Science Computer

Sir Tim Berners-Lee is a British computer scientist. He was born in London, and his parents were early computer scientists, working on one of the earliest computers. Growing up, Sir Tim was interested in trains and had a model railway in his bedroom. He  recalls : “I made some electronic gadgets to control the trains. Then I ended up getting more interested in electronics than trains. Later on, when I was in college I made a compute r  out of an old television set.” After graduating from Oxford University, Berners-Lee became a software engineer at  CERN , the large particle physics laboratory near Geneva, Switzerland. Scientists come from all over the world to use its accelerators, but Sir Tim noticed that they were having difficulty sharing information. what is www ? what is web browser ? - The purpose of a web browser is to bring information resources to the user. -  With an Internet Connection established, you start  Web Browser. - The browser retrieves and displays

DEFINITION : A company that provides internet connection and services to individuals & organizations. Responsibilities of an ISP - Providing and maintaining a connection to the internet. - Support the hardware and software needed to service that connection. - Provide 24 hour customer service and technical support. IP ADDRESS What is IP address? - A number that uniquely identifies each computers or device connected to the internet. - IP addresses are also referred to as IP numbers and Internet addresses. IP Usage: - A way to find specific server or computer on the internet or a network.  - Provide identity to a computer in a network. IP Structure: - Number in each group between 0 and 255. - Commonly written in decimal. - It is 32 bit long, each group is 8  bits long. - For example: 128.35.0.72 IPV4 : - IPv4 an address consists of 32 bits which limits the address space to 4294967296 (2 32 ) possible unique addresses. IPV6 :

1. Digital Subscriber Line - Fast direct internet access via standard telephone line. - Requires DSL modem. - Example: Streamys without WiFi  2. Cable Internet Service  - Most widely used home broadband connection - Provides high - speed internet access through the cable television network via a cable modem. 3. Fixed Wireless  - Uses radio transmission towers rather than satellites. - Not available in all areas. - Provides high - speed internet connection using a dish - shaped antenna to communicate via radio signals.  4. Satellite Internet Service  - More expensive than cable or DSL. - Provides high - speed internet connections via satellite. - A satellite dish communication with a satellite modem. 5. Fiber To The Premises  - Delivers over fiber - optic cabling all the way to the building. - Uses fiber - optic cable - Provide high - speed internet access to house and business users. 6. Cellular Radio Network - Access via m

ISDN(INTEGRATED SERVICE DIGITAL NETWORK) - also transfer data over ordinary telephone lines - Typically uses two phone lines to transfer data - ISDN requires a special ISDN modem - Characteristics of ISDN:    1. Faster, but pricey    2. Doesn’t tie up phone line   3. Used by businesses and individuals Direct Connection / Broadband Internet Connection :  (always on connections) 1.  Many home and small business users connect to the Internet via high-speed broadband Internet service 2. PC is continually connected to the Internet 3. Direct connections are typically broadband 4. Used in the home and office 5. Because you are always connected, it is important to protect your computer from hackers

CONVENTIONAL DIAL-UP   (to connect to the Internet, your computer dials its modem and connects to a modem attached to a computer belonging to your ISP.) ⇝ PC has to dial via a phone line to connect ⇝ Characteristics of Conventional dial-up :  1. Slower, but cheaper 2. Ties up phone lines 3. Relatively secure from hackers    Example :- Jaring , TMNet ADVANTAGES DISADVANTAGES -            Include inexpansive hardware -            Slow connection speed -            Provides the user with the convenience of using his account.       -      Telephone line will be tied up while accessing the internet

↠ INTERNET - Internet is a worldwide collection of networks that connects millions of businesses, government agencies, educational institutions, and individuals ↠ INTRANET -  An intranet ( intra means within ) is an internal network that uses internet technologies. - N etwork which only available inside an organization or a company . ↠ EXTRANET -  An extranet is the portion of a company’s network that allows customers or suppliers of a company to access parts of an enterprise’s intranet . - An extranet provides a secure, physical connection to the company’s network . ADVANTAGES & DISADVANTAGES OF INTERNET,INTRANET & EXTRANET  The Internet Advantage Disadvantage INTERNET Software Downloads: -  Can freely download software like utilities,games,music,videos,movies,etc from the internet. E-mail:             -  People can sent messages. It is delivered instantly to people anywhere in the world, unlike traditional mail t

WHAT IS NETWORK TOPOLOGY? A network topology refers to the layout of the computers and devices in a communications network. TYPES OF NETWORK TOPOLOGY ↠ STAR TOPOLOGY - a  topology  for a Local Area Network (LAN) in which all nodes are individually connected to a central connection point, like a hub or a switch. A  star  takes more cable than e.g. a bus, but the benefit is that if a cable fails, only one node will be brought down. ↠ BUS TOPOLOGY -  specific kind of network   topology   in which all of the various devices in the network are connected to a single cable or line. In general, the term refers to how various devices are set up in a network ↠ RING TOPOLOGY -  a network  topology  in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a  ring . Data travels from node to node, with each node along the way handling every packet.

CATEGORY CLIENT SERVER PEER TO PEER SET UP More difficult to set up Easy to set up INSTALLATION More expensive to install Less expensive to install IMPLEMENTATION Big corporations or organizations with high security data Small businesses and home users SIZE For medium and large network For small network fewer than 10 computers. OPERATING SYSTEM Needs a specific operating system such as Windows Server 2008. Does not need a specific operating system. TRAINING Needs training Does not need training

WHAT IS NETWORK ARCHITECTURE? The configuration of computers, devices and media on a network. PEER TO PEER NETWORK CLIENT SERVER NETWORK