History and Details of the Internet

(taken from Prof. Rhode's notes)

History

Started in1969 Arpanet with 4 computers
The Internet was a federally funded network for DoD, government and research universities
It uses TCP/IP - Transmission Control Protocol/Internet Protocol - became the communication standard
Designed to be robust; assumed errors would occur: network nodes stop, natural disasters, military strikes, lines are cut, etc.

Design

The Internet is a message delivery system among host computers. ip.jpg (12543 bytes)

Decentralized
Automatic reconfiguration of message delivery
Messages regardless of content are split into small packets (esp. large messages) up to 1500 bytes
Packets of messages may not necessarily follow same path to destination
Receiver must reconstruct the whole message from the packets and may even receive them out of order.
Each computer on the Internet has a unique IP number (quad: 123.156.178.209)
Routing refers to the passing of messages along the nodes of the Internet towards the message destination

The Internet is a network of networks

Growth was not part of the original design. 40M people, 100K networks, in 150 countries, transferring 20Tbytes per month
Original maximum was 256 computers (intended to be mainframes)
127 Class A nets each can be composed of millions of hosts
+ thousands of Class B nets where each can be composed of up to 65000 hosts
+ millions of Class C nets where each can be composed of up to 250 hosts
Plans are for a IPv6 standard to allow host addressing to be ample.

Packets have the following information

Source IP address - the host computer's address that sent the message
Destination IP address - the host computer's address that is to receive the message
Packet number - the sequence number of the packets that make up the message
Message ID - identification of the message
The message itself

Applications: E-mail

E-mail was one of the first applications developed for the Internet. The standard that has remained to deliver messages is SMTP which stands for Simple Mail Transfer Protocol. This is supposedly simpler than an earlier protocol.

Messages are delivered with a store and forward technique.

Communication is asynchronous: the receiver need not be logged on to receive a message.

Social aspects of e-mail

verification of who sent the message (SMTP can be fooled)
accountability is easier on systems on which you must log on
permanence of the message (email is placed on system back up tapes. ask Oliver North)
flaming
spamming
SHOUTING
emoticons ;-)
free, usage is not regulated
consider copyright laws

Domain Names

Domain names provides a way for people to refer to host computers by name rather than IP address quads.

Computers on the Internet may be named, although it is not required. A computer name also uses dot notation, that is, periods between the names. A computer's IP name typically has three parts:

the local machine name
a name for the institution, company or organization
a top level domain

United States top level domains	Domains for other countries, for example:
.edu higher educational institutions .com commercial enterprises .net network organizations .mil U.S. military .gov U.S. government .org other organizations	.uk United Kingdom .au Australia .fr France .de Germany .jp Japan .ca Canada .us United States .pa.us Pennsylvania .nj.us New Jersey

The pair of names from parts 2 and 3 constitute the domain name that is unique to the Internet, world-wide, for an institution, company or organization. For example, juniata.edu is the domain name for Juniata College, ibm.com is the domain for IBM, whitehouse.gov is the domain for the Whitehouse.

A domain corresponds to the first two or three numbers of an IP address. For example juniata.edu resolves to the numbers 192.112.102 and whitehouse.gov resolves to 192.137.240.

Applications: Usenet News

Newsgroups are discussion groups in which the postings are moved around the Internet newsgroup hosts. You need a newsgroup reader such as found in Netscape or Internet Explorer.

There are around 18K newsgroups. Juniata no longer maintains a news feed, however because of the amount of messages generated. You must locate another newsgroup host such as dejanews.com.

Posting
Lurking
Moderated vs unmoderated
Spamming and cancelbots
targets for pyramid schemes
Newbie
FAQ - Frequently Asked Questions

Fortunately many of the useful newsgroups have copies available on the WWW. Search engines may make give you pointers to entries that are hits to your request.

Applications: The World Wide Web

The latest service to the Internet. Hottest and fastest growing.

Terms related to the web:

CERN - a Swiss research institution developed the concept in 1989
HTTP - hypertext transfer protocol
hypertext - text with images, audio, video, links to other documents; formatting information is also embedded
HTML - hypertext markup language - the embedded commands for formatting and hyperlinking
search engines - massive computer hosts that walk the web and index all that it can find
browser - the program to surf the net on your PC
server - the program that delivers HTML documents from a host computer

Factors in web growth

Easy to use - almost entirely mouse driven to follow links and control the display
Easy to search - well, almost...
Easy to create a web page - anyone can be a publisher
No restrictions - no commercial restrictions