Slide 15.3: Internet addressing
Slide 15.5: A web architecture
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Internet Addressing (Cont.)

Domain Name
A domain name is an Internet address. Assume your organization’s name is MARIO, Inc. You could register the domain name MARIO.COM. Your e-mail address could be name@mario.com and the web site is www.mario.com.

Domain Signifies Domain Signifies Domain Signifies
.net U.S. network .org U.S. nonprofit .au Australia
.com U.S. commercial .coop Cooperatives .ca Canada
.edu U.S. educational .info Unrestricted .cn China
.gov U.S. government .mil U.S. military .in India
Internet Protocol (IP)
IP is the Network layer for the TCP/IP protocol suite widely used on Ethernet networks. The command host—DNS lookup utility— can be used to find the domain name and IP address: 
 Unix> 

 Unix>
The values of CGI environment variables are
From it, our IP address is 172.16.182.173, which is for the domain name of our web server: undcemcs01.und.edu, which may reside in the machine undcemcs01. Usually, one domain name has several IP addresses, e.g., undcemcs01.und.edu points to 172.16.182.173 and 172.16.182.174.