Class 7 Topics

1
Class 7 -- Topics

• Midterm next week (Dont forget!)
• A history of the Internet
• The physical Internet
• The virtual Internet
• The World Wide Web (WWW)
• Navigating the WWW
• HTTP/ISP/FTP/M-O-U-S-E

2
Regional Networks
We know that a local area network (LAN) is
something we see in office buildings, college
campuses and large organizations. A wide area
network (WAN) is often a larger network that just
ties these smaller ones together. Thus, regional
networks covered large areas of the country like
the west coast, the New York area and
the Southeastern part of the United States.
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The Internet - A history
NYSER
UCB
A
C
SURA
B
4
Identifying specific machines
A.UCB.EDU
Machine A at UCB
UCB
A
B.SURA.EDU
Machine B at SURA
C
SURA
Machine C at SURA
C.SURA.EDU
B
5
Identifying specific machines
A.UCB.EDU
UCB
A
C
SURA
C.SURA.EDU
B.SURA.EDU
B
6
Identifying specific machines
A.UCB.EDU
NYSER
UCB
A
B
B.NYSER.COM
C
SURA
C.SURA.EDU
B.SURA.EDU
B
7
Too many names!
To prevent one site (say, NYSER.COM) from having
the same name as a machine at another site
(UCB.EDU), the domain is added to the machine
name to give us the Fully Qualified Domain Name
(FQDN).
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Many names, one machine
At times, it is useful to have more than one
name associated with a given machine. However, we
still need to uniquely identify each machine
without having to know all possible names, thus
there are Internet Protocol numbers (IP numbers).
9
IP Numbers
An IP number is composed of 4 sets of numbers,
ranging from 0 to 255, for example 128.163.128.1
9 128.1.128.1 128.163.136.2 127.0.0.1
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Converting IP s and names
T1.mscf.uky.edu 128.163.132.101 t8.mscf.uky.edu
128.163.132.108 pigpen.ate.uky.edu
128.163.130.10 The conversion is handled by the
system using a distributed database called
the nameserver or nameservice.
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ISP - Internet Service Provider
An ISP is an Internet Service provider which is
simply an organization (a company, school, etc.)
that provides access to the Internet, usually by
phone.
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Dial Up Access to the Internet
One method computers use to connect to the
Internet uses an everyday phone line and a modem.
One computer (the client or remote end) calls up
another computer (the host or ISP end) and
the two computers speak via their modems over the
phone line.
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PPP - Point to Point Protocol
The language some computers use to establish a
connection to the Internet is called a protocol.
A few years ago, the most common form was called
SLIP for Serial Line Internet Protocol. Today,
an improved form is known as PPP
or Point-to-Point Protocol.
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Chaney_at_ms.uky.edu
An email address is composed of two parts, the
user id and the domain name. The domain name
may be a machine or it may reflect a domain for
machines. The domain section uniquely identifies
the machine to deliver the mail to whereas the
user id section specifies the individual user
for the mail.
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Http//www.ms.uky.edu/ma194
A Universal Resource Locator (URL) has three
parts The service (http//), the machine to
access (www.ms.uky.edu) and the pathname of the
web page (which is often the name of the user on
the machine.)