Transcript Bit by bit - Unit 4 – THE INTERNET AND THE WWW

Bit by bit - Unit 4 – THE INTERNET AND THE WWW
p. 65
What is the Internet?
Navigate:
1 v.i. Travel in a ship, sail. L16. b Walk steadily; keep on one's course. US
slang. c (Be competent to) sail a ship. L19.
2 v.t. Sail on or across (the sea, a river, etc.). b v.t. & i. transf. Make or find
one's way across (an area of ground); colloq. steer (oneself, a course, etc.)
through a crowd etc. c v.t. Travel, fly through, (the air).
3 a v.t. Sail, direct, manage, (a ship). L17. b v.t. Fly, manage, direct, (an
aircraft, balloon, etc.). Now spec. plot and supervise the course of (an aircraft
or spacecraft). c v.i. Plot and supervise the course of a motor vehicle. M20.
4 v.i. Of a ship: sail, ply.
Excerpted from Oxford Talking Dictionary. Copyright ® 1998 The Learning Company, Inc. All
Rights Reserved.
Bit by bit - Unit 4 – THE INTERNET AND THE WWW
Surf:
surf /sf/ n. 1 The swell of the sea which breaks upon a shore, esp. a shallow
shore; an instance of this.
2 The mass or line of foam produced by this.
1 v.i. Form surf. rare.
2 v.i. Ride on the crest of a wave towards the shore by standing on a surfboard.
3 v.t. a Ride (a boat) on the surf. b Surf at (a specified place). c transf. Ride
illicitly on the roof or outside of (a train). slang.
Excerpted from Oxford Talking Dictionary. Copyright ® 1998 The Learning Company, Inc. All
Rights Reserved.
Bit by bit - Unit 4 – THE INTERNET AND THE WWW
An official definition (Bit by Bit, p.65):
“The Federal Networking Council (FNC), agrees that the following language
reflects our definition of the term ‘Internet’. ‘Internet’ refers to the global
information system that
(i) is logically linked together by a globally unique address space based on the
Internet Protocol (IP) or its subsequent extensions/follow-ons;
(ii) Is able to support communications using the Transmission Control Protocol
(TCP/IP) suite or its subsequent extensions/follow-ons, and/or other
IP/compatible protocols;
(iii) Provides, uses or makes accessible, either publicly or privately, high level
services layered on the communications and related infrastructure
described herein.”
In a few words:
The Internet is a world-wide group of connected networks to allow public
access to information and services.
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What is a Protocol?
1) Protocols are the rules of communication.
2) A protocol is a method by which two computers
agree to communicate. As human beings, we use
language as a protocol.
3) A protocol is a standard format (created by international
networking authorities) for sending and receiving information,
error checking and data compression. There are lots of
different types of protocols such as FTP, TFTP, BOOTP, SNMP,
SMTP and MIME to name a few. The majority of protocols are
implemented within the TCP/IP protocol suite.
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What is TCP/IP?
TCP/IP is a name given to the collection (or suite) of networking protocols
that have been used to construct the global Internet.
TCP/IP protocols are not used only on the Internet. They are also widely
used to build private networks, called internets (spelled with a small
'i'), that may or may not be connected to the global Internet (spelled
with a capital 'I'). An internet that is used exclusively by one
organization is sometimes called an intranet.
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How does the Internet work?
The Internet is basically a huge collection of computers that can
all communicate with each other. Every computer that connects
to the Internet is given a special address called an IP address.
When you connect to the Internet you become part of this huge
Network and so when, for example, you type in a web address you
are in fact sending a request to other computers on the network
that hold that site (computers that hold web sites are called
servers and your computer is called a client).
Each request is like a package of information that your computer
Sends out and this package contains information about the
website you want to see and also the address of your computer.
Bit by bit - Unit 4 – THE INTERNET AND THE WWW
Computer networks transfer data from each another
by packets of data. A packet is a unit of data.
Packet switching is the process in which packets
are sent in different routes to find their destination.
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IP:
•
envelopes and addresses the data
•
enables the network to read the envelope and
forward the data to its destination
•
defines how much data can fit in a single
"envelope" (a packet)
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TCP:
•
breaks data up into packets that the network can handle
efficiently
•
verifies that all the packets arrive at their destination
•
"reassembles" the data
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An IP address is like a telephone number, except that it has
decimal points in it e.g.
125.4.68.97
2.57.893.61
They have four sets of numbers separated by three decimal
points. Each set of numbers has 1,2 or 3 numbers, but
never more than 3.
Your ISP (Internet Service Provider) may give you a different IP
address every time you use the Internet.
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Who is in charge of IP Addresses?
There are 3 different address books (Regional Internet Registries) for
different parts of the world.
www.ripe.net (Europe, the Middle East, Central Asia and African
countries north of the equator)
www.arin.net (American Registry for Internet Numbers)
www.apnic.net (Asia Pacific regions)
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What is an Internet address?
As you have learned every computer in the Internet must have
a unique and specific address. An Internet or IP address
consists of four numbers separated by periods. Don't
worry, only computers are expected to remember all these
numbers without getting confused. For humans, we use the
Domain Name System (DNS).
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What are domains?
Like IP addresses which are numerical, the alphabetical domain names are
also separated by periods or dots. Thus, the U.S. Library of Congress will
have an IP address of 140.147.248.7 and the domain name will be
www.loc.gov.
Domain names have the format: hostname.subdomain.top-level-domain.
Here are the existing top-level domains in the Internet:
.com - commercial
.edu - educational
.net - network
.org - organization
.gov - government
.mil - military
Other countries sometimes add their codes at the end, such as .au for
Australia, .ph for Philippines, and .fr for France.