Transcript The Internet and the Information Highway

What is the Internet?
• The US military wanted a network that was
robust under enemy attack.
• US academics wanted a network that would
allow researchers to share information and
computing resources.
• Their joint efforts resulted in ARPAnet.
• ARPAnet was launched in 1969
• Internet is: A global interconnected network
of computer networks plus the information
held in those networks.
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Rules and conventions:
Addresses
• Every computer that is directly connected to the
Internet has two addresses.
• The formal address is the four number
IP
address (e.g. 139.80.91.23).
• The informal (‘human’) address is the
hostname (e.g. atlas.otago.ac.nz).
• A Domain Name Server (DNS) translates
between the two.
• The human address may have an alias (e.g.
cs.otago.ac.nz for atlas.otago.ac.nz).
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Rules and conventions:
Domain Names
• What means atlas.otago.ac.nz?
• Part after leftmost ‘.’ is called domain name.
• Highest level (rightmost) is the country code or
country domain (.nz: New Zealand).
• Next level is more properly called the ‘domain’
(of interest) (.ac: academic).
• Below, the institution or subdomain (.otago).
• Finally the machine or local identifier (atlas).
• In the USA the highest level is the ‘domain’:
.com, .edu, .gov, ... Country code not used.
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Rules and conventions:
Internet Protocols — TCP/IP
• TCP = Transmission Control Protocol
Controls correct transmission of a
message chopped up in packets
• IP = Internet Protocol
Controls the routing from source to
destination node. Use the IP
addressing system of the Internet
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Internet Services
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Electronic mail and mailing lists
Newsgroups
Telnet (remote login) and ftp (file transfer)
Real-time communication
World Wide Web
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