Local virtual directories created for folders stored on any hard drive installed on the computer running IIS.
When configuring a local virtual directory, you will be asked to assign an alias to that folder. This alias can be folder's name or any other name that identifies the site to the end user. Also, you will be asked to enter the path of the virtual directory.
Remote Virtual Directory
Remote virtual directories created for folders on hard drives installed on other computers within the IIS domain.
When configuring a remote virtual directory, you will be asked to assign an alias to that folder. You will also ask for the Universal Naming Convention (UNC) address for the folder. To access the folder using the UNC, you will have to enter a valid username and password. All visitors who access data in the virtual directory will automatically use this username and password.
A virtual directory is a folder that appears to the users, to be in the wwwroot (home) folder. However, a virtual directory can be on any computer in the same Microsoft Windows NT domain. Virtual directories created for folders located on:
The same hard drive as the wwwroot directory.
Another hard drive, inside the local computer.
Another computer's hard drive on the network. This machine must be in the same Microsoft Windows NT Server domain as the IIS computer.
Virtual directories established for both WWW and FTP services running on IIS.
Virtual servers allow you to host multiple Web and FTP sites on one computer, reducing the need to allocate a computer and software for each site. Virtual servers using Host Headers allow one IP address to be used for multiple Web sites. Virtual servers also enable centralized administration and simple upgrading of known software.
Virtual directories offer the Web administrator flexibility when determining where files stored on the server. Files stored are most easily updated or accessed. Also, the additional storage capacity added without shutting down the server.
Implementing virtual directories may result in a slight performance drop when accessing folders contained on another computer's hard drive. This performance drop associated with the transfer speed of data over a Local Area Network (LAN).
Hosting multiple virtual servers on the same computer may reduce the overall performance of the server. Web Virtual servers using Host Headers require a Web browser that is HTTP version complaint.