Virtual Servers
In a Nutshell - CIW Course Section 3, Part A1, Chapter 9
Virtual Servers
A virtual server is an additional instance of a given server on any individual machine. In the context of this course it refers to web servers. Apache, Domino, Netscape, and Microsoft Internet Information Server allow additional instances to be created. However web servers are not the only servers that can create virtual instances of themselves, database servers such as Microsoft SQL server can also act as a virtual server.
Shared Virtual Servers
Shared virtual servers will share one network card and one IP address. Each server will be allocated a different port number to uniquely identify it. Any port number higher than 1023 may be used for a shared virtual server.
Simple Virtual Servers
Simple virtual servers will share one network card but will each have it's own IP address on that network card. This is dependent on the operating system being able to bind more than one IP address to a network card. Unix and Microsoft Windows 2000 both allow multiple IP addresses to be bound to one network card.
Dedicated Virtual Servers
Each virtual server has it's own IP address on it's own network card. This is more suitable for high throughput servers where the individual network card can handle the higher bandwidth demands.
In order to access the virtual server by specifying a domain name or server name, it is necessary to ensure that DNS has the domain name, IP address and port number entered.
Familiar Virtual Servers
If you have a Web site hosted by an Internet Service Provider, you are using a virtual server, albeit this may be implemented in a different way to those detailed above. It is unlikely that your Web site is using a unique instance of the server, rather it will be sharing the server with many other hosted sites.