What Is Server?

          The server is a computer system that provides a specific type of service in a computer network. Server powered by a processor that is scalable and RAM, also comes with a specific operating system, referred to as the network operating system or network operating system. The server is also running administrative software that controls access to the network and the resources contained therein, as well as file or printer device (printer), and provides access to the workstation network members.          

          Generally, in the server operating systems are applications that use the architecture client / server. An example of this application is the DHCP Server, Mail Server, HTTP Server, FTP Server, DNS Server, and others. Each server operating systems typically bundle these services or those services are also available from third parties. Each service will respond to the request from the client. For example, the DHCP client will provide a request to the server running the DHCP server, when a client needs an IP address, the client will give the command / request to the server, in a language understood by the DHCP server, the DHCP protocol itself.          
          Examples of server operating system is Windows NT 3.51, followed by Windows NT 4.0. Currently the system is quite popular is Windows 2000 Server and Windows Server 2003, and Sun Solaris, Unix, and GNU / Linux.          
          The server is usually connected to the client with UTP cable and a network card. The network card is usually a PCI or ISA card.          
          Server function very much, for example, to websites, science, or just data storage. But the most common is to connect the client computer to the Internet.          
          The server is a computer that is central to the management and other computers. Therefore, the server computer must have a higher specification than the client-clientnya. Furthermore servers have different types, some of them: 

Samba server 

          Samba (server message block) protocol file sharing and printer sharing to rival the existing protocol that Novell's IPX-based. SMB is the protocol file sharing and printer sharing first to run on multiple protocols: TCP / IP, NetBEUI, IPX / SPX. In other words, the SMB server can replace the Novell server without having to change the infrastructure of the network. 

 FTP server 

          File Transfer Protocol (FTP) is a protocol that serves for the exchange of files in a network that uses TCP connections instead UDP.Dua important in FTP is an FTP Server and FTP Client.FTP server is a server that is running software that works to provide exchange services where the file server is always ready to provide an FTP service gets a request (request) from client.FTP FTP client is a computer that is requesting a connection to the FTP server for file exchange purpose. Once connected to the FTP server, the client can download, upload, rename, deleting, etc. in accordance with the permission granted by the FTP server.         
          The purpose of the FTP server is as follows: 
• For the purpose of data sharing 
• To provide indirect or implicit remote computer 
• To provide storage for user 
• To provide reliable data transfer and efficient 

 DNS server 

          Domain Name System (DNS) is an application service on the Internet that translates a domain name into an IP address and one of a kind system that serves the request mapping IP address to FQPN (Fany Qualified Domain Name) and from the FQDN to an IP address. DNS is usually used in applications related to the Web Browser sererti internet or e-mail, where DNS helps map the host name to an IP address of a computer. Besides being used in the Internet DNS can also be implemented to a private network or the Internet.DNS Functions. 
1. Regulatory Framework delivery controversially takes advantage of DNS record type, the TXT record. 

2. Provides flexibility for computer failures, some DNS servers provide protection for each domain. Precisely, Thirteen root servers (root server) is used by the entire world. 

DNS Advantage 
1. DNS is easy to be implemented in the TCP / IP 
2. DNS server is easy to configure (for admins) 
3. Users no longer bother to remember the IP address 

Lack DNS 
1. DNS is not easy to implement 
2. Inconsistent
3. Can not make a lot of domain names. 

Web Server 

          Web Server is a server software that functions accept HTTP or HTTPS requests from clients, known as a web browser and send the results back in the form of web pages are generally in the form of HTML documents. One of the popular web server on Linux is Apache. Apache is a cross-platform web server that can run on multiple platforms such as linux and windows. Web Server is a computer that provides services to the internet. The server is also called the host. So that you can put your web design into the net, then you should have the first room on the Internet, and the room is provided by the server. 

Mail server

          Mail servers used to transfer e-mail on TCP / IP network or can be called as a software program that distributes files or information in response to requests sent via email, it is also used in Bitnet to provide similar services FTP.Mail server is the most important in making the point of webmail mail database in the network to perform resource sharing, and can be used to facilitate the Company in the manufacture of webmail. Of the many advances in information technology and e-mail communication is a pretty useful tool among masyasrakat worldwide, with email we can interact and exchange information with each other. Besides that we also need a mail server that can be termed as the post office that regulates the process of sending and receiving messages is also a message storage using database systems. 

 Proxy Server 

          Proxy server is a server computer or computer program that can act as the other computers to make requests for content from the Internet or intranet.          Proxy Server acts as a gateway to the Internet for each client computer. Proxy server is not visible to the client machine: a users interact with the Internet through a proxy server will not know that a proxy server is handling the request does. Web servers that accept requests from the proxy server will interpret these requests as if the request came directly from the client computer, not from the proxy server.          Proxy servers can also be used to secure private network that is connected to a public network (like the Internet). Proxy servers have more functionality than a router that features packet filtering proxy server because it operates at a higher level and have a more thorough control of the access network. Proxy server that serves as a "security agent" to a private network, commonly known as a firewall.