Download Networks Local area network

Networks
Networks Topology
Local area network (LAN(
Wide-area network (WAN(
Know the Definitions of Local Area Networks (LAN)
and Wide Area Networks (WAN).
• LAN
– A LAN (Local Area Network) is a system whereby individual
PCs are connected together within a company or organization
• WAN
– A WAN (Wide Area Network) as the name implies allows you to
connect to other computers over a wider area (i.e. the whole
world).
Know the Definitions of Local Area Networks (LAN)
and Wide Area Networks (WAN).
• If ten people are working together within an office
it makes sense for them all to be connected.
• In this way the office can have a single printer
and all ten people can print to it.
• In a similar way other devices such as
modems or scanners can be shared.
• Even more useful is the ability to share
information when connected to a network.
Networks Architecture
peer-to-peer
all nodes on a network are
equal and resources are
shared equally
client/server
Networks Topology
Bus
Token Ring
Star
Networks Protocols
Data packets
TCP/IP : Transmission Control Protocol/Internet Protocol
HTTP : Hypertext Transfer Protocol
PPP : Point-to-Point Protocol
FTP : File Transfer Protocol
Repeater
A repeater is used to extend the signal distance of the
cable by regenerating the signal .
Hub
if an 8-port hub receives a signal on
port 4, the hub immediately passes the
signal to ports 1, 2, 3, 5, 6, 7, and 8 .
Switch
sends the message out only to the port on which
the addressee workstation exists based on a
MAC table that is created by listening to the
nodes on the network .
Bridge
Bridges are used to connect
two different LANs or two
similar network segments
Router
This device sends data across
networks using the logical or
network address of a message to
determine the path that the data
should take to arrive at its
destination .
Modems
(modulator/demodulator)
Dial-Up Networking
Converts the digital data signal of the PC
into the analog data signal
plain old telephone system (POTS)
public telephone switched network (PTSN)
Internet / Intranet
Domains
domain is a collection of hardware and
software resources and the user accounts
that have access to them .
Internet Domains
Internet domain : Domain Name Server/System (DNS).
www.yahoo.com
Top-Level Domains (TLDs)
TLD
Purpose
.com
Unrestricted, but intended for commercial entities
.edu
U.S. educational institutions
.gov
U.S. government agencies
.info
Unrestricted use
.mil
U.S. military
.net
Unrestricted use, but intended for network access providers
.org
Unrestricted use, but intended for nonprofit organizations and
organizations that don't fit elsewhere
A Little About the Technology
• A message sent over the Internet is divided
into uniformly sized packets
– Each packet labeled with its destination address
• Transmission Control Protocol/Internet
Protocol (TCP/IP)
– TCP creates and reassembles packets
– IP handles addressing
• Ensures that packets are routed to their ultimate
destination
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The Internet Service Provider
and the Browser
• An Internet service
provider (ISP) provides
the server computer and
software to connect to
the Internet
– Online service, such as
America Online, includes
Internet access, Internet
service, and a browser
• When you connect to the
Internet, the browser
displays a home page
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Browser Functions
•
•
•
•
•
Menus and buttons
Uniform Resource Locator (URL)
Plug-ins
Web page programs
Wireless Internet access
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File Transfer Protocol (FTP)
• A protocol for transferring files among computers
• FTP servers maintain collections of downloadable
files
– Downloading can often be done anonymously, without logging
in
• Many FTP servers can be accessed through Web
browser
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Mail Server
• Collects and stores messages in mailbox
• E-mail address consists of user name, followed
by @ symbol, then domain name of mail server
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E-Mail Client Software
• Allows you to manage your e-mail messages
• Features
– Address books
– The ability to attach files
•
Some e-mail servers block all attached files
– Filters
•
•
Direct incoming e-mail to specific folders
Block spam
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