L.O: STUDENTS WILL BE ABLE TO DESCRIBE HOW THE

INTERNET USES ADDRESS HIERARCHY.

25-50 minutes (about 1 class period)

DO NOW:READ

Unit 4 Lab 2: Reliable Communication, Page 3

WHY DO HOUSES AND OTHER BUILDINGS HAVE “ADDRESSES”?

The Internet uses two hierarchical addressing systems: domain names and IP addresses.

People use domain names (like snap.berkeley.edu) to visit

websites.

Computers translate domain names to IP addresses (like

128.32.189.18) to locate and send data behind the scenes.

A hierarchy is an arrangement of things with the broadest or highest category at the top

and things ranked into subcategories below.

Before there was “an internet”, there only small networks of computers.

Every computer knew the “names” of every other computer in the network.

Today, there > 3 billion computers on the Internet. So now, a hierarchy allows the system to distribute requests for IP

addresses to domain name servers across the growing network.

Domain Name HierarchyThis is the structure of a URL (Uniform Resource Locator ):

the path in a URL locates a specific file in a hierarchy of folders on the server

domain names locate a specific website within a

hierarchical domain name system (DNS).

The domain name system (DNS): simplifies the process of finding the computer with the

desired domain name.

Where’s the file?!

The path in a URL locates a specific file in a hierarchy of folders on the server, domain names locate a

specific website within a hierarchical domain name system (DNS).

DNS servers don’t need huge lists of EVERY host name in the world.

All a computer needs is to know is where to find a root domain server where to find the top level domains .

Example .org, .edu…

The root domain may be a country code (such as .mx for Mexico) or a category code (like .gov for government). The

last two segments of a domain name (like berkeley.edu) make up the primary domain, the main address for a site.

store.parks.ca.gov is a subdomain of .ca.gov

Which of the following could be a subdomain of the domain

bicycles.com?1.bicycles.co.uk2.bicycles.com.org3.bicycles.org4.about.bicycles.com

about.bicycles.com could be a subdomain on the

bicycles.com domain.

IP Address HierarchyWhen we type in a domain name, the browser

queries (asks) the domain name system to find the Internet Protocol (IP) address of the server we want

to visit.

Domain name:www.Amazon.com

Amazon’s IP address:192.168.1.1

Query:What’s amazon’s IP?

Both the domain name syntax and IP addresses are hierarchical; however unlike domain names, IP

addresses are hierarchical from right to left

Every computer has its own IP address

Domain names and IP addresses are hierarchical from “smallest” to “largest”

small largestsmalllargest

Independent work/homework:

1.Reread your notes and Unit 4 Lab 2: Reliable Communication, Page 3

2. Write an explanation of the DNS and IP address hierarchy.

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.