what is the internet?

goalsformalize your understanding of the way the internet and websites work

internet structure and protocolconnecting through the cloud

1

internet, you say? what is an internet?

◦ global network of connected devices

◦ client: a computer/program used to access information or services on another computer/program

◦ server: a computer/program that provides information or services to another computer/program

how does one connect to this “internet”?

◦ LAN (local area network)◦ ISP (internet service provider)◦ IP address (internet protocol)

internet addresses

the “cloud

”

client 1.22.33.

4

server 5.66.77.

8

speaking the same language

◦ router: directs data to the appropriate place

◦ TCP/IP (transmission control protocol/internet protocol)

◦ TCP = what is it◦ IP = where is it going

data transfer

◦ information that is being sent is broken down into “packets” via TCP

◦ routers forward the data packets to their destination using decentralized transmission

◦ inbound packets are reassembled upon receipt via TCP

data transfer

terminal AISP/

routers on routers

terminal 2

data packets

DNSusing domains to connect users to your site, email, and more

domain nameshow humans use the internet

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names and addresses

◦ did you know? people generally cannot retain or process information as well as computers

◦ a domain name is essentially an alias for an IP address

◦ by using the domain name system, domains can be mapped to a number of internet resources and functions

what’s in a name?

◦ URL: http://www.buzzfeed.com/quizzes

◦ prefix: http◦ subdomain/host name: www.◦ domain: buzzfeed.com◦ name: buzzfeed◦ extension/top-level domain: .com◦ subfolder: /quizzes

names and addresses

◦ URL: your request◦ prefix: what type of resource you

are looking for◦ subdomain/host name:

subsection of a domain◦ domain: the server you want to

access◦ subfolder: the location of your

request on the server

name serversthe translators of the machine world

3

finding a resolution

◦ when you enter a domain name into your browser, you issue a request for information

◦ that request is transmitted to a domain name server that directs your computer to where that information can be found

◦ packets are sent back to your IP address from a web server

web/mail servers v name servers: dawn of justice

◦ name servers: contain information related to the location of resources associated with a domain

◦ web servers: house site content

◦ mail servers: handle and store messages being relayed to or from a domain name

you. look. fetching.

your computer

name server

web server

data

you. look. fetching.

your computer

name server

web server

data

binary view

yes no

are you connected to the internet?

HTTP request sent from your IP address

error displayed for no internet connection

does the domain exist? request is routed to the domain name server

browser error displayed for failure to resolve

domain

is there a website associated with the

domain?

request is forwarded to the site’s IP

address/web serveruser is directed to a

parking page

is there a page located at the requested URL?

web server packets returned and interpreted

by browser404 error displayed for

page not found