Internet 101 #2

IP address

Every device connected to the Internet has at least one unique IP address. The IP address has two parts - the network address and the host address. (How you split the IP address into network and host is a bit tricky for humans to do...)

Q: What has more than one IP address?

Notes

Name resolution

Notes

Domain Name Space (DNS)

Notes

Name Lookup

Notes

Root Server Addresses

Notes

Top level domain Country Code

Notes

Top level domain Country Code 2

la -- Laos Currently being marketed as the unofficial domain for Los Angeles[9]
li -- Also used by Long Island
to -- Tonga: Torrent, Turin, Toronto, Tokyo, or Tocantins
tv -- Tuvalu: television (the domain is currently operated by dotTV, a VeriSign company; the Tuvalu government owns twenty percent of the company.)

Notes

Protocol: Layering Model 1

Layering is another innovation that was driven by a philosophy of connection.

Without layering, you designed an integrated network from top down. For example, every component of the (original) telephone network was designed for telephony. Every component of a utility network (think electricity, gas...etc) was designed for a specific use in mind.

The internet protocol was designed with a different ideology.

Layering is another innovation that is unique. Before, if you wanted a network, you designed it integrated top down. (Telephone). But once you designed it, you can't use it to carry gas, or water
If something that has depth has a white cloth on it, it is a bed. That is the definition of a bed.
Application sees a bed. It doesn't care.
TCP (remember routers can drop packets. the job of TCP is to keep track)
The most important is the physical layer is separated.
There are many networking device right - ether net, wi-fi, cell phone. if you have anything that transmit data, all you have to do is right code for the physical layer.

Wok

Lets imaging that you snuck in a cell-phone or a sattelite-phone into a remote censured village. Now you connect a USB-wireless device to a Wok and you can send the Internet signal all the way across the village.
It's very easy to connect to the Internet (or very hard to censure) because it can connect to so many thing.

Protocol: Wok as a Physical Layer

Youtube video

Nobody above the physical layer need to know that it is running on a Wok

Different ideology to telephone system where switchboard was specific to the system and of high quality

from wikipedia

Notes

iPhone WiFI/Celllular

Two physical devices: Cellular & WiFI

Notes

Hyperconnectivity -- Politics in the technological!

Easy to connect different devices (again, very resilient).
Devices can be very poor to very high-end. Doesn't matter. (Compare this with the ideology of telephone networks)
No need to change/modify application.
Chrome will work regardless of whether it is on a wireless network or on a wired network.

Use the bed analogy again.
As far as the application is concerned, it sees a bed and sends requests only pertinent to the application. (It does not have to worry about anything about the network whether it is sending something it using WI-FI or ethernet).
And on the other side, it looks as though something meaningful is coming out of the bed.

Protocol: Each Layer Talks to Its Peer (Interactive)

Watch what "protocol" means in practice. Application, TCP, and IP each carry on their own private conversation with the matching layer on the other machine. Data only physically moves down one stack, across the wire, and up the other, but logically, each layer believes it is talking straight across to its peer.

What "protocol" means technically

An agreed set of rules that lets two peers exchange messages: the format of a message (syntax), the vocabulary of legal messages, the order they are allowed to occur in (the state machine), and the meaning of each one, including what to do on error or timeout.
The rules are written down in public (RFCs) so anyone can implement them. That is why any browser can talk to any web server, with no prior arrangement between the two vendors.
A protocol is defined only between peers on the same layer. HTTP says nothing about Wi-Fi. IP says nothing about your browser. Each layer's rules are independent of the layers above and below it.
Result: interoperability without a central authority. What holds the network together is agreement on the rules, not ownership of the wires.

Application does not have to worry about TCP or IP, it only speaks its own protocol (HTTP, FTP...) to the Application on the other end.
TCP does not have to worry about Application or IP, it only speaks TCP to the TCP on the other end.
IP does not have to worry about Application or TCP, it only speaks IP to the IP on the other end.
That per layer, peer to peer conversation, independent of the layers above and below, is what "protocol" means here.
Use the interactive demo to step through a request going down Host A's stack, across the physical network, and back up Host B's stack.
Technical definition to say out loud: format, vocabulary, legal order, meaning. Written in public so strangers can interoperate.
Galloway's move: same definition, then widen it to "correct or proper behavior within a system of conventions", so protocol becomes a management system.
The stop sign example works well here. No one stops you, but you cannot drive if you ignore it.
TCP/IP horizontal vs DNS hierarchical is the pair to plant now, since DNS was covered earlier in this deck.

Protocol

Layering allows for layer to layer communication. From the application's point of view, it only has to think about the application to application communication method.

Communication between web browser and web server:

Using file transfer protocol

Protocol mismatch:

Application does not have to worry about whether it is going through a Wireless network or a wired network
All an application has to do is to worry about how to communicate with other applications. And this is called a protocol
A protocol is a predefined rule on how to communicate with the other end.

ftp, sftp, ssh, http, shttp manually telnet into web server and show 1. how simple the http protocol is. 2. how it has no concern for lower layers (it doesn't care whether it is on the cell network or not)