Networking

Network: A group of computers that can communicate with each other directly

Internet(work): A collection of networks where devices on one network and can communicate with devices on other networks. Normally, you have a router that connects adjacent networks -- the router can be thought of as being a member of any network it is connected to.

packet: when information is being sent across a network it is broken into packets by the sender and reassembled by the recipient (by TCP/IP)

(On windows) Windows+R->”cmd”->OK-> ipconfig -all

This will show:

A bunch of stuff and TCP/IP information (these four are almost always needed):

  1. IPv4 Address -- e.g. 127.16.5.31, 192.1.68.1.4 (4 numbers separated by three dots -- no number greater than 255; there are other rules but be able to identify one using these simple rules). An IP address uniquely identifies a computer on a network. Not all IP addresses are unique but all ones accessible over the internet will have one or more unique IP addresses.
  2. Subnet Mask -- don’t need to know but tells the computer what network they are on -- if you look at computers from the same network the first part of their IP address will all be the same but the last part won’t (which particular numbers
  3. DNS Server- converts domain names (“amazon.com”) to IP addresses
  4. Default Gateway-- A different term for something that can deliver your packets to another network -- normally a router or something acting as one.

Physical Address (48-bit MAC address) -- this is the Ethernet/Wi-Fi address

Just know that there’s an address for ethernet and there’s also the IP address(TCP/IP has little to do with Ethernet other than that IP can use Ethernet to deliver packets)

Networks are built with Two types of technologies- LAN and WAN

LAN: Local Area Network tech. connects many devices in a small area (such as an office)

WAN: Wide Area Network tech. connects 2 to several computers over long distances

LAN tech.:

●Ethernet: Uses cables and typically switches. Devices connect to each other’s MAC addresses (the Physical address, above)

● Wi-Fi -- actually defined like Ethernet but for radio waves

Switches work with Physical (e.g. Ethernet) addresses

WAN tech.:Fiber, other business/infrastructure connections. Also, internet connections could be considered WAN technology(so ISP could be thought of as providing WAN connections (in the form of DSL/Cable lines))

TCP/IP -- the LAN/WAN technologies are for networks -- but we really need larger internetworks (the internet or a business’s intranet). TCP/IP is a suite of protocols that does things like error detection/recovery (TCP), and addressing (IP addresses). Routers work with IP addresses, not MAC/Ethernet Addresses

Facts to know:

  1. TCP/IP is about delivering packets/files across networks
  2. IP addresses on a network are similar but not identical
  3. IP addresses must be unique on a network
  4. IP (internet protocol) uses LAN/WAN technologies to deliver packets -- IP is what allows us to compose the various technologies (Ethernet/Wi-Fi/DSL/Fiber/Cell) into one giant internetwork (the internet) and many smaller ones (business and university internetworks/intranets)
  5. Routers, which are really TCP/IP devices, route packets between networks -- they don’t store the IP addresses of individual devices but, rather, the common part of the devices on your network. An analogy -- routers aren’t like mailmen that get the packages/packets to your door but, rather, like a large mail processing center that gets it to your local post office (which you can think of as the local post office).
  6. Switches, Ethernet devices, connect devices on the same network (some business switches can handle multiple LANs at the same time)
  7. Wi-Fi is specified just like Ethernet except that it adds the obvious issues like network names (SSIDs) and other issues like encryption (so communication over the network is confidential, to some degree).
  8. Wi-Fi, because it is broadcast (like old ethernet), has issues with too many computers in one area
  9. DNS -- changes domain names (amazon.com/google.com) into IP addresses -- The WWW runs over the internet
  10. Troubleshooting Questions: “Where do you think the problem might be if…”
  11. “...no one in your office can get online?”
  12. “...only you can’t get online?”
  13. “...no one but you can get online and everyone else is connected wirelessly?”
  14. “...no one in your office can get to superduperhotfashion.com but can get to other websites?”
  15. “...no one can get online but you happen to remember the IP address of a corporate website as 176.1.25.111 and you can get to it?”