The Internet: What is it? How does it

work?

There are supposedly at least 14 billion pages on the internet and, as per Smithsonian, “from every single one of these pages you can navigate to any other in 19 clicks or less.”

A History of Internet Connectivity: 1970s

December 1969 June 1970 December 1970 August 1972

July 1976June 1974 July 1977

Source: http://som.csudh.edu/cis/lpress/history/arpamaps/

A History of Internet Connectivity: TODAY!

How many Internet Users are there?

http://www.internetlivestats.com/internet-users/

1993!!!

So what is this thing we call….the Internet

Internet Service Providers• You first connect to an ISP and then to the Internet!!

• The ISP then connects you to the Internet

• Remember the YouTube example about crazy Aunt Ruth

Ste

p

1

Step 2

BIG

Ca

ble

What do these Big Cables look like?http://www.submarinecablemap.com/Interactive Cable Map!!!:

Video: Here's what it takes to lay Google's 9,000km

undersea cable

Anatomy of a URL

• URL: uniform resource locator. Identifies resources on the internet along with the application protocol needed to retrieve it

• Protocol: set of rules for communication—sort of like grammar and vocabulary in a language like English

• Other Protocols: • SMTP, FTP, IMAP

Host Names, Domain Names, Domain

• hostname: the place/computer you are looking for on a network

• domain name and domain: name of a network associated with an organization, and the type of network

• In the USA, we use: org-name.org-type

• Example: http://mis320.weebly.com

• http = Hypertext Transfer Protocol• mis320 = hostname• weebly = domain name• .com = Commercial organization

Path and File Names

• Path: a folder location

• File: the file within the folder• files are usually written in the

hypertext markup language (HTML), which is basically the language of the web

• Example: • tech/index.html• Tech = technology folder• index.html = name of file

IP Addresses• IP Address: where you live on the Internet; Unique series of numbers that identify computers on the Internet

• you get an IP address from the organization you are connected to the internet through

• At home, your ISP assigns you an IP address• At WWU, Western’s ISP assigns you one

• No two computers have the same IP address

• IPv4 Examples: (composed of 4 segments) WE ARE RUNNING OUT!!!

• 72.246.51.15 = www.nasa.gov• 152.91.56.138 = www.gov.au• 208.185.127.40 = www.about.com

• IPv6 Examples: (composed of 8 segments)

• 3ffe:1900:4545:3:200:f8ff:fe21:67cf• 21DA:D3:0:2F3B:2AA:FF:FE28:9C5A

The Domain Name Service• People don’t remember IP Addresses do they use words (google.com, wwu.edu, etc.)

•Domain Name Service: a distributed database that looks up the host and domain names that you enter and returns the actual IP address for the computer that you want to communicate with

Watch it all come together

how to read a Web address every device connected to the Net needs an IP address the DNS can look at a Web address and find the IP address of the machine that you want to communicate with

• But..

What do we know so far….

How does a Web page, an e-mail, or an iTunes download actually get from a remote computer to your desktop????

• Webpages, videos, pictures, are TOO BIG!!!!

•TCP: works its magic at the start and endpoint of the trip—on both your computer and on the destination computer you’re communicating with

• TCP slices up the web page into small chunks of data called packets

• Packets: smaller pieces of information containing part of an entire transmission

• IP: route the packets to their final destination

TCP/IP

A Packet’s Tale

HOA#7: Internet Security