Chapter 3

 Help you understand different types of servers commonly found on a network including: ◦ File Server ◦ Application Server ◦ Mail Server ◦ Proxy Server ◦ Print Server ◦ Backup Server

 Stores user data files.  Network Operating System (NOS) allows accounts to be set up.  Requires username and password.  Can only access your own files.

 Stores applications for use across networks.  The application server can be used in two ways: ◦ For storing installation files which can easily be deployed across client machines.  Low network traffic but increase in required processing power at client side. ◦ Allows applications that are installed on the server to be run by client from the server side.  High network traffic but less demand on processing at client side.

 Manages mail in and out of a network. ◦ Checks income s for viruses ◦ Filters out SPAM s ◦ Provides central address book for the organisation ◦ Sets and inbox sizes  Useful for both internal and external .

 Used to cache web pages.  When a request is made to a web server, a web page is downloaded and displayed on the client’s computer. It is also stored or ‘cached’ on the proxy server.  Requests for the same page are then downloaded from a proxy server which is much quicker than downloading from the internet.

 Also act as a security buffer.  Clients make a request for a file on a file server.  The proxy intercepts the request and checks the client’s authenticity. ◦ Checks validity of user and they have authorisation to receive a file.  Proxy then requests the file from the file server and forwards it back to the client.  The client never has direct access to the file server.

 Allows access to a shared printer.  Usually come with spooler software. ◦ Spoolers collect jobs that have been sent to a printer, puts them in a queue, and then forwards the print queue to the printer.  Printers work much slower than a computer. This is why we use a spool. ◦ Computers would slow down if each file was sent to a printer as the computer would have to wait for the printer to catch up with it.

 The backup server backs up all data on the network.  If all users save data on the server, the server can automatically back-up files over night.  This means that if data is lost it can be recovered. ◦ It may not be the most up to date version but it is better than having to start again.  It will usually make use of tape drives.