L.O: STUDENTS WILL BE ABLE TO EXPLAIN WHAT

THE INTERNET IS.(15-30 minutes <1 class period)

DO NOW: READUnit 4 Lab 2: Reliable

Communication, Page 1

What Is “the Internet”?

I BOUGHT IT OFF “THE

INTERNET”!ISN’T IT COOL!

The Internet is a network of independent but connected devices all

over the world.

People talk as if "the Internet" and "the World Wide Web" are the same thing, but

they are not.

The World Wide Web is the collection of interlinked website documents (such as HTML files) that you can view with a

web browser by typing addresses like http://bjc.berkeley.edu/website/privacy.html.

Most web pages are written with HTML (hypertext markup language) and interpreted

by your browser using HTTP (hypertext transfer protocol).

What is a “URL”?

• protocol—the standard for communication between browsers and servers (usually "http" or "https")

• domain name—the name of the server that hosts the data

• path—the location of the data in a hierarchy of folders on the server

A URL, or Uniform Resource Locator, is an address for accessing specific web data located on a server (a computer hosting data for others to access). URLs can be broken into

three parts:

For example, the URL shown above tells a browser to use the http protocol to access the bjc.berkeley.edu server and

then go to the website folder and open the privacy.html file

For You To Do:

• Describe the parts of this URL for the Snap! logo:• http://snap.berkeley.edu/Logo5.png

the Internet is more general than the World Wide Web. It also supports email, file

transfers, mobile apps, texting (a.k.a. SMS or Short Message Service), and many other ways

that computers communicate behind the scenes.

The Internet is a massive network of computers that communicate, facilitating communication around the

globe. They do this primarily by using a pair of protocols (standards for communication) that you

will learn more about in lab U4L3:• IP (Internet Protocol), an

addressing system that finds paths to distant computers

• TCP (Transmission Control Protocol), a reliable transmission system that sends and tracks binary sequences of data that are split into small packets sent separately

The algorithms that ensure data reach their destinations must continue to work even as

the Internet grows. So, the Internet was designed to be: REDUNDANT AND

HIERARCHICAL

Redundant: There are multiple pathways among the physical connections of the Internet to create redundancy. Even if one pathway is unavailable, there is still another way to transmit a message from sender to receiver (as shown

below)

Hierarchical: There are two hierarchical Internet addressing systems, domain names (as shown below) and IP addresses. These address

hierarchies works much like the postal system, which locates people first by state, then city, then street, then house number, then

apartment, and then finally person.

Enduring Understandings:

• EU 6.1 The Internet is a network of autonomous systems.• EU 6.2 Characteristics of the

Internet influence the systems built on it.

Learning Objectives:• LO 6.1.1 Explain the abstractions in the

Internet and how the Internet functions. [P3]• LO 6.2.1 Explain characteristics of the

Internet and the systems built on it. [P5]• LO 6.2.2 Explain how the characteristics

of the Internet influence the systems built on it. [P4]

Essential Knowledge:

1. EK 6.1.1A The Internet connects devices and networks all over the world.

2. EK 6.1.1C Devices and networks that make up the Internet are connected and communicate using addresses and protocols.

3. EK 6.1.1D The Internet and the systems built on it facilitate collaboration.

4. EK 6.1.1G The domain name system (DNS) translates names to IP addresses

Essential Knowledge:• 5. EK 6.2.1A The Internet and the systems

built on it are hierarchical and redundant.• 6. EK 6.2.1B The domain name syntax is

hierarchical.• 7. EK 6.2.1C IP addresses are hierarchical.• 8. EK 6.2.2A Hierarchy and redundancy help

systems scale.

Essential Knowledge:

• 9. EK 6.2.2B The redundancy of routing (i.e., more than one way to route data) between two points on the Internet increases the reliability of the Internet and helps it scale to more devices and more people.

• 10. EK 6.2.2C Hierarchy in the DNS helps system scale.

• 11. EK 6.2.2I The size and speed of systems affect their use.