When we talk about servers, we usually do it on the machines that populate the Internet and data centers, where all the digital services we enjoy today fall. There are different types of servers. Although we could also be talking about a software program in a client/server programming model. Therefore, this would be the first classification of servers, depending on whether we refer to hardware (machines) or software (programs):
Software server: a computer program that provides a service or response to other computer programs or users.
Hardware server: physical equipment on which programs or applications are executed.
Sometimes, what used to be a hardware server, becomes a software server because the power of the machines today is very large and can serve many software servers at the same time.
In this article we will focus on the main hardware and software servers because depending on their content and application, we have a great variety:
Different types of servers
Depending on the role they play and ordering them alphabetically, we can talk about:
It acts as a communication bridge between networks, servers, and users. They are usually computers that are located at the border of different networks, with communication cards and authentication mechanisms to allow passage between them. An example could be the old remote access server of the Polytechnic University of Valencia, which users called using a modem and allowed them to access the university’s internal network, to check their notes and other campus services.
Its function is to serve as a repository or storage of computer files. An example can be the servers that Google Drive or Dropbox uses to save our documents, photos, videos …
As its name implies, it stores databases and provides management and consultation services to the clients that connect. Almost all servers perform this function because every application usually has a database, but there are dedicated exclusively to this service, such as the servers of a bank’s central databases.
It is responsible for managing email: send, receive, and store messages. Every Internet domain usually has one, which is responsible for managing their email accounts, for example, www.domain.com would have a server that would manage emails of the type email@example.com. Surely you sound protocols like POP3, SMTP, IMAP … these servers use them to communicate with each other and distribute email messages throughout the world.
DNS is the English acronym Domain Name System. It translates the IP address of a physical Internet server, such as 220.127.116.11 into a domain name, easily identifiable by humans, such as www.example.com.
Today it is almost obsolete, due to the rise of email. Performs the management of electronic faxes, similar to the mail server: send, receive and store messages.
In environments where many print jobs are performed, such as a large office, there is usually a server of this type, which is responsible for processing print jobs and sending them to the corresponding printers.
Manages telephone calls or IP voice, offers switchboard functions such as call waiting, and transfers or routes calls to other servers. Today virtually all telephone exchanges are virtual, managed by telephone servers.
Its function is to replace the main server (of any type) in case of a failure or error that does not allow to continue offering service. All current digital services infrastructure is based on architectures with backup servers to prevent possible hardware failures. If one server has a problem, another goes into service almost instantly.
It offers protection and security services to a network such as anti-intrusion systems, antivirus, antimalware, firewalls …
It executes applications and offers the services of these to the clients that connect. They can be of a very varied nature, practically every service in the cloud or Internet runs in them. The execution of applications usually triggers the connection to other types of servers such as databases.
Its task is to store a copy of the information of a web server to speed up its delivery to Internet clients. If we think of the worldwide web. We could use a proxy server in each continent to improve the latency of users accessing from different parts of the world.
The virtualization, so fashionable today, allows that within a single physical server several logical servers that customers eyes act as independent servers running. This allows to increase the degree of server utilization and improve efficiency. Based on the use of the same by one or more clients, we could classify the virtual servers in:
Shared virtual server: offers its services to more than one different client or company.
Dedicated virtual server: offers its services to a single client or company, which access exclusively.
They store web pages and distribute them on the Internet or to the clients that connect. They use protocols such as HTTP or HTTP2 to serve documents in HTML, PHP, ASP … The most popular: Apache, NGINX, Lighttpd, Microsoft IIS.
Those are the different types of servers.