Microsoft KB Archive/841144

= You are incorrectly permitted to turn on the &quot;DHCP server&quot; option for a virtual network in Virtual Server 2005 =

Article ID: 841144

Article Last Modified on 11/2/2007

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APPLIES TO


 * Microsoft Virtual Server 2005 Standard Edition

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SYMPTOMS
In Microsoft Virtual Server 2005, after you create a virtual network that is connected to a network adapter on the physical computer, you are incorrectly permitted to turn on the DHCP server option for that network.

For example, after you create the virtual network, you are permitted to click DHCP server, and to then click to select the Enabled check box.



WORKAROUND
To work around this problem, turn off the DHCP server option for the virtual network or make sure that you configure a unique DHCP scope for the DHCP server on that virtual network. To turn off the DHCP server option for a virtual network, follow these steps:
 * 1) Start the Virtual Server Administration Website tool. To do this, click Start, point to All Programs, point to Microsoft Virtual Server, and then click Virtual Server Administration Website.
 * 2) Under Virtual Networks, point to Configure, and then click the virtual network that you want to configure.
 * 3) Click the DHCP server link, click to clear the Enabled check box, and then click OK.

To configure the DHCP scope for a virtual network, follow these steps:
 * 1) Start the Virtual Server Administration Website tool. To do this, click Start, point to All Programs, point to Microsoft Virtual Server, and then click Virtual Server Administration Website.
 * 2) Under Virtual Networks, point to Configure, and then click the virtual network that you want to configure.
 * 3) Click the DHCP server link, and then click to select the Enabled check box if it is not already selected.
 * 4) In the Network address box, type the IP address range that you want the virtual network to use.

For example, type 192.168.0.0.
 * 1) In the Network mask box, type the subnet mask for the network address that you specified.

For example, type 255.255.255.0.
 * 1) In the Starting IP address box, type the starting IP address of the range of IP addresses that you want the DHCP server to assign to DHCP clients.

For example, to configure the virtual network DHCP server to distribute IP addresses starting from 192.168.0.55, type 192.168.0.55.
 * 1) In the Ending IP address box, type the ending IP address of the range of IP addresses that you want the DHCP server to assign to DHCP clients.

For example, to configure the virtual network DHCP server to distribute IP addresses ending at 192.168.0.200, type 192.168.0.200.
 * 1) In the Virtual DHCP server address box, type the IP address that you want DHCP clients to use to connect to the virtual DHCP server.

For example, type 192.168.0.1.
 * 1) In the IP address lease time box, type the time value that you want the assigned IP address to be valid for.

When this value expires, the DHCP client must obtain a new IP address from the virtual DHCP server. Typically, a DHCP client tries to renew its IP address when 50 percent of the IP address lease time expires. A short DHCP lease time makes more IP addresses available to DHCP clients, while a longer DHCP lease time reduces network traffic from DHCP clients that submit IP address renewal requests.
 * 1) In the Lease renewal time box, type the time value that you want to the DHCP client to wait before it tries to renew its current IP address with the virtual DHCP server.

A shorter time value reduces the chance that a DHCP client will be not be able to renew its IP address, while a longer lease renewal time reduces network traffic that is caused by IP address lease renewal requests.
 * 1) In the Lease rebinding time box, type the time value that you want the DHCP client to wait before it tries to obtain an IP address from any available DHCP server.

This value is used if the DHCP client cannot successfully renew its IP address from the DHCP server. A shorter time increases network traffic, while a longer time increases the chance that the DHCP client will be not be able to obtain an IP address from a DHCP server.
 * 1) After you have configured the DHCP server settings, click OK.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
If you turn on the DHCP server option on a virtual network that is connected to a network adapter on the physical computer, and if you configure the DHCP scope for that virtual network to the same scope that is used on the external network, you may experience IP address conflicts between computers on the external network and virtual machines that are connected to your virtual network. Therefore, we recommend that you do not turn on the DHCP server option on a virtual network that is connected to a network adapter in the physical computer.

