Event ID 1012 — DHCP Lease Availability

Applies To: Windows Server 2008

Internet Protocol (IP) addresses are leased by the Dynamic Host Configuration Protocol (DHCP) server to its clients. Each lease has an expiration date, which the client must renew if it is going to continue to use that IP address. The DHCP server cannot issue leases to clients if the number of available IP addresses in the scope is insufficient.

Event Details

Resolve

Take no action

A DHCP client might decline an address from the server if:

• A reservation is already assigned to another media access control (MAC) address.
• Static IP addresses on the network are put under exclusion ranges.

This condition should resolve itself, but if it persists, you can reconfigure reservations or exclusion ranges on the DHCP server.

Reconfigure client reservations

Client reservations allow you to reserve a specific IP address for permanent use by a DHCP client. Typically, reservations are used if the client has an IP address that was assigned by using another method for TCP/IP configuration.

Reservation IP addresses cannot be modified. If you want to change the IP address of a reservation, delete the reservation, and then re-create it with the new IP address.

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

To delete the reservation and then re-create it with the new IP address:

1. At the DHCP server, click Start, point to Administrative Tools, and then click DHCP.
2. In the DHCP console tree, click Reservations.
3. In the details pane, select the reserved client for which you want to change the IP address.
4. To delete the current reservation, on the Action menu, click Delete.
5. Add a new reservation in DHCP that uses the new IP address for the client.

Reconfigure exclusion ranges

To prevent address conflicts, the scopes that you define must exclude the IP addresses of devices that you statically configure, such as DHCP servers. By setting exclusion ranges, an administrator can exclude IP address ranges within a scope so that those addresses are not offered to DHCP clients. When you create a new scope, immediately exclude IP addresses of the existing statically-configured computers. Excluded IP addresses can be active on your network, but only when these IP addresses are manually configured or distributed as reserved IP addresses.

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

To reconfigure exclusion ranges:

1. At the DHCP server, click Start, point to Administrative Tools, and then click DHCP.
2. In the DHCP console tree, expand the scope you want to configure.
3. Select and right-click Address Pool under the appropriate scope.
4. Select New Exclusion Range.
5. In the Add Exclusion dialog box, type the starting and ending IP addresses of the exclusion range, and then click Add.

Verify

To verify that the DHCP server has enough IP addresses available to lease, ensure that Scope in the DHCP console tree displays a green up arrow icon.

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

1. At the DHCP server, click Start, point to Administrative Tools, and then click DHCP.
2. In the DHCP console tree, view the scope icon. It should be a green up arrow.

Related Management Information

DHCP Lease Availability

DHCP Infrastructure