DHCP: The server should be bound to an IPv4 address

  • Article

Applies To: Windows Server 2008 R2, Windows Server 2012

This topic is intended to address a specific issue identified by a Best Practices Analyzer scan. You should apply the information in this topic only to computers that have had the Dynamic Host Configuration Protocol Best Practices Analyzer run against them and are experiencing the issue addressed by this topic. For more information about best practices and scans, see Best Practices Analyzer (https://go.microsoft.com/fwlink/?LinkId=122786).

Operating System

Windows Server 2008 R2, Windows Server 2012

Product/Feature

Dynamic Host Configuration Protocol (DHCP)

Severity

Error

Category

Prerequisite

Issue

This DHCP server is not bound to an IPv4.

Impact

A server that is not bound to an IPv4 address cannot lease IPv4 addresses, or any other network configuration, to DHCP client.

Resolution

Using DHCP MMC, add bindings to one or more IPv4.

You may encounter this error if you don’t have a static IP address assigned to your DHCP server, or if you have a multihomed DHCP server. A multihomed DHCP server is a computer running Windows Server 2008 R2 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 R2 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 R2 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.

Note

  • 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 R2 and are inconsequential for server bindings.

  • DHCP servers running Windows Server 2008 R2 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).

    • To perform these procedures, you must be a member of the Administrators group, or the DHCP Administrators group, or you must have been delegated the appropriate authority.

    To Add IPv4 Bindings

    1. Click Start, click Administrative Tools, and then click DHCP.

    2. In the console tree, right-click the DHCP server to which you want to add bindings.

    3. Click Add/Remove Bindings in Server Binding Properties, select check boxes for any statically configured network connections that should be enabled for use with IPv4 at the applicable DHCP server.

    4. Click OK.

    Additional references

    For updated detailed IT pro information about DHCP and selectively enabling or disabling DHCP server bindings, see the Windows Server 2008 R2 documentation on the Microsoft TechNet Web site.