Learn about networks............

1.  Definition:
A network is a way to connect computers for communication, data exchange
and resources
Common Types of Network:
LAN (Local area network )
It’s a data communication system consisting of several devices such as
computers and printers. in this network computers are near to each OTHER
AND PHYSICALLY CONNECTED WITH CABLES
WAN (Wide area network):
one or more LAN’s are connected together generally across a wide a
geographical area.
CHAPTER 7
NETWORKS

2. Hybrid Networks
 Between LAN and WAN structures, you will find hybrid networks such as campus
area networks (CANs) and Metropolitan area networks(MANS.
 A new form of network type is emerging called home area networks(HANs)
 CAMPUS AREA NETWORKS( CANs):
it follows the same principle as a local area network, only on a larger and more
diversified scale. Different campus , offices can be linked together.
METROPOLITAN AREA NETWORKS( MANs):
It’s a larger scale network that connects multiple corporate LANs together. MANs
usually are not owned by single organization –their communication devices and
equipment are usually maintained by group or single network provider that sells its
networking services to corporate customers.

3. Contd…
 Home area networks(HANs)
 This network contained within a user’s home that connects
a person’s digital devices, from multiple computers and
their peripheral devices e.g. Printers, telephones , VCR,
DVDs.
* Peripheral devices are expensive ones such as high volume
laser printers,

4. Intranets and extranets
 An intranet is the generic term for a collection of
private computer networks within an organization.
 An extranet is a computer network that allows
controlled access from the outside for specific business
or education purposes.
 Intranets and extranets are communication tools
designed to enable easy information sharing within
workgroups.

5. How Networks are structured
 SERVER- BASED NETWORKS
Here you must know about Node. NODE is a processing location
that can be a PC or some other devices such as a networked printer.
Server based networks include many nodes and one or more servers
which control user access to network’s resources.
 CLIENTS/SERVER NETWORKS
Here individual computers share the processing and storage
workload with a central server. This arrangement requires special
software for the nodes and server.. Its can be used on LAN’s or
WANs.

6. PEER to Peer networks
 In this network , all nodes on the network have equal relationships to all others ,
and all have similar types of software that support the sharing of resources
What are the sophisticated tools to combat cyberslacking involving the internet?
1. Web Filters: Filtering software enables companies to block employee access to
certain web sites
2. Surveillance software: Software enables managers to review an employee’s
internet activities in real time e.g. uploading, downloading, chatting etc.
3. Proxy servers: This type of software can be configured to trap network traffic that
is coming from or going to unauthorized source.
4. Packet Sniffers: It examine all packets being transmitted over a network. Packet
sniffers are effective at detecting traffic bound for internet services e.g. FTP

7. Topologies
 Definition:
Network topology is the arrangement of various elements (nodes) of a computer network.
There are further topologies:
1. Bus topology: this network uses one cable. All nodes and peripheral devices are connected in a
series to that cable, a special device called terminator that attach with cable’s starting and
ending point, to stop network signals so they do not bounce back down the cable.
2. Star topology: All nodes are connected to a device called hub and communicate through it.
Some hubs are known intelligent hubs( because they monitor traffic and help prevent collisions)
3. Ring topology: it connects the network’s nodes in a circular chain with each node connected
to next. The last node connected to the first, so completing the ring
4. Mesh topology: This is the least used topology and most expensive to implement.in this a
cable runs from every computer to every other computer.

9. Protocol:
 A protocol is an agreed- upon format for transmitting data
between two devices,. Some popular protocols include
TCP/IP ( the internet protocol), Net-BIOS/NetBEUI

10. Broadband connections
 DEFINITION:
 Broadband is used to describe any data connection that can transmit data faster
than is possible through a standard dial up connection using modem.
 DSL: called digital subscriber line( DSL) is very popular especially with home
users.
 Cable modem connections: it enables home computer users to connect to the
internet through their cable TV connection with higher speed than those offered
by dial up connections
 All above services are not suitable for transmitting live video and sound.as a
result communications companies offer a service called ATM. This protocol
designed to send voice, video and computer data over single network.