Mail servers have a centrally-located pool of disk space to store and share emails for network users. There are two main categories, outgoing mail servers and incoming mails servers. Outgoing mails servers as known as SMTP servers. Incoming mails servers come in two varieties, POP3 and IMAP. Web servers usually use the POP3, IMAP, SMTP and HTTP protocols.
An application server is a mixed framework of software that allows both the creation of web applications and a server environment to run them. It can often be a complex stack of different computational elements running specific tasks that need to work as one to power the multiple clouds and web-based software and application. An application server is designed to install, operate and host applications and associated services for end users. It is commonly paired with a web server or contains a web server which means the two can be converged and named a web application server.
File Transfer Protocol (FTP)
A separate control and data connections are used by the FTP between the client and the server. It is possible for the FTP users to authorize themselves in the form of a username and a password. They can connect using anonymous names if the server isn’t configured to allow them. For transmission security, the username and password need to be encrypted using the FTP and SSL. FTP sessions work in passive or active modes. In active mode, after a client initiates a session via a command channel request, the server initiates a data connection back to the client and begins transferring data. In passive mode, the server uses the command channel to send the client the information it needs to open a data channel, because passive mode has the client initiating all connections, it works well across firewalls and network address translation (NAT) gateways.
A data base server is a program that offers database services to other computer programs or computers with the use of client-server functionality. There are some database management software such as MySQL that depend on the client-server model for database access. This type of server is accessible either via a “front end” that runs on the user’s computer where the request is made or the “back end” where it is served such as data analysis and storage.
Domain Name System (DNS) Server
A computer server that hosts a network service for offering response to queries is called a name server. It maps either an addressing component or numeric identification. This is done by the server to give response to a network service protocol request. DNS servers mainly translate domain names and host names into the corresponding numeric Internet protocol address (IP address). DNS also helps to recognise a namespace of the Internet, used to identify and locate computer systems and resources on the Internet. There are 13 important DNS root servers on the internet that store a complete database of domain names and their associated public IP addresses. These top-tier DNS servers are named A through M for the first 13 letters of the alphabet. Ten of these servers are in the US, one in London, one in Stockholm and one in Japan.