming to have sent a message is actually the same person. This basic flaw in the protocol was later to be exploited by viruses and worms, and by security frauds and spammers for forging identities. Some of these problems are still being addressed.

In 2004 ,when internet standards for email begin to mature the POP(Post office protocol) serves began to prepare as a standard -before that each server was a little different. POP was an important standard to allow users to develop mail
that would work with each other.

Now internet mails is defined by a large number of standard and recommendations by the Internet Engineering Task Force (IETF). However only, a few of protocols used in Internet mails are full IETF standards. Most of these standards are begin used by for people writing Internet mail software.

How Emails Works

Email Protocols

Sending Emails

- SMTP (Simple Mail Transfer Protocol)

Receiving Emails

- POP3( Post Office Protocol version 3)

- IMAP4( Internet Mail Access Protocol version 4)

POP3 is meant to be used if you own an individual device.
IMAP is designed to be used on different devices.

How to access your emails ?

They are:

Webmail is a web-based email brewers, the examples are Gmail, Yahoo mail and AOL(that is America online).

An Email Client is a computer program( or an application) used to access user`s email
The Examples of Email Client are Microsoft Outlook, Mozilla Thunderbird and MAC based Airmail.

Transmission Mode and Media

noreply@blogger.com (Unknown) — Fri, 3 Apr 2020 02:24:00 -0700

Transmission mode

Transmission refers to the process of the data travelling process from one point to another.

There are three modes of data transmission correspond to the three types of circuits available. These are:

1. Simplex 2. Half-duplex 3. Full duplex

Simplex:-

Simplex communicates imply a simple method of communication. In this communication there is one way communication. Television is a very good example of this communication. The main transmitter sends out a signal but is doesn’t expect a reply as the receiving unit can’t issue a reply back to transmitter.

Half duplex :-

In half duplex, both units Communicates over the same medium, but only one unit can send at a time. While one unit is in send mode the other unit is in receiving mode. Walkie-talkie is a good example of half duplex.

Full duplex:-

Full duplex communication allows information to flow simultaneously in both the directions on transmission path. Use of full duplex improve the efficiency line of the communication. Internet uses full duplex communication.

Transmission media

Transmission media reference to the actual physical channel of the transmission. There are several physical channel through which data can be send Or receive from one point to another in a local area network. Media is divided into two categories.

Guided media

Guided media reference to the method of sending a data over which signal can travel in a network. Guided media is bounded to their region.

Twisted pair

A twisted pair cable consist of two insulted copper wire typically 1mm thickness. The wires are twisting together. The purpose of twisting a wire is to reduce electrical interference from similar pairs of the wire.

Advantage of Twisted pair cable.

(I) Being the older method repairment and service surface of the cables are easily available.
(II) It is the least expensive media of transmission.

(III) It can be used for both analog and digital communication.

Disadvantage of Twisted Pair

(I) Easily pickup noise signal which results into higher rate of error.
(II)It is lightly to break easily.

Coaxial cable

Coaxial cable consists of a stiff(teak)copper wire as the cable wire as the code, surrounded by insulator material the insulator is encased by a cylindrical conductor offen as a closely wired braided mesh. The outer conductor is protected by plastic jacket. The signal is transmitted by a inner copper wire and it is electrically protected by the other metal mash. Twisted pair cables available in two kinds.
One kind 50 OHM, widely used in digital transmission. The other kind 750 OHM, commonly used for cable TV transmission. Coaxial cable has a band wide in the range of 300 to 400 MHz

Fiber optic cable

Fiber optic uses reflection to guide light through a channel. The fiber optic cable is the newest form of guided media. This media is superior in data handling and security characteristic. The fiber optic cable transmit light signals rather than electromagnetic signals. There are two sources available for fiber optic cable for data transmission these are
(I) light emitting diode(LED)
(II) Light Amplification by Stimulated Emission of Radiation LASER)

Advantages of Fiber optic cable

(I) Higher bandwidth- it can support higher bandwidth and hence can transfer data at a higher rate.
(II) These cables are much lighter than the copper cables.
(III) These cables are more immune to immune to tapping than the copper cables.
(IV) Immunity to electromagnetic interface.

(V) less signal attenuation - its transmission distance is greater than the twisted pair and it can run for 50 kilometre without regeneration.

Disadvantages

(I) Installation or maintenance- it needs is expertise which is not available everywhere.
(II) Undirectional- propagation of light is a direction undirectional and we need two fibres for bidirectional communication.
(III) Costly- the cables and interfaces used are relatively expensive.

Unguided Media

Unguided media is used for transmitting the signal without any physical media. It transports electromagnetic waves and is often called wireless communication. Signals are broadcast through air and received by all who have device to receive them. Media in which the signals are not guided through a solid medium or signals are unbounded are known as unguided media there are several methods which are in used to transmit electromagnetic energy are as follow:

(I) Radio wave(II) Micro wave(III) Infrared

1. Radio wave

Radio signals have been used for a long time to transmit analogue information.

