This document discusses different types of computer networks including LANs, WLANs, and WANs. It describes the hardware and software requirements for each network type. LANs are used for intranets and business networks within an organization. WLANs allow for wireless connectivity using Wi-Fi standards. WANs connect LANs across broad geographic areas using the internet, VPNs, and other wide-reaching networks. Common network hardware includes PCs, servers, switches, routers and cabling. Software like FTP, HTTP, and VPN protocols are used to transfer and secure files between networked devices.

1. Computer Networks
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2. Network Types
• LAN: Local Area Network
• WLAN: Wireless Local Area Network
• WAN: Wide Area Network
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3. LAN
• Intranet
• Local email
• Business network
Hardware requirements
• PC
• Hub
• Switch
• Router
• Dedicated cabling
• Server
• Network card
Software requirements
• FTP
• HTTP
• Telnet
• SSH
• Router software
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4. WLAN
4
• Wi-Fi (IEEE 802.11 standards – b, g, n)
• Infrared
• Spread spectrum transmission (walkie-talkie)
Used for:
• Email
• Business network
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5. WAN
• Internet
• Extranets
• Email
• Virtual private network
(VPN)
• Video conferencing
• Business network
• Telephone call centre
• Booking system
• Online shopping
• Online banking
Hardware requirements
• PC
• Modem
• Hub
• Switch
• Router
• Server
• Proxy server
• VPN
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6. Network
Hub
• Used to connect computers to server/computer
• Not a very efficient network device as it sends data to all linked devices
• Hubs may amplify received signal
• Hubs work at MAC level (MAC - Media Access Control address of NIC)
Switch
• An advancement on a hub
• It directs the data stream only to the addressed device
• It prevents congestion on a segment of network
• Switches use a list of device addresses
• Redirects ‘ack’ packet (Acknowledgement packet) directly to sending
computer
• Switches also work at MAC level
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Hardware devices

7. Network
Router
• Gateway device
• Links LANs to make a WAN
• Includes a firewall
• Directs packets according to their IP address
• Stores list of connected devices
• Redirects packets to correct switch/hub
• Translates protocols (between networks) - bridge
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Hardware devices

8. Network
Cabling can be twisted pair, coaxial or fibre
optics
Servers:
• Link computers/store files/applications
• Can be for storage, web, proxy, email, etc.
Network interface card (NIC):
• Allows the processor to connect to a server
• Allocated IP address of the computer
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Hardware devices

9. FTP – File Transfer Protocol
Network protocol used to transfer files from one computer to another TCP-
based network (as the Internet)
HTTP – HyperText Transfer Protocol
Foundation protocol of data communication for the World Wide Web
Telnet
• Used to gain access to another users computer/remote access to server
• Used to transfer/access data
• Requires a password login id
• Lacks security
• Uses TCP/IP protocol (as a lower level)
Secure Shell (SSH)
Network protocol for secure data communication via a secure channel
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Network
Protocols (Software)

10. • Ring
• Bus
• Star
• Tree
10
Network Topology
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11. • Physical security
–Locked room
–Security guard
• Software security
11
Network security
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12. Network security
Software security:
• Firewall
• Digital certification
• Encryption
• Anti virus software
• User ID
• Password
• Anti spam
• Anti pop up software
• Anti spyware software
• Authentication
techniques
• Wired equivalent
privacy (WEP)
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13. Electronic conferencing
Types:
• Video conferencing
• Phone conferencing
• Instant messaging
Used in:
• Business conferences
• Linking schools
• Research meetings
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14. Electronic conferencing
Software requirements
• Conference software
• VOIP software
• Instant messaging
Hardware requirements
• PC
• Phone
• Webcam
• Microphone
• Speakers
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