Creating a virtual network

Creating a virtual network

A virtual network consists of one or more virtual machines configured to access local or external network resources. A virtual network is configured to use either a network adapter in the physical computer or no network adapter.

  • If a network adapter in the physical computer is selected, then any virtual machines attached to the virtual network can access the networks to which that physical adapter is connected.
  • If no network adapter is selected, then any virtual machine attached to the virtual network becomes part of the internal virtual machine network. An internal virtual machine network consists of all virtual machines that are attached to a virtual network, which is configured to use no network adapter. Each internal virtual machine network is completely isolated from all other internal virtual machine networks.

Virtual Server supports an unlimited number of virtual networks, and an unlimited number of virtual machines can be connected to a virtual network.

Using a virtual DHCP server

A virtual network includes a virtual Dynamic Host Configuration Protocol (DHCP) server that can provide IP address leases to virtual machines only. You can use the virtual DHCP server instead of configuring a virtual machine as a DHCP server. The virtual DHCP server is disabled by default. If the virtual network is not attached to a physical network adapter, and a virtual DHCP server is activated, then the DHCP server is isolated from all other virtual machines and the host operating system.

Even though the DHCP server is isolated, it assigns unique IP addresses from the range specified. For example, if a virtual network with a virtual DHCP server is configured to use as the starting IP address range, it will assign IP addresses from through only to the virtual machines attached to its virtual network. No other virtual DHCP server will assign an IP address in the range from through The virtual DHCP server reserves the first 16 IP addresses from the start of the specified IP address range; these addresses are never assigned. For more information, see Configure the virtual DHCP server.

Configuring multiple virtual networks on a single physical network adapter

You can associate multiple virtual networks with a single physical network adapter. To do this, first create a virtual network. Next, associate the virtual network with a physical network adapter. Then, attach one or more virtual machines to the virtual network. If you want multiple virtual networks connected to the host operating system, create additional virtual networks and then repeat this procedure.

Virtual networks are not portable

When a virtual network is created, its configuration is dependent on the configuration and physical hardware, such as the type and number of network adapters, of the host operating system. The configuration and physical hardware of a host operating system are likely to be different across computers on which Virtual Server is installed. This makes virtual network portability unrealistic.


If you want to configure a virtual machine without any type of network connectivity, do not attach it to any virtual networks. When you create a virtual network, a virtual network configuration (.vnc) file is created. By default, all .vnc files are located in the \Documents and Settings\All Users\Documents\Shared Virtual Networks folder. For networking best practices, see Best practices for Virtual Server.