Transcript networks

NETWORKS
Definition
A combination of hardware and software
that allows computers to exchange data
and share software and devices, such
as printers.
Networks are widely used because:
Allows users to reliably share and exchange
data
Can reduce costs by sharing devices such as
printers
Offers security options including password
protection to restrict access to certain files
Simplifies file management through
centralized software updates and file backups
Provides e-mail for network users
Networks are classified
by:
Size (LAN, WAN, MAN, HAN)
Architecture (peer-to-peer, client/server)
Topology (refers to arrangement of
nodes on the network)
Transmission Media
Computers must be connected in order to
transmit data between nodes. Cable
transmission media includes twistedpair wiring, coaxial cable, and fiber optic
cable. Wireless transmission media
includes infrared signals, broadcast
radio, cellular radio, microwaves, and
communication satellites.
Bandwidth
The amount of data and the speed at
which data can travel over a media is
called bandwidth, which is measured in
bits per second(bps).
Peer-to-Peer Architecture
Each computer on the network is
considered equal in terms of
responsibilities and resource sharing.
Client/Server Architecture
Network consists of a group of computers,
called clients, connected to a server. A
server is a computer with more RAM, a
larger hard disk, and sometimes
multiple CPUs that is used to manage
network functions.
Bus Topology
A physical LAN
topology that uses a
single central cable,
called the bus or
backbone to attach
each node directly.
Star Topology
Each node is attached
to a hub, which is a
device that joins
communication lines
at a central location
on the network.
Ring Topology
Each node is
connected to form a
closed loop. A LAN
with a ring topology
can usually cover a
greater distance
than a bus or star
topology
Different nets
Intranet – a network that is used by a single
organization. The purpose of an intranet is to
share information.
Extranet – extends an intranet by providing
various levels of accessibility to authorized
members of the public.
Internet – the largest and most widely
accessed network, a world-wide network of
computers that is not controlled by any one
organization.
Internet
Numerous networks all linked together
through routers. A router is a device
that connects different network
technologies. Networks connected to
routers use TCP/IP (Transmission
Control Protocol / Internet Protocol)
software to communicate.
Telecommunications
Conventional modem – uses standard telephone lines
to convert analog signals to digital data. 56 kbps
DSL (Digital Subscriber Line) – uses a standard
telephone lines with transmissions up to 640 kbps.
Cable modem – transmits data through coaxial cable
television network. 2 mbps – 10 mbps
Leased/Dedicated lines – permanent connection to the
Internet that is always active. A T-1 carrier is a type of
leased line that transmits data at 1.544 mbps
ISDN (Integrated Services Digital Network) – is a
digital telephone network provided by a local phone
company. 64 kbps
Common Terms
Firewall
Blog
Spam
Boolean logic
Spyware
IP address
Encryption
Virus
Trojan Horse
Worm
Antivirus programs
Crackers,Hackers
Phishing
IT professional