Electromagnetic waves ranging in frequencies between 3 kilo-Hertz and 1 Giga-Hertz are normally called radio waves. Radio waves are easy to generate and can travel long distances and can penetrate buildings easily, therefore widely used for communication. These are omni-directional which implies that these travel in all directions from the source, so the transmitter and receiver do not have to be carefully aligned physically.

Characteristics of radio waves

1. Radio waves are easily to generate
2. They can travel long distance
3. they are used in both indoor and outdoor communication because they can penetrated (pass through) any solid object.
4. They are omni-directional means they can travel in all the directions from the source so that the transmitter and receiver don't have to be carefully physical aligned.

Microwave transmission

Microwave can transmit signals between hundred megahertz to 10 gigahertz they are directionally the Waves travel in short line can therefore normally for casted the signal are transmit and receiving can be done using parabolic directional antennas unlike radio waves microwaves don't pass through building microwaves transmission depends upon weather and frequency. Microwaves is by far the most widely used form , form of radio transmission it operates in the gigahertz range with data rate in order to hundreds of Mbps per channel telecommunication carries and TV stations are the primary users of microwave transmission.

Unidirectional property of microwave helps in avoiding interference by a pair of aligned Antennas to another.High frequency microwaves cannot be receive inside the building.

Types of microwave communication system

There are two types of microwave communication system:-
(I) Terrestrial
(II) Satellite

(I)Terrestrial

Terrestrial microwave system typically used relay travels of direction parabolic antenna to send and receive signals in lower gigahertz range. Terrestrial microwave system are used when travelling cost prohibitive search an area or crossing rivers on the signals are focused and Antennas are line of sight.

(II) Satellite

An important form of microwave system is satellite system which is essentially a microwave system plus a large repeater in the sky. The signals transmitted by Earth station are received amplifier and re- transmitted to other earth station by the satellite. Satellite are capable for supporting and enormous numbers and variety of channels, including TV, telephone and data.

3. Infrared

Infrared signals range between 300 gigahertz to 400 Tera-Hertz. These can be used for short range communication. High range infrared rays cannot be used for long range communication at is cannot be penetrate walls. This also helps in avoiding interface.

Infrared signals are generated and received using optical transceivers. Infrared systems represent a cheap alternative to most other methods, because there is no cabling involved and necessary equipment its relatively cheap. Data rate similar to those of twisted pair are easily possible. Applications are limited because of distance limitations( of about 1 kilometer) . It cannot be used outside building as rays of Sun contain infrared which leads to interface in communication. Infrared having wide bandwidth can be used to transmit digital data with have a very high data rate. Infrared signals can be used for communication between keyboard, mouse and printers.

Computer Virus

noreply@blogger.com (Abhay maurya) — Tue, 31 Mar 2020 01:32:00 -0700

Virus

- A Virus is a program that copies itself and infected a PC, spreading from one file to another, and then from one PC to another when the files are copied or shared. Viruses can be very destructive, causing loss of information

- Computer virus is a malicious program or code that gets copied or attached to other files in a computer without the knowledge of the user and as a result malfunctions the computer in one or the other way.Once a virus invades a system it copies itself and spreads from one file to another and then from one computer or network to another when the file are being copied or shared. The virus modified files and even the operating system itself. Viruses can be very destructive,causing loss of information.

- A computer Virus is a malicious software program designed to damage a computer or interfere with other programs and functions.

- A virus is just a computer program.Like any other program,it contains instructions that tell your computer what to do.But unlike an application, a virus usually tells your computer to do something you don’t want it to do, and it can usually spread itself to other files on your computer and other people’s computer.

V - Vital

I - Information

R - Resource

U - Under

S - Siege

Do you know

The First PC Virus was a boot sector virus called (C)Brain,created in 1986 by the farooq Alvi Brothers,from pakistan.The creeper Virus written by Bob Thomas in 1971 was first detected on ARPANET,in the early 1970s.

The following are the important characteristics of a virus:

1. It is able to replicate.
2. It requires a host program as a career.
3. It is activated by external action.

4. Its replication ability is limited to the (virtual) system.

How do computer viruses spread?

We have learnt that a computer virus is a piece of self-replicating code attached to some other pieces to code. Computer viruses move from computer to computer by attaching themselves to files or boot records of disks and diskettes. These days it is common to find viruses in e-mail attachments and other program that can be downloaded from the internet. Sometimes the virus code maybe harmless for example, it may display funny message for play a tune.But sometimes it may be very harmful and may proceed on to delete and modified files. Viruses can also spread via an infected pen drive ,CD, DVD or other storage media.

Types of Virus

- Boot Sector Virus

- Macro Virus

- File Virus

- Network Virus

- Stealth Virus

- Space Filler Virus

- FAT Virus

- Worms

- Directory Virus

1. Boot Sector Virus

This type of virus is attached the boot sector by attaching itself the DOS boot sector on floppy diskettes or the master board record on hard disks.So they are called as the boot record infector of system virus. Such virus are of the memory resident type.

1. Macro virus:-

• A macro virus is an instruction that carries out program commands automatically .

• Macro viruses are macros that self-replicate.

