A Windows Vista-based DHCP client does not accept a new IP address until two DHCPOFFER packets are exchanged
In a Worldwide Interoperability for Microwave Access (WiMAX) network, you have a Windows Vista-based Dynamic Host Configuration Protocol (DHCP) client computer. After this client computer receives a DHCPNACK packet, the computer incorrectly rejects the DHCPOFFER packet from the DHCP server. This DHCPOFFER packet contains a new IP address. The client computer does not accept the new IP address until two DHCPOFFER packets are exchanged between the server and the client. This behavior slightly delays the client computer when it obtains a new valid IP address.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB955352.