Why and when to use virtual hosting

 

Virtual hosts allow the administrator to isolate, and independently manage, multiple sets of resources on the same physical machine.

Suppose an ISP has two customers whose Internet sites it would like to host on the same machine. The ISP would like to keep the two sites isolated from one another, despite their sharing a machine. The ISP could associate the resources of the first company with VirtualHost1 and the resources of the second company with VirtualHost2.

Now suppose both company's sites offer the same servlet. Each site has its own instances of the servlet, which are unaware of the other site's instances. If the company whose site is organized on VirtualHost2 is past due in paying its account with the ISP, the ISP can refuse all servlet requests that are routed to VirtualHost2. Even though the same servlet is available on VirtualHost1, the requests directed at VirtualHost2 will not be routed there.

The servlets on one virtual host do not share their context with the servlets on the other virtual host. Requests for the servlet on VirtualHost1 can continue as usual, even though VirtualHost2 is refusing to fill requests for the same servlet.

Multiple IP addresses can be bound to linux boxes using IP Aliasing. On Solaris boxes, use logical interfaces to bind additional ip addresses.

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Configure virtual hosts