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Instructor: Ch. Bilal Ahmad Khan

Internet and Cyberspace

History of Communication and Internet

Slide Rule-1621

Mechanical Adding Machine -1642

Ada Lovelace - 1843

Telegraph Message Machine - 1844

First Telephone - 1876

History of Communication and Internet

First Radio Signal - 1895First Radio Broadcast -1907

First ATM - 1963

Internet Operation

Internet Operation

Applications of Internet

Data Transmission Capacity

Bandwidth, or channel capacity, is an expression of how much data - text, voice, video, and so on - can be sent through a communications channel in a given amount of time

The type of data transmission that allows only one signal at a time is called baseband transmission

several signals can be transmitted at once, it’s called broadband transmission

Broadband - very high speed - connections Fiber Optics, DSL, cable, and satellite and other

wireless connections

Physical Connection for Internet

Wired Dialup ISDN DSL T1

Wireless Through Air Link (e.g. PTCL EVO, Wateen,

Wi-Tribe) Satellite

Data Transmission Speed

bps Bits per second Eight bits equals one character, such as A, 3, or # Kbps

Kbps kilobits per second 1 thousand bits per second

Mbps megabits per second 1 million bits per second

Gbps gigabits per second 1 billion bits per second

Connecting with Internet

Narrowband Dialup Connections

Connecting with Modem Modems and Call Waiting

Source: Using Information Technology by William and Sawyer

Connecting with Internet

High Speed Phone Lines ISDN (Integrated Services Digital Network)

consists of hardware and software that allow voice, video, and data to be communicated over traditional copper-wire telephone lines

DSL (digital subscriber line) uses regular phone lines, a DSL modem, and special technology to transmit data in megabitsper second

T1 line, essentially a traditional trunk line that carries 24 normal telephone circuits and has a transmission rate of 1.5 to 6 Mbps

Connecting the Internet

Source: Using Information Technology by William and Sawyer

Wireless Connections

Satellite Communications Communications satellite, a space station that transmits radio

waves called microwaves from earth-based stations Wi-fi

802.11 standards by IEEE of wireless transmissions Transmission of data at up to 54 Mbps 300-500 feet covered by access point

2G Used for mobile communications

3G High-speed wireless technology that does not need access

points because it uses the existing cell phone system

Working of Internet

Client computer requesting data or services Normally a computer in front of user

Server Is a central computer supplying data or

services requested of it Also known as host computer

Working of Internet

Point of Presence Local access point to the internet A collection of modems and other equipment in a local

area POP acts as a local gateway to the ISP’s network

Network Access Point A routing computer at a point on the internet where

several connections come together Owned by a network service provider

Internet Backbone High-speed, high-capacity transmission lines that use

the newest communications technology to transmit data across the internet

Working of Internet

Working of Internet

Protocols Set of rules, that computers must follow to transmit data

electronically The protocol that enables all computers to use data

transmitted on the internet is called Transmission Control Protocol/Internet Protocol, or TCP/IP,

Packets TCP/IP breaks the data in a message into separate

packets Fixed-length blocks of data for transmission

IP Address Internet Protocol (IP) address uniquely identifies every

computer and device connected to the internet

World Wide Web

Design and Develop Web Site

Choose the name of website

Buy domain name with Web Host

Web Host provides web space

Upload files to the web server

Write the URL in the web browser

Browse the website

Client Server

DatabaseSend

RequestRequest

Data

Fetch

DataFetch

Reply

World Wide Web

Design and Develop Database

Design and Develop Web Site

Choose the name of website

Buy domain name with Web Host

Web Host provides web space

Upload files to the web server

Write the URL in the web browser

Browse the website

Client Server

Database

Data

SQL Query

Send

RequestRequest

Data

Fetch

DataFetch

Reply

World Wide Web

URL URL (Uniform Resource Locator) is a string of

characters that points to a specific piece of information anywhere on the web

World Wide Web

Protocol (http://) HyperText Transfer Protocol (HTTP) , the communications rules

that allow browsers to connect with web servers Another protocol is ftp://

Domain Name Domain is simply a location on the internet, the particular web

server

Directory Name The directory name is the name on the server for the directory,

or folder, from which your browser needs to pull the file

File Name The file is the particular page or document that you are seeking

Search Engines

Search services are organizations that maintain databases accessible through websites to help you find information on the internet

Search engines are programs that enable you to ask questions or use keywords to help locate information on the web

Spiders - also known as crawlers, bots (for “robots”), or agents – that crawl through the World Wide Web, following links from one web page to another and indexing the words on that site

Search Engines

Individual Search Engines Compiles its own searchable database on the web Hits are defined as the sites that a search engine

returns after running a keyword search Examples are Bing, Yahoo, Google etc

Subject Directories Created and maintained by human editors, not

electronic spiders, and allows you to search for information by selecting lists of categories or topics

Examples are Galaxy, Google Directory, LookSmart, Open Directory Project, and Yahoo! Directory

Search Engines

MetaSearch Engines Allows you to search several search

engines simultaneously Examples are Clusty, Dogpile, Mamma,

MetaCrawler, and Webcrawler etc Specialized Search Engine

Help locate specialized subject matter, such as material about movies, health, and jobs

Examples are imdb, expedia, rozee, career etc

Emails and More Modes of Communication

Simple Mail Transfer Protocol Post Office Protocol Version 3 Internet Message Access Protocol