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The term Computer Network is used when two or more computers connected together to
share data files, Internet, printer, applications etc. Network can be very simple,
such as a small group of computers that are connected to share the resources
using a hub (or switch) or
they can be very complex covering large geographical areas that use multiple
media (like Frame Relay, leased lines, Ethernet etc.) and protocols (like
TCP/IP, Novell, AppleTalk). |
LAN:
LAN is the acronym of Local Area Network, and usually limited to a specific area
or location. For example, LAN used in a factory is limited within the boundary
of that building. Several small LANs can be combined to make a big LAN using
routers, and switches. Users in a small LAN can be grouped into a workgroup.
A big LAN may consist of several such small groups of users.
WAN:
WAN stands for Wide Area Network. A WAN may be spread across several cities,
states, and countries. WANs normally use public switched networks, and telecom
lines to communicate across boundaries.
WAN vs LAN:
The Internet is an example of Wide Area Network.
Full-Duplex and
Half-Duplex Communications:
The term Full-Duplex communication mean simultaneous flow of information in both the directions. The term Half-Duplex mean, communication in only one direction at any given point of time.
Host, Workstation,
and Server:
Host, Workstation, and Server are the most common network entities used.
Hosts:
Host
is a generic term representing a network node, and could mean a work station, or
a server. It is most commonly used when
discussing TCP/IP-related services and functions. Workstations, servers, and any
other network device as long as it has one or more IP address it can be
considered as hosts.
Workstations:
The term network normally refers to any computer that is connected to the
network; a workstation is a computer that can request resources. Workstations
can be clients, but not all clients are workstations. For example, a printer can
request resources from the network, but it is a client and not a workstation.
Servers:
A Server provides required resources to its
clients. The Server will have a Network Operating System (NOS) that enables the
communication between the Server and Clients. Usually, servers are
specialized for single purpose such as file server, proxy server etc. Of course,
you can configure a single server to do several jobs like authentication, file
services, proxy services etc., but that depends on how much load the server can
take, and provision for future expansion. The following are the some server examples that are dedicated to a single task:
File Server:
A file server stores, and distributes files over the network to work stations.
Print Server: A print server will have one or more printers attached either directly or indirectly (through network), and are managed by the print server. Typically, print requests from work stations go to the print server, and the print server manages the print job for the work station. Now, with the advent of Network Printers, the need for a separate server computer for print services is diminishing.
Proxy Server:
Performs a function on behalf of other computers.
Application Server:
Hosts one or more network applications.
Web Server:
A Web Server holds and delivers web pages and other web contents using HTTP, and
other web based protocols.
Mail Server:
A Mail Server is responsible for storing all incoming and outgoing emails. It
also receives and delivers individual emails to respective work stations. The
work stations normally use email client software to communicate with the Mail
Server.
Fax Server:
Sends and receives faxes for the entire network without the need for
Remote Access Server (RAS): Sometimes, it may be necessary to access a corporate network from a remote place. This can be achieved by Remote Access Server. With the help of a RAS, remote users with appropriate client software can connect to the server using dial-up access or leased line.
Client/Server
Network:
The
client/server network uses a Network Operating System (NOS) to manage the entire
network from a centralized point, that is the server. The clients make requests
to the server and the server responds with the information or access to a
resource.
Peer-to-Peer
Network:
In Peer-to-Peer networks, the connected computers share the resources. If a user of one computer wants to access a resource on another computer, the security check for access rights is the responsibility of the computer holding the resource. With computers becoming more and more powerful in terms of computing resources, peer-to-peer networking is gaining popularity.
Client/Server network vs Peer-to-Peer Network:
The client/server network is more
organized and it is easy to find files and resources because they are
stored at a centralized location (Server computer). The security of client/server network is high that all the
usernames and passwords are stored in the same database and individual users can’t
use the server as a workstation. Hence a client/server network gives a better
protection against accidental/intentional misuse.
On the other hand, in a Peer-to-Peer network, by spreading the resources across individual workstations, it is possible to use the resources of these machines.
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