What is a server?
A server is a computer or system that across a network distributes resources, data, services, or applications to other computers known as clients. In principle, computers are called servers when they share resources with client machines. Web servers, mail servers, and virtual servers are among the several kinds of servers.
At the same time, an individual system may contribute resources and take resources from another system. This implies that a device may function as both a server and a client.
Mainframe computers and minicomputers were among the earliest servers. The term comes from the fact that minicomputers were significantly smaller than mainframe computers. However, as technology advanced, they grew to be considerably bigger than desktop computers, making the title "microcomputer" a bit of a misnomer.
Initially, such servers were linked to terminals, which did not do any real computation. Dumb terminals accepted input through a keyboard or card reader and output the results of any calculations to a display screen or printer. The server was used to do the calculations.
Later, servers were often single, powerful computers linked to a group of less powerful client computers through a network. The client-server paradigm is a network architecture in which both the client computer and the server have computational capability, but some duties are allocated to servers. Even while it wasn't called that by that name in prior computer architectures, such as the mainframe-terminal model, the mainframe did operate as a server.
As technology has progressed, so has the definition of a server. A server nowadays might just be software operating on one or more physical computer devices. Virtual servers are a term used to describe these types of servers. Virtual servers were first utilized to expand the amount of server operations that a single hardware server could do. In today's world, virtual servers are often hosted by a third-party on hardware located across the Internet, in a process known as cloud computing.
A server, such as a mail server, may be built to do a specific purpose, such as accepting and storing messages before delivering it to a requesting client. Servers may also perform a variety of functions, such as storing data and accepting print jobs from clients before sending them to a network-attached printer.
The operation of a server
A device must be set to listen to requests from clients across a network connection in order to act as a server. This capability may be found as an installed program, a role, or a mix of the two in the operating system.
Microsoft's Windows Server operating system, for example, has the ability to listen for and reply to client requests. In addition, added roles or services expand the types of client requests that the server may handle. Another example is an Apache web server, which is an extra program placed on top of an operating system that answers to Internet browser requests.
A client makes a request across the network when it needs data or functionality from a server. This request is received by the server, which replies with the necessary information. This is the client-server networking request and response paradigm, often known as the call and response model.
As part of a single request and response, a server will frequently perform a variety of additional tasks, such as verifying the requestor's identity, ensuring that the client has permission to access the data or resources requested, and properly formatting or returning the required response in the expected manner.
Servers of various types
Servers come in a variety of shapes and sizes, and they all serve various purposes. One or more of the following server types may be found in many networks:
- Servers that store files
File servers are computers that store and deliver files. Files hosted on a server may be shared by several clients or users. Furthermore, instead of striving to ensure security and integrity for information on every device in an organization, centrally storing files allows for simpler backup and fault tolerance solutions. To boost performance, file server hardware may be built to optimize read and write speeds.
- Servers for printing
Print servers are used to manage and distribute printing capabilities. Rather of installing a printer on each workstation, a single print server can handle many clients' printing requirements. Some higher-end printers now have their own built-in print server, eliminating the need for a separate computer-based print server. This internal print server likewise works by responding to client print requests.
- Servers for applications
Instead of client computers executing apps locally, application servers execute them. Application servers are often used to execute resource-intensive programs that are shared by many users. This eliminates the need for each client to have enough resources to execute the apps. It also eliminates the need to install and maintain software on several computers rather than just one.
- DNS servers (Domain Name System)
DNS servers are application servers that offer name resolution to client computers by transforming 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 may be used to request a computer name that is otherwise unknown. When a client requires the address of a system, it makes a DNS request to a DNS server with the name of the requested resource. From its collection of names, the DNS server replies with the required IP address.
- Servers that handle email
Mail servers are a typical application server type. Emails sent to a user are received by mail servers, which hold them until a client on behalf of that user requests them. With an email server, a single computer may always be correctly setup and connected to the network. Rather of needing each client computer to have its own email subsystem operating all of the time, it is then ready to send and receive messages.
- Servers for the internet
A web server is one of the most common kinds of servers on the market today. A web server is a kind of application server that hosts applications and data that users request through the Internet or intranet. Web servers react to requests for web pages or other web-based services from browsers on client computers. Apache web servers, Microsoft Internet Information Services (IIS) servers, and Nginx servers are all common web servers.
- Servers for databases
Companies, customers, and other services utilize a stunning quantity of data. Databases have a lot of that information. Databases must be accessible by several clients at the same time, and they may take up a lot of disk space. Both of these requirements lend themselves to storing databases on servers. Database servers execute database applications and handle a large number of client queries. Oracle, Microsoft SQL Server, DB2, and Informix are all popular database server software.
- Servers that are virtual
Virtual servers have taken over the server world. Unlike conventional servers, which have an operating system installed on machine hardware, virtual servers are solely defined by specialized software known as a hypervisor. Each hypervisor may simultaneously operate hundreds, if not thousands, of virtual servers. Virtual hardware is presented to the server as if it were actual physical hardware via the hypervisor. The hypervisor sends the actual computing and storage demands onto the real hardware underlying the virtual server, which is shared across all the other virtual servers.
- Proxy servers are computers that act as intermediaries between two parties
Between a client and a server, a proxy server functions as a middleman. A proxy server accepts the request from the client and isolates either the clients or the servers for security reasons. It sends the request to another server or process instead of answering to the client. After receiving the answer from the second server, the proxy server responds to the original client as if it were responding independently. Neither the client nor the answering server must connect directly to each other in this manner.
- Servers for monitoring and management
Other systems and clients are monitored and managed by certain servers. Monitoring servers come in a variety of shapes and sizes. Several of them listen to the network and receive every client request and server answer, whereas others do not send or receive data. The monitoring server may therefore maintain watch of all network traffic, as well as client and server requests and servers, without interfering with their processes. Monitoring clients, such as those used by network managers to keep an eye on the network's health, will send queries to a monitoring server.
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