• These virus affects microsoft office application such as WORD and EXCEL.

• Examples:- Relax,MelissaA and Bablas etc.

2. File virus

• File virus attack and modify executable pr program file (having extension .com , . exe, . bat). Normal intelligence memory and slowly in infective other virus.

When one of these programs is run,directly or indirectly.

• There are large number of viruses which belongs to this category.

3. Stealth viruses:-

• It has ability to hide itself from some antivirus software programs.

• Some antivirus program can’t detect them.

4. E-mail :-

• It is a type of virus that spread easily through attachments to an e-mail messages or a downloaded file.

• These viruses can replicate itself by automatically mailing copies of itself to all the email ids present in the address book.

That is why it is important that you never open e-mail attachments unless you know the sender.

Effects of computer virus

• Corrupting files

• Formatting the hard disk, thus destroying date

• Slowing down the system

• Deleting the system files or renaming the system files makes the system hung.

Prevention of computer virus

• Install an antivirus software.

• Regularly update the program.

• Try to avoid downloading and installing software from the internet.

• Install only registered copies of software on the system.

WIRELESS NETWORK

noreply@blogger.com (Abhay maurya) — Tue, 24 Mar 2020 10:43:00 -0700

When two or more or entities are connected without any networking cable, it will be called wireless network. Like cell phone, to simple home wireless network internet connection,bloetooth and more, every thing comes under wireless networking.

Diffrent type of wireless network-

1.Inrfared data Associate(IrDA)

Data Association has developed a standard where data is transmitted via infrared light waves. in case of IrDA, as the data transfer is done through infrared, you can send data one device at a time.

2.Bluetooth-

Bluetooth uses 2.45 gigahertz radio waves to sheare data between device. The technology is limited to a short distance of 10 ft but it can cross walls in order to transmite data. this also comunicats without wire.

3.HomeRF.

HomeRF was designed for home radio frequency work group and it is a spacification that works from home devices.it has 6 voice and 1 data channel. the network is slow and works in limited rang but it is cheap.data channel of 802.11 wireless ethernet spesification by the IEEE is used for the transfer and it can be inly used for computer.in case you need to connect the printer,you frist to need to the home computer.

Wi-Fi.

Wireless fidelity is used to transmit radio frequency to all connected devices.

• personal computer

• video game console

• smartphones and tablets

• modern printers

Types of Wireless Network:-

1.WLAN

Wireless local Area network also know as WLAN offers wireless network communication over a short distance. It user radio or infrared signals instead of traditional network cables. It allows mobile user to connect to local area network (LAN) through wireless connection. Most commonly used protocols are wifi and Bluetooth.

2.WPAN.

A wireless personal area network or WPAN is a kind of personal area network that allows user to interconnect their devices central on an individual workplace.

It offer wireless connectivity. WPAN uses a specialised technology that permits communication within a rang of 10 metres only. Bluetooth is one such technology.

3.Wireless Ad Hoc Network

A wireless ad hoc network is a decentralized tyep of wireless network that does not rely on pre-existing infrastructure like wired network,Router or access point in managed wireless network, it is a particularly helpful in sharing file or data directly from one device to another but have on Wi-Fi connectivity.

4.Wireless MAN.

Wireless Metropolitan Area Network of WMAN is a not shot Wireless networking that comes with a projected coverage area (called range) of more or less the size of a city.Wireless man is based on the IEEE 802.16 standard and it has effective transfer speed of 1-10 MBPS within a range of 4-10 kilometres.

5.Wireless WAN

Wireless wide area network or wireless WAN is a special type of network that gives out signals within a range of several miles to a moving or stationary device.It is commonly now as "wireless broadband" or "broadband wireless" this type of larger network often requires some type of encryption of security that a local area network may not require.example- Skype Wi-Fi

6.Cellular Network

A cellular network is a radio network which offers coverage over a land area through cell (mobile device).each of these cell is encorporated with fixed location Transceiver know a base station.

All cells together provide radio coverage over larger geographical areas cellular network comes with the boons like increased capacity larger area coverage and minimum in inference from there signals.

Wireless fidelity(wifi)-

Wireless fidelity for Wi-Fi is a technology that sends radio waves to offer network connectivity. A Wi-Fi connection can be established by using a wireless adaptor that creates hotspot.Hotspot is an area in vicinity of a wireless router which is again connected to the network and permits user to access internet connectivity. This technology is based on the 802.11 IEEE network standard. the direct sequence spread spectrum(DSSS) offer highest data speed which of 11 Mbps. in case of intererence,data speed drop to Halves.

Advantages of Wi-Fi-

IT office higher data speed as much as 11 mbps.
Allows user to access network resource from nearly any conneniet location within their primary networking environment.
User can even access the network outside their normal work environment, for example Most coffee shop offer free wireless internet connection or to their customers.

Disadvantages of Wi-Fi-

Speed of data aften fluctuares in case of wireless fidelity in such case data call quality is greatly hampered.
It has Limited radius of action thus is quite suitable for home networking but fails to offer coverage for larger area
wireless network, typically utilize some forms of encryption technology and some of the, commonly used encryption methods are valuable and easy to hack this cases serious security threat.

