Computer Networks

Please watch video regarding following  topics       Computer Networking Part -1

Internet and WWW

Web site and  Web portal
Web page and Home page
URL









What is internet ?

Q2. What is WWW ?  How it is different from Internet?

WWW is a part of internet not the whole internet. Internet  include www,FTP,email, P2P, Telnet, Chat etc.

Website is group of realted web pages. Every web page is a digital file designed using HTML language

Ever web site is place is placed or hosted on a computer that is connected to the internet called web server.

In a website web pages are interlinked via special links called hyperlink.

A website is the collection of web pages whereas a portal acts as a gateway to world wide web and provides many services. An organisation owns a website. 
A web portal linked to many other websites that provide these services. 
web portal  Examples : Google,Yahoo,Rediff, MSN
Website Examples:  cbseacademic.in, ncert.nic.in

Every website/web resource  has a unique address on internet called URL

Home page: It is the top level web page of a web site. This is the page that gets displayed first of all when a web site is opened 

Must watch the video and subscribe the channel to crystal  clear concept 

Web Address(URL)


Unique Address of Your web page


Every website is a collection of web pages. An every website is hosted or placed on web server.

E.g
https://computersciencejnvchandigarh.blogspot.com/2020/04/what-is-ip-addressing-write-shortnote.html

E.g
https://navodaya.gov.in/nvs/nvs-school/CHANDIGARH/en/home/index.html

Part of URL : 
Type //domain name //path with file name

The Type of server or protocol e.g http,https, ftp,gopher etc
The  domain name or address of the server on the internet
The location of file on the server

A domain name is a human-readable name—like amazon.com—that we type in a web browser URL field. The Internet Corporation for Assigned Names and Numbers (ICANN) manages  these domain names

Top Level Domain (TLD)

TLD refers to the last part of a domain name

.com – Commercial  /gov – government  /edu – Educational /org – Organizations (mostly non-profit)./mil – Military. /net – Network organizations./.in-india/jp japan/uk- united kingdom

IP address

Unique numeric address to identify a device or website on the internet called IP address.

A domain name is a Web address, such as google.com, that is linked to an IP address (which represents a physical point on the Internet). When someone types a domain name google.com into a Web browser, the requested Web page displays.
 

DNS server contain records of domains names and there related ip address in form of table similar to contact book stored names and there related mobile numbers.

Protocols 

Set of rules that define communication between two or more devices over a network

HTTP & HTTPS
FTP & SFTP

VoIP:

Voice over Internet Protocol (VoIP), is a technology that allows you to make voice calls over internet.

NFC(Near Field Communication):

 It is a protocol used to provide secure short range wireless connectivity between two electronic devices within the distance of 4-5 cm.

SMTP(Simple Mail Transfer Protocol )

 is an Internet protocol for sending e-mail across the internet. 

POP3 (Post Office Protocol 3)

It  is a  standard protocol  That define the rules about receiving  emails from a remote server to a local email client. 

IMAP(Internet message Access Protocol) :
It is also e-mail receiving protocol. POP support where single application access the email while IMAP support where multiple application access the email . 

SCP(Secure CoPy Protocol):

It  allow you to transmit files remotely connected computers over internet with encryption benefits.

TCP/IP :  (Transmission control protocol/ internet protocol)

It is a protocol the govern transmission data over internet.  TCP/IP It is the basic communication language or protocol of the Internet. 

TCP is responsible for the data delivery  of packets and IP is responsible for the logical addressing. IP obtain the address and TCP guarantees delivery of data to that address. 

TCP/IP is responsible for dividing of a message or file into smaller packets that are transmitted over the Internet at source end and reassembling the packets into the original message.

IP handles the address  part of each packet so that it gets to the right destination.

Remote login programs

User can access remote computers desktop  such as a home computer from remote location and can work remotely.

Telnet  and SSH are two remote login programs or protocols

The telnet is an older technology while  SSH(Secure SHell)  is secure then telnet. Data is encrypted before starting communication.

