Transcript presentation source

CPT 499 Internet Skills for
Educators
Session Two
Class Notes
Internet Services
Telnet Service
Using the Telnet service entails
establishing a Telnet session
between your computer and the
remote system you are trying to
access
Internet Services
Telnet session - A connection to a
host computer using the telnet
program, which allows the remote
computer to appear as a directly
attached terminal.
Internet Services
The session has a client part, the
Telnet program on your local
system and a server part, usually a
Telnet server running on the
remote system
Internet Services
Once a session is established, the
client and server programs work
together to provide the user with a
terminal window or session that
allows the user to interact with the
remote system
Internet Services
Usenet - A facility of the
Internet, also called “the news,”
that allows users to read and
post messages to thousands of
discussion groups on various
topics.
Internet Services
Newsgroup - A forum for
discussion of a specific topic in
Usenet.
Internet Services
Discussion Group - A discussion group is a
form of e-mail in which people who want
to exchange information on a particular
topic send e-mail to members of a list.
The Intranet Journal Web site offers
robust discussion groups on Intranet
topics.
Internet Services
Threaded Discussion - A threaded
discussion is a listing of e-mail
messages that follow a particular train
of thought.
An excellent tool for keeping up on the
latest trends and developments in
technology.
Internet Services
Chat Room - A chat room works similar to
e-mail in that a message is typed and
conveyed electronically over the
Internet or Intranet.
Text-based conversations
Message is received and responded to in
real time
Internet Services
The recipient of the message is there to
receive it and respond to it
As the recipient types response, it is
visible on the sender’s computer screen
Can also involve multiple participants
Internet Services
Chat rooms can be used to facilitate
teams whose members reside in
various locations.
Internet Services
Spam - A Usenet posting that
violates news etiquette by being
indiscriminately sent to multiple
newsgroups.
Internet Services
Video Conferencing - Video conferencing
is a technology that allows people
located in different locations to meet
and communicate visually via the
Internet or Intranet.
Internet Services
Internet Telephony - Internet telephony
is the ability to transmit voice over the
Internet, similar to telephone
conversations.
Today’s hardware and software leave a lot
to be desired
Internet Services
Whiteboarding - Whiteboarding is an
Internet application in which two or
more users in different locations can
view and edit the same document on
line at the same time.
Changes show up automatically on each
user’s computer screen as they are
made.
Internet Services
A different color is used for
each user.
Internet Services
Push Technology - Push technology
provides users with custom data
sent directly to their computer
desktops.
TCP/IP
Data is transmitted across the
Internet through a series of
protocols known collectively as
TCP/IP (Transmission Control
Protocol/Internet Protocol)
A protocol is an agreed upon set of
conventions that define the rules of
communication.
TCP/IP
The sending and receiving computers on
the Internet follow the TCP/IP
protocol to ensure that data is
transmitted correctly
Data travels across the Internet
through several levels of networks
until it reaches its destination.
TCP/IP
E-mail messages arrive at the mail
server from a remote PC or from a
node on a LAN.
The message then leaves the local mail
server and travels through a router (a
special purpose computer) that
ensures each message is sent to its
correct destination.
TCP/IP
The mail message will pass through
several networks to get to its
destination.
Each network has its own router that
determines how best to transmit the
message closer to its destination.
The network router considers the
traffic on the network.
TCP/IP
A message passes from network to
network until it arrives at the
destination network.
The message is then sent to the
recipient, who has a mailbox on
that network.
TCP/IP
TCP/IP
TCP/IP applies to all types of data.
Data is sent across the Internet in
packets.
Each packet is limited in size.
Rules for creating, addressing, and
sending the packets are specified
by TCP/IP.
TCP/IP
TCP/IP is actually two separate
protocols.
TCP is the portion that divides the
file to be sent into packets.
TCP then numbers each packet so
that the message can be
reconstructed at the other end.
TCP/IP
IP is the portion that sends each
packet on its way by specifying the
address of the sending and
receiving computers so that the
routers can do their job.
TCP/IP
The TCP/IP protocol is very clever.
The division of large files into
smaller pieces ensures that no
single file monopolizes the network.
TCP/IP
TCP/IP by dividing the file ensures
that the data arrives correctly.
Static [noise] on a telephone line can
be devastating when a file is
transmitted and a byte or bytes
are lost or corrupted.
TCP/IP
The larger the file the greater the
chance of corruption, since the
chance of noise being introduced is
greater.
Small pieces and verification that the
packets are received correctly, helps
ensure data integrity.
TCP/IP
Only incorrect packets need to be
sent again, not the entire file.
TCP/IP connections are expensive
and most cannot justify the high
cost of a permanent TCP/IP
connection to the Internet.
TCP/IP
A standalone personal computer usually
accesses the Internet through a dialup connection via a modem.
This is a temporary connection known
as a SLIP [Single Line Internet
Protocol] or PPP [Point to Point
Protocol] connection.
TCP/IP
SLIP or PPP enables full access to
the Internet as long as the
telephone connection is live.
Internet is built in layers around the
TCP/IP protocol
TCP/IP
TCP/IP
The sending computer
the application layer creates the
message and passes it to the
transport layer
the transport layer divides the
message into packets
the Internet layer addresses the
packets
TCP/IP
The network access layer then sends
the message across the Internet to
its destination.
The process is reversed at the
receiving computer.
Each computer on the Internet must
have TCP/IP drivers or stacks
TCP/IP
Each computer must also have a
unique IP address that identifies
the computer as a node on the
Internet
IP addresses may be permanent or
temporary [changes from session to
session]
TCP/IP
The IP address is composed of four
numbers
Each less than 256
Each separated by a period
Example 134.68.80.40
Each site on the Internet applies for a
block of IP addresses
TCP/IP
Mnemonic addresses rather than
numeric IP addresses can be used
The network administrator assigns
IP addresses to all devices on the
network
The protocols are hardware
independent
TCP/IP
Numeric IP addresses are easy to
process by a computer
However, individuals would rather
use names [mnemonic equivalents]
Which is easier 134.68.80.40 or
webwilly.engr.iupui.edu?
TCP/IP
Domain Name System [DNS]
provides the mnemonic for an IP
address
DNS also ensures that every site on
the Internet has a unique address
TCP/IP
DNS divides the Internet into a
series of networks called domains
which enable data to be sent across
the entire Internet
Each site attached to the Internet
belongs to one of the domains
TCP/IP
Examples
edu --- educational institutions
gov --- government entities
com --- commercial entities
mil --- military organizations
net --- network service providers
org --- nonprofit organizations
TCP/IP
Large domains are subdivided into
subdomains
Mnemonic names must be translated
into IP addresses
A domain root server maintains
information about IP addresses in
its domain