Frequency or Wi-Fi Band-

Wireless fidelity network with 802.11b IEEE standard can transfer data at a speed of 2.4 gigahertz and this data transfer speed goes up to 5 gigahertz with 802.11a IEEE standard.

Security encryption standard supported by Wi-Fi are-

WEP:-WEP means fired Equivalent privacy. It is a security protocol for using wireless network which encodes transmitted data whenever web was an early attempt to secure wireless network and better security is now available such as VPN and WPA.

WPA:-WPA standard for Wi-Fi protected access Wi-Fi standard that was design to improve upon the security feature of WEP. The technology is designed to work with exacting Wi-Fi products, which I have been enable with web that is software upgrade to existing hardware.

↡

ITL Wireless Equipment.

Wireless access point router and personal computer memory card International Association card are main wireless equipments

In a computer networking wireless access point router is a networking hardware device that allows a Wi-Fi compatible device to be connected to a wired network. (Wireless access point),in general connect to the router as a standalone device, but sometimes it is an integral part of the router itself.
Personal Computer memory card International Association card (PCMCIA)are the hardware interface which are silghtly bigger in size than your credit card. It enables additional Functionality for your laptop and other Wi-Fi compatible portable device.

Wireless Access Point-

LINKSYS model number BEFW11S4 is a commonly used wireless access point router WAP router which support protocol standard including IEEE 802.3u (100baseTX) and IEEE 802.11b(wireless). This device has a built in router capability and it obtain an IP and uses DHCP it features 4 built in Port switches. This device is fully configurconfigurable through simple web interface.

Wireless Cards-

Wireless cards of a data speed of 11 MBPS with compatibility with 802.1 b IEEE standards. 4 3com cards of model no. 3CRWE62092A and four ORiNOCO(Lucent) card of model number 012352/G are usually used to moderate Wi-Fi set-up.

NETWORK DEVICES

noreply@blogger.com (Unknown) — Tue, 24 Mar 2020 10:35:00 -0700

Networking Devices
The Networking devices are intelligently designed to connect two or more trough a data path.Apart from sharing files,these devices enable printers and machine sharing.The communicating devices set up a path that connects all computers in the network.Network is a collaboration or connection of two or more zones or devices through a common linking method. The network allows the nodes to share resources between the linked systems. This is applicable in telecommunication ,internet and even offline data sharing.

What is the use of network devices?
Network devices or internet working devices are used to establish a network connection inside the corporate environment.

In this image , HUB,Bridge and Switches are used to implement a switched network of the devices,while router is used to interconnect multiple switched networks.

There are certain hardware devices used within the network to connect two or more computers or peripherals.

NIC
Repeater
HUB
Switch
Gateway
Router
Modem

1. NIC

NIC stands for NETWORK INTERFACE CARD. Sometimes it is also called by the name "NETWORK INTERFACE CONTROLLER".It is indeed a circuit board or a card that is installed in a computer so that it can be connected to a network. Actually the network interface card provides the computer with a dedicated, full time connection to a network. Personal computers and Workstations on a local area network(LAN)typically contain a network interface card specifically designed for the LAN transmission technology.

2. REPEATER

Repeater is a network devices, which used to regenerate or replicate a signal. It removes the unwanted noise in an incoming signal.Unlike an analog signal, the original digital signal,even if weak or distorted ,can be clearly perceived and restored.With analog transmission, signals, are re-strengthened with amplifiers which unfortunately also amplify noise as well as information. Repeater operates at Layer 1 of OSI.

3. HUB
Basically a hub is a common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets. HUB operates at Layer 1 of OSI.

4. BRIDGE
Bridge devices inspect incoming network traffic and determine whether to forward or discard it according to its intended destination. An Ethernet bridge, for example , inspects each incoming Ethernet frame-including the source and destination MAC address, and sometimes the frame size - in making individual forwarding decisions.Bridge devices operates at the data link layer(Layer 2) of OSI model.

5. SWITCH

switch is very common types of networking devices that channels coming data from any of multiple input ports to to specific output port that will take the data toward, its intended destination in a telecommunications network. In the traditional circuit switched Telephone Network ,one or more switch are used to set up a dedicated communication through temporary connection for circuit for data exchange between two or more network devices .O n an Ethernet LAN ,the switch determines from the physical device like MAC address in each incoming message frame which output port to forward it to and out of . In an internet, a switch determines from the IP address in in each packet and the output port of switch is connected to the next part of the the intended destination.

6.GATEWAY
A Gateway is a network node which connects two networks in a different protocols. Gateways can take several forms including routers or computers and can perform a variety of tasks. These range from simply passing traffic on to the next hop on its path to offering complex traffic filtering, proxies or protocol translations at various network layers. The most common Gateway is the internet gateway, which connects home or enterprise network to the internet .An internet gateway also often acts as a security node ,variously filling one or more security roles,such as proxy server, firewall or Network Address Translation(NAT)server.Software-defined WAN(SD-WAN) and virtual WAN systems server as gateways between an enterprise network and two or more wide area network(WANs).

