V

vendor class

An administrative feature that allows DHCP clients to be identified and leased according to their vendor and hardware configuration type. For example, assigning a vendor class of HP to a printer vendor such as Hewlett-Packard would allow all Hewlett-Packard printers to be managed as a single unit so they could all obtain a similar DHCP leased configuration. See also Dynamic Host Configuration Protocol (DHCP); lease.

virtual cluster

A Network Load Balancing cluster that you create by assigning specific port rules to specific virtual IP addresses. With virtual clusters, you can use different port rules for different Web sites or applications hosted on the cluster, provided each Web site or application has a different virtual IP address.

virtual directory

A directory name , used in an address, that corresponds to a physical directory on the server. Sometimes called URL mapping.

virtual local area network (VLAN)

A logical grouping of hosts on one or more local area networks (LANs) that allows communication to occur between hosts as if they were on the same physical LAN. See also host; local area network (LAN).

virtual private network (VPN)

The extension of a private network that encompasses encapsulated, encrypted, and authenticated links across shared or public networks. VPN connections typically provide remote access and router-to-router connections to private networks over the Internet. See also routing; tunnel.

virtual server

A virtual computer that resides on a Hypertext Transfer Protocol (HTTP) server but appears to the user as a separate HTTP server. Several virtual servers can reside on one computer, each capable of running its own programs and each with individualized access to input and peripheral devices. Each virtual server has its own domain name and IP address, and each appears to the user as an individual Web site or File Transfer Protocol (FTP) site. Some Internet service providers (ISPs) use virtual servers for those clients who want to use their own domain names . Also called a Web site.

volume set

A volume that consists of disk space on one or more physical disks. A volume set is created by using basic disks and is supported only in Windows NT 4.0 or earlier. Volume sets were replaced by spanned volumes , which use dynamic disks. See also dynamic disk.