INTERNET INFRASTRUCTURE

Ø  Hierarchy of networks

-          From a single computer to LAN

-          From LAN  to ISP

-          From ISP to www

Ø  Needed to connect to internet

-          Computer

-          Web browser

-          Internet access ( from ISP – internet server provider )

Ø  Policy and procedure required to access to the internet quit complicated

INTERNET PROTOCOL (IP)

Ø  Standard protocol that provide a common layer over dissimilar network

Ø  To move packets among ‘host’ camp true gateways

Ø  Consist of 32 bits ( shown as 4 octets of  number  from 0 – 255 represented in decimal from instead of binary)

Ø  E.g. : 168.212.226.204

       : 10101000.11010100.11100010.11001100

1 IP = 4 octet

1 octet = 8 bit

24 bit = 3 octet

Ø  IP add consist of 2 part :

1)      Identifying the network

2)      Identifying the node/ host

Ø  Class of addresses determines  which part belong to the network add & which part belong to node

Ø  All node an a given network share the same network prefix but must have a unique host number.

Ø  There are five classes of available IP ranges: Class A, Class B, Class C, Class D and Class E, while only A, B, and C are commonly used. Each class allows for a range of valid IP addresses.

Ø   Below is a listing of these addresses.

Class	Address Range	Supports
Class A	1.0.0.1 to 126.255.255.254	Supports 16 million hosts on each of 127 networks.
Class B	128.1.0.1 to 191.255.255.254	Supports 65,000 hosts on each of 16,000 networks.
Class C	192.0.1.1 to 223.255.254.254	Supports 254 hosts on each of 2 million networks.
Class D	224.0.0.0 to 239.255.255.255	Reserved for multicast groups.
Class E	240.0.0.0 to 254.255.255.254	Reserved for future use, or Research and Development Purposes.

Ø  Ranges 127.x.x.x are reserved for the loopback or local host, for example, 127.0.0.1 is the common loopback address. Range 255.255.255.255 broadcasts to all hosts on the local network.

DOMAIN NAME SYSTEM

Ø  The DNS translates Internet domain and host names to IP addresses. DNS automatically converts the names we type in our Web browser address bar to the IP addresses of Web servers hosting those sites.

Ø  DNS implements a distributed database to store this name and address information for all public hosts on the Internet. DNS assumes IP addresses do not change (are statically assigned rather than dynamically assigned).

ISP (INTERNET SERVICE PROVIDER)

An ISP (Internet service provider) is a company that provides individuals and other companies access to the Internet and other related services such as Web site building and virtual hosting. An ISP has the equipment and the telecommunication line access required to have a point-of-presence on the Internet for the geographic area served. The larger ISPs have their own high-speed leased lines so that they are less dependent on the telecommunication providers and can provide better service to their customers. Among the largest national and regional ISPs are AT&T WorldNet, IBM Global Network, MCI, Netcom, UUNet, and PSINet.

HTTP (HYPER TEXT TRANSFER PROTOCOL)

Short for Hyper Text Transfer Protocol, the underlying protocol used by the World Wide Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For example, when you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page.

The other main standard that controls how the World Wide Web works is HTML, which covers how Web pages are formatted and displayed.

HTTP is called a stateless protocol because each command is executed independently, without any knowledge of the commands that came before it. This is the main reason that it is difficult to implement Web sites that react intelligently to user input. This shortcoming of HTTP is being addressed in a number of new technologies, including ActiveX, Java, JavaScript and cookies.