7.ROUTER
Router is one of the most used networking device used to sharing internet connection between two devices.The operation of router is complicate as it can both Software and Hardware and operates at layer 3 of OSI

The connections established through router can be

Ethernet to Ethernet- The main router can either be Linksys or a third party and will be referred to as the main router .The second router should be Linksys and will be called secondary router.If you want to cascade a non Linksys router to the main router you need to call its manufacturer for support

MAN to WAN- Connecting one of the Ethernet ports of the main router(MAN) to the internet port (WAN)of the secondary router. This type of spilling required the main router and the secondary router to have different it segments. This connection makes it easier to identify which router the computer and other devices in the network are connected to since they will have different LAN IP segments. However, computers that are connected to the main router will not be able to communicate with the secondary router and vice versa since there are two different networks. Before you connect a Linksys router to another router ,make sure that both routers have different IP address. This is necessary to avoid conflict and connectivity issue in the Local Network if they have similar IP addresses.

TOKEN RING to ETHERNET - Token ring Local area network(LAN) technology is a Communications protocol for local area networks.

8.MODEM

Modem stands for modulator-demodulator. A modem is a device or program that enables a computer to transfer data over for example telephone or cable lines. Computer information is stored digitally whereas information transmit over telephone lines is transmitted in the form of analog waves. A modem converts between these two forms analogue to digital and vice versa.

Introduction of Networking

noreply@blogger.com (Abhay maurya) — Tue, 24 Mar 2020 10:30:00 -0700

Networking

A network is a group of computers and other devices connected together. These connections can be with cables, wireless connections, or both.Many components and technologies are working together behind the scenes to ensure a networked computer can access resources on the network.

It also consists of a collection of computers,printers,scanner and other devices that are connected

together.

Networking has single purpose to share information as fast as possible.

Benefits of Networking

-file sharing:-

All types of data(Audio,Video,Text and image)can be easily shared and accessed on network.

-Resource sharing-

Resources like scanner,printers,network data and applications can be accessed by remote connection devices using network connected devices.Example, a application can be shared by multiple users.

-Internet sharing:-

A single internet connection can be shared with multiple users and devices.

-Increasing storage capacity:-

Access any types of media files stored remotely on other computers storage devices (Example NAS-Network Attached Storage)

The basic types of network

Computer users use their computers for browsing the Internet, sending and retrieving email, scheduling meetings, sharing files, preparing reports, exchanging images, downloading music, and maybe checking the current price of an auction item on the Internet. All this requires computers to access multiple networks and share their resources. The multiple networks required to accomplish this are the local area network (LAN), the enterprise network, the campus area network (CAN), the metropolitan area network (MAN), Metro Ethernet, the personal area network (PAN), and the wide area network (WAN).

LAN :- LAN stands for Local Area Network.It is used to network computers within a limited area like offices ,school by using the network media. The area covered upto 1 k.m no need a internet another name intranet.

CAN:- Campus Area Network is an interconnected of local area network(LANs) within a limited geographical area. Campus network can be additional to the set of wireless connections,content several buildings to the same network,but it is not the same thing.A can is smaller than a wide area network.Example, corporate office campus, university etc. have interconnected administrative buildings.

MAN:- Metropolitan Area Network which optimized for a larger geographic area than a LAN, ranging from several blocks of buildings to entire city.Two or more LAN connected with each other is called metropolitan area network is covered a whole city.Example cable network another name extranet.

WAN:- Wide Area Network that is a network connection of wide area such as the world.Example -internet(covered whole city)

PAN:-Personal Area Network which is referred to the interconnected of information technology devices mostly up to 10 meters.These interconnected devices might include laptop computers,mobile phones,printers or other computer device.It is also known as a wireless personal area network(WPAN).

ANTIVIRUS

noreply@blogger.com (Abhay maurya) — Tue, 24 Mar 2020 01:12:00 -0700

Today, a lot of antivirus software are available in the market with advanced technology settings.

Each antivirus software may have a set of specific tools or technologies to detect and prevent virus and security threats in an individual system and systems in an office set up.

Types of Scan

Scan type	Description
Real-time scan	Scans files on the system automatically as it is received, opened, downloaded, copied, or modified
Manual Scan	Scans a file or a set of files or complete system as initiated by the user
Scheduled Scan	Scans files on the system automatically based on the time and date set by the administrator or user
Scan Now	Scans a file or a set of files or complete systems as initiated by the administrator
Startup Scan	Runs every time the PC is booted, a quick scan of the disk`s boot sectors and critical system files

Conventional and Smart Scans

Scheduled scan settings can be configured or applied to one or several clients or domains, or to all clients that the server manages.

Conventional scan stores all Office Scan components on the client computer and scans all files locally.

Smart scan uses an advanced scanning architecture that is based on the threat signatures that are stored in-the-cloud.

Antivirus Tools

Antivirus software need regular updates to counter the new viruses or threats.

Most popularly antivirus tools include.

