U3

• IP address


  Unique public address for the router or gateway of a network
• Private IP address


  Not unique, changes when a portable device is moved
• IPv4 address


  4 numbers (each stored using 8 bits) separated by a full stop
• IPv4 addressing system is running out of possible addresses due to the rise in networked devices
• IPv6 address


  128-bit address usually represented in hexadecimal, provides enough addresses for all devices on the planet
• MAC address


  Unique hexadecimal identification number assigned to every Network Interface Card used in networked devices
• The MAC address will always be the same, even if the IP address changes
• TCP (Transmission Control Protocol)

  Breaks data down into smaller pieces called packets that allow it to be transported, then puts the pieces back together in the correct order on the receiving computer
• IP (Internet Protocol)


  Standard set of rules used to ensure that computers on the Internet send information to the correct address
• Every computer on a network must have its own unique IP address
• TCP/IP Protocol is made up of TCP and IP protocols which enable communication between devices over a network
• Network protocols


  • FTP (File Transfer Protocol)
  • HTTP (Hyper Text Transfer Protocol)
  • HTTPS (Hyper Text Transfer Protocol Secure)
  • SMTP (Simple Mail Transfer Protocol)
  • POP3 (Post Office Protocol 3)
  • IMAP (Internet Message Access Protocol)
• FTP


  Used to transfer files from one location to another
• HTTP


  Used to control the format and transfer of web pages over the Internet
• Data packets


  Smaller parts into which files are broken down when sending data across a network
• HTTPS


  HTTP used over a secure connection on which all data sent and received is encrypted
• Whole files are too large to transfer as one unit so data packets allow data to be transferred across a network quickly
• SMTP


  Used to send emails to a mail server
• Transferring data packets across a network

  1. Packets are redirected by routers across networks

  2. Packets may split up and use alternative routes to reach the destination address

  3. Data is reassembled back into the original file at the destination address
• POP3


  Used to retrieve emails from a remote mail server
• Wireless Access Point (WAP)


  Provides a link between wireless and wired networks, creating a wireless local area network that allows WiFi-enabled devices to connect to a wired network
• IMAP


  Used to manage remote mailboxes and retrieve emails from a remote mail server, more advanced than POP3
• Examples of a wireless access point


  • WiFi or Bluetooth hotspot in a coffee shop or airport
• Wireless Access Point


  May be a separate device or built into another device such as a router
• TLS(transport layer security)


  Provides communication security between client/server applications that communicate with each other over the Internet
• Router


  Used to transfer data packets between networks
• Layering


  • Organising protocols of similar functions into 'layers' to simplify the overall task
  • Makes it possible to adjust individual layers without affecting the whole network standard
  • Protocols can be divided into two parts: logically based (concerning the data itself) and physically based (wired or wireless)
  • There is a hierarchy of layers, with each layer providing a set of specific functions to the layer below it
  • Inter-layer communication is achieved through interfaces called Service Access Points (SAPs)
• How a router works


  1. Receives data packets

  2. Uses the IP address in the packet header to determine the best route to transmit the data

  3. Transfers data from router to router across the internet towards the destination

  4. Stores the IP address of each connected computer and uses a routing table to calculate the quickest and shortest route
• Layers


  • Application
  • Transport
  • Internet
  • Network
• Switch


  Used to connect devices together on a LAN
• Receiving Data


  Responsible for making sure data is in the correct format for the software receiving it
• How a switch works

  1. Receives data packets from a connected node

  2. Reads the destination address in the packet header

  3. Forwards the data directly to its destination

  4. Generates a list of the MAC addresses of all connected devices and scans for a matching destination address before sending
• Sending Data


  Responsible for establishing connections across the network and transmitting data across the physical network
• Network Interface Controller (NIC)


  Internal piece of hardware required for a computer to connect to a network, includes a MAC address used when sending data across a LAN, connected to the network via an ethernet cable
• NICs used to be separate expansion cards but are now typically embedded on the motherboard
• Packets


  • When a file is sent over a TCP/IP network, it is divided into packets for routing, which then travel different routes and are reassembled into the original file at the receiving device
  • Splitting data into packets allows for faster data transfer and more secure data transmission
  • Each packet contains the data, packet number, sender's IP address, receiver's IP address, protocol, and checksum number
• Types of transmission media

  • Ethernet cables
  • Fibre Optic cables
  • Coaxial cables
• Network protocols are rules and standards for communication between network devices, governing all aspects of network communication from sending and receiving messages to formatting files for different types of messages
• Ethernet cables


  • Used on a LAN to transfer data between nodes and hardware such as switches, examples include Cat5e and Cat6
• Fibre Optic cables


  • Very fast but more expensive and fragile, used to send data quickly along a WAN, data is sent as pulses of light