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Fluency
Chapter 3
The Basics of Networking
What is the Internet?
► The
totality of all wires, fibers, switches,
routers, satellite links, and other hardware
for transporting information between
addressed computers.
►What’s
your address?
How have computers changed our
lives?
► For
the better?
► For
the worse?
► What
effect has it had on the influence of
the English language?
Communication Categories
► Synchronous
► Asynchronous
► Broadcast
► Multicast
► Point-to-point
So what category
does the Internet fit into?
Computer addresses
► Each
computer connected to the Internet is
given a unique IP (Internet Protocol)
address
► IP address – currently series of 4 numbers
separated by dots: e.g. 213.43.1.156
► Each # can be in range of 0-255
► Internet protocol moving to Version 6 (IPv6)
with a 16-byte address system.
Domain Names
►A
more human-friendly way of addressing
computers based on a hierarchy of domains.
► Domain – related group of networked computers
► markel.faculty.msmc.edu
Name System (DNS) translates the
domain name into its 4-number IP address
► DNS server – a computer that keeps a list of the
symbolic names and the corresponding IP
addresses
► Domain
Top Level Domains
► .com
► .org
► .mil
► .net
► .gov
► .edu
In addition there’s a 2-letter country code:
.uk, .au, .fr etc. that identifies countries
TCP/IP
Transmission Control
Protocol/Internet Protocol
► TCP
– breaks a transmission up into small
fixed-size packets
► Each packet contains the following:
 Data being sent
 Destination IP address
 Sequence #
► IP
- re-orders the packets at the destination
to assemble the information
Characteristics of TCP/IP
► Packets
are independent
► Packets are transmitted over the Internet
using whatever route is available
► Transmissions often rely on multiple
technologies to move the packets through
the Internet:
 Telephone lines
 Fiber optics
 Dedicated lines
Networks
► WAN
– wide-area networks: networks
designed to send information between two
locations not directly connected.
 Packets take several “hops” before delivery
► LAN
– local-area network. Computers are
directly cabled or “channeled” together.
Most LANs use Ethernet technology.
Connecting to the Internet
► ISP – Internet Service Provider
 Examples?
 Connection method:
►
►
Modem
DSL (digital subscriber line)
► Network
connections
 LANs connect to the Internet via a gateway.
Information from a remote Web computer is sent across
the Internet, through the gateway to the organization’s
intranet, and across the LAN to the user’s computer.
The World Wide Web
Web servers – computers programmed to
send files to browsers running on other
computers connected to the Internet.
► Subset of the Internet
► Each web page has a unique address called
a Universal Resource Locator or URL
► Built on a client-server relationship
►
The URL
The URL consists of three parts:
► Protocol: http:// - stands for Hypertext Transfer
Ptococol
► Server computer’s name
► Pathname of the particular page
http://domain.address/pathname
http://faculty.msmc.edu/markel/cit1100/outline.html
Structure of emails and URLs
► Email:
[email protected]
 The receiver can have dots, dashes, and
underscores.
► URL:
http://domain.address/pathname
 The domain address has one or more dots, no
@, no slashes.
 Spaces are not allowed in email or URLs.
Describing a Web Page
• Web pages stored as a description of how
they should appear
• Description file is called the source file
• Written in HTML (hypertext markup
language)
• Markup languages describe document
layout
• Hypertext – breaks linear sequence of text
through links: non-linear and dynamic
Directory Organization
folder
root
page
index.html
cit1050
cit1100
csc1200
mst1010
outline.html
grading.html
assignments
folder
Assignment1.html
path
Th . . .th . . . that’s all, folks!