McAfee AVERT Stinger.
Microsoft Malicious Software Removal Tool
Symantec Virus Removal Tools
F-secure Virus Removal Tools

These tools are available free of cost but are not a substitute for installed antivirus software.

Best Practices for Using Antivirus

To make correct and effective use of antivirus, ensure to:

- Configure the antivirus correctly as per the required policies
- Check the required system specifications properly before installing
- Set antivirus to regularly update latest virus or malware definitions and solutions
- Schedule a time and date for regular and detailed scan
- Check the antivirus is not blocked or disabled
- Download updates and patches for troubleshooting specific malware
- Ensure the installation is successful and the antivirus is running correctly

SPYWARE

Spyware is infiltration software that secretly monitors unsuspecting users.

Hackers use spyware to obtain sensitive information, such as password, from the user`s computer

Spyware is often attached to free online software downloads or to links that are clicked by users.

Spyware and cookies are similar, but spyware conducts infiltration activity continuously until it is removed by specific anti-spyware tools.

Trojan

A Trojan is also known as a Trojan virus horse-cause harm to a computer system.

Types of Trojan horses:

- Backdoor Trojan
- Downloader
- Infostealer
- Remote access Trojan
- Data sending Trojan
- Destructive Trojan
- Proxy Trojan

Most of Trojan give attacker control over victim`s computer.

Malware

`Mal’icious Soft`ware’=MALWARE=Any software that harms a computer system.

Malware can be Worms

- Viruses
- Trojans
- Spyware
- Adware
- Rootkits

Malwares generally

- Steal protected data
- Delete documents
- Installs software against user`s approval.

NETWORK TOPOLOGY

noreply@blogger.com (Abhay maurya) — Mon, 23 Mar 2020 10:12:00 -0700

WHAT IS TOPOLOGY ?

Network topology is the arrangement of the various elements (link,nodes,etc)of a computer network.

essentially,it is the topological structure of a network and may be depicted physically or logically.

➤Topologies are divided into two types. one is called physically topology and another one is logically topology.

physical topology is placement of the various components of a network, including of a device location and cable installation,while logical topology illustrates how data flow within a network, regardless of its physical design.

Distances between nodes, physically inner connection,transmission rates,or signal types may differ between to network, yet their topology may be identical.

- There are a number of reasons to understand about topology-

· The network topology impact performance

· The network topology is a factor in determining the media type used to cable the network.

· The network topology impacts the cost of cabling the network.

· Some access method works only with specific topologies.

· Knowledge of network layout /topology helps to optimize the network performance and troubleshoot network performance issues.

· The table show the cable types associated with each topology.

TYPES OF TOPOLOGY-

There are 6 types of different topology-

BUS TOPOLOGY.
RING TOPOLOGY.
STAR TOPOLOGY.
MESH TOPOLOGY.
TREE TOPOLOGY.
HYBRID TOPOLOGY.

1.BUS TOPOLOGY.

Bus topology is a network where all the nodes are connected with each other with a single common cable .when one node wants to access another node on the network then it puts a message addressed to that device on the bus network.

BUS TOPOLOGY

Advantages of bus topology-

It is very easy to connect to node or peripheral in this network.
Bus network requires less cable length than any other topologies.

Disadvantages of bus topology-

Is the total network as a depended on a single cable so if any problem occures in then main cable, the enter network shut down.
This network cannot be used as a stand alone solution in a large building.

2.Ring topology:-

when each devices is serial in a closed ring pattern with a single cable then the network system is called a ring topology.as a train crosses all the platforms to reach its destination,ring topology does he same to pass a message from one node to another node.

Advantages of ring topology-

The network does not anything without order. it needs to access the token & the opportunity to transmitte.
In this network each and every node has equal access to resources.
The performance does not interrupted by any addition components.
Network server not needed to control the connection between node.

Disadvantages of ring topology-

In this network if any node break down then the entire network system stop working.
The speed of transferring data is slower then any topology because the packet data passes all of through.
The entire network could be affected by moving,adding and changing of devices.

3.Star topology.

In this confirmation all node are connected to a central hub with separated cable.here the central node or hub act like the main server and the other nodes which are connected to the central node,act like client devices.

Advantages of star topology-

in this type of network it is very easy to add or remove a node to the network system.
here if any fault occures it is very easy to find out and fix it up.
if anyone node faces problem, the rest nodes performs smoothly without effecting the whole network.

Disadvantages of star topology-

It is more expensive then any other topologies to build up the network because it requires excessive length of cable.
The entire network goes down if the central node (hub)does not work properly and also if the other important nodes are disconnected from the network,example file server node stop working.
The central hub expensive which makes the network more expensive.

4.MESH TOPOLOGY.

Here each and every network is interconnected with each other. it work independently.

Advantages of mesh topology-

Adding or removing node in this network could be done easily without interrupting the other node and the network.
Here the transmission of data very easy because it transfer data from different nodes simultaneously.
In this confirmation transfer of data does not get affected by peripherals because if one node fails there is always an alternative one.

Disadvantages of mesh topology-

It is very hard to configure the network and very difficult to maintain.
Mesh topology is comparatively expensive when compared with other topologies like ring and star topology.

