1. The Internet
CSCI 101

2. What is the Internet? The largest computer network in the world
A giant network of networks. Connecting billions of users.

3. Internet History Concept of the internet was made in late 1950s
During the cold war they had two goals in mind for the internet
Secure communication
Enable all computers to communicate

4. ARPANET
The original internet was called the Advanced Research Projects Agency Network (ARPANET)
Began with university research institution attempting to communicate with each other
Vinton Cerf and Robert Kahn are considered the “fathers” of the internet as they developed the first communication protocols.
First message was sent from the University of California to the Stanford Research Institute

5. ARPANET

6. Web is not the Internet
The world wide web is a subset of the internet which is responsible for rendering information via html pages through browsers.

7. Communication Protocols
Computer network protocols are just like conversations, with requests and responses. Hi
Network connection req
Well Hello there!
Network connection response
Got the time?
It’s 2:00
Get
time
<file>

8. Internet Protocol (IP) Address
When you connect to the internet you are given a unique identification number (IP address)
A set of four groups of numbers separated by periods, e.g
Each website has it’s own Unique IP address
For example Amazon’s website is we give it the user friendly name so it’s easier for us to remember.

9. Sending Data over the internet
Data is broken into smaller chunks called packets
Packets are sent via various routes
when the packets get to their destination to message is reassembled

10. Why Break into Packets
Sending large chunks of data ties up the line and slows communication.
It’s easier to recover form error with packets, as you simply resubmit the packet rather than the entire message.
The packets can take different routes to balance the load.

11. What does each Data Packet Contain?
Senders IP Address
Receivers IP address
Reassembly instructions (How many packets are in message, and which packet this is)
Data begin sent
Max size 64Kb

12. Sending a Message
Cidney is sending a message to her parents back home.
Rock Hill
Seattle
Cidney
Mom and Dad
I miss you both
Breaks up into packets
I mis
s you
both

13. Sending a Message
Cidney is sending a message to her parents back home.
Rock Hill
Seattle
both
I mis
Cidney
s you
Mom and Dad
I miss you both

14. Sending a Message
Cidney is sending a message to her parents back home.
Rock Hill
Seattle
Cidney
Mom and Dad
I miss you both
Message received and put back together

15. Firewalls
Designed to block unauthorized access into and out of the network.
Packet screening: examine incoming data packets to ensure they are properly authorized before letting them through..
Firewall

16. How it all works http://www.youtube.com/watch?v=PBWhzz_Gn10
This video is a good illustration of how message are sent over the internet

17. World Wide Web
Servers scattered all throughout the world, that communicate with each other.
Communicate through internet protocols

18. TCP/IP The main protocols used throughout the internet are TCP/IP
Named after Transmission Control Protocol / Internet Protocol
TCP prepares the data for transmission, and provides error checking and resending lost data.
The IP is the protocol that sends the packets from router to router

19. Ping
A program used to test the reachability of network designations. (CSI).
Computers running IP software send out ping requests, which can be sued to test who is on the NTWK.
Ping was the name used when submarines send out a sonar pulse and wait for a response. (CSI)

20. HTTP (Hypertext Transfer Protocol)
Transfer html data (web pages) from the server to the client (your computer)
http request e.g.
Enter in browser url
http response
sends Amazon webpage to browser

21. URL (Uniform Resource Locator)
The address of a webpage.
Most websites have multiple webpages each with their own unique URL, just like every house on a block has it’s own address
Protocol
domain
Path or
subdirectory
File

22. DNS (Domain Name System)
Phone book for the internet.
Just like people can be uniquely identified by their SSNs, computers, and websites can be identified by their IP address, or the user friendly version, domain name)

23. Domain Names The number of top level domains keeps increasing.
ICANN is responsible for organizing the top level domains.

24. How To Get Your Own Domain Name
Buy a server, or server space
Buy a domain name that is freely available on ICANN
Associate your domain name with your server