1.3.1 Networks and topologies

• Local Area Network (LAN)


  Small geographic area. All the hardware for the LAN is owned by the organisation using it. Wired with UTP cable, fibre optic cable or wireless using routers and Wi-Fi access points
• Wide Area Network (WAN)


  Large geographic area. Infrastructure is hired from telecommunication companies who own and manage it. Connected with telephone lines, fibre optic cables or satellite links
• Client-server network

  A client makes requests to the server for data and connections. A server controls access and security to one shared file store. A server manages access to the internet, shared printers and email services. A server runs a backup of data
• Peer-to-peer network

  All computers are equal. Computers serve their own files to each other. Each computer is responsible for its own security and backup. Computers usually have their own printer
• Wireless access point(WAP)


  A networking hardware device that allows a Wi-Fi device to connect to a wired network
• Router

  A router sends data between networks. It is needed to connect a local area network to a wide area network. It uses the IP address on a device to route traffic to other routers
• Switch

  A switch sends data between computers on a local area network. It uses the NIC address on a device to route traffic
• Network Interface Card/Controller (NIC)


  A computer hardware component that connects a computer to a computer network
• Transmission media

  The physical media over which data is transmitted, e.g. twisted copper cable, fibre optic etc.
• The Internet

  The Internet is a worldwide collection of interconnected computer networks. It is an example of a WAN, albeit the very largest one which exists!
• Domain Name System (DNS)


  The Internet's equivalent of a phone book. They maintain a directory of domain names and translate them to Internet Protocol (IP) addresses. This is necessary because, although domain names are easy for people to remember, computers or machines access websites based on IP addresses
• Hosting

  Websites stored on dedicated servers. Reasons include: Websites need to be available 24/7. Accessed by thousands of users at a time. Strong protection from hackers. They need an IP address that doesn't change
• The Cloud

  Remote servers that store data that can be accessed over the internet. Advantages: Access anytime, anywhere from any device. Automatic backup. Collaborate on files easily
• Web server

  A program that uses HTTP (Hypertext Transfer Protocol) to serve the files that form Web pages to users, in response to their requests, which are forwarded by their computers' HTTP clients. Dedicated computers and appliances may be referred to as Web servers as well
• Client

  A client can be thought of as computing device which requests or is using the services from some remote / connected server
• Network topology

  The physical or logical arrangement of connected devices on a network e.g. Computers, switches, routers, printers, servers etc.
• Star topology

  Computers connected to a central switch. If one computer fails no others are affected. If the switch fails all connections are affected
• Mesh topology

  Switches (LAN) or routers (WAN) connected so there is more than one route to the destination. e.g. The Internet More resilient to faults but more cable needed
• Local Area Network (LAN)


  A network that connects devices close to each other e.g. school, house
• Wide Area Network (WAN)

  A network within a large geographical area e.g. internet
• Latency

  Time between sending data and receiving it
• Latency

  There is more than one route for data to take on a mesh network
• Mesh network

  Lots of cabling and redundant switches are needed, expensive
• Mesh network

  Makes sure there are multiple routes
• Router

  Sends data between networks
• Router

  Uses IP address
• Domain name server

  Map a domain name in a URL to an IP address
• Full mesh network

  All the switches are connected to each other
• Switch

  Used in local area network to segment different parts of the network
• Network interface controller

  Connects a device to a wired or wireless network connection.
• Bandwidth

  Amount of data that can be transmitted in a given time
• Network topology

  Arrangement of devices on a network and how they are connected to each other
• Star network

  Use switches and paired wires for transmit and receive so data from two sources is not sharing same physical cables so high performance as no data collisions can occur.
• Star network

  Every computer is connected to a switch using one connection.
• Fibre optic

  High bandwidth and cost
• Hosting

  Dedicated servers connected to the internet, storing copies of websites