5.TREE TOPOLOGY.

A tree topology looks like a branches of the tree where each and nodes are connected with its parent's node. it is also called by the name star+bus topology.

TREE TOPOLOGY

Advantages of tree topology-

Here finding finding out ant fault is very easy and not too hard maintain.
If one of the any nodes get damaged the other hierarchical nodes are not affected.
It is very easy extend he network as much administrator wants.

Disadvantages of tree topology-

The network require a high maintenance.
A lot cable is require to establish the network system.
Trouble shooting of problems is highly difficult.

6.HYBRID TOPOLOGY.

Hybrid topology is the combination of two or more different network topologies.

this network is a mixture of both to-peer-to-peer and client server network. it can be either wired or wireless network.

Advantages of hybrid topology-

Here in this network the troubleshooter is far better than any other topologies.
this type of network is very easy to expand.

Disadvantges of hybird topology-

The structure of the network is hard to understand.
It is very expensive to build up the entire network because of the requirement of cable and other peripherals.
Multi-station access unit MAU is required.

IP(Internet Protocol) and Version

noreply@blogger.com (Abhay maurya) — Mon, 23 Mar 2020 04:40:00 -0700

- IP is a method by which data is sent from one computer to another over the network.Each computer which is a connected to the internet has atleast one IP address which uniquely identifies one computer from another computer.
- Internet protocol has provides each computer on a network with a unique identifier.
- The IP address is designed and controlled by Internet Assigned Number Authority(IANA).

- All computers on the Internet have unique IP addresses. As long as the IP addresses are valid, any computer can reach any other computer on the Internet with this IP address.

- A network address is an identifier for a node or network interface pf a telecommunication network.

- Network addresses are often designed to be unique across the network,although some networks allow for a local or private addresses that may not be one network.

More than one type of network addresses may be used in any one network.

There are 2 types of address

1. Physical address,example Hardware address(MAC address)

2. Logical or Software address,For example IP address.

IPv4

- Internet Protocol version 4 (IPv4) has been the standard IP addressing scheme since the 1980s. It’s used to get TCP/IP traffic from one computer to another computer over a network.

- An IP address is a unique address used to identify each device (i.e.computer,mobile devices,printers,etc) connected to an IP network.Internet protocol version 4(IPv4) is currently the most used addressing standard,however,IPv6 is also being used widely.

- An IPv4 address contains 32 binary bits.

- It has 4 octets.
- Every octet has 8 bits.
- IPv4 provides 4.3 billion IP address.

Classes on IPv4

	8 bits	8 bits	8 bits	8 bits
Class A	Network	Host	Host	Host
Class B	Network	Network	Host	Host
Class C	Network	Network	Network	Host
Class D	Multicast
Class E	Research

Class A

- Class A is used for large scale organizations.

- It is used for hosting.

- start from 0 to 127.

- Example - 102.126.17.226 or 10.0.10.100

Class B

- Class B is used for medium scale organizations.

- Class B from 128 to 191

- example :- 168.122.226.204 or 172.16.10.199

Class C

- Class C is used for small scale organizations.

- Class c is from 192 to 223

- example :- 200.168.212.226 or 192.168.100.100

Class D

- Class D used for Multicast.

- Class D is from 224 to 239

- Example :- 224.0.0.6 or 224.0.0.10

Class E

- Class E used for Research and Development.

- Class D is from 240 to 255

-Example:- 243.164.65.28

Division of IP address

IP addresses are divided into two types

- Network ID(Net ID)

- Host ID

The network portion is under the control of IANA and host portion in used by users.

Subnet Mask

Subnet mask is used to identify the number of bits in the network portion and the host portion in a subnet.

-In a subnet mask

ones represent network
Zeros represent the host

Default subnet mask

Types of IP address

1. Unicast address

- Unicast address identifies a single network interface.The IP delivers packets sen to unicast address to that specific interface.

- Example:192.168.4.1

2. Multicast address

- It is used to communicate nodes that are in a groups.

- Routing protocol used multicast address.

- Example: 224.0.0.10

3. Broadcast address

- A broadcast address is used to broadcast message to all nodes in a network.

4. Private address

- An IP address is considered private if the number falls with one of the IP address ranges reserved for private networks such as LAN.

- Private IP address are not routable over internet.

5. Public address

- Public IP address are routable over internet are unique.

6. Reserved IP address

- Reserved IP address used for special purposes .

OSI MODEL

noreply@blogger.com (Abhay maurya) — Mon, 23 Mar 2020 01:03:00 -0700

OSI MODEL:-

An open systems interconnect(OSI) reference model was developed by the international organization for standardization in 1984 to enable different type of network to be linked together.

the model contains seven layers. these layer describe networking function from the physical network interface to the software applications interfaces.the intent of the OSI MODEL is to provide a framework for the network that ensure compatibility in the network hardware and software and to accelerate the development of new network technologies.

1.Physical layer:-

The physical layer is responsible for the transmission and reception of unstructured raw data between a device and a physical transmission medium. It converts the digital bits into electrical, radio, or optical signals. Layer specifications define characteristics such as voltage levels.

example:- UTP,fiber and network interface card (NICs).

