DHCP network interface card bindings
Applies To: Windows Server 2008 R2
A multihomed DHCP server is a computer running a Windows Server® 2008 operating system that uses the DHCP service for more than a single network connection. For a server computer to be multihomed, each network connection must attach the computer to more than a single physical network. This requires that additional hardware (in the form of multiple installed network adapters) be used on the computer.
A computer running a Windows Server 2008 operating system can perform as a multihomed DHCP server. For multihomed servers, the DHCP service binds to the first IP address statically configured for each network connection in use.
By default, the service bindings depend on whether the first network connection is configured dynamically or statically for TCP/IP. Based on the method of configuration it uses, reflected by its current settings in Internet Protocol (TCP/IP) properties, the DHCP Server service performs default service bindings as follows:
If the first network connection uses a manually specified IP address, the connection is enabled in server bindings. For this to occur, a value for IP address must be configured and the Use the following IP address option selected in Internet Protocol (TCP/IP) properties. In this mode, the DHCP server listens for and provides service to DHCP clients.
If the first network connection uses an IP address configured dynamically, the connection is disabled in server bindings. This occurs when the Obtain an IP address automatically option is selected in Internet Protocol (TCP/IP) properties. For computers running Windows Server 2008 operating systems, this is the default setting. In this mode, the DHCP server does not listen for and provide service to DHCP clients until a static IP address is configured.
The DHCP server will bind to the first static IP address configured on each adapter.
By design, DHCP server bindings are enabled and disabled on a per-connection, not per-address basis. All bindings are based on the first configured IP address for each connection appearing in the Network Connections folder. If additional static IP addresses (for example, as set in Advanced TCP/IP properties) are configured for the applicable connection, these addresses are never used by DHCP servers running Windows Server 2008 and are inconsequential for server bindings.
DHCP servers running Windows Server 2008 never bind to any of the NDISWAN or DHCP-enabled interfaces used on the server. These interfaces are not displayed in the DHCP console under the current server bindings list because they are never used for DHCP service. Only additional network connections that have a primary static IP address configured can appear in the server bindings list (or be selectively enabled or disabled there).