10.1The Historical Development of the Internet and WWW Internet A worldwide network which connects millions of small computer networks all over the world Estimated Internet users worldwide: over a billion Country Internet users (million) UK35.8 USA203 China103 Japan78.1 Country Internet users (million) Hong Kong4.9 South Korea31.6 Singapore2.1 India39.2

10.1The Historical Development of the Internet and WWW The ARPANET ARPA: Advanced Research Projects Agency In 1969, four universities in the USA connected their computers by telephone lines to create a network called ARPANET Stanford Research Institute University of Utah UCSB UCLA ARPANET

10.1The Historical Development of the Internet and WWW The Growth of the Internet National Science Foundation Network (NSFNET) Establish in 1985 A general-purpose research network Enabled the connection of regional networks Most universities connected to the ARPANET eventually moved to NSFNET The global network system was known as the Internet

10.1The Historical Development of the Internet and WWW The Growth of the Internet NSFNET served as the high-speed communication backbone for the Internet until 1995 Hosts Responsible for providing services and network connections for other computers By 2004, there were over 900 million hosts connected to the Internet

10.1The Historical Development of the Internet and WWW The World Wide Web A collection of hypertext documents called web pages Stored on servers connected to the Internet Stored Server Connected to the Internet My webpage Hello world! This is my first webpage! My webpage Hello world! This is my first webpage! My webpage Hello world! This is my first webpage! Hypertext document

10.1The Historical Development of the Internet and WWW The World Wide Web Web page An electronic document written in hypertext format The hypertext can be interpreted and displayed by a web browser My webpage Hello world! This is my first webpage! HTML text Displayed in a browser

10.1The Historical Development of the Internet and WWW The World Wide Web WWW included text-only pages at first Mosaic was the first web browser that could support audio, video clips, forms, bookmarks and history files. Mosaic – the first web browser that supports multimedia

10.1The Historical Development of the Internet and WWW The World Wide Web WWW included text-only pages at first Mosaic was the first web browser that could support audio, video clips, forms, bookmarks and history files. Mosaic – the first web browser that supports multimedia

10.2Making Connections How to make a connection To make a connection, a person needs to register an account with an Internet service provider set up the necessary computer equipment install the appropriate software establish a connection

10.2Making Connections Internet Service Provider A company that provides Internet access service Usually offers subscribers a communication software package for establishing connection with the ISP server Users are provided with a user name, a password and all the necessary information Users can log on to the Internet via modem Bandwidths vary from 56 Kbps to 1000Mbps

10.2Making Connections Dial-up Access Connection To connect to the Internet using dial-up access, a person needs A dial-up modem A telephone line Modem Converts digital signals into analogue signals and vice versa can be installed internally or externally Maximum transmission speed of a dial- up modem is 56 Kbps

10.2Making Connections Dial-up Access Connection Internal modem A modem expansion card to be placed on a motherboard

10.2Making Connections Dial-up Access Connection External modem External modem - a single device that can connect to the connection port of the computer

10.2Making Connections Dial-up Access Connection Software for Internet access A web browser – for viewing web pages An program – for receiving and sending s Communication software - for establishing connection with ISP

10.2Making Connections Integrated Services Digital Network (ISDN) Works on the same principle as dial-up access To establish ISDN connection, one needs An ISDN modem A telephone line Data Transmission Transmission speed: 128 Kbps Data is transmitted along ISDN line as digital (not analogue) signals Transmission in digital form is more stable

10.2Making Connections Broadband Connections Features Transmission speed 1.5 Mbps Mbps Much higher than standard 56Kbps modem High speed enables continuous transmission of video, audio and 3-D animation Constant availability with no dialing required Simultaneous use of data and voice connections

10.2Making Connections Broadband Connections To make a broadband connection, a person needs A digital modem Can send and receive digital data from the ISP through a dedicated transmission cable A network interface card Network interface card (nic)

10.2Making Connections Broadband Connections Two main broadband systems for domestic users Broadband system Description ADSL Uses standard telephone line ‘asymmetric’: download speed (1.5-9 Mbps) >> upload speed (16-640Kbps) Example service provider: Netvigator Cable modem Connects a computer to a cable TV network Designated capacity (30 Mbps) shared among users Data transfer rate: 1.5 Mbps Example service provider: i-Cable

10.2Making Connections T-carrier Provides a permanent connection between the network server and the ISP’s server Allows network users to access the Internet simultaneously Different carriers support different data transmission speed T-1 Maximum data transfer speed: 1.54 Mbps T-1 Maximum data transfer speed: 1.54 Mbps T-3 Maximum data transfer speed: 44 Mbps T-3 Maximum data transfer speed: 44 Mbps

