Networks

• A LAN(Local area network) is a network that only covers a single site
• Advantages of using a LAN:

  • Easier to share files
  • Can share same hardware e.g. printers on a LAN
  • Can install and update softwares all at once
• A WAN(Wide area network) is a network that connects networks in different geographical locations
• Advantages of using a WAN:

  • Allows to share data securely, so private information can be shared
  • WAN has a dedicated bandwidth, so large amounts of data can be shared
• Bandwidth is the amount of data that can be transferred in a given time. The greater the bandwidth, the better the performance of a network.
• Wired connections tend to improve the network, in comparison to wireless networks, as they are faster and more reliable.
• Wireless performance depends on signal quality, which is affected by factors such as physical obstructions, and interference from other wireless networks.
• The number of users in the network affects the performance of the network. The more users present, the higher the chances of causing congestion, hence slowing down the network.
• Network hardware 1:

  • Network interface controller(NIC) is an internal piece of hardware that allows a device to connect to a network
  • Routers are responsible for transmitting data between networks. They tend to direct data(in units called packets) to their destination
  • Switches control devices on a LAN. Switches receive data(in units called frames) from one device and transmit this to the device on the network with the right MAC address
  • wireless access points tend to connect devices in a LAN wirelessly
• MAC addresses are unique identifiers that are assigned to devices and cannot be changed. Each device needs an identifier, so it can be found on a network
• Network hardwares(2)

  Ethernet cables:

  • CAT5e Cable:
  • - Twisted pair cables , containing 4 pairs of copper wires, which are twisted to reduce internal interference.
  • Coaxial Cables:
  • - Made of single copper wire surrounded by a plastic layer of insulation and a metallic mesh which provides shielding from outside interference
  • Fibre Optic Cables :
  • - Transmits data as light. They are high performance, but expensive cables - they do not suffer from interferences and transmit over very large distances without loss of signal quality
• • A client-server network is managed by a server. The devices that are connected to a server are called clients.
  • Files and software are usually stored centrally.
  • Clients send requests to the server, which processes the request and responds
• Advantages of using a Client-server network:

  • Easier to keep track of files as they are stored centrally
  • Easier to perform back-ups
  • Easier to install and update software
  • Easier to manage network security
  • Servers are very reliable and are always on
• Disadvantages of using a Client-server network:

  • Expensive to set up
  • Server dependence- if server goes down all clients lose access to their work
  • The server may be overloaded if too many clients are accessing it simultaneosly
• • A peer-to-peer network is a network in which all devices are equal, and are connected to each other without a server/
  • Files are stored on individual devices and are shared to each other
• Advantages of using a peer-to-peer network:

  • Easy to mantain
  • No dependence on a server. If one device fails, the whole network isn't lost
• Disadvantages of using a peer-to-peer network:

  • No centralized management - backups are more complicated
  • Copying files between devices create duplicate files, so it is easy to lose track of what's stored
  • Peer machines are less reliable and chances of data losing are high
  • Machines are prone to slow down when other devices access them
• In a star topology, all devices are connected to a central switch or server that controls the network.
• Advantages of a star topology:

  • If a device fails or a cable is disconnected, the rest of the network is unaffected
  • It's simple to add more devices to the network
  • Better performance that other setups
• Disadvantages of a star topology:

  • In wired networks, every device needs a cable to connect to the central switch or server. This can be expensive
  • If there is a problem with a switch or a server then the whole network is affected
• • In a bus topology, all devices are arranged in a line, connected to a single backbone cable. devices share data in both directions, which causes data collisions which slows the network
• • In a ring topology, data moves in one direction around the ring preventing collisions. But only one device can send data at a time and data passes through many devices before reaching its destination.
• • In a mesh topology, each computer system is connected to every other computer system
• Advantages of a mesh topology:

  • If one cable or system fails then data packets can take an alternative route and still reach their destination address.
  • New systems can be added to the system without affecting the network
  • A mesh topology can usually withstand large amounts of data traffic
• Disadvantages of a mesh topology:

  • It can be expensive to install and maintain, due to the large amounts of cable needed
  • Redundant cables are something that should be avoided
• A network protocol is a set of rules for how devices communicate and how data is transmitted across a network
• An IP address is a unique identifier given to a device when it accesses an IP network
• TCP(Transmission control protocol) sets the rules for how devices connect on the network. It is in charge of splitting data into packets and reassembling the packets back into the original data
• IP(Internet Protocol) is responsible for directing packets to their destination across the network
• A layer is a group of protocols which have similar functions
• Advantages of using layers:

  • It breaks network communication into manageable pieces
  • They can be changed without affecting other layers
• • The Internet is the network of networks
  • The world wide World Wide Web eb(www) is a collection of websites that are hosted on web servers and are accessed through the HTTP protocol
  • URLs are addresses used to access web servers and resources on them.
  • Domain name service(DNS) is used to translate website domain names into IP addresses
  • Domain name servers store IP addresses and match domain nams
• Cloud computing acts as an extension of a traditional client-server network where user files are stored centrally on a network server
• Pros of the cloud:

  • Users can access files and applications from any connected device
  • Easy to increase how much storage is available
  • No need to buy expensive hardware
• Cons of the cloud:

  • needs a connection to the internet
  • Dependent on host
  • ata stored in the cloud can be vunrebale to hackers