2.DATA LINK LAYER.:-

Handle error recover,flow control(Synchronization),and sequencing(which terminals are sending which are receiving). it is considered the "media access control layer" (MAC) addressing is defined .the ethernet 802.3 standard is defined in this area, which is why the mac address is sometime called the ethernet address.

3.NETWORK LAYER:-

Accepts outgoing messages and combine messages or segment into packets,adding a header that including routing information. it acts as the network controller.

4.TRANSPOT LAYER:-

The transport layer responsible for end-to-end communication over a network. It provides logical communication between application processes running on different hosts within a layered architecture of protocols and other network components.is considered the message integrity between source and destination.

5.SESSION LAYER:-

Provide the control function necessary to established, manage, and terminate the connection are required to satisfy the user request. example of network file system(NFS) and structure query language (SQL).

6.PRESENTATION LAYER:-

Accept and structures the message for the application.it translate the message from one code to another in necessary for data compression and encryption.examples of technologies working in this layer are American Standard Code for information Interchange (ASCII)and join photographic expert group(JPEG).

7.Application layer:-

Interacts with application program that incorporate a component such as your internet browser and Email. this layer for responsible for logging the message in, interpreting the request,and determining what information is needed to support the request.

example the hypertext transfer protocol.

OPERATING SYSTEM(OS).

noreply@blogger.com (Abhay maurya) — Sun, 22 Mar 2020 09:12:00 -0700

Introduction of operating system

first,let us understand what is meant by an operating system(OS).

A computer system comprises of :

--HARDWARE

--SOFTWARE

The two to major types of software are:

-System software

-Application software

OPERATING SYSTEM

OS is a most common system software program that runs on a computer.

An operating system acts as an interface between the user and the computer and manages the execution of all types of programs.

Example:- A operating system helps to perform basic task such as recognized the input from the keyboard and sending the output to the display screen of the computer.

An operating system perform the following function:-

➡️device management (controlling input/output devices).

➡️memory and file storage management.

➡️process management.

➡️user application program management.

➡️error management.

➡️CPU scheduling.

➡️providing interface for interaction between user and computer system.

Types of operating system

-GRAPHICAL USER INTERFACE(GUI)

Provides interface having icons,menu etc. the user to interact with the computer,for example,windows,Linux etc.

-COMMAND LINE INTERFACE(CLI)

Interface that allow user enter command and text to interact with the computer.for example MS-DOS(disk operating system)Unix etc.

➡️ Different types of operating system according to mode of use

NETWORK OPERATING SYSTEM

An operating system designed to support a network.It enables the various computers connected to the network of share resource such as data,files,devices etc.

CLIENT OPERATING SYSTEM

An operating system that runs on desktop or notebook computer.It also knows as standalone operating system.

Client operating system

Computer

noreply@blogger.com (Abhay maurya) — Sun, 22 Mar 2020 07:19:00 -0700

What is a computer?

A computer system is a mix of electronic hardware and software.

It accepts data as input and processes it to provide us with an output.But,it can only follow the instructions that we give it.

A computer is similar to a television, which takes input from a remote control like the channel number and display the output on the TV screen in the form of the correct channel.

INPUT-PROCESS-OUTPUT

Input

- An input device is used to feed information to the computer.

- It is also used to instruct the computer to perform specific actions, such as opening a file,closing a file or saving a file.

- The most commonly used input devices on a computer are keyboard and mouse.

Process

-The process device performs actions as per your instructions and gives the required output.
- It also stores information in storage devices so that you can view if or use it at a later point in time. Some examples of process device is processor and storage devices are RAM, hard drive and DVD/CD drive.

Output

-These devices are used to display or produce the result.

-A simple example of outputs anything you view on your computer monitor.Another example of an output device is a printer.

Parts of computer

Power supply

This is responsible for converting the power received from the main-line (AC)into the power required by the motherboard (DC) and other components to operate.

Expansion cards(Graphic card)

Expansion cards are added to the computer to boost the performance or update the capabilities of the computer.They include video or graphic card,sound card,network card and Bluetooth.

Back USB connector

A Universal Serial Bus(USB) connector is a connector between a computer and a peripheral devices such as a mouse and keyboard.

Random Access Memory(RAM)

Ram stores all the instructions that you provide when the computer is on.

Router

A router is a networking device that forwards data packets between computer networks.

Modem

A modem is a combined device for modulation and demodulation,for example,between the digit data of a computer and the analogue signal of a telephone line.

CPU

The central processing unit is the brain or the engine of the computer.It processes all the instructions that you give to the computer and carries out the required tasks.

Motherboard

The motherboard is a printed circuit board(PCB) to which all the other components are connected.It helps all components to work together to produce the required output and controls the functioning of the various components.

Heat Sink Assembly

A heat sink is an electronic device that include a fan to keep the processor and other parts of the CPU cool because the CPU produces a lot of heat ,while active.

Audio connector

Audio connector can include connectors for the microphone,speakers and headphones.