10.2Making Connections Wireless Connections Two ways to obtain Internet access for mobile devices such as mobile phones, PDAs and handheld computers Wireless Application Protocol (WAP) General Packet Radio Services (GPRS) WAP A communication protocol for communication between handheld wireless devices Maximum data transfer rate: 10 Kbps – 153 Kbps

10.2Making Connections Wireless Connections GPRS A technology designed for mobile phones Maximum data transfer rate: Kbps Provides a constant connection Connection requires GPRS network card

10.2Making Connections Wireless Connections GPRS A technology designed for mobile phones Maximum data transfer rate: Kbps Provides a constant connection Connection requires GPRS network card

10.3Introduction to TCP/IP Transmission Control Protocol/ Internet Protocol (TCP/IP) The communication protocol suite of the Internet TCP Divides the message into packets Verifies the correct delivery of packets from node to node Triggers retransmission until a packet is correctly and completely received Reassembles the received packets into original message on recipient side

10.3Introduction to TCP/IP Transmission Control Protocol/ Internet Protocol (TCP/IP) IP Adds destination address to every packet Routes the packet to the destination through network server

10.3Introduction to TCP/IP Transmission Control Protocol/ Internet Protocol (TCP/IP) How a message is transmitted using TCP/IP

10.3Introduction to TCP/IP Transmission Control Protocol/ Internet Protocol (TCP/IP) How a message is transmitted using TCP/IP

10.4IP Address IP Address Uniquely identifies every computer on a network A computer connected to the Internet must use the IP address issued by the InterNIC (Internet Network Information Centre) InterNIC’s homepage –

10.4IP Address IP Address Structure of IP address 32-bit numeric address Expressed as four denary numbers separated by periods Example: is the IP address of the Hong Kong Observatory web site IP address expressed in 32-bit binary number Equivalent IP address in decimal representation

10.4IP Address The Classes of Ipv4 Address Each IP address consists of two parts Network address Identifies a particular network Host address Identifies a device in the network Clas s Class number Partition of IP address Number of hosts owned Network Size A016,777,214Huge B Large C Medium to small

10.4IP Address The Classes of Ipv4 Address Internet Protocol Version 6 (Ipv6) New address system Accommodates more IP addresses Meets the current growth of the Internet IPv4 and IPv6

10.4IP Address The Classes of Ipv4 Address Internet Protocol Version 6 (IPv6) New address system Accommodates more IP addresses Meets the current growth of the Internet IPv4 and IPv6

10.5Domain Names and Domain Name Servers Domain Names Associate an easy to remember name to an IP address Official terminology: Fully Qualified Domain Name (FQDN) Corresponds to Corresponds to Domain nameIP Address

10.5Domain Names and Domain Name Servers Domain Names Structure Each domain name consist of two or more groups of characters separated by periods Each group identifies the top-level domain (TLD), second level domain or the host name

10.5Domain Names and Domain Name Servers Domain Names

10.5Domain Names and Domain Name Servers Domain Names Common TLDs TLDType of organization com Commercial organizations edu Educational institutes gov Government (US) org General organizations mil Military (US) net Network provider Country- code TLD Country au Australia cn China de Germany fr France uk United Kingdom jp Japan

10.5Domain Names and Domain Name Servers Domain Names Non-US domain names use country-code TLD based on the country which the server is in Network Solutions A company which ensures no duplication of domain name

10.5Domain Names and Domain Name Servers URL Full name: uniform resource locator Refers to a particular web page or a file residing on a web site protocoldomain namefolder namefile name Format of URL

Domain Name Servers (DNS) Translate domain names to IP addresses The translation process is called name resolution Enable users to access a registered domain by its domain name instead of its IP address Process DNS receives a domain name Searches for the associated IP address If no datum available, asks other DNS on the Internet Process continues until IP address is found 10.5Domain Names and Domain Name Servers

Domain Name Servers (DNS) 10.5Domain Names and Domain Name Servers Domain name DNS Case I: relevant data in its database Case II: no relevant data in its database DNS IP address Relevant data found Input domain name Ask other DNS Output IP address

Domain Name Servers (DNS) 10.5Domain Names and Domain Name Servers Domain name DNS Case I: relevant data in its database Case II: no relevant data in its database DNS IP address Relevant data found Input domain name Ask other DNS Output IP address