NETWORKS

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NETWORKS

• Mr. Blochowski

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Definition

• A combination of hardware and software that
  allows computers to exchange data and share
  software and devices, such as printers.

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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

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Networks are classified by

• Size (LAN, WAN, MAN, HAN)
• Architecture (peer-to-peer, client/server)
• Topology (refers to arrangement of nodes on the
  network)

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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.

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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).

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Peer-to-Peer Architecture

• Each computer on the network is considered equal
  in terms of responsibilities and resource sharing.

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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.

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Bus Topology

• A physical LAN topology that uses a single
  central cable, called the bus or backbone to
  attach each node directly.

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Star Topology

• Each node is attached to a hub, which is a device
  that joins communication lines at a central
  location on the network.

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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

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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.

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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.

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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

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Common Terms

• Firewall
• Blog
• Spam
• Boolean logic
• Spyware
• IP address
• Encryption

• Virus
• Trojan Horse
• Worm
• Antivirus programs
• Crackers,Hackers
• Phishing
• IT professional