Computer science

Page 1

Servers and networks

2 parts to client server:

- Client (your device) - requests resources or services from server

- Server - Powerful computer - provides resources or services - Antivirus , data etc - if lots of requests slows down the server

Page 2

LANS & WANS

One or more servers may be part of a local area network

A server may be part of a wide area network

Google has servers in lots of countries (WAN)

Our school is a LAN

WANs are made up of LANs

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A file server holds all the data files and databases as well as managing backups

A print server may organise printing on different printers

An email server may receive emails, detect and block spam as well as distribute emails to users

A web server may host the school's external website

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Client

Sends a request to the server

Waits for a reply

Receives a reply

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Server

Server waits for request

Acknowledges the request

Server may need to pass the request to another server becoming a client

The requested data is sent back to the client

Page 6

Central server used to manage security

Some files are held on the server

Some processing tasks are performed

Clients issue requests to the server for services

Suitable for many types of organisation

Can require specialist IT staff to administer the network

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Peer to peer

No central server

Cheaper

No central server to control files or security

All computers can easily see files on other computers

All computers can communicate without a server

if a computer is switched off data can't be retrieved

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Easy to set up

Don't need any specialists

Individual devices can share resources

Users can communicate directly with each other and share files

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Drawbacks

Viruses and malware are easily spread

Data backup has to be done in each computer

Files aren't centrally organised but stored individually and could be hard to locate if files are not organised