Computersight -

Although there are too many different types of servers for me to mention them all here, I will endeavor to present basic information about a few of the more common server types that exist in the networks of today.

The Server Is For All of Us

The first point of note is that servers are not the exclusive prerogative of the client/server network model. They exist in the peer-to-peer network model. They exist in most small user environments. Even those with just the one computer and a network device called a router.

Remember, the moment you connect two computing devices you have a network and wherever a network exists then in all likelihood you will find servers. The point is that a server is not necessarily a separate discrete machine; it is a piece of software acting as an entity, which exists within a computing platform.

The server platform can be any computing device. It could be your desktop PC, or even the laptop, a PDA, an iPod, your phone or any other computing platform what so ever. Mr. Bill Gates reportedly said that he could foresee the day when there would be a computer everywhere in our homes.

Unfortunately, this alone is useless. We humans are users and as such, we consume services. Services are what that which serves provides. In other words, the server entity provides a service or services that other entities consume including the server itself, other servers and users (us).

Your toaster can be a computer containing platform housing a piece of software, called a server, which performs specific functions when asked to do so. In which case these functions would be to have the toast ready just they way you like it when you want it. This would be a type of server called a toaster server.

Without the special piece of “toaster server” software, it would be just another piece of overpowered hardware with some bread in it. Servers are everywhere and they are permeating our lives ever more every day. Just check out your mobile phone. It is the server software inside, which makes it all work at the touch of a button.

Another example that most of us users are generally unaware of is the fact that in using an Internet connection courtesy of an ADSL broadband modem/router we are in fact using a number of servers. There will be a DHCP server, a DNS server, some form of authentication server, a service management server and quite a few more.

Server Types

There are a number of different server types. The delineation between them marked by the differences in the nature of the services that they provide.

These services that servers may provide include all manner of “low level” services, automated services, transparent services, higher level services, user input triggered services, instantaneous services, dependant and independent services, service suites, operating system services, application services and many more. We are going to look at some of each.

Dynamic Host Configuration Protocol (DHCP) Server

The DHSP server can automatically assign a client with an Internet Protocol (IP) Address. The DHCP server is one of the automated that I alluded to when mentioning the single PC and router network above. This type of server once correctly configured can function automatically without the need for human intervention.

Domain Name Service Server (DNS)

The DNS server assigns “human friendly” names to machines and services. For more information, regarding naming services and building your own naming conventions and structures click here Building Your Own Naming Convention.

Domain Controller Server

The domain controller is a directory and name server commonly found in Microsoft Windows Server network environments. The domain controller typically provides authentication, logon privileges, rights and permissions.

In Microsoft Windows Server environments, the domain controller also manages Group Policy. Domain controllers and Group Policy are topics that I will discuss in another article.

File and Print Servers

In most instances, the File and Print servers come in combination as standard features of most operating systems today. This holds true for the Network Operating System (NOS). Together these two servers typically deliver such services as:

• Data Storage Management
• Network Print Server and Print Device (the physical device) Management
• Regulation of File and Print/Printer Resources Access Management
• Monitoring of File and Print/Printer Resources
• File, Folder and Print Services Sharing and Management

Here are a few of the more popular Network Operating Systems (NOS) that natively provide support for File and Print Servers:

• Microsoft Windows Server 2003, Microsoft Windows 2000 Server, Microsoft Windows NT and the more recent Microsoft Windows Server 2008
• Mac OS X Print Server
• Novell SUSE Linux 10.2 Enterprise Edition
• RedHat Linux Server
• Ubuntu Server Edition
• Netgear’s self contained network (Ethernet LAN) attached print server
• Samba – Samba is a free, open-source software solution that allows users to share files among computers running Windows, UNIX, & Mac.

Note: Microsoft’s Windows 2000 and XP operating systems do have built-in file and print server functionality. However, it is the Microsoft’s Windows Operating System (OS) server editions provide significantly better security and scalability than their “general purpose” Windows operating systems.

The Application Server

The application server sometimes referred to as middleware because they may function in between database servers and end users.

The Mail Server

The Email server provides support enabling the transfer and storage of email over private networks (LAN) and across the Internet (WAN).

The Proxy Server

The proxy server acts as an intermediary between LAN users & the Internet. In order to do so proxy servers need to perform a number of server service functions including:

• Masking – Masking of private network IP Addresses to enable devices with private (IP Addresses) network addresses to access the Internet
• Security – Strengthens security by only allowing certain requests to come through and by providing virus protection
• Web Page Caching – The proxy server can cache web page data for a specified period. This allows more rapid future access to the web resource.
• Examples – Some examples of proxy servers include Wingate, Squid etc.
• Microsoft Windows 2000 Server - MS Windows 2000 server or later does not require a dedicated proxy server as this functionality ships with these server platforms by default.

The File Transfer Protocol (FTP) Server

File Transfer Protocol (FTP) servers make it possible to move files from one computer to another via the Internet. Common features and functionality include:

• User Authentication
• File Transfer Policies
• Detailed Activity Logging
• Virtualisation Technologies and Implementations
• Automation Capabilities

The Terminal Server

Dumb terminals (thin clients) supporting only a mouse, keyboard, monitors or printers can attach to the network via standard ports. This means that a dedicated Network Interface Cards (NIC) is no longer a prerequisite for the client and server to communicate via terminal services.

Further more the terminal server performs any processing that is required and sends the result back for the user to see. It provides the Windows desktop GUI to machines that do not have this capability themselves.

It is the job of the network administrator the network administrator will then be able to manage them.

Microsoft’s Terminal Server is a prime example that has been included in their Windows 2000 operating systems (both client and Server versions) and later server versions of the Windows operating system.

The Web Server

The web server’s primary function is to give access to Internet users to attach to the server in order to view and maintain Web pages. Web Browsers such as Microsoft Internet Explorer and Netscape use standard protocols to request documents from a Web server on behalf of a user.

The Web server will retrieve the requested documents and forward them to the Web browser that originally made the request.

Web Server Technologies Supported

Web servers support a variety of technologies including CGI scripts, Active Server Pages, and secure connections to extend the power beyond the basic HTML code. The two most popular Web servers today are:

• Apache (for “A patchy” Web server)
• Internet Information Services (IIS) – Microsoft Internet Information Services (IIS)

There are too many other different types of server for me to cover them all here in this short article. I do hope that information presented here helps you to understand the server better.

For additional information, check the article “Server Platforms”. Until then enjoy!