Everything you do on the internet from Social networking, Emailing to watching videos make use of the server. All the applications you use on the internet are actually hosted in some remote computer called server.
A Computer on the network which serves other computers is called a server.
In simple sense, it is a computer on the network which basically serves the requests of the client computers on the network. The request from client may be request for some resource such as some file or some web page,these are all taken care by the server. A client simply has to connect to a server on the network and request for resources, if the client is authorized for that resource than definitely the client is served by the server.
Server Operating Systems :
Since a server serves some thousands of clients at any time,the server OS should be Robust, Stable and Secure to meet the demands of the clients connected to it.
There are these special purpose server operating systems which are designed and built specifically to make the server robust,stable,secure and scalable.
A server operating system is not packaged with lots of GUI and flashy applications as seen on normal desktop OS, this is to avoid security vulnerabilities in the server systems.
In server OS you will be given a command prompt,using which required software packages such as Apache Web server, Filezilla, MySQL should be configured and installed.
Some of the well known server operating systems are :-
Ubuntu Linux server.
Red Hat Linux Enterprise Edition.
OpenSuSE Linux Enterprise Edition.
Windows 2008 Server. etc
Server Hardware :
A Server should be up and running 24 hours a day , 7 days a week . Usually the server is booted once or twice in 2-3 months. So, you definitely need special purpose hardware to build such robust,reliable and persistent systems.
- Server Processors : Intel XEON processors are used which are robust and reliable.
- Redundant Power Supplies : Usually servers are provided with 2-3 power cables , to make sure that even if one power cable fails the server is still up and running.You can Hotswap these power modules which basically means that you can remove the faulty power cable and replace with another power cable without rebooting the system.
- RAID ( Redundant array of Inexpensive disks ) : Raid is used to make multiple physical hard disks to fall into a single logical disk. RAID is basically an array of Hard disks which are Hotswappable . Once the hard disks change in the RAID they are configured accordingly to fit in the new hard disk .
- ECC RAM : Since servers need a lot sophisticated RAM which does not get corrupted easily, a special purpose RAM known as ECC RAM is used which does error checking and corrections.
Server Functions :
Servers provide varied functionality to all its clients depending on the request.
Servers are configured with the following software packages to serve clients :
- Apache Web Server : Is a software installed on the server which is used to fetch web pages to the client. IIS is used in-case of Windows 2008 Server.
- FTP Server : Software which serves the clients with files.
- Mail Servers : Which help to send and receive electronic mails.
- Active Directory Service
and much more..
Authentication :
Server resources are protected to prevent illegal access to the data.So usually a client is given permissions to access only specified regions of data on server.So client sends the username and password to the server and then server validates the information and sends back the access token which is used further to access the authorized resources on the server.
Servers are indeed the king of networks in the sense they fulfill all the demands of there clients . Analogy being servers to be the king and clients to be the people in the kingdom ruled by the king.
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