Networks

Networks

LAN
1. A LAN is a local area network and is used for local devices
2. Advantages
  1. Much cheaper to set up than a WAN
3. Disadvantages
  1. Cannot provide network for as many devices.
WAN
1. A WAN is a wide area network that spans a relatively large geographical area
2. Disadvantages
  1. They are very expensive too set up
3. Advantages
  1. They can spread long distances and provide networks in a large area
Topologies
1. Bus
  1. A single cable connects all the computers. All the clients and servers connect to this cable
2. Ring
  1. Each computer is connected to two other computers in a ring formation
3. Mesh
  1. Each computer is connected to one or more other computers
    1. Packet Switching
      1. So for this one. Whatever kind of data you are trying to send through the network is chopped into smaller parts and sent down different paths. This means that some parts of the information get there later than others creating LAG
    2. Pathfinding
      1. When either the packet switch or circuit switch is active it needs to find a suitable path to its device or server. The way it does this is by using path finding algorithms. Some paths are cheaper than others so these algorithms try and find the cheapest one
    3. Circuit Switching
      1. Circuit switching finds a path in the network and blocks any other devices from using it, an example of where this is used is a telephone call. It eliminates LAG
4. Star
  1. All computers are connected to a central hub or switch
Ethernet and Wi-Fi
1. Ethernet
  1. Ethernet is a wired connection / protocol used for wired connection
2. Wi-Fi
  1. Wi-Fi is the protocol for wireless connection
    1. 801.11
      1. wifi
    2. Bluetooth
      1. small range wireless connection
HTTP and HTTPS
1. HTTP(Hyper Text Transfer Protocol)
  1. Standard protocol used for requesting a HTML file from a webserver
2. HTTPS
  1. Secure version of HTTP that encrypts your data beforehand in order to stop interception
POP3 and SMTP
1. POP3(Post office protocol 3)
  1. protocol used for downloading email from a server. Its old and can only be accessed from one device
2. SMTP(Simple Mail Transfer Protocol)
  1. Uploads mail to a server for it to then be received and downloaded by POP3
IMAP
1. IMAP(Internet Message Access Protocol)
  1. replaced POP3 as does not need to be downloaded from the server and can be kept on there. As well as this it can be read and accessed on many different devices unlike POP3
FTP
1. FTP(File Transfer Protocol)
  1. Protocol used for transferring files between 2 computers and normally used by web developers to upload their HTML files to their websites
TCP/IP Layers
1. Application Layer: Provides application services
2. Transport Layer: Handles data consistency (error checking)
3. Network Layer: Provides network addressing and routing
4. Data Link Layer: Prepares and corrects data for physical
5. Physical Layer: Transmits and receives bits
6. Each layer performs its own protocol action, then passes on the data to the next layer.
IP Adresses
1. Internet Protocol addresses are the unique identifiers assigned to computers on a TCP/IP network (including the internet)
2. IPV4: Between 0.0.0.0 and 255.255.255.255, there are 2 to the power of 32 different values. This version of the IP address system is called IPV4
3. IPV6: uses a 128 bit address. This is 2 to the power of 128 different possible addresses.
DNS
1. Every computer on the internet is identified by its IP address
  1. When you type a web address into a browser, your ISP (Internet service provider) sends the domain name to its DNS server, wich returns the IP address
    1. DNS is essentially a large address book

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	Created by seb beckwith almost 4 years ago