A server is a device or machine that over a network distributes resources, data, facilities, or programs to other computers known as clients. In theory, computers are called servers as they share resources with client machines. Web servers, mail servers, and virtual servers are among the various types of servers. At the same time, an individual system will provide resources and use resources from another system. This means that a computer will act as both a server and a client.
Mainframe computers and minicomputers were among the first server. The name comes from the fact that minicomputers were much smaller than mainframe computers. However, as technology advanced, they grew to be far larger than desktop computers, making the word “microcomputer” a bit of a misnomer.
Initially, such servers were linked to terminals, which did not do any actual computation. Dumb terminals accepted input through a keyboard or card reader and output the results of any computations to a display screen or printer. The server was used to perform the calculations.
Working Of A Server
A system must be configured to listen to requests from clients over a network connection in order to act as a server. This functionality can be found as an installed feature, a position, or a combination of the two in the operating system. Microsoft’s Windows Server operating system, for example, includes the ability to listen for and respond to client requests. In addition, installed roles or services expand the types of client requests that the server can handle. Another example is an Apache web server, which is an external program built on top of an operating system that responds to Internet browser requests.
A client sends a request over the network when it requires data or features from a server. This request is received by the server, which responded with the necessary details. This is the client-server networking request and response model, also known as the call and response model.
As part of a single request and response, a server will often perform a variety of additional tasks, such as verifying the requestor’s identity, ensuring that the client has permission to access the data or services requested, and properly formatting or returning the appropriate response in an expected manner.
Types of servers
Data servers are computers that store and distribute data. Files stored on a server may be shared by several clients or users. Furthermore, instead of having to provide protection and integrity for data on any computer in an enterprise, centrally storing files allows for faster backup and fault tolerance solutions. To boost performance, file server hardware can be built to optimize read and write speeds.
Client computers run applications locally, while application servers run applications remotely. Application servers are often used to run resource-intensive applications that are shared by several people. This eliminates the need for each client to have adequate resources to run the applications. It also eliminates the need to install and manage software on many computers rather than just one.
DNS servers are application servers that offer name resolution to client computers by translating names that humans can understand into machine-readable IP addresses. The Domain Name System (DNS) is a globally distributed database of names and other DNS servers, each of which can be used to request a computer name that is otherwise unknown. When a client requires the address of a device, it sends a DNS request to a DNS server with the name of the requested resource. From its table of names, the DNS server responds with the required IP address.
Mail servers are a popular application server category. Emails sent to a user are received by mail servers, which store them before a client on behalf of that user requests them. With an email server, a single computer can still be correctly configured and connected to the network. Rather than needing each client machine to have its own email subsystem running all of the time, it is then ready to send and receive messages.
One of the most abundant types of servers in today’s market is a web server. 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 Apache web servers, Microsoft Internet Information Services (IIS) servers, and Nginx 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. Common database server applications include Oracle, Microsoft SQL Server, DB2, and Informix.
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 a 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. The virtual server uses the virtual hardware as usual, and the hypervisor passes the actual computation and storage needs onto the real hardware beneath, which is shared among all the other virtual 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.
Monitoring and management servers
Some servers exist to monitor or manage other systems and clients. There are many types of monitoring servers. Several of them listen to the network and receive every client request and server response, but some do not request or respond to data themselves. In this way, the monitoring server can keep track of all the traffic on the network, as well as the requests and replies of clients and servers, without interfering with those operations. A monitoring server will respond to requests from monitoring clients such as those run by network administrators watching the health of the network.