Computer science

• Computer networks are made up of multiple computers linked together to share information and resources
• A computer network is a system in which multiple nodes connect with one another in order to share information and resources
• Computer Network Elements


  • Hardware
  • Software
  • Client Devices
  • Connection Media
• Hardware


  The backbone of a network, including network cards, routers/switches, modems, and Ethernet repeaters
• Software


  Protocols and other tools that allow the hardware to interact with the network
• Client Devices


  Computers and mobile devices that are linked to the network and require access
• Connection Media


  The means by which network nodes are connected, either wired (e.g. Ethernet cables) or wireless (e.g. radio signals)

  
• Transmission Media Types


  • Wired/Guided (e.g. Twisted Pair Cable, Coaxial Cable, Optical Fibre Cable)
  • Wireless/Unguided (e.g. Radiowaves, Microwaves, Infrared)
• Hardware Needed for Computer Communication

  • Network Interface Card (NIC)
  • Network Hub
  • Ethernet Switch
  • Network Bridge
  • Router
  • Network Gateway
  • Modem
  • Network Firewall
  • Network Cable

  
• Network Interface Card (NIC)


  Allows computers to connect to and communicate over a network

  
• Network Hub


  Simple, inexpensive device that connects multiple computers, but broadcasts all messages to all connected devices
• Ethernet Switch


  More intelligent device that checks the destination of messages and only forwards them to the intended recipient

  
• Network Bridge


  Filters data traffic at a network boundary, dividing a LAN into two segments
• Router


  Connects a LAN to a WAN such as the internet
• Network Gateway


  Joins together two networks that use different base protocols
• Modem


  Translates digital signals from a computer into analog signals that can travel across phone lines
• Network Firewall


  Protects a computer network from unauthorized access
• Network Cable


  Used to physically connect different devices to form a network
• Gateway


  A device that connects a network and controls access to other networks
• Modem


  A contraction of the terms modulator and demodulator. Modems translate digital signals from a computer into analog signals that can travel across conventional phone lines. The modem modulates the signal at the sending end and demodulates at the receiving end.
• Network Firewall


  Protects a computer network from unauthorized access. Network firewalls may be hardware devices, software programs, or a combination of the two. They guard an internal computer network against malicious access from the outside and can also be configured to limit access to the outside from internal users.
• Network Cable


  Used to connect together different devices to make up a network. Most networks still use cables rather than wireless because they can carry much more data per second and are more secure (less open to hacking).
• Proxy Server


  A computer that is configured to share a resource, typically an Internet connection. Other computers can use the proxy server to request a web page, which the proxy server will then retrieve using its own Internet connection and return to the requesting computer.
• Proxy servers are frequently used instead of routers because additional software such as anti-virus and web filtering can be easily installed on the computer.
• Advantages of Computer Networks

  • Effective communication
  • Convenient resource sharing
  • Easier file sharing
  • Higher level of flexibility
  • Inexpensive
  • Efficient
  • Boosts storage capacity
  • More secure
  • More robust
  • Less vulnerable to viruses and malware
• Disadvantages of Computer Networks

  • Ineffective communication
  • Less effective resource sharing
  • Difficult file sharing
  • Low flexibility
  • Expensive
  • Inefficient
  • Limited storage capacity
  • Less secure
  • Lacks robustness
  • More prone to attacks
• A more technically sound person is needed to handle computer networks compared to a person with basic skills.