Reserved IP can be issued to any client if DHCP failover is configured in Windows Server 2012 R2 or Windows Server 2012

Symptoms

Consider the following scenario:

• You configure Dynamic Host Configuration Protocol (DHCP) failover in Windows Server 2012 R2 or Windows Server 201.

• You configure exclusion ranges in a scope.

• You configure reservations for IP addresses from an exclusion range.

• A DHCP server issues an IP address to one of the clients that have reserved MAC addresses.

• You run the ipconfig /release command at a command prompt on the client that has reserved MAC address to force it to free its IP address.

In this scenario, the reserved IP address can be issued to any client.

Resolution

To resolve this issue for Windows Server 2012 R2, install update 2919355.
To resolve this issue for Windows Server 2012, install update rollup 2919393.

For more information about how to obtain update 2919355, click the following article number to go to the article in the Microsoft Knowledge Base:

2919355 Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 Update April, 2014
For more information about how to obtain this update rollup package, click the following article number to go to the article in the Microsoft Knowledge Base:

2919393 Windows RT, Windows 8, and Windows Server 2012 update rollup: February 2014

Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

For more information about the ipconfig command, go to the following Microsoft website:

General information about the ipconfig commandFor more information about how to manage scopes, go to the following Microsoft website:

How to manage scopes

References

See the terminology Microsoft uses to describe software updates for more information.