A server is a computer or system that provides resources, data, services, or programs to other computers, known as clients.
How a server works
To function as a server, a device must be configured
to listen to requests from clients on a network connection. This functionality
can exist as part of the operating system as an installed application, role, or
a combination of the two. For example, Microsoft’s Windows Server operating
system provides the functionality to listen to and respond to client requests.
Additionally installed roles or services increase which kinds of client
requests the server can respond to.
Types of servers
There are many types of servers that all perform
different functions. Many networks contain one or more of the common server
types:
- ü File
servers
- ü Print
servers
- ü Application
servers
- ü Mail
servers
- ü Web
servers
- ü Database
servers
- ü Virtual
servers
- ü Proxy
servers
File servers
File servers store and distribute files. Multiple
clients or users may share files stored on a server. In addition, centrally
storing files offers easier backup or fault tolerance solutions than attempting
to provide security and integrity for files on every device in an organization.
File server hardware can be designed to maximize read and write speeds to
improve performance.
Print server
Print servers allow for the management and
distribution of printing functionality. Rather than attaching a printer to
every workstation, a single print server can respond to printing requests from
numerous clients.
Application servers
Application servers run applications in lieu of client
computers running applications locally. Application servers often run
resource-intensive applications that are shared by a large number of users.
DNS servers
Domain Name System (DNS) servers are application
servers that provide name resolution to client computers by converting names
easily understood by humans into machine-readable IP addresses. The DNS system
is a widely distributed database of names and other DNS servers, each of which
can be used to request an otherwise unknown computer name. When a client needs
the address of a system, it sends a DNS request with the name of the desired
resource to a DNS server. The DNS server responds with the necessary IP address
from its table of names.
Mail servers
Mail servers are a very common type of application
server. Mail servers receive emails sent to a user and store them until
requested by a client on behalf of said user. Having an email server allows for
a single machine to be properly configured and attached to the network at all
times. It is then ready to send and receive messages rather than requiring
every client machine to have its own email subsystem continuously running.
Web servers
A web server is
a special kind of application server that hosts programs and data requested by
users across the Internet or an intranet. Web servers respond to requests from
browsers running on client computers for web pages, or other web-based
services.
Common web servers include:-
- Ø
Apache web servers,
- Ø
Microsoft Internet
Information Services (IIS) servers and
- Ø Nginx servers.
Database servers
The amount of data used by companies, users, and other
services is staggering. Much of that data is stored in databases. Databases
need to be accessible to multiple clients at any given time and can require
extraordinary amounts of disk space. Both of these needs lend themselves well
to locating such databases on servers. Database servers run database
applications and respond to numerous requests from clients.
database server applications include:-
- Ø
Oracle,
- Ø
Microsoft SQL
Server,
Virtual servers
Virtual servers are taking the server world by storm.
Unlike traditional servers that are installed as an operating system on machine
hardware, virtual servers exist only as defined within specialized software
called hypervisor. Each hypervisor can run hundreds, or even thousands, of
virtual servers all at once. The hypervisor presents virtual hardware to the
server as if it were real physical hardware.
Proxy servers
A proxy server acts as an intermediary between a
client and a server. Often used to isolate either the clients or servers for
security purposes, a proxy server takes the request from the client. Instead of
responding to the client, it passes the request on to another server or
process. The proxy server receives the response from the second server and then
replies to the original client as if it were replying on its own. In this way,
neither the client nor the responding server needs to directly connect to each
other.
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