What is cyber crime? Give some example.

Any criminal offence that is involves the use of computer, any electronic device and internet is called cyber Crime.

Example : Phishing, credit card frauds, cyber bullying, illegal downloading, cyber terrorism, Cyber stalking , child abuse, Internet fraud (online scams), Hacking etc

What is scam ? Give some suggestions to avoid scam

Any fraudulent business practice that extracts money from an unsuspecting, ignorant person is called scam. Scams committed over the internet are called online Scam.

Steps to avoid online Scams:

1.Never reply to emails from any unknown or unreliable source

2.Never respond to an e-mail or advertisement claiming you have won something

3.Never CLICK on any link that you have received in your email

4.Never enter personal information or any financial information on unsecured website

Note : The site that do not employ HTTPS and do not have padlock sign is unsecure website

What is identity theft ? How can we prevent identity thefts?

The act of a person obtaining information illegally about someone else. Thief's try to find such information as full name, maiden name, address, date of birth, social security number, passwords, phone number, e-mail, and credit card numbers. The thief can then use this information to gain access to bank accounts, e-mail, smartphones, identify themselves as you, or sells your information.

When someone’s personal information is obtained, a thief can commit any of the following crime

Credit card fraud: can block your original card and asking for new duplicate card

Bank or finance fraud: They may take out loan for mortgages or a car in your name

Phone or utility fraud: Using your information , they can get new phone or other utilty

Change your personal information: by changing your sensitive information like phone number for getting SMS updates of your bank account

Follow few steps in order to prevent identity theft:

üEnsure strong and unique password

üDo not post confidential information online

üDo not post personal information on  social media

üShop from known and trusted websites only

üDownload only well known apps

üInstall advance malware and spyware tools/Antivirus

üUse the latest version of the web browser

üAlways update your system and the software

What do you understand by plagiarism? Why it is punishable offence

It is stealing someone else’s intellectual work such as idea, literary work or academic work etc. and representing it as your own work without giving credit to creator or without citing the source of information. 

“The act of presenting another’s work or ideas as your own, Without Giving Credit”

“Copy Words or Ideas from Someone Else’s Work, Without Giving Credit”

Plagiarism is considered academic dishonesty and a breach of journalistic ethics.

Plagiarism is a serious problem. If you as a student are caught plagiarising it can have serious consequences for you future academic and work career.

What do you mean by Privacy Law ?

Privacy law refers to the laws that deal with the regulating, storing, and using of personally identifiable information of individuals, which can be collected by governments, public or private organisations, or other individuals.

What do you mean by Propertary License ?

Proprietary License: 

This is the most restrictive. 

The idea behind it is that all rights are reserved.

 It’s generally used for proprietary software where the work may not be modified or redistributed.

Example of Proprietary License software's

Microsoft Window, MS Office, Google Earth, WinRAR ,Oracle version of java , Adobe Photoshop etc

What is software license ? What are the benefits/use of software licensing?

A software license is a legal instrument governing the use or redistribution of software.

1.By using licensed software , you are able to contribute to the further development of the software you are using.

2.Allows you to legally distribute software within your organization as covered by the licensing agreement. Using Software That Is Not Licensed Is Against the Law

3.Receive Around-The-Clock License Support/ expert help and advice(license support) whenever you have a concern or query regarding your software

4.The Right Software License Can Save You Money

Explain the following terms:

1.GPL  2. CC License  3. Apache License 4. Free and Open source License

5. Proprietary License:

GPL

The GNU General Public License (GNU GPL or GPL) is a widely-used free software license, which guarantees end users the freedom to run, study, share and modify the software.

CC license:

A Creative Commons (CC) license is one of several public copyright licenses that enable the free distribution of an otherwise copyrighted "work". A CC license is used when an author wants to give other people the right to share, use, and build upon a work that they (the author) have created.

Apache License:

It is  permissive free software license written by the Apache software foundation.

Rights are granted forever

Rights are granted for one country, automatically considered as worldwide.

