NETWORKS NETWORKS Mr Blochowski Definition A combination of hardware and

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NETWORKS NETWORKS Mr Blochowski Definition A combination of hardware and Powered By Docstoc

   Mr. Blochowski
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
Can reduce costs by sharing devices such as
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

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 twisted-
 pair wiring, coaxial cable, and fiber optic
 cable. Wireless transmission media
 includes infrared signals, broadcast
 radio, cellular radio, microwaves, and
 communication satellites.
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
           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
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.
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        Virus
Blog            Trojan Horse
Spam            Worm
Boolean logic   Antivirus programs
Spyware         Crackers,Hackers
IP address      Phishing
Encryption      IT professional

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