1. Unit 4, Lesson 11 How Data Travels the Internet
AOIT Principles of Information Technology
Unit 4, Lesson 11 How Data Travels the Internet
Copyright © 2007–2012 National Academy Foundation. All rights reserved.

2. The Internet is the world’s largest computer network
The Internet is a vast network of linked computers. It is the world’s largest WAN.
Image retrieved from on June 21, 2012, and reproduced here under the terms of the Creative Commons Attribution 2.5 Generic license. Image created using data from The Opte Project.
Does this artist’s interpretation of the Internet remind you of anything?

3. Each device on the Internet has an IP address
An IP address for a computer is like a street address for a house.
The TCP/IP Properties window shows the computer’s IP address.
Can you find your computer’s IP address?

4. All data travels the Internet in frames that contain packets
Web pages and files travel as a series of packets encapsulated in a frame.
Routers receive the frame and process the packet information.
The router removes the outside layers and then determines how to send the data to the correct destination.
Header
Sender’s IP address
Receiver’s IP address
Protocol
Packet number
Payload
Data
Trailer
Data to show end of packet
Error correction
Breakdown of a generic packet

5. Most people access the Internet from a LAN
A LAN diagram showing IP addresses and how each computer connects to the Internet

6. Data on the Internet travels through Internet service providers (ISPs)
ISPs connect through routers that interconnect the LANs and WANs on the Internet.
As data travels, it “hops” from router to router to reach its destination.
Traceroute is a utility you can use to show how data is routed through the Internet.
Traceroute display

7. Use the Ping utility to check network connections
The Ping utility sends test packets over the Internet and then evaluates if the machine they are sent to receives them.
Pinging a computer can tell you whether your connection to that machine is working.
Ping display

8. A firewall protects you from Internet threats
A firewall can be software or hardware based.
Do you know if there is a firewall on your computer?

9. Schools and businesses customize their firewalls
Most schools and businesses customize their firewalls with rules that determine what traffic is allowed on their network.
What do you think are some of the rules that determine what information passes from the Internet to your school computer?

10. The Internet is a complicated yet effective network system
The Internet uses a complicated yet highly effective system for sending and receiving data.
Every day billions of data packets travel the Internet delivering information to millions of users around the world.