Rights for no fee or Royalty

Free and Open source License

They allow software to be freely used, modified, and shared. Two sub types :

Permissive: 

Provide source code to use,copy,modify,publish and distribute. 

But distribution can only be made without source code.e.g W3C,Apache,BSD,MIT

Copyleft: 

Source code provided and use is free to use, change and distribute. E.g GPL,LGPL,MPL,Creative Common license

GPL: copy any no of time, distribute the code and You can charge a fee

Explain following open source terminology :
1. FLOSS 2. Freeware  3. OSS 4 Shareware

Free Software(Free libre Open Source Software(FLOSS)):

 Free as well as open Source. code is available. They are freely accessible and can be freely used, changed, improved, copied and distributed by all and payments are not needed for free Software.

Freeware

It refers to copyrighted computer software that anyone can download from the Internet and use for free, for an unlimited time. All the features are free.

Permit redistribution but not modification (their source code is not available). Freeware is distributed in Binary Form (ready to run) without any licensing fees.

Open Source Software(OSS)

Source code is available. Come free of cost or with nominal charges Customer can modify and redistribute without any limitation

Shareware 

üThe term shareware refers to commercial or proprietary software that is copyrighted, but which may be copied for others for the purpose of their trying it.

üMost of the times, all features are not available, or have limited use. To use all the features of the software, user has to purchase the software.

üIt is often offered as a download from an Internet website or as a compact disc included with a magazine.

üits source code is not available and modification to the software are not allowed. 

CyberEthics for E-commerce

Buying and selling of goods and services over internet  and making payments  over internet is call E-commerce. Each stake holder must ensure that no one is cheated or fooled in any form. 

Ethics related to e commerce:

1.Privacy 2.Online Fraud 3.IPR 4.Plagiarism 5.Digital property rights

Privacy

qIt is the protection of personal information given online while carrying transaction .

qIt is related to a company’s policies on the use of user data. Because it can be misused for online frauds or cyber crimes.

qMerchant or seller must state about how the user data will be used, in the terms and conditions of its site.

qMerchant must ensure the user about data safety by implementing proper safety and security  measures such as https protocol, SSL,TCL protocols so that user’s data is safe from hackers.

qUser must go through the terms and conditions of seller/merchant site before  providing any sensitive information and make sure that the site is safe site by checking https protocol and padlock sign etc

Web server

It is a special type of server that can handle http request. There are two type of http request GET and POST

Example of web servers: IIS, tomcat, WebLogic etc.

Web client: 

The request for web services or websites or webpages. All web browsers are example of web clients.

Web Browser  

It is a software that is used to explore web sites. Text only browser: access web in text only mode e.g. Lynx

Graphical Browser: that can access web with multimedia contents(text, audio and video). E.g. Firefox , Opera ,Chrome, Mozilla, Internet Explorer, Net scape

Social networking:

Use of internet based social media programs to make connection with friends, family, classmates, customers and clients.

Social networking sites:

are websites that provide a venue for people to share their activities  with family, friends and colleagues. E.g Facebook, twitter, Wikipedia, Flickr, LinkedIn, blogger etc.

Advantages: 

Easier to connect with people 2. interactive involvement 3. Bring more awareness 4. Easy to conduct discussion and collect Opinions

Disadvantages: 

1. Misuse of information 2.Fake profile 3. Peer Pressure 

4. Irresponsible Behavior 

E-Reservation: Reservation of tickets or hotel rooms or tourist package etc. through internet is called e Reservation. Any one can check  the availability of tickets/rooms  and can reserve online  railways or airways or bus tickets. or hotel rooms or tourist packages.

Benefits: 1.Easy access 2. Available any time and any where 3. Fast 4.

Application area of E reservation: 

travel tickets, Hotel rooms, Sport matches, Movie and theater, Events etc.

E –Governance:

Delivering of Government services to the common man in his locality via internet . The NeGP (National e goveranance Plan) has been formulated by the government to promote e governance.

Major e governance projects in India:

Indian passport and visa portal 2. income tax portal 3. National portal of india 4. DRDO  5. RTI portal 6. supreme court of India 7. Indian courts

E-Groups:

It refers to an online community where people discuss on topics of common interest. It allows users to create, post and comments. A message posted in group is called post. All the posts are listed together on a discussion board. Which is viewable to all the members of the group.

  The members of an e group can post a message and upload as well as download files from the group. A conversation on a group with response and replies on a single topic is called threaded conversation or threaded messages

Benefits: 1. It’s a venue to make new friends. 2. It keeps you touch with other members. 3. You can build a community without the technical knowledge.

E- Learning: Learning  system that we can obtain from internet using electronic devices. It is also called online learning or online education.

  E learning made teaching , training and learning much easier

Advantages: 1. reduced overall cost 2. can take place anytime and anywhere 3. Easily manageable 4. Use of multimedia make in more interactive 5. self directed and self paced

E-Learning software's: moodle, olat, h5P, chamili, siminars, udemy, articulate, udacity, skill share etc.

Application area of E learning: e- classroom, assessments, e-simulation, Problem solving games, learning support, MOOC(Massive Open online Course)

E-Banking: banking services through internet using electronic devices. It is also called online banking  or internet banking or virtual banking  or phone banking. It offer bank transactions using internet. All bank services like paying bills, transferring funds, viewing account balance etc.

  For online banking bank provide user id and password

Advantages of E-Banking: 1. Easy access  2. Access any time and any where 3. Fast 4. worldwide connectivity 5. Direct customer control 6. No physical interface between the customer and the institution is required

Disadvantages:

E- Shopping: buying and selling of product online is called e- shopping. Consumers can buy a variety of items from online stores such as books, clothing, household items, toys, hardware, software, health, insurance etc.

Advantages: 1. No crowds 2. More variety 3. Easy Price comparisons 4. More control 5. Better price 6. No pressure 7. Any time and any where. 8. Easy access 9. save time and money

Disadvantages:   1. Delay in delivery 2. Fraud in online shopping 3. Product Quality 4. Unclear website conditions 5. You cannot bargain 6. Hidden cost and shipping charges 7. Lack of interaction 8. Return of product in difficult

Sites:www.flipkart.com, www.snapdeal.com , www.amazon.in, www.bigbasket.com, www.jabong.com etc

Threats: 

1. gaining access sensitive data such as user-id, passwords, credit card information etc.  

2. Using viruses to corrupt your system.

3. unwanted spamming 

4. gaining access to your location details 

5. gaining access to your shopping history, and habbits

Security concerns 

1. Phishing  2. Sniffing the network 3. Guessing passwords 

Mobile Technologies

SMS stands for Short Message Service. It is a technology that enables the sending and receiving of messages between mobile phones. SMS first appeared in Europe in 1992. One SMS message can contain up to 160 characters . Longer messages will automatically be split up into several parts.

MMS: stands for multimedia Messaging service. It is a technology that is used to send or receive multimedia messages between mobile phones. Multimedia message may include text, image, audio or video content

2G(Second Generation)

2G networks developed as a replacement for first generation (1G).

It is generaly known as GSM (Global System for Mobile Communications)

2G standard is used in Mobile phones.

It can handle data speeds of  up to 250 kbps.

 GSM standard is transmitted at frequencies between 900 Mhz and 1800Mhz.

 It allowed  some data along with calls in the form of text messages.

3G(Third Generation)

3G is the third generation of wireless mobile telecommunications technology.

3G support Videoconferencing.

3G support IPTV (TV through the internet)

Several times higher data speed compare to 2G

3G offer speeds of 500 kbps to 2 Mbps, but over the years, it is now as high as 20 Mbps.

It can handle data in form of text messages and multimedia such as a audio/video messages along with voice calls

4G(Fouth Generation)

4G is the Fourth Generation of wireless mobile telecommunications technology.

Support interactive multimedia

High speed , High capacity and low cost per bit

4G offer speeds of 10-15  Mbps, which go up to 50 Mbps.