Networks

Networks

1. The Internet is not the WWW

   • Internet is hardware.
     • This means Servers, Cables, Hubs, Routers, Switches... Physical things.
   • WWW is software.
     • This means files and programs.

2. Packets

   • Contain IP addresses of both sender and receiver (Submask).
   • Contains sequence numbers.
   • Have lifespans (Timing out).
   • Use cheapest available path, not necessarily the most direct.
   • Always has more than 1 route (Fault tolerance).
   • What all data is transferred through. Some images, videos, or audio files may be too big for just 1 packet, and could be split in to multiple packets. These multiple packets are identified by TCP (Transmission Control Protocols), and, if all packets are there, the packets are reformed by the Router.

3. LAN & WAN

   • Difference is in GEOGRAPHICAL SIZE.
   • WAN is wider, using EXTERNAL HARDWARE such as satellites. A university may use this.
   • LAN is local, using INTERNAL HARDWARE such as cables. A shop or a home may use this.
   • A WAP is a Wireless Access Point. Or sometimes a Wired Access Point.

4. Arpanet

   • The first network.
   • Arpanet was used to connect Silos during the cold war, for immediate response to nuclear attack.

5. Connections

   • Ethernet
     • The fastest wired connection possible (currently) is Fibre Optics, made of Glass.
     • Often used for modern wired connections. Before this was Coaxial.
     • Wires can bottleneck, slowing down data transfer.
   • Bluetooth
     • Slow, very limited range, very limited bandwidth. Just *not very good*.
   • WiFi
     • Wireless. Slower than wired but it's better than Bluetooth.

6. IPs

   • IP addresses change regularly, for security. MAC addresses do not, but are much harder to crack.
     • Some IPs, like the IPs of servers never change. And devices like printers.
     • The reason for this being - There's no point in giving a printer that kind of security against a hacker.
     • The most they could do with a printer is *waste your ink*.

7. Virtual Networks

   • Virtual Networks can piggyback off of existing infrastructure. They are flexible and organised. They can also use privileges - some users may (or may not) do certain things, see certain things, etc,
   • Virtual Private Networks (VPN)
     • All about freedom, privacy and security. VPNs were used by employers to securely access networks remotely from home. Today, they are available to everyone. They are able to bypass blocks to content by a government by accessing servers that do host that content.
       • Example, if my country has not got access to a video - I can access a server not in my geographical country and then view it.

8. Domains and DNS

   • Domains are a collection of IPs, but some pages may use 1 IP. This results in redirection.
   • DNS is the server responsible for keeping track of names of the servers. It identifies IPs.

9. HTTP & FTP

   • HyperText Transfer Protocol tells a device to arrange packets for use in a browser. (HTML)
   • File Transfer Protocol is used for transferring files.

10. Cloud

    • A collection of servers. While it does store data, it can also run (host) programs.

11. URL (Unique Resource Location)

12. Transmission Control Protocol

13. This mind-map is a network, with nodes.

    • Meta