OVERVIEW OF THE INTERNET

DEFINITION 

The internet is a worldwide collection of networks that links millions of businesses government agencies, educational institutions and individuals.

EVOLUTION OF THE INTERNET:

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ADVANTAGES AND DISADVANTAGES OF INTERNET , INTRANET AND EXTRANET

TYPE OF NETWORK	ADVANTAGES	DISADVANTAGES
	1.can freely download software from the Internet	1,more prone to virus attack and crashing up issues
	2.can perform all your transactions online	2.people are drifting apart from their friends and family
INTERNET	3.people can sent messages	3.danger for children like pornographic sites
	4.can find any information on any kind of subject	4.theft of personal information
	1.commercial data is kept secure	1.high financial cost incurred
	2.email remain private and may also be encrypted	2.potentially compromise security by allowing virus infection
INTRANET	3.high bandwidth and no connection limits	3.staff needs training
	4.reliable	4.information overload
	1.exchange large volume of data using EDI	1.can be expensive to implement and maintain
	2.share product catalogs exclusively with trade partner	2.security can be a concern
EXTRANET	3.collaborate with other companies
	4.jointly develop and use training programs with other companies

DIFFERENCE BETWEEN LAN,MAN AND WAN

LAN

A LAN is a network that connects computers and devices in a limited geographical area.

MAN

MAN is a high-speed network that connects local area networks(LAN) in a metropolitan area such as a city or town.

WAN

A WAN is a network that covers a large geographic area(such as city,country or the world)using a communications channel that combines many types of media such as telephone lines,cables and radio waves.

CRITERIA	LAN	MAN	WAN
NETWORK SIZE	small size(in a building)	larger size(in a cities or campus)	largest size(different states or countries)
SPEED	fastest in data transferring	slower in data transferring	slowest in data transferring
COMMUNICATION DEVICES	connected using hub,switch,router	connected using hub,switch,router	connected using satellite communication
COST	less cost set up and maintenance	more cost to set up and maintenance	costliest set up and maintenance
NETWORK OWNERSHIP	private-control by single person	private-control by single entity	not owned up anyone organization

DIFFERENCE BETWEEN STAR,BUS AND RING TOPOLOGY

	BUS TOPOLOGY	STAR TOPOLOGY	RING TOPOLOGY
CHARACTERISTICS
PERFORMANCE WITH FEW NODES	medium	fast	slow
PERFORMANCE WITH MANY NODES	most effective	some effect	affected
EASE OF TROUBLESHOOTING	fairly easy	easy	hard
COST OF INSTALLATION	low	high	high
EASE OF SETTING UP AND MODIFYING	easy to set up and modifying	easy to set up and modify	easy to set up but harder to modify

NETWORK TOPOLOGY

WHAT IS NETWORK TOPOLOGY?

A network topology refers to the layout of the computers and devices in a communications network.It refers to both the physical and logical layout of a network.

physical-The arrangement of a cabling is the physical topology.

logical-The path that data travels between computers on a network is the logical topology.

Network topology can be devided into three types that commonly used.Star topology,Bus topology and Ring topology.

Star topology.

All the computers and other devices on the network connect to a central device,thus forming a star.

Bus topology.

A bus network consists of a single central cable (backbone), to which all computers and other devices connect.

Ring topology.

On a ring network,a cable forms a closed loop(ring) with all computers and